" 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. This includes damage to our skin's connective tissue, the induction
of DNA lesions known to promote the development of skin cancer and aging,
and the impairment of mitochondria functioning resulting in cell death.
High doses of riboflavin have also been shown to induce damage to retina cells
in the eyes of research animals.
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
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. "
Photoreceptor damage following exposure to excess riboflavin.
" Photoexcitation of RF may potentially occur in vitro and in vivo in the organs and
tissues that are permeable to light, such as the eye or skin, and damage HA and
other cell-matrix components causing inflammation and accelerating aging. "
But then :
" Under these conditions, riboflavin increased the life span of the flies exposed to
constant light by as much as 25%. We conclude that riboflavin confers some degree
of protection against the effects of constant light exposure. "