Caroline Bolton-Smith

Accuracy of the estimated prevalence of obesity from self reported height and weight in an adult Scottish population

STUDY OBJECTIVE To determine whether self reported heights and weights from Scottish adults can provide an accurate assessment of obesity prevalence in the population. DESIGN Standardised clinic measurements of weight and height were compared against self reported values on a postal questionnaire in the fourth Scottish MONICA cross sectional study. SETTING A sex and five year age band stratified random population sample drawn from general practitioner registers in north Glasgow in 1995. Response rate 63% for men and 62% for women. PARTICIPANTS A total of 865 men and 971 women aged between 25 and 64 years. RESULTS Men and women under-reported their weight by a mean (SD) of 0.63 (3.45) kg and 0.95 (2.64) kg respectively, and their height by a mean (SD) of 1.3 (2.50) cm and 1.7 (2.37) cm respectively. Estimated body mass index, BMI (kg/m2) varied from true (measured) BMI by +0.19 (1.40) for men and by +0.17 (1.34) for women. The only age/sex group in which BMI was under-estimated from self reports (mean 0.2) was the 55–64 year old women. Prediction equations that explained 90% (men) and 88% (women) of the difference between self reported and measured height included age and self reported weight. The equivalent prediction equations for weight explained 93% of the difference between self reported and measured weight for men and included smoking and diabetic status, while for women 96% of the variance was explained with no further variables being significant. Sensitivity and specificity for determining clinical obesity (BMI⩾30) were 83% and 96% respectively for men, and 89% and 97% for women. CONCLUSIONS This Scottish population was unique in the under-reporting of height as well as weight, which resulted in BMI estimates with low error. These data suggest that self reported weights and heights would be satisfactory for the monitoring of obesity prevalence in Scotland.

Antioxidant vitamin intakes assessed using a food-frequency questionnaire: correlation with biochemical status in smokers and non-smokers

The increasing interest in the possible role of antioxidant vitamins in many disease states means that methods of assessing vitamin intakes which are suitable for large-scale investigations are now required. The suitability of the food-frequency questionnaire, which was developed by the Medical Research Council - Cardiff Group, for determining dietary intake of antioxidant vitamins in epidemiological studies was investigated in 196 Scottish men. The validity of the dietary data was assessed by comparison with serum vitamin concentrations, and separate analyses were performed for current smokers and non-smokers. The results showed that total energy intake and the percentage of energy derived from sugar were higher in smokers, and that both dietary and serum values of vitamin C, beta-carotene and vitamin E were lower in smokers than non-smokers. After adjustment for serum lipids, energy intake and body mass index, correlation coefficients between dietary and serum vitamins C and E were similar for smokers (r 0.555 and 0.25 respectively) and non-smokers (r 0.58 and 0.32 respectively). Correlation between dietary and serum carotenes was reduced from 0.28 in non-smokers to 0.09 in smokers and correlations for retinol and total vitamin A were weakly significant only for non-smokers. The food-frequency questionnaire assigned greater than 70% of subjects correctly into the upper or lower plus adjacent tertiles of serum vitamin values, with the exception of beta-carotene and total vitamin A for smokers. Thus, the food-frequency questionnaire appeared to be an adequate tool for assigning individuals into tertiles of serum antioxidant vitamins with the main exception of beta-carotene for smokers. Marked differences do occur between the vitamins and between the smoking groups which may reflect reduced accuracy of reporting on the food-frequency questionnaire or differential absorption and metabolism of the vitamins.

Nutrient intakes of different social-class groups : results from the Scottish Heart Health Study (SHHS)

Food frequency questionnaire and socio-demographic data were collected from over 10,000 Scottish men and women aged 40-59 years in a cross-sectional study of coronary heart disease (CHD) risk factors. Dietary intake, including the antioxidant vitamins C and E and beta-carotene, was assessed for different socio-economic groups. Trends in nutrient intakes were found with social-class (occupational) groups I-V. The non-manual-manual distinctions were clear even after standardizing for serum cotinine, and alternative classification by housing tenure and level of education did not confound the social-class effect. Total energy intake was significantly higher in the manual (men 10,363 KJ, women 7507 KJ) than in the non-manual (men 9156 KJ, women 7169 KJ) groups, and all nutrient amounts except for vitamin C, vitamin E, beta-carotene and fibre were significantly higher in the manual than the non-manual groups. Alcohol intake was lower in manual women, but higher in manual men compared with their respective non-manual groups. Sex and social-class differences were maintained after adjusting for total energy. Women in general, and manual women in particular, had the highest percentage energy from total fat (40.2) and saturated fat (18.2), while the percentage energy from polyunsaturated fat was lower in men than women, and lowest in manual men (4.4). The polyunsaturated:saturated fat (P:S) ratios were, for non-manual and manual men 0.32 and 0.31, and for non-manual and manual women 0.31 and 0.28. Fibre and antioxidant vitamin intakes, when expressed as nutrient densities, were lower in men than women, and lowest in manual men. Overall, men and women in manual occupations had a poorer-quality diet than did those in non-manual occupations. The coincident low P:S ratios and low antioxidant vitamin intakes in manual groups may contribute to an increased risk of CHD. Thus, the findings are compatible with the view that poor diet may be a contributory factor to the higher mortality rates for CHD which occur in the lower socio-economic groups.

Two-year randomized controlled trial of vitamin K1 (phylloquinone) and vitamin D3 plus calcium on the bone health of older women.

Dietary supplementation with vitamin K1, with vitamin D3 and calcium or their combination, was examined in healthy older women during a 2‐year, double‐blind, placebo‐controlled trial. Combined vitamin K with vitamin D plus calcium was associated with a modest but significant increase in BMC at the ultradistal radius but not at other sites in the hip or radius.

Compilation of a provisional UK database for the phylloquinone (vitamin K1) content of foods.

This paper reports the compilation of a food composition database for phylloquinone (vitamin K1) derived from the direct analysis of foods, recipe calculation and the assignment of values based on food similarities. All the basic and other food items used in these calculations had been analysed by HPLC and about 170 of the items had been obtained and assayed in the UK. Recipe calculations took account of the cooking method and changes in water and fat content. Currently, approximately 1501 food items with Royal Society of Chemistry/Ministry of Agriculture, Fisheries and Food food codes have been allocated a vitamin K1 value, and a further 282 new recipe codes are included in the database. Representative values from each food group are reported together with an indication of the potential variation. Detailed examples of some recipe calculations are included, and also the impact of changing the type of fat in recipes. Vitamin K1 is associated with, and most abundant in, photosynthetic tissues of plants. Accordingly, the highest concentrations (3000-6000 micrograms/kg) are found in dark-green leafy vegetables and herbs, such as kale, parsley, spinach and green cabbage. Intermediate concentrations (1000-2000 micrograms/kg) are found in plants with paler leaves such as white cabbage and lettuce or in green, non-leafy vegetables such as broccoli and brussel sprouts. Fats and oils contain variable amounts of vitamin K1 with the highest concentrations (300-1300 micrograms/kg) in soyabean, rapeseed and olive oils and the margarines based on them. Other foods such as dairy products, meat dishes and cereal-based foods (bread, biscuits, cakes, desserts etc.), although not in themselves particularly rich in vitamin K1 (< 200 micrograms/kg), may contribute significantly to intakes when consumption of green vegetables is poor. Within the scope of this present study, it has not been possible to address issues such as inter-sample variability, losses during storage or the bioavailability from different foods and further work on these aspects is needed.

The effects of dietary fatty acid supplementation on endothelial function and vascular tone in healthy subjects.

OBJECTIVE Evaluation of the effects of supplementation of n-3 and n-6 fatty acids on vascular tone and endothelial function in healthy men and women aged 40 to 65 years. METHODS In a double-blind, randomised, placebo controlled study, 173 healthy volunteers took one of six oil supplements for 8 months. Supplements were placebo, oleic acid rich sunflower oil, evening primrose oil, soya bean oil, tuna fish oil, and tuna/evening primrose oil mix. Endothelium-dependent and independent vascular responses were measured in the forearm skin using laser Doppler imaging following iontophoretic applications of acetylcholine and sodium nitroprusside, respectively. RESULTS Acetylcholine, but not sodium nitroprusside responses were significantly improved after tuna oil supplementation (P=0.02). Additionally, there were significant positive correlations between acetylcholine responses and n-3 fatty acid levels in the plasma and erythrocyte membrane phospholipids after tuna oil supplementation. No significant changes in vascular response were seen after supplementation with any of the other oils. CONCLUSIONS Fish oil supplementation has a beneficial effect on endothelial function, even in normal healthy subjects. Modification of the diet by an increase of 6% in eicosapentaenoic acid and 27% in docosahexaenoic acid (equivalent to eating oily fish 2-3 times/week) might have significant beneficial effects on cardiovascular function and health.

Evidence for age-related differences in the fatty acid composition of human adipose tissue, independent of diet

Objective: To test the null-hypothesis that no age difference in adipose tissue fatty acid composition exists independent of dietary fat intake. Design: A cross-sectional survey of coronary heart disease risk factors, the Scottish Heart Health Study, provided needle biopsy adipose tissue fatty acid data and food frequency-derived dietary data. Setting: Twenty-two Scottish Districts between 1984 and 1986. Subjects: A total of 10 359 men and women aged 40–59 y were randomly recruited in sex and five-year age bands from GP lists. A sub-set of 2308 men and 2049 women (42%) provided satisfactory adipose tissue and dietary data. Main outcome measures: Multiple regression analysis (adjusting for dietary fats, body mass index and smoking, with and without menopause status for women) of the relationship between individual fatty acids in adipose tissue and age, and between age and the ratio of linoleic acid (C18:2, n-6) to gamma-linolenic acid (C18:3, n-6) as an indicator of δ-6 desaturase activity. Results: Sex-consistent changes with age occurred for linoleate (adjusted regression slope±s.e. for men −0.299±0.1339 and for women −0.504±0.1731) and gamma-linolenate (adjusted regression slope±s.e. for men −0.141±0.0341 and for women −0.154±0.0469) both P<0.0001. These changes gave rise to a significant increase (P≤0.005) in the C18:2, n-6 to C18:3, n-6 ratio with age. Dihomo-gamma-linolenic acid (C20:3, n-6) and docosahexa- plus docosapentaenoic acids (C22:5+C22:6, n-3) also increased significantly with age (P≤0.01). For the latter, the adjusted regression slopes were far greater for women (0.596±0.0575) than men (0.131±0.0417). Conclusions: The results show that ageing does influence adipose tissue fatty acid composition independent of diet. The sex differences may partially be due to inadequate adjustment for changes in sex hormone status in males with ageing. Using the current indicator, a decline in the rate limiting step of delta-6 desaturation appeared to occur with age, and was greater in women than in men. These results may indicate that an increase in dietary gamma-linolenic acid (C18:3, n-6) is necessary with age to offset the relative imbalance between PUFA levels which appears to occur. However, any direct health benefit regarding the common diseases of ageing from such a strategy still remain to be clarified. Sponsorship: The Scottish Office Home and Health Department funded the Scottish Heart Health Study. CBS thanks Scotia Pharmaceuticals Limited for financial support.

Coffee and tea consumption and the prevalence of coronary heart disease in men and women: results from the Scottish Heart Health Study.

STUDY OBJECTIVES--The aim was to determine if there was a relationship between coffee or tea consumption and the prevalence of coronary heart disease in Scotland. DESIGN--The relationship between self reported coffee and tea consumption and the prevalence of coronary heart disease (history, symptoms, or electrocardiographic evidence) was investigated using multiple logistic regression analysis in the Scottish Heart Health Study (SHHS), a cross sectional study. SETTING--Twenty two Scottish districts were surveyed for the SHHS between 1984 and 1986. SUBJECTS--A total of 10,359 men and women aged 40-59 years were studied. MEASUREMENTS AND MAIN RESULTS--Of the 9740 subjects who were assigned a category, 21.8% (2122) were classified as having indications of coronary heart disease. Men and women were combined in the odds ratio analysis because they showed almost identical patterns in the prevalence of coronary heart disease across the coffee and tea quarters (grouped according to consumption). Those who did not drink coffee had a significantly higher (p < 0.05) prevalence of coronary heart disease than the three groups for coffee drinkers. Adjustments for risk factors including cigarette smoking, total blood cholesterol, and diastolic blood pressure did not remove the significance of the odds ratios. There was a positive dose-response effect between tea consumption and coronary heart disease which was removed after adjustment for various risk factors. CONCLUSIONS--These findings do not support a positive relationship between coffee or tea consumption and coronary heart disease in this British study where most coffee consumed is instant coffee.

Plasma vitamin C and food choice in the third Glasgow MONICA population survey

STUDY OBJECTIVE To determine the contribution of different foods to the estimated intakes of vitamin C among those differing in plasma vitamin C levels, and thereby inform dietary strategies for correcting possible deficiency. DESIGN Cross sectional random population survey. SETTING North Glasgow, Scotland, 1992. PARTICIPANTS 632 men and 635 women, aged 25 to 74 years, not taking vitamin supplements, who participated in the third MONICA study (population survey monitoring trends and determinants of cardiovascular disease). MEASUREMENTS AND MAIN RESULTS Dietary and sociodemographic information was collected using a food frequency and lifestyle questionnaire. Plasma vitamin C was measured in non-fasted venous blood samples and subjects categorised by cut points of 11.4 and 22.7 μmol/l as being of low, marginal or optimal vitamin C status. Food sources of dietary vitamin C were identified for subjects in these categories. Plasma vitamin C concentrations were compared among groups classified according to intake of key foods. More men (26%) than women (14%) were in the low category for vitamin C status; as were a higher percentage of smokers and of those in the older age groups. Intake of vitamin C from potatoes and chips (fried potatoes) was uniform across categories; while the determinants of optimal versus low status were the intakes of citrus fruit, non-citrus fruit and fruit juice. Optimal status was achieved by a combined frequency of fruit, vegetables and/or fruit juice of three times a day or more except in older male smokers where a frequency greater than this was required even to reach a marginal plasma vitamin C level. CONCLUSION Fruit, vegetables and/or fruit juice three or more times a day increases plasma vitamin C concentrations above the threshold for risk of deficiency.

Childhood obesity and socioeconomic status: a novel role for height growth limitation.

OBJECTIVE:To assess prevalence and socioeconomic context of overweight and obesity in a cohort of Scottish children.DESIGN:Cross-sectional study.SETTING:Primary schools in Dundee, Angus, and Fife, Eastern Scotland, UK.PARTICIPANTS:A total of 1240 boys and 1214 girls aged between 4–10 y.MAIN OUTCOME MEASURE:Weight, height and body mass index (weight/height2).RESULTS:Overall overweight or obesity prevalence was 24.6%, while prevalence of obesity alone was 6.1%. Individuals from schools with a high level of low-income families were 65% more likely to be overweight as judged by BMI. However, these children weighed the same as more affluent children of the same age, but were 1.26 cm shorter.CONCLUSION:These data confirm the continued increase in childhood obesity in the UK and reveal a role for height-growth limitation in the absence of overall growth restriction, among children from low-income groups. This observation raises important questions regarding socioeconomic environmental factors in promoting the currently increasing levels of obesity.