Although B vitamins are water soluble and don't stay long in your body, large doses of certain B vitamins can cause serious toxicity, as summarized below. The same is true of vitamin C
, the other water soluble vitamin.
Unfortunately, there is no requirement for supplement labels to warn of these toxicities. As we have shown in our B Vitamin Supplements Review
, many vitamins and energy drinks exceed the established Upper Tolerable Intake Levels (which vary by age) for B vitamins. If you have an established deficiency, high doses may be necessary; otherwise, remember that "more" does not necessarily mean "better."
Toxicities from B Vitamins
||Skin flushing/pain; liver toxicity; elevated blood sugar
||Nerve damage, skin lesions
|B-9 (Folate/Folic Acid)
||Kidney damage; masking of B-12 deficiency
||Acne/rosacea a side effect in some people
More information about the beneficial and toxic effects of these vitamins, including associated dosage, is found in the B Vitamin Supplements Review