Vitamin C, an Antioxidant that May Enhance Immunity and Reduce Depression

Vitamin C is an essential vitamin, meaning that it cannot be produced by the body and must be obtained via certain foods (such as citrus fruits) or supplementation. It is a popular safe dietary supplement with antioxidant or pro-properties, depending on the body’s requirements.

Why Might Vitamin C Be Beneficial?

As we age, our cells become less adept at removing reactive oxygen species that are produced by the cell’s metabolism. These reactive oxygen species can damage cell components and ultimately accelerate the ageing process. As an antioxidant, vitamin C may protect against the onset of chronic diseases by protecting cells against oxidative stress.

Vitamin C is also often supplemented to ward off the common cold, but only appears to be effective in doing so in those who are more susceptible to colds, such as athletes. However, vitamin C supplementaion does appear to be effective in reducing the duration of colds.

It also appears to have neuroprotective and antidepressant effects, and may reduce blood sugar.

What Is The Evidence Behind Vitamin C Supplementation?

There is evidence that vitamin C can reduce biomarkers of oxidation, although this evidence is somewhat mixed, and the effect may not be particularly strong, with some studies finding no significant benefits.

Evidence for vitamin C conferring protection against the common cold is more convincing. A meta analysis of 29 studies concluded that while vitamin C does not reduce the incidence of colds in the normal population, it does reduce the duration of illness by up to 14%. It has been suggested that vitamin C could protect against COVID-19, but there is currently no evidence to support this claim.

The exact mechanism by which vitamin C reduces depression is unknown, but it ultimately appears to act by blocking potassium channels, as do most antidepressants. However, more research is needed to investigate the antidepressant effects of vitamin C in humans. A small trial with 30 participants suggested that serum vitamin C was significantly lower in depressed patients. A randomised and double blind placebo-controlled trial found that 3000mg/day of vitamin C reduced depression scores. However, a longer trial reported that adding vitamin C to the antidepressant citalopram had no significant effect on depressive symptoms.

Vitamin C supplementation may therefore be beneficial due to its antioxidant properties and its potential neuroprotective and antidiabetic effects, but more human research is needed to confirm some of these benefits. Nevertheless, supplementation of less than 2000mg a day is unlikely to be harmful and likely to be beneficial, though it may interact with some common drugs such as warfarin.