Excess Vitamin B2 – Riboflavin Can Be Toxic!

In fact, the naturally occurring riboflavin found in our skin and eyes has been implicated to play a pivotal role in many of the damaging effects of UV light exposure ⁶. This includes damage to our skin’s connective tissue ⁷, the induction of DNA lesions known to promote the development of skin cancer and aging ^{8 9}, and the impairment of mitochondria functioning resulting in cell death ^{10 11}. High doses of riboflavin have also been shown to induce damage to retina cells in the eyes of research animals ¹².

Surprisingly, while the combination of riboflavin and light has been studied because of its adverse effects on cells grown in culture and exposed to light—and riboflavin and light have been used as a model for inducing things as diverse as liver dysfunction, cataracts and mutations—the nutrition industry has failed to heed the warning that damage may be caused by high doses of riboflavin supplements.

This is partly due to confusion because a diet deficient in riboflavin is a risk factor for things like cataracts, while at the same time, the combination of riboflavin and light is often used by scientists to cause cataracts in animal research. As always, the dose makes the poison, and this means that if you take nutritional supplements you should make sure you consume an adequate amount of riboflavin daily, rather than an excess of riboflavin.

The human requirement for riboflavin is less than 2 milligrams a day, but many common vitamin supplements contain 10s or 100s of milligrams. There is little (if any) scientific justification for taking supplements of riboflavin greatly in excess of the known dietary requirement. However, there is a lot of scientific evidence and speculation that the combination of abnormally high blood, eye and skin levels of riboflavin, combined with a lifetime of sun exposure, may have serious negative consequences, and actually cause the damage we are trying to prevent. The combination of sunlight and abnormally high tissue levels of riboflavin from excess supplementation is a toxic combination that should be avoided.

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