Vitamin C and risk of death from stroke and coronary heart disease in cohort of elderly people.

Abstract

Objectives--To determine whether vitamin C status, as measured by dietary intake and plasma ascorbic acid concentration, is related to mortality from stroke and coronary heart disease in people aged 65 and over.

Design--A 20 year follow up study of a cohort of randomly selected elderly people living in the community who had taken part in the 1973-4 Department of Health and Social Security nutritional survey and for whom dietary and other data had been recorded.

Setting--Eight areas in Britain (five in England, two in Scotland, and one in Wales).

Subjects--730 men and women who had completed a seven day dietary record and who had no history or symptoms of stroke, cerebral arteriosclerosis, or coronary heart disease when examined by a geriatrician in 1973-4.

Results--Mortality from stroke was highest in those with the lowest vitamin C status. Those in the highest third of the distribution of vitamin C intake had a relative risk of 0.5 (95% confidence interval 0.3 to 0.8) compared with those in the lowest third, after adjustment for age, sex, and established cardiovascular risk factors. The relation between vitamin C intake and stroke was independent of social class and other dietary variables. A similar gradient in risk was present for plasma ascorbic acid concentrations. No association was found between vitamin C status and risk of death from coronary heart disease.

Conclusion--In elderly people vitamin C concentration, whether measured by dietary intake or plasma concentration of ascorbic acid, is strongly related to subsequent risk of death from stroke but not from coronary heart disease.

Introduction

Antioxidant vitamins may be important in protecting low density lipoproteins from oxidation by free radicals.(1)(2) Because oxidative modification of low density lipoproteins may enhance their atherogenic potential,(3) dietary antioxidants have a potential role in the prevention of cardiovascular disease. The most important dietary antioxidant in terms of intake is vitamin C, and evidence from ecological studies links low intake of this vitamin with increased rates of cardiovascular disease. In Britain, for example, rates of stroke and coronary heart disease are highest in regions where consumption of fruit and vegetables is lowest.(4)(5)

During 1973-4 the Department of Health and Social Security surveyed random samples of people aged 65 and over living in eight areas of Britain (five in England, two in Scotland, and one in Wales) to assess the nutritional state of the elderly population. The areas were chosen so that the socioeconomic characteristics of the study sample were representative of non-institutionalised elderly people in Britain. We examined the association between vitamin C status, as measured by either dietary intake or plasma ascorbic acid concentration, and mortality from stroke and coronary heart disease in a 20 year follow up study of this national sample.

Subjects and methods

During 1973 and 1974, 1775 people were randomly sampled in eight areas of the country from family practitioner committee lists …