Association of plasma vitamin C concentration to total and cause-specific mortality: A 16-year prospective study in China

Plasma vitamin C and total mortality have shown an inverse relationship in cohort studies in the United States and Western Europe. In economically developing areas (where vitamin C deficiency is a larger problem), studies are lacking.

Methods

To assess whether plasma vitamin C influences total mortality in low-income regions, researchers evaluated data from the General Nutrition Intervention Trial (NIT) cohort in Linxian China.

Nearly 30,000 participants (aged 40-69 years) enrolled in the NIT study in 1986. In 1999-2000, most of the living participants provided fasting blood samples. Participants were observed until 2016. Vital statuses and causes of death were documented. The current study relied on data from 948 randomly selected individuals who provided blood samples in 1999-2000.

Vitamin C is an essential nutrient that must be obtained from the diet as it cannot be synthesized by humans.

Results

Over 16.4 years of follow-up, there were 551 deaths out of 948 subjects. People with the highest plasma vitamin C quartile concentrations had a 25% lower risk of total death than those with the lowest quartile. When compared with people with low vitamin C (≤ 28 micromol/L), people with normal vitamin C levels had a 23% lower risk of death overall and a 38% lower risk of death from heart disease. When vitamin C was analyzed as a continuous variable, each 20 micromol/L increase in vitamin C concentration reduced the risk of total death by 10% and the risk of heart disease by 17%.

Conclusions

Vitamin C is an essential nutrient that cannot be synthesized by humans. It is required for collagen synthesis, neurotransmitter production, and as a scavenger of free radicals. This study adds new evidence that higher plasma vitamin C levels are associated with lower total mortality in economically developing areas.

Wang, S.M., Fan, J.H., Taylor, P.R., Lam, T.K., Dawsey, S.M., Qiao, Y, & Abnet, C.C. (2018). Association of plasma vitamin C concentration to total and cause-specific mortality: A 16-year prospective study in China. Journal of Epidemiology and Community Health, 72(12), 1076-1082.