Age and Ageing (1979), 8, 177

VITAMIN C, HIGH DENSITY LIPOPROTEINS AND HEART DISEASE IN ELDERLY SUBJECTS C. J. BATES 1 , M. K. BURR 2 AND A. S. S T LEGER 2 1 M.R.C. Dunn Nutrition Unit, Milton Road, Cambridge *M.R.C. Epidemiology Unit (S. Wales), 4 Richmond Road, Cardiff

Summary

INTRODUCTION

A link between vitamin C status and cholesterol metabolism is supported by many experimental and epidemiological studies (see reviews by Krumdieck & Butterworth 1974, Ginter 1978, Turley et al. 1978, Hughes 1976) but its relevance to atherogenesis, and the relations between vitamin C and plasma cholesterol levels in man, is still obscure. Recently, considerable interest has been directed towards the high density lipoprotein (HDL) fraction of plasma cholesterol, as a potent indicator and predictor of cardiovascular disease in man (Miller et al. 1977, Gordon et al. 1977), low levels being associated with high risk. Vitamin C status is known to affect various aspects of liver function (Degkwitz & Staudinger 1974, Zannoni & Sato 1975, Street & Chadwick 1975, Ginter 1978) and could thus be important in controlling the turnover of specific lipoproteins (Nikkila 1978). In a pilot study (Bates et al. 1977) a positive inter-subject correlation was observed between HDL cholesterol and plasma or buffy-coat vitamin C in a small group of elderly men; the women did not, apparently, show this relationship. The present study is an investigation of a larger group of elderly people living at home. Subjects and Methods The population studied comprised all persons aged 70 years and over who were registered with general practitioners and living in a South Wales town. Residents of old people's homes and longstay wards were excluded from the survey. A 10% random sample was taken from the list of the local practitioners; the subjects selected were visited, the object of the study was explained and their consent requested. Those who had an acute illness when first contacted were seen on their 15

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Plasma vitamin C, total and high density lipoprotein (HDL) cholesterol and cortisol levels were measured in a random sample of 337 elderly subjects living at home in S. Wales; measurements of relative body weight and information about fruit intake, smoking habits and symptoms of cardiovascular disease were also collected. There was a sex difference, over all age groups, in plasma vitamin C and in total HDL cholesterol levels. Plasma vitamin C was strongly correlated with fruit intake in both sexes. Both HDL cholesterol and low and very low density lipoprotein (LDL + VLDL) cholesterol levels tended to increase with increasing plasma vitamin C but this reached significance only-for the LDL + VLDL fraction. In addition, HDL cholesterol was negatively correlated with Quetelet's index in the women. Symptoms and medication for heart disease did not correlate significantly with plasma vitamin C or with HDL cholesterol levels, but reported angina showed a weak positive association with total cholesterol in the men, and there was some evidence of increased cortisol levels in subjects with heart disease.

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recovery or else counted as refusals. Height and weight were measured; smoking habits, usual fruit intake and consumption of vitamin supplements were determined by questionnaire, and heart disease was recognized by reported symptoms (angina) or by regularly prescribed medication (glyceryl trinitrate, Sustac, Trasicor, digitalis or digoxin). Samples of venous blood were collected in heparin, were centrifuged within 2 h, and part of the plasma was mixed immediately with metaphosphoric acid (final concentration 2% w/v) and later with ethanol (final concentration 33% v/v) for plasma vitamin C assay (Pelletier 1968, Bates 1977). Losses of vitamin C were less than 4% during 1—4 weeks storage at — 25 °C. Total and high density lipoprotein cholesterol levels were measured by the enzymic assay of ROschlau et al. (1974), with a Boehringer Mannheim kit, before and after precipitation of low and very low density lipoproteins (LDL + VLDL) with heparin and manganous chloride (Burstein et al. 1970). No interference was observed by moderate amounts of added ascorbic acid in the present study (cf. Pesce & Bodourian 1977). Plasma cortisol was measured by a minor modification of the method of Murphey (1967).

The sample comprised 123 men and 273 women, and blood was obtained from 109 men and 228 women, giving response rates of 86.6% and 83.5% respectively. The mean age of the men was 76.0 years and that of the women was 77.0 years. The distributions of plasma vitamin C, total cholesterol and HDL cholesterol levels were positively skewed; this was especially marked for plasma vitamin C, for which geometric means are therefore reported, but for other variables the departure from Gaussian distribution was smaller, and arithmetic means were considered appropriate (Table I). There was a consistent sex difference, over all age groups, in plasma vitamin C, in total plasma cholesterol and in HDL cholesterol: the two latter being significant at the 1 % level overall (Student's t test). Plasma vitamin C tended to decline with age, significantly for the women (P< 0.05). Total cholesterol also declined with age in the women, but HDL cholesterol did not change with age in either sex and was not significantly related to smoking habit. Log (HDL cholesterol) was inversely correlated with log [(LDL + VLDL) cholesterol]: significantly for the women (P

Vitamin C, high density lipoproteins and heart disease in elderly subjects.

Age and Ageing (1979), 8, 177 VITAMIN C, HIGH DENSITY LIPOPROTEINS AND HEART DISEASE IN ELDERLY SUBJECTS C. J. BATES 1 , M. K. BURR 2 AND A. S. S T L...
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