The effect of ascorbic acid on the seasonal variations in serum cholesterol levels

One gram of ascorbic acid (Vitamin C) administered randomly to a group of healthy young people (aged 29 +/- 5 years) produced a significant mean fall in serum cholesterol of 16 per cent within two months. A similar supplement to a group of healthy older people (aged 58 +/- 3 years) produced a significant mean fall in serum cholesterol of 14 per cent but required six to 12 months' administration. Serial observations on a mixed age group of healthy people (aged 38 +/- 12 years) over one calendar year revealed a seasonal fluctuation in serum cholesterol, the lowest levels being in summer (June 5.5 +/- 0.7 mmols/l) and the highest levels in winter (January 6.4 +/- 0.8 mmols/l), a significant rise of 16 per cent. These changes showed an inverse relationship with the leucocyte and serum ascorbic acid levels which also revealed a seasonal fluctuation, the months April/September being higher than the months October/March. The administration of 1g of ascorbic acid per day throughout the year abolished the winter rise in serum cholesterol levels. These results are discussed in the light of the relationship between cholesterol and vascular disease and the observations by Sir Richard Doll that lowering the cholesterol level, whether achieved by drugs or diet, results in a reduction in morbidity from myocardial infarction.