Genetic variations may affect vitamin C absorption

A variation in the gene responsible for intestinal vitamin C uptake may increase the risk of an insufficient supply, says a new UK study.

In the study, blood samples obtained from 3,425 women were analyzed to assess the relationship between genetic variations of a vitamin C transporter and circulating concentrations of vitamin C (1). The researchers identified a variation in the gene encoding for a protein involved in intestinal vitamin C uptake which was associated with a reduction in circulating concentrations of L-ascorbic acid (vitamin C). This finding was confirmed then in an analysis of a further 15,000 men and women. The relationship was not affected by any other factors studied, such as cigarette smoking, which has long been known to lower circulating vitamin C concentrations.

The researchers concluded that their findings may have important implications when considering the relationships between vitamin C intake, circulating vitamin C concentrations, and health. Specifically, the identified genetic variant could be used to determine the causal effect of lifetime variation in vitamin C concentrations on disease risk. Many studies suggest that individuals with low vitamin C status are more likely to develop a variety of illnesses such as atherosclerosis, type 2 diabetes, and certain cancers.

Experts suggest that these findings need to be considered in future studies and that they shed important light on previous research reporting on inconsistent relationships between vitamin C intake or status and disease risk (2).

1. Timpson N. J. et al. Genetic variation at the SLC23A1 locus is associated with circulating concentrations of L-ascorbic acid (vitamin C): evidence from 5 independent studies with > 15,000 participants. American Journal of Clinical Nutrition. 2010; 92:375–82.
2. Michels A. J. et al. A new twist on an old vitamin: human polymorphisms in the gene encoding the sodium-dependent vitamin C transporter 1. American Journal of Clinical Nutrition. 2010; 92:271–2.