Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury A comparison with the general population

(1)

Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury

- A comparison with the general population

Master Thesis by

Emma Kristine Amory

Department of Nutrition Faculty of Medicine University of Oslo

November 2016

(2)

(3)

Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury

A comparison with the general population

Emma Kristine Amory

Supervisors:

Monica Hauger Carlsen Hanne Bjørg Slettahjel

Vegard Strøm

Master Thesis Department of Nutrition

Faculty of Medicine

UNIVERSITY OF OSLO

November 2016

(4)

2016

Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury

Emma Kristine Amory

http://www.duo.uio.no

Print: Copy Cat, Forskningsparken

(5)

Acknowledgements

The present work was conducted at the Department of Nutrition, Faculty of Medicine, at the University of Oslo and Sunnaas Rehabilitation Hospital, between January 2016 and

December 2016.

I would like to extend my sincere gratitude to my primary supervisors Monica Hauger Carlsen and Hanne Bjørg Slettahjel, for valuable guidance, sharing your knowledge, commitment and encouraging support. I would also like to extend my gratitude to my co- supervisor Vegard Strøm, for taking the time to critically review my work and provide insightful feedback. It has been a privilege to be part of your research group. My sincerest appreciation to all my supervisors for professional guidance, helping me maintain progress and providing valuable encouragement and support.

I would also like to thank the spinal cord injury research group at Sunnaas Rehabilitation Hospital, for valuable insights and feedback.

Thanks to Siv Anita Horn and Toril Johanne Stensrud, for assisting with the patient search in the medical journal records. Also, thanks to the user consultants at Sunnaas Rehabilitation Hospital, for feedback on the food frequency questionnaire.

Lastly, I would like to extend my appreciation to my family, friends and fellow master students, for your support and encouragement.

Oslo, December 2016.

Emma Kristine Amory

(6)

(7)

Abstract

Introduction: A spinal cord injury (SCI) results in loss of or impaired motor and / or sensory function. Consequences of SCI include loss of muscle mass and increased fat mass resulting in reduced basal metabolic rate and energy expenditure. Secondary health complications include cardiovascular disease, diabetes, osteoporosis, pressure ulcers, obstipation and urinary tract infections. A diet low in energy and rich in micronutrients and antioxidants may be beneficial for SCI individuals to prevent secondary complications. As previous studies imply sub-optimal diets in SCI populations, there was a need for exploring the diets of SCI

individuals in Norway in order to identify needs for nutritional guidance.

Aims: The aims of this study were to characterize the diet of the SCI population in Norway, with regards to intakes of foods and beverages, energy, macro- and micronutrients and foods contributing to antioxidant intake. To compare intakes with a reference population, and determine the proportion of the SCI population complying with the dietary guidelines.

Subjects and methods: The study was a cross sectional survey of 96 men and women with SCI, at least two years post injury. Study participants were previous patients at Sunnaas Rehabilitation Hospital. Dietary intakes were assessed using a validated semi-quantitative food frequency questionnaire (FFQ), designed to capture habitual intake over the preceding 12 months, including products known to be important sources of antioxidants. Intakes were compared to the population from the nationwide dietary survey, Norkost 3, the population from the FFQ evaluation study (antioxidant reference population), and the dietary guidelines.

Results: Energy intakes among men with SCI were 15 % less than men of the reference population (p=0.002). There was no difference in energy intakes between women of the two populations. Compared to the reference population, the SCI population consumed more vegetables, fruits, nuts, seeds and olives, as well as alcohol (p<0.001 for all comparisons).

The SCI population complied with the dietary guidelines to a greater extent than the reference population. Intakes of vitamin C and E were significantly higher among the SCI study population (p< 0.001). Insufficient intakes of vitamin D, -A calcium, zinc and selenium were identified in parts of the SCI population, and supplements were used by 81 %.

Antioxidant intakes in the SCI population were not different from the antioxidant reference population (p=0.06), and coffee was the main contributor to antioxidant intakes.

Conclusion: The SCI population consumed high amounts of several foods beneficial in reducing risk of secondary complications. The SCI population was a heterogenous group, which has implications on energy intake. Nutrient density was generally high, although insufficient intakes of several micronutrients were identified.

(8)

(9)

List of abbreviations

ASIA American Spinal Injury Association

AIS American Spinal Injury Association Impairment Scale AHA American Heart Association

BMI Body mass index CVD Cardiovascular disease E % Energy percentage FFM Fat free mass

FM Fat mass

FFQ Food frequency questionnaire FRAP Ferric-reducing ability of plasma

ICD International Statistical Classification of Diseases KBS Kost beregnings system (Nutrient calculation system)

MJ Mega joule

MUFA Monounsaturated fatty acids

NorSCIR Norsk ryggmargskaderegister (Norwegian spinal cord injury register) PAL Physical activity level

PUFA Polyunsaturated fatty acids ROS Reactive oxygen species SCI Spinal cord injury SD Standard deviation UTI Urinary tract infection

(10)

(11)

List of figures and tables

Figure 1 Anatomy of the Spinal Cord.

Figure 2 Flow chart over study design, data collection and data control.

Table 1 Subject characteristics.

Table 2 Food and beverage consumption of the SCI population and Norkost 3 population.

Table 3 Food and beverage consumption of men and women with paraplegia or tetraplegia.

Table 4 Energy intake, absolute macronutrient intakes and percentage of energy from macronutrients, for the SCI and the Norkost 3 populations

Table 5 Energy intake, absolute macronutrient intakes and percentage of energy from macronutrients, for men and women with paraplegia or tetraplegia.

Table 6 Micronutrient intakes for men and women with paraplegia and tetraplegia.

Table 7 Micronutrient density as intakes per 10 MJ per day, for men and women with paraplegia and tetraplegia.

Table 8 Supplement use among SCI men, women and the population total.

Table 9 Micronutrient intakes for men and women of the SCI and the Norkost 3 population.

Table 10 Micronutrient density, per 10 MJ per day, for the SCI and Norkost 3 populations.

(12)

Table 11 Proportions of men and women of the SCI and Norkost 3 populations complying with the quantitative Norwegian dietary guidelines.

Table 12 Proportions of men and women of the SCI and Norkost 3 populations complying with the Norwegian recommendations for percentages of energy from macronutrients.

Table 13 Proportions of men and women of the SCI and Norkost 3 populations with micronutrient intakes at or above recommended levels.

Table 14 Food and beverage contributions to antioxidant intake; percentages of total antioxidant intake.

(13)

List of Appendices

Appendix I Invitation letter and consent form

Appendix II Letter of reminder

Appendix III Food frequency questionnaire (FFQ)

Appendix IV Supplementary results:

Table I: Food and beverage consumption for men and women with complete and incomplete SCI

Table II: Energy and macronutrient intakes for men and women with complete and incomplete SCI

Table III: Micronutrient intakes of men and women with complete and incomplete SCI

Table VI: Micronutrient density as intakes per 10 MJ per day, for men and women with complete and incomplete SCI

(14)

(15)

1 Introduction

1.1 The spinal cord

The spinal cord is a cylindrical collection of nervous tissue situated within the vertebral canal (1). The spinal cord is part of the central nervous system, of which nerves extending from the brain to the various segments of the spinal cord control the voluntary muscles of the limbs, as well as viscera and blood vessels of the thorax, abdomen and pelvis (1). Furthermore, the spinal cord relays sensory information from the various parts of the body to the brain (1).

The spinal cord has a regional segmentation of 31 segments comprising of motor and sensory neurons (1). For each segment, nerve roots emerge from and enter the spinal cord between the vertebrates. There are 8 cervical nerve roots (C1-C8), 12 thoracic (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5) and 1 coccygeal (Co1) (Figure 1). Each nerve root relays sensory information from skin areas, called dermatomes, and signal motor control to a group of muscles, myotomes (2). The autonomic nervous system regulates cardiovascular,

thermoregulatory and splanchnic circulation, which supplies blood to the gastrointestinal tract, pancreas, liver and spleen (3). A spinal cord injury is an injury of the nerves of the spinal cord, which may affect sensory, motor and autonomic signals at the site of the lesion (2).

1.2 Spinal cord injury

Spinal cord injury can arise from trauma to the spinal cord or of non-traumatic causes, such as infections or operations (4). An injury to the neural fibers of the spinal cord causes among other processes; cell necrosis, inflammation and production of free radicals leading to tissue damage (5, 6). Neural cell death and tissue damage disrupts sensory and motor signals to and from the brain, as well as affect autonomic signals (2, 6).

1.2.1 Prevalence and incidence of Spinal cord injury

Due to variations in quantity and quality of data collection on spinal cord injury (SCI) in various countries, the global incidence is unclear (7). Current data suggests an estimated international incidence of 40 to 80 new cases per million population per year, the equivalent

(18)

of between 250 000 to 500 000 spinal cord injuries globally per year (7). The majority of injuries originate from trauma, most commonly caused by traffic injuries, falls, violence and sports. However, more recent data indicate a slight trend towards an increase in the share of non-traumatic SCI.Incidence rates of traumatic SCI are higher among males and most common in young adults (7). Traffic injuries are the leading cause of traumatic injuries, whilst there are indications of a higher incidence of falls among the elderly population.

During 2015, the Norwegian Spinal Cord register (NorSCIR) recorded 122 newly acquired spinal cord injuries in Norway, of which 69.9 % were male and 30.1 % female (4). Based on data from 2011 throughout 2015, traumatic spinal cord injury has a higher occurrence in Norway compared to non-traumatic injuries, at 60.1 % and 39.9 % respectively (4). The majority of spinal cord injured persons in Norway are men, at 70.1 % versus 29.9 % women (4). The most common type of SCI amongst men is traumatic injuries, where causes are mainly due to falls, sports- or transportation injuries, whilst non-traumatic injuries are most common among women (4).

The highest incidence of spinal cord injury in Norway during 2015 was in the age group of 46 to 60 years, accounting for 31 % of registered spinal cord injured persons in Norway (4).

The incidence in the age groups 16 to 30 years and 61 to 75 years was 25 % and 24 % respectively (4). The lowest incidence was in the age group 31 to 45 years (4). In 2014, the highest incidence was registered in the age group 61 to 75 years, with 33.4 % of newly acquired injuries (8). Furthermore, there was a higher incidence in the age group 31 to 45 years (24 %), and only 14 % of newly acquired injuries were in the ages 16 to 30 years of age during 2014 (8).

1.2.2 Categorization of SCI

A spinal cord injury (SCI) can be categorized based on the neurological level injury,

determined by the affected segments of the spinal cord . Furthermore, spinal cord injuries are categorized by the severity of the injury, determined by the degree of implication for sensory and motor function.

Paraplegia and tetraplegia

A spinal cord injury that affects the thoracic, lumbar or sacral segments, is defined as paraplegia (2). Paraplegia refers to impairment or complete loss of motor control of muscles and / or sensory function, or either the one or the other. Arm function will not be affected.

(19)

However, depending on the specific level of the injury, legs, trunk and organs of the pelvis may be affected. Loss of motor- and or sensory function in the spinal cords cervical segments is referred to as tetraplegia (2). A spinal cord injury of the cervical segments leads to

impairment or loss of function of the legs, trunk, organs of the pelvis, as well as the arms.

Incomplete and complete

An incomplete injury is defined as an injury where there is some preservation of motor or sensory function below the level of injury (2). This includes the sacral segments S4-S5. In other words, there is only impaired, and not complete loss function. With a complete injury there is no preservation of motor or sensory control below the site of injury, including the sacral segments (2).

AIS scoring of injury

The American Spinal Injury Association (ASIA) has developed international standards for the neurological and functional classification of spinal cord injury (2). The degree of motor or sensory function preserved or lost creates the basis for classification into 5 categories of the ASIA impairment scale (AIS) based on scores of motor and sensory function (2). The AIS category A indicates a complete injury, where there is no sensory or motor function preserved in the sacral segments (2). In AIS category B, “Sensory incomplete”, motor function is lost below the neurological level of injury, but sensory function is preserved (2). The AIS categories C and D denote two degrees of “Motor incomplete” injuries, where some motor function below the level of injury is preserved to different extents (2). Meanwhile, with an AIS category E, sensory and motor function is normal, and denotes individuals with a SCI with previous impairments, but regained function. Furthermore, incomplete syndromes may have various presentations (2). Conus medullaris syndrome involving the conus medullaris of the lumbar segment, and Cauda equina syndrome involving the cauda equina (lumbosacral segment), may present with flaccid paralysis and areflexic bowel and bladder (2).

(20)

Figure 1: Anatomy of the spinal cord showing the vertebral column, the spinal cord, spinal nerves of the cervical, thoracic, lumbar and sacral segments, as well as gross schematics of main functions of the various spinal segments. (Figure from International perspectives of spinal cord injury (7))

1.3 Physiological consequences and role of nutrition

1.3.1 Altered body composition and reduced metabolic rate

Following spinal cord injury (SCI), loss of innervation of the muscles coupled with any acute stress response of trauma, leads to rapid muscle atrophy (9). Muscle atrophy occurs within few weeks after injury and is known to continue throughout the first year following injury, leading to a significant decrease in muscle mass particularly below the site of injury (9, 10).

Furthermore, hormonal changes regarding reduced growth hormone and insulin like growth factor, as well as changes in the sympathetic nervous system, contribute to the reduction in

(21)

muscle mass (9). As muscles are metabolically active, a significant reduction in muscle mass is accompanied by a reduction in energy expenditure and therefore energy requirements (9).

The basal metabolic rate (BMR) of individuals with SCI can be 14-27 % lower than able- bodied individuals (11).

SCI is found to significantly influence body composition (9). The decrease in fat-free mass (FFM) and subsequently lowered BMR, metabolic and hormonal changes as well as limited physical inactivity is accompanied by an increase in fat-mass (FM) (9). Evidence suggests that two-thirds of individuals with SCI become overweight or obese (9). Bone mass is also reduced in SCI persons mainly due to less mechanostatic stimulation of bone resorption. BMI of individuals with SCI is usually normal despite reduced muscle and bone mass, due to increases in fat mass (9).

1.3.2 Secondary health considerations

Type II diabetes and cardiovascular disease.

Due to reduction in fat free mass (FFM) and physical inactivity, SCI individuals are prone to weight gain (9). Overweight and obesity are risk factors for developing metabolic syndrome, type II diabetes mellitus and cardiovascular disease (CVD) (12). Reduced muscle mass in individuals with SCI reduces the amount of muscle available for glucose uptake, and leads to an increase in blood glucose and circulating insulin (13). Consequently, they are at increased risk of glucose intolerance and insulin resistance compared to able bodied individuals (9).

Furthermore, gene expression in muscle cells involving glucose uptake, glycogen storage, lipid oxidation and energy homeostasis have been found to be down-regulated in individuals with SCI compared to able-bodied controls (14, 15). The physical inactivity, reduction in FFM, and the consequent weight gain and metabolic changes increase the risk of metabolic syndrome, CVD and type II diabetes in individuals with SCI (16). There is an increase in the prevalence of overweight, dyslipidemia, metabolic syndrome, diabetes, and an increased risk of CVD among individuals with SCI (13, 16, 17). Furthermore, dysfunction of the autonomic nervous system following SCI affects cardiovascular regulation of blood pressure, heart rate, thermic regulation, as well as in increased risk of coagulative dysfunction due to physical inactivity, all contributing to an increase in various cardiovascular complications (16). The risk of acquiring cardiovascular disease and the risk of mortality increases with higher neurological levels of injury, completeness of injury and age (16, 17).

(22)

Osteoporosis

There is an increased prevalence of osteoporosis in individuals with SCI (18, 19).

Immobilization and reduced mechanical load results in severe bone loss directly after injury, and a high prevalence of low-impact bone fractures in the chronic stage (18, 19). However, mechanisms causing osteoporosis in individuals with SCI is not fully understood and may be attributable to several factors (20). Hormonal changes in insulin-like growth factor (IGF), testosterone and pituitary hormones may play important roles in the pathogenesis. Increased renal secretion and reduced intestinal absorption of calcium, as well as vitamin D deficiency are also important factors in the development of osteoporosis in individuals with (20). There is evidence that individuals with SCI have a higher prevalence of vitamin D deficiency and insufficiency compared to able-bodied controls (21).

Neurogenic bowel and bladder

Alterations in the autonomic nervous system following spinal cord injury can result in severe neurogenic colorectal and bladder dysfunction (22). Reduced peristalsis can lead to delayed gastric emptying and prolonged colonic transit time (23). Severity of symptoms are related to the severity of the spinal cord injury (24). Obstipation, abdominal discomfort and defecation abnormality are common problems (22, 24, 25). The consequences of neurogenic bowel disorder are found to greatly impact quality of life (24, 26). Normally, dietary fiber can increase bulk and decrease colonic transit time (27). However, dietary fiber does not

necessarily have the same effect on a neurogenic bowel, and should be adjusted individually (28). Fiber along with sufficient water intake, is necessary to increase bulk, as fiber has a water binding capacity (27). However, some individuals with SCI limit water intake in order to avoid the need to frequently empty the bladder (29)(personal communication).

Neurogenic bladder dysfunction is also a result of disturbed autonomic control (30, 31).

Bladder dysfunction can manifest as hyperreflexibility characterized by overactivity of the bladder, which leads to high pressure and the risk of upper urinary tract deterioration as well as urinary incontinence (30, 31). A sacral lesion can lead to areflexic or hyporeflexic bladder with loss of micturition reflex and possible incontinence (30, 31). Common complications of neurogenic bladder dysfunction are urinary tract infections (UTI), bladder and renal stones and upper and lower urinary tract deterioration (30). Also, the risk of developing bladder cancer is 20 times higher in spinal cord injured individuals (30). Among other procedures, management includes self catheterization, which poses an increased risk of UTI´s (30).

Frequency of self-catherization, as well as the effect of fiber in the colon, depends on fluid intake (27, 30).

(23)

Pressure ulcers

Following spinal cord injury, pressure ulcers are a common complication (32). They most commonly occur over the bony prominences of the sacrum, hip, heels and ankles and are classified in different stages of severity (32, 33). Reduced muscle mass around exposed areas, immobility, reduced blood flow and decreased ability to regulate body temperature by

sweating, predisposes to pressure ulcer formation (32). Pressure ulcers can greatly impact quality of life, by being a physical, psychological and social strain on SCI individuals (32).

Reoccurring pressure ulcers are common, where diabetes, cardiovascular disease and smoking have been identified as risk factors of reoccurrence (32). Malnutrition and undernutrition increases the risk of developing pressure ulcers (34). Zinc, vitamin C and copper are necessary for collagen formation, skin integrity and wound healing (35).

Furthermore adequate energy and protein is necessary (35). SCI patients with pressure ulcers have been found to have lower levels of zinc, albumin and pre-albumin than SCI individuals without pressure ulcers (34). Adequate intakes and nutritional support of protein, vitamin C, - E, zinc and selenium are associated with accelerated wound healing and may have a

preventive effect on formation of pressure ulcers (36, 37).

1.3.3 Oxidative stress and antioxidants

Damage to the spinal cord leads to neural cell necrosis, inflammation, lipid peroxidation and production of free radicals or reactive oxygen species (ROS) (6, 38). ROS are a normal part of cell functioning, involved in signalling for cell growth, part of the response to exercise as well as the immune response to disease and injury (6, 39, 40). However, in excess, ROS can lead to oxidative damage of proteins, lipids, DNA and result in oxidative stress (6). To balance out the formation of free radicals, the endogenous antioxidant defence as well as exogenous antioxidants from the diet constitute the antioxidant defence (6). Exogenous antioxidants of the diet are many, where some of the most important include vitamin E, vitamin C, ß-carotene and other carotenoids, and flavonoids (41). Several fruits, berries, vegetables, herbs and spices, nuts, teas, coffee and chocolate are particularly rich in antioxidants (42). Furthermore, copper, zinc and manganese are co-factors for the enzyme superoxide dismutase (SOD), which plays an important role in the endogenous antioxidant defence (41).

(24)

Oxidative stress is associated with the pathogenesis of several diseases, thereof

cardiovascular disease and cancer (6). There is evidence that oxidative stress is involved in promoting muscle atrophy following SCI (40). Furthermore oxidative stress can lead to muscle fatigue, which could compromise rehabilitating exercise (6). Normally there is a balance between oxidative products and the antioxidant defence (6). Meanwhile, individuals with SCI have been found to have higher levels of oxidative stress as well as a reduced antioxidant defence compared to able-bodied individuals, up to one year post injury (43). A study by Bastani et al. found that, 12 months post injury, SCI patients had up to 64 % lower levels of the antioxidants carotenoids and vitamin E in plasma compared to able-bodied, healthy controls (43). Furthermore, vitamin E showed a trend toward decreasing levels during the 12 months post injury (43). A study on individuals with a SCI of at least a two year duration, found that 16 – 37 % of participants had serum levels of vitamin A, C and E below the range of reference (44).

Coffee has been identified as a main contributor of antioxidants in the Norwegian diet, found to explain 54 % of variations in antioxidant intake among 6514 Norwegian women (45).

Fruits and vegetables were the second largest source or antioxidants, explaining 22 % of variations in intake. Other important contributors were tea, red wine, blueberries, walnuts and broccoli (45).

The total antioxidant content of foods and beverages can be measured using the Ferric

reducing ability of plasma (FRAP) assay (42, 46, 47). The FRAP assay measures antioxidants with reduction potentials which are below the reduction potential of Fe³⁺/Fe²⁺, to assess the antioxidant capacity of food (42, 48). However, the bioavailability of the antioxidants consumed are influenced by a number of factors, thus the antioxidant content of food does not directly assess the subsequent antioxidant activity in cells (42).

1.4 Dietary data on people with spinal cord injuries

In preventing and managing many of the risk factors associated with spinal cord injury, diet plays an important role. Despite the importance of diet, there are only a handful of studies that have assessed the diets of spinal cord injured persons. Current knowledge on the diets of SCI individuals implies: a high consumption of fat, saturated fat and simple carbohydrates,

(25)

varying intakes of dietary fiber, low consumption of fruits and vegetables, and insufficient intakes of several vitamins and minerals, especially of vitamins C, -E and -D, calcium, zinc and iron (49-54).

The study by Sabour et al. in 2012, found that, among 162 men and women with spinal cord injury, there was a high intake of fat and simple carbohydrates at the expense of complex carbohydrates, fiber and protein (49). They found a tendency to healthier diets, including higher fiber intakes and decreased intakes of energy, fat, saturated fat and carbohydrates with increasing duration since injury and age. There were no differences between persons with paraplegia compared to tetraplegia in absolute intakes of nutrients (49). Furthermore, there were almost no differences in diet between persons with complete and incomplete injuries, except for significantly lower intakes of monounsaturated fatty acids (MUFA´s) among persons with complete injuries.

A study conducted in Chicago, USA, of 95 men with paraplegia found that despite mean energy intakes equivalent to American recommendations, 56 % of participants were overweight (50). They found that a high percentage of energy intakes came from fat and saturated fat and that salt consumption was high. The participants consumed less fruits, vegetables and dairy products than recommended. Daily recommended intake of vitamin C was not met by 25 % of participants and 43 % consumed less than the adequate daily intake of calcium (50). Persons at risk of having an unhealthy diet had among other factors, a high BMI, lived alone and were smokers.

Approximately 25 years ago, Levine and colleagues conducted a study of 33 people with paraplegia and tetraplegia in Florida Pennsylvania, USA. They found that fat intake

accounted for 37.9 % of energy intake amongst males and 31.5 % of energy intake amongst females (51). Ratios of polyunsaturated fatty acids (PUFA´s) to saturated fat, were far below the American Heart Association's (AHA) recommendations. Consumption of dietary fiber was only 25 % of the AHA daily recommended intake, and carbohydrate consumptions were below the lower end of recommendation (51). Males had intakes of vitamin E, zinc, calcium, magnesium, vitamin A and several b-vitamins that were below the recommended daily allowance (RDA). Females had insufficient intakes of zinc, calcium, iron and magnesium (51).

(26)

Perret and Stoffel-Kurt in Germany conducted a comparison of subjects with spinal cord injuries in the acute and the chronic phase, and found that for subjects in the acute phase, soft drinks accounted for 15.6 % of carbohydrate intake, accompanied by high intakes of

phosphate (52). They also found insufficient intakes of several micronutrients, including vitamins C, E and D, iron and potassium in both the acute and chronic group. Fat

consumption accounted for 36.3 % of energy intake in the chronic group, whilst protein accounted for 16.8 % (52).

Comparing intakes of SCI individuals with participants of the CARDIA study, Lieberman et al. found that fewer SCI participants met the recommended daily servings of fruit, whole grain and dairy (53). Furthermore, SCI individuals consumed less sugar, and intakes of vitamin D and calcium were less in the SCI population (53).

A study conducted on individuals with a spinal cord injury classified as A or B on the ASIA impairment scale; found that intakes of carbohydrate, protein and fat were not different between subjects with paraplegia and tetraplegia (54). However, except for females with paraplegia, fat and carbohydrate intakes were greater than recommended (54).

All these studies suggest that persons with spinal cord injuries have a less than optimal diet, with significant potential for improvement, particularly by increasing fruit and vegetable intake, reducing fat intake and ensuring sufficient intakes of vitamins and minerals.

1.5 Methods to determine dietary intake

Dietary intakes can be measured using various methods (55, 56). The time frame of which the diet reflects can be retrospective or prospective, and the duration of time used to register intake can vary (55, 56). Furthermore, methods can be open or closed, in the sense that food and beverage items can either be fixed or determined by any items used by the participant (55, 56).

Retrospective methods include diet history interview, food frequency questionnaires and 24- hour recalls (55, 56). Using a diet history, the participant is interviewed about their typical diet in a given time period, for example the past week, month or year. As this is an open

(27)

method, details of the diet and eating pattern can be mapped (55, 56). However, this is a time consuming and cognitively challenging method not suitable for large epidemiological studies (55, 56).

A food frequency questionnaire (FFQ) is based on the diet history interview, but is a closed method (55, 56). The FFQ provides a list of food and beverage items with alternatives for the frequency of which the item is consumed per day, week, month or year (55, 56). The

participants are asked to specify how often they consume each item in a given time period.

An FFQ can be non-quantitative, where only frequency of consumption is specified (56). A semi-quantitative FFQ also gathers information on the quantity of food consumed each time as they include alternatives for typical portion sizes, whilst a quantitative FFQ does not provide alternatives for portion sizes, but participants can specify any amount consumed (55, 56). The selection and number of items can vary based on the objective of the study, as well as the duration of time in which the diet is intended to be captured (56). The method can capture habitual intake and seasonal variations in the diet. The FFQ has traditionally been the predominant method used in large population based studies (55, 56). This is because it permits reaching a large number of participants, is cost effective and poses little burden on the participants (55, 56). However, as there is a defined number and selection of food and beverage items in the FFQ, it may fail to capture intakes of various foods and the level of detail is limited (55, 56).

In a 24-hour dietary recall method the participant is interviewed and asked to report all food and beverages consumed during the preceding 24-hours, either face to face with the

interviewer or via telephone (55, 56). The interview is often structured and includes probing questions to ensure a detailed description of intake, food preparation and meal pattern. A series of interviews in various time periods is used in some studies to collect data on the participants´ habitual intakes (55, 56). This is, like the FFQ, used in large studies, but is an open method with a higher level of detail (55, 56). However, it is more time consuming and costly (55, 56).

Retrospective methods rely on the participants’ ability to correctly remember dietary intakes (55, 56). With prospective methods however, participants record intakes at the time of consumption. Diet records or food diaries are prospective methods, which can be open in design, where subjects write down their consumption in booklets, or more closed in design where they fill out diaries with selections of food items or groups and note the amount

(28)

consumed (55, 56). A variation of the method is weighed food records, where subjects weigh and record exact amounts consumed, a detailed but challenging method, mostly used in validation studies (55). Diaries or records pose a higher burden for participants, and their prospective nature can induce changes in behaviour and intake (55, 56).

1.6 Norwegian dietary recommendations

The National Nutrition Council has developed dietary guidelines for the Norwegian

population, with the intent to promote public health and prevent non-communicable diseases, released by the Directorate of Health in 2011 (57). The guidelines are developed using a defined methodology for a systematic literature review of research on food and beverages, as well as nutrient based research (57). The dietary guidelines comprise of both qualitative and quantitative guidelines and are based on an overall assessment of food and nutrient research, Norwegian food traditions, transitions in the Norwegian diet, as well as the Norwegian nutrition recommendations (57).

The Norwegian nutrition recommendations of 2014 derive from the Nordic Nutrition Recommendations of 2012 (58, 59). The Norwegian nutrition recommendations include recommendations on the composition of the diet, energy- and nutrient intakes as well as physical activity (58). These recommendations are intended to cover the primary needs of nutrients to ensure growth and development, promote public health, and prevent the occurrence of nutrition-related and non-communicable diseases (58).

Both the Dietary Guidelines and the Norwegian nutrition recommendations are intended for the general population (57, 58). For parts of the population with specific considerations, the guidelines and recommendations need to be adjusted to suit specific needs (58). There are guidelines developed by various international councils taking into account a wide range of diseases or health considerations, utilized by dieticians and health personnel. However, there are no guidelines available for individuals with spinal cord injury, taking into account their specific health considerations. As persons with SCI are at increased risk of acquiring various non-communicable diseases, when taking into account physiological consequences of SCI, dietary guidelines and nutrient recommendations may need to be adjusted to their impaired function and secondary health considerations.

(29)

1.7 Indications for the present study

SCI may lead to severe disability and several complications, and rehabilitation can be

extensive (60). Prevention and treatment of common complications should include preventing loss of muscle strength, conservation of bone density, ensuring a functional digestive system, preventing pressure ulcers, UTI’s, cardiovascular disease and diabetes, as well as increasing overall quality of life (60). To achieve optimal rehabilitation, an interdisciplinary approach is essential, including among others, psychologists, physiotherapists, occupational therapists, social workers and dieticians (60).

The increased risk of overweight, obesity, CVD and type II diabetes sets requirements for a diet among SCI individuals which balances energy intake to the reduced energy needs compared to able-bodied persons, a favourable fat intake and limited sugar consumption.

Furthermore, the increased oxidative stress observed in the year post injury, risk of pressure ulcers and UTIs may cause for a greater need of certain micronutrients in SCI individuals.

Especially of antioxidants, vitamin C, -E, and -D, zinc, calcium, as well as adequate protein intake may be beneficial for SCI individuals. Furthermore, increased osteoporotic risk requires sufficient vitamin D and calcium. It seems a diet low in energy and rich in micronutrients for SCI individuals is in order to prevent secondary complications of SCI.

Such a diet is obtained by a plant-based diet low in energy-, fat- and sugar-dense foods, with sufficient protein and favourable fat intake. Furthermore, adhering to Norwegian guidelines on dietary and nutrient intakes would be beneficial for preventing non-communicable diseases, of which SCI individuals are at increased risk.

As previous dietary studies on SCI individuals imply suboptimal diets, there is an interest of exploring the diets of SCI individuals in Norway to identify needs for nutritional guidance in this population. This is the first study conducted in Norway exploring the dietary intakes of individuals with a spinal cord injury.

(30)

2 Aims for this master thesis

The main aims for this master thesis were the following:

 To characterize the diet in a population of persons with chronic spinal cord injury in Norway, (the SCI population), with regards to the intakes of

o Foods and beverages

o Energy, macro- and micronutrients

o Foods and beverages contributing to antioxidant intake

 To compare the diet and nutrient intakes of the SCI population to a reference population

 To determine the proportion of the SCI population that comply with the quantitative Norwegian dietary guidelines

(31)

3 Subjects and methods

3.1 Study design

The present study was a cross sectional survey with the objective of investigating the habitual diet of persons living with a spinal cord injury in the chronic phase, with emphasis on the consumption of antioxidant rich foods. Dietary intake was measured using a semi-

quantitative food frequency questionnaire. Subject recruitment and data collection was conducted between April 2016 and June 2016.

The study was based on collaboration between the Department of Nutrition, Faculty of Medicine at the University of Oslo, Norway, and the Spinal Cord Research Department at Sunnaas Rehabilitation Hospital, South- Eastern Norway Regional Health Authority, Oslo.

3.1.1 Ethics

The study was approved by the Data Protection Official for Research, in accordance with the Personal Data Act and the Personal Health Data Filing System Act (2016/1255). A written informed consent form was obtained from participants upon enrolment. In the event that the participant was unable to sign the consent form, a proxy consent was obtained from the participant's representative. Participation was voluntary and subjects were informed of their right to withdraw their consent at any time during the study, without specifying their reason for withdrawal.

Each participant was randomly allocated an identification number, used on data collected from the food frequency questionnaire. The coding list containing names and their respective identification numbers was securely stored at the Spinal Cord Research Department at Sunnaas Rehabilitation Hospital, accessible to study personnel only.

(32)

3.2 Study population

Subjects were previous patients at Sunnaas Rehabilitation Hospital, over the age of 18, living with a spinal cord injury in the chronic phase. A search in the electronic medical journal records at Sunnaas Rehabilitation Hospital was carried out the 23^rd of February 2016, based on inclusion criteria. The inclusion criteria comprised of having a spinal cord injury, either tetraplegia or paraplegia, complete or incomplete and included AIS-scores A through E. The injury would have to had to occurred at least two years prior to enrolment, and subjects had to be at least 18 years of age. Furthermore, in an effort to ensure a certain level of proficiency in the Norwegian language for correct completion of the food frequency questionnaire, being born within Scandinavia was a criterion for inclusion. Exclusion criteria involved persons without a spinal cord injury, persons who had emigrated from the country and those without a registered home address.

The search in the electronic journal records was based on ICD-10 diagnostic codes. Codes used in this study were G28 Paraplegia and tetraplegia, G82.0 Non-spastic paraplegia, G82.1 Spastic paraplegia, G82.2 Unspecified paraplegia, G82.3 Non-spastic tetraplegia, G82.4 Spastic tetraplegia and G.82.5 Unspecified tetraplegia. Further search specifications were, hospital admission between year 2000 and year 2013, including specification of admission date, birthdate in 1997 or earlier, and information on the type of injury. Duplicates and registered deceased persons were removed.

From the journal search, 1610 persons met the inclusion criteria (Figure 2 a). Thereof, 121 persons were registered as deceased in the journal records. A random sample of 562 persons, from the remaining 1489 persons, was extracted with use of a random sample generator in Microsoft Excel 2010. The sample was reviewed in the National Registry to ensure exclusion of any additional deceased persons, as well as persons who otherwise had criteria for

exclusion (Figure 2 a). A total of 400 persons were invited to participate. Each participant was randomly allocated an identification number used on all data collected.

(33)

a b

Figure 2a and b: Flow chart over study design, data collection and data control.

Medical journal search:

Eligible subjects by inclusion criteria n=1610

Review of subjects in the Population Registry

n= 562

Excluded (n= 162):

-Deceased (n= 105) -Emigrated (n= 13)

-Country of birth outside of Scandinavia (n= 34) -No address (n= 6)

-No information found (n= 4) Invited subjects

n=400 Invitation letter

Consent form

Food Frequency questionnaire Letter of reminder

Registered as deceased in journal database

n= 121

Response n=106

Included subjects N= 96

Excluded due to non-SCI diagnosis (n=3)

Subjects meeting inclusion criteria n=103

Insufficient data (n=17) Excluded due to insufficient dietary data

(n=7)

Completed FFQ (n=10) Dietary data control

Random sample n=1489

Re-contact (n=11)

(34)

3.3 Data collection

Dietary data was collected using a semi-quantitative food frequency questionnaire (FFQ).

The FFQ was posted to participants along with the invitation letter, a consent form ass well as a postage paid envelope for returning their responses by mail (Figure 2 a) (Appendix I). They were instructed to return the completed questionnaire with the consent form in order to participate. Instructions on how to complete the FFQ and correctly check the boxes were incorporated as the first page of the FFQ, including an example and how to handle a

misregistration. Subjects were informed that they might be contacted by telephone following enrolment to clarify their answers in the FFQ if necessary. A reminder was sent to those who had not responded four weeks after the initial invitation letter (Appendix II).

3.4 Data collection instrument

3.4.1 The semi-quantitative Food Frequency Questionnaire (FFQ)

The semi-quantitative food frequency questionnaire (FFQ) was designed to capture the participants´ habitual diet over the preceding 12 months, covering the total energy intake of the diet (Appendix III). The FFQ included food products known to be important sources of antioxidants in the Norwegian population, based on a screening of the antioxidant content of 3100 food and beverages using measured as the ferric-reducing ability of plasma (FRAP) assay (42, 45).

The FFQ was developed at the Department of Nutrition, part of the Faculty of Medicine at the University of Oslo. The FFQ was validated on a population in the Oslo area in 2007, using weighed diet records as well as the activity meter ActiReg® (61-63). The original FFQ covering 14 pages, included 270 food items and 19 supplements, and has been updated and revised as part of this study. The revised FFQ consists of 16 pages containing questions about the intake of 284 food- and beverage items and 20 dietary supplements.

The FFQ included four open-ended questions where participants could specify any additional spices and herbs or supplements included in their diet that were not specified in the FFQ.

Two questions allowed participants to list other food- or beverage products in their diet that were not included in the questionnaire, and voice other comments they might have had.

Similar food items were sorted according to food groups and meal patterns common to the

(35)

Norwegian diet. Options for frequency of consumption of a particular item included “never, never/seldom, times per day, times per week or times per month”. Portion sizes were

specified in various household units: glasses, cups, decilitres, tablespoons, teaspoons, slices or pieces, according to the type of food or beverage described.

Dietary questions within the FFQ totalled 13 pages, in addition to a page on dietary supplements and the remaining two pages were dedicated to additional questions, such as anthropometry, tobacco use, illnesses and medications as well as various questions specific to the subjects´ spinal cord injury which were included as part of this study (cf. Additional questions in the FFQ).

3.4.2 Revisions of the FFQ

Dietary data

The FFQ was updated and revised to better reflect newer food products as well as current availability in the market. A total of 16 food and beverage products were removed and 30 were added to the questionnaire. Items removed included items from dairy products, juices and squashes, teas, coffee and spices. Basis for the removal of products was primarily their lack of availability in the market place. However, some items were also removed due to their lack of usefulness, as discovered from the validation study of 2007 (64). This was mostly applicable for questions regarding spices and herbs (64).

Items were added to the FFQ in the effort to provide options according to market availability and assumed dietary habits of the study population in question based on diet counselling at Sunnaas hospital (personal communication). Of items added to the questionnaire, 30 items were added under the categories: cheeses, dairy- and dairy replacement products, fruit- and vegetable juices, smoothies, iced tea- and coffees, dinner dishes, fruit, vegetables, spices and herbs. Furthermore, six cereal and yoghurt items were merged into three questions.

The units in which beverage portion sizes were described, were updated to resemble more modern glass- and cup sizes as well as take into account variations in cup sizes amongst the general population (65). One glass of water, juice, squash or a cup of coffee was described as the equivalent to 2 dl, one cup of lattè or cappuccino equalled 3 dl and a cup of tea 2,5 dl.

The item “espresso” was accompanied by capsule coffee in the revised version, and the unit was consequently changed to equal 0,3 dl, the standard volume of an espresso (65).

(36)

Questions on supplements were also revised. Vitamin D, calcium and magnesium were added to the list of vitamin- and mineral supplements. Some antioxidant supplements were

originally listed by the various brand names. However, the revised FFQ includes antioxidant supplements listed by their generic names. Supplements added to the questionnaire were assumed to be commonly consumed by the Norwegian population and the SCI population (66, 67), (personal communication).

Additional questions in the FFQ

The FFQ was also updated and revised to better fit the subject group with regard to background questions. Some questions were removed as they were not applicable for this study population, and additional questions relevant to the subjects´ spinal cord injury were included as part of this study.

The two pages of the FFQ dedicated to questions regarding anthropometry, tobacco use, illnesses and medications, were part of the unrevised version. As part of the anthropometry section, subjects were asked to specify any amputations to enable correct calculations of their body mass index and when the registered weight was measured. Questions regarding the classification of the subjects´ spinal cord injury, including when the injury occurred, were added to the questionnaire. Furthermore, questions dedicated to mapping the occurrence and duration of pressure ulcers were added to the questionnaire. Osteoporosis, depression and anxiety were incorporated into the list of diagnoses within the illnesses section, as well as a question on current medications. A question dedicated to surveying living situations was also included in the questionnaire. Questions regarding physical activity were removed and the section on tobacco use was shortened to only entail current use.

As a result of pilot feedback obtained from user consultants at Sunnaas Rehabilitation Hospital, the checking-boxes were enlarged and more spaciously distributed in an effort to accommodate participants with impaired motor function in the upper extremities.

(37)

3.5 Populations of reference

Data from two study populations were used as reference for the dietary data in this study. The population from the nationwide dietary survey of 2010-2011, Norkost 3, conducted by the Directorate of Health, the Norwegian Food Safety Authority and the University of Oslo, was used as a reference population for intakes of food and nutrients (68). The study population consisted of 862 men and 925 women between the ages 18 and 70 years. Dietary data was collected using two 24-hour recalls by telephone, four weeks apart. The dietary data from this population was used as a reference to the habitual dietary and nutrient intake of the general population.

The second population of reference was from the FFQ validation study in 2007, where data was collected using the FFQ as applied in the present study, pre-revisions (61, 62). The study population consisted of 232 men and women over 18 years of age from the Oslo area. Data from this study was used as a reference to the intake of foods and beverages rich in

antioxidants and total antioxidant capacity.

3.6 Data processing

Returned food frequency questionnaires were assessed in regards to completeness prior to further processing (c.f 3.6.1 Missing values). As the FFQ was optically readable,

questionnaires were scanned into the Cardiff TeleForm® software, version 10.5.1. The software proofreads the answers in the FFQ pending approval by the handler. An additional proofreading was performed by the handler to ensure correct registration of answers and impute according to the study's protocol for missing values (c.f 3.6.2 Imputation and 3.6.3 Double registrations). The data was automatically transferred into the IBM SPSS® Statistics software version 22, where each registration for frequency and portion size was represented by a letter. The SPSS® data file was subsequently processed using a syntax file to produce the correct data files for import of data into the KBS software system. The KBS software system, (Kost Beregnings System) version 7.3, 2016 is a food and nutrient calculation system developed at the Department of Nutrition, University of Oslo, Norway (69). Estimations of food and nutrient intakes were carried out in the KBS program from the AE-14 database, which automatically produces excel files with the chosen intake calculations. Further analysis

(38)

of data was carried out in Microsoft Excel 2010 and the statistical software IBM SPSS®

version 22.

3.6.1 Missing values

The returned food frequency questionnaires were assessed regarding completeness prior to further processing. Questionnaires, in which 50 % of food and beverage items or more were left unanswered, were considered incomplete and excluded from the dataset (70-72). When omitted answers were randomly distributed throughout the questionnaire, and totalled less than 50 % of all items, omitted items were assumed to be rarely consumed or not at all (70- 72). In this case, the questionnaires were considered complete and were included in the dataset following imputation according to the study's protocol for missing values. In the event that missing values totalled more than 50 % or were deemed a substantial amount, or when a whole food group or page was omitted whilst the remainder of the questionnaire was

satisfactorily completed, the participants were contacted by telephone in order to complete the questionnaire. Some participants were also contacted to clarify various answers subject to confusion. Where contact could not be obtained, and the questionnaire remained incomplete, the questionnaire was excluded.

3.6.2 Imputation

When neither frequency nor portion size for an item were answered, the item was registered as not consumed. In cases where the frequency of consumption of an item was omitted, but the portion size was answered, the item received the smallest frequency option.In the event that the frequency of intake was answered, but the portion size was omitted, the smallest portion size option was imputed (72, 73).

3.6.3 Double registrations

In cases where an item had been answered twice for frequency or portion size, the mean option of the two registrations was chosen. In the event that the mean fell between two

frequency or portion size alternatives, the lesser option was imputed. The smallest option was also chosen when double registrations were adjacent.

(39)

3.6.4 Processing data from reference populations

Data from the reference populations were accessed through the food and nutrient calculation system (KBS). As the youngest participant in the present study was 21 years of age, only data from the reference populations´ participants 21 years of age or older were included for

analysis.Data from the nationwide dietary survey, Norkost 3 was originally processed in the N3 database in KBS. Calculation of data from Norkost 3 for the purpose of this study was also carried out in the N3 database. Data from the FFQ validation study was calculated in the AE-07 database, as originally utilized for this dataset. Further analysis of data were, as for the present study data, carried out in Microsoft Excel and the statistical software SPSS®.

3.7 Calculations of dietary intake

The KBS software system estimates dietary intake of participants based on nutrient values of food and beverages from the Norwegian food composition table (69). The selection of calculations from KBS utilized were food and nutrient intakes as grams, milligrams or micrograms per person per day, the percentage of energy intake from macronutrients per person per day and various food and beverages contributions to antioxidant intake.

Supplements

The nutritional contents of cod liver oil and omega 3 fatty acid supplementation registered in the FFQ were computable in estimations of nutrient intakes of the population. Other

supplements listed in the FFQ were not computable, as they were not optically readable from the FFQ when scanned into the Cardiff Teleform software.

3.8 Statistical analysis

Sample size calculation was based on the mathematical formula by Cole, TJ (1997) with a confidence level of 95 % and a margin of error of 5 % (74). Based on this formula, 21 subjects per group were necessary to find a 20 % difference in energy intake (MJ/day), as energy needs are suggested to be 14 to 27 % less in SCI individuals than able-bodied (11).

Dietary data did not show a normal distribution. Thus, results are presented as medians with 25 and 75 percentiles. Differences in food and nutrient intakes were analysed using Mann-

(40)

Whitney U tests. Differences in the distribution of usage of supplements, and compliance with the quantitative dietary guidelines and nutrient recommendations, were investigated using Chi-square test of independence and Fisher´s exact test. Results were considered to be statistically significant at p < 0.05. All data was analysed using IBM SPSS® statistical software version 22.

3.9 My contributions to the study

My work on this project commenced in December 2015, with a review of the study protocol under finalization. As of January my work included revising the FFQ, including editing of the FFQ in the Cardiff TeleForm® software. Also, recruitment of participants in terms of setting specifications for the medical journal record search criteria, in cooperation with employees at Sunnaas Rehabilitation hospital. This included checking each subject against the National registry according to inclusion criteria and extracting address information, writing the invitation letter, following up with reminders, preparations in terms of posting as well as sending out to invitees. Further work involved assessment of returned FFQ´s, including dietary data control, contacting the necessary participants via telephone for clarification of answers, scanning and proof-reading the FFQ´s in the Cardiff TeleForm® software. Finally, data analysis in the KBS software system and the statistical software IBM SPSS®.

(41)

4 Results

4.1 Response

A total of 400 persons were invited, where 106 responded to the invitation and filled out the questionnaire, giving a response rate of 26.5 %.Three respondents were excluded from the dataset due to non-SCI diagnosis (Figure 2 b). Out of the returned questionnaires, 18 were insufficiently completed. Two questionnaires had more than 50 % of the items missing, and four had one or more whole sections missing or substantial numbers of missing portion sizes, and were directly excluded. For the remaining eleven incomplete questionnaires, the

respective participants were contacted by telephone to complete the questionnaire or clarify responses (Figure 2 b). As a result, 10 questionnaires were completed and included in the dataset, leaving a total of seven responses excluded due to insufficient dietary data (Figure 2 b). The final dataset consisted of 96 participants, 24 % of invited subjects.

4.2 Subject characteristics

The subjects´ characteristics are presented in Table 1. There were 64 males and 32 females in the study population. The participants’ age ranged between 21 and 86 years, and the

population of men were older than the women (p=0.05) (Table 1). The median time since injury for the participants was 14.5 years, and average body mass index was 25.0 kg/m2. The vast majority of participants reported they did not use tobacco, and the most common living arrangement was living with family.

The majority of the study population had paraplegia, with an even distribution between men and women (Table 1). The populations´ spinal cord injuries (SCI) were mostly incomplete.

There were fewer complete SCI relative to incomplete SCI amongst females compared to males (p=0.05). Among subjects with paraplegia, 45 % had a complete SCI and 53.3 % had incomplete injuries, there were information on completeness of injury was missing for one participant. Whereas only 27.8 % of subjects with tetraplegia had a complete SCI, 72.2 % had incomplete injuries. There were no significant differences in the distribution of gender, age, duration since injury or body mass index between participants with paraplegia and

tetraplegia.

Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury A comparison with the general population

Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury

- A comparison with the general population

Master Thesis by

Emma Kristine Amory

Department of Nutrition Faculty of Medicine University of Oslo

November 2016

Dietary, nutrient and antioxidant intakes in individuals with chronic spinal cord injury

A comparison with the general population

Emma Kristine Amory

Supervisors:

Monica Hauger Carlsen Hanne Bjørg Slettahjel

Vegard Strøm

Master Thesis Department of Nutrition

Faculty of Medicine

UNIVERSITY OF OSLO

Acknowledgements

Abstract

List of abbreviations

List of figures and tables

List of Appendices

Table of contents

1 Introduction

1.1 The spinal cord

1.2 Spinal cord injury

1.2.1 Prevalence and incidence of Spinal cord injury

1.2.2 Categorization of SCI

1.3 Physiological consequences and role of nutrition

1.3.1 Altered body composition and reduced metabolic rate

1.3.2 Secondary health considerations

1.3.3 Oxidative stress and antioxidants

1.4 Dietary data on people with spinal cord injuries

1.5 Methods to determine dietary intake

1.6 Norwegian dietary recommendations

1.7 Indications for the present study

2 Aims for this master thesis

3 Subjects and methods

3.1 Study design

3.1.1 Ethics

3.2 Study population

3.3 Data collection

3.4 Data collection instrument

3.4.1 The semi-quantitative Food Frequency Questionnaire (FFQ)

3.4.2 Revisions of the FFQ

3.5 Populations of reference

3.6 Data processing

3.6.1 Missing values

3.6.2 Imputation

3.6.3 Double registrations

3.6.4 Processing data from reference populations

3.7 Calculations of dietary intake

3.8 Statistical analysis

3.9 My contributions to the study

4 Results

4.1 Response

4.2 Subject characteristics