What You Should Know Before  Taking Vitamin B12 Supplements

Although there is no tolerable upper limit established to Vitamin B12 supplementation, there are some risks associated with taking excessive levels of the nutrient. People who ingested vitamin B6 and B12 multivitamins noticed acne on their face and arms following excessive supplementation. Rosacea, a reddening of the face and a flushed appearance have also been reported. These side effects were more common in women. There is also an association between large amounts of vitamin B12 and blood clotting too rapidly.

Vitamin B12 warnings are most often associated with supplementing with a vitamin B12 injection. The B12 shot carries risks that are common to any type of injection, including redness, itching, pain and swelling at the injection site. There also is a risk of an allergic reaction to either the man made form of vitamin B12, cobalamin, or to inactive ingredients in the shot. If swelling of the face or hands occurs following an injection of vitamin B12 people are advised to call a doctor immediately.

Vitamin B12 also blocks absorption of cimetidine, a stomach acid reducing drug also known as Tagamet. Use of stomach acid reducing drugs blocks absorption of vitamin B12 so the relationship between these two factors is not clear. Many people have signs of B12 deficiency and should supplement the nutrient due to the use of acid reducing drugs, dietary or genetic factors.

Vitamin B12 is produced from a type of yeast that ferments naturally inside the liver. It is found in food including calves liver, shellfish, seafood, and beef. B12 is also found in brewer’s yeast and certain types of sea vegetables. Vitamin B12 warnings from the diet are mostly those that one would find from excessive consumption of meats including constipation, weight gain and lethargy.

In rare cases megadoses of B12 can speed up the production of cancer cells. This is much rarer than not having enough of the nutrient in the bloodstream due to anti cancer drugs but should be noted. Because vitamin B12 aids in the production of red blood cells, an excessive amount could in certain circumstances cause the cancer cells to multiply rapidly.

People with a hereditary eye condition known as Leber’s disease should not supplement vitamin B12 due to the risk of nerve damage to the eye. Additional vitamin B12 warnings are that it can contribute to hyperthyroidism or polycythemia vera, the formation of too many red blood cells. Excessive amounts of vitamin B12 may also exacerbate mitral valve prolapse, a heart condition, or cause heart palpitations or nervousness.

Vitamin B12 is generally considered safe with no upper dosage limit in healthy individuals. Many more people have difficulty due to vitamin B12 deficiency than due to excessive intake of the nutrient.

It is best to keep vitamin B12 warnings in mind and to talk to a doctor before beginning any supplementation plan. A blood test can be performed to check levels of vitamin B12 in the body and to make an informed choice regarding any type of supplementation that may be needed.