Harvard Study Finds Long-Term Vitamin E and C Supplementation Is Safe

A recent study found that use of vitamin C and E supplements over a long period of time did not increase the risk of prostate cancer, despite a previous, widely published study’s finding to the contrary. It additionally found that vitamin C may provide some protection against colorectal cancer.

The Harvard researchers used data from the Physicians Health Study II, a randomized trial that included 14,641 US male physicians age 50 and younger. They were given either 400 IU of vitamin E every other day, 500 mg of vitamin C daily, or equivalent placebos. The treatment period lasted from 1997 to 2007 and the follow-up period ended in June 2011.

After analyzing the data, the researchers found that neither vitamin had an effect on prostate cancer, total cancer, or other cancer endpoints. They did find, however, that during the eight year intervention period, vitamin C was associated with a 21% reduction in colorectal cancer. However, this association did not become statistically significant until the 3.8 year follow up period, when the reduction seen reached 46%.

The study was published in the September 2014 issue of The American Journal of Clinical Nutrition.

Vitamin E has eight different forms: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta) and has been shown to help many aspects of the body. Tocopherol is the most common form in both the American diet and European diets. Tocotrienols are less prominent in the Western diet.

Previous studies have shown that vitamin E intake is associated with lower cholesterol, healthier skin, maintaining a proper hormonal balance, and preventing amyotrophic lateral sclerosis (ALS).

Vitamin C is an essential nutrient that has been linked to numerous other health benefits including heart health, brain health, eye health and improved mood. It can be found in high levels in citrus fruits and dark leafy greens such as cantaloupe, oranges, kiwis, and papaya, and in dark leafy greens such as broccoli and kale.