What If You Take Too Much Vitamin B12?

It is important to maintain normative dosages of the 13 essential nutrients daily. Often, ingesting disproportionate amounts of any given vitamin or mineral can result in deficiencies in other nutrients and other health complications. Moreover, ingesting excessive amounts of a nutrient can result in toxicity. Excess vitamin B12 consumption could suggest a nutritional disproportion; however, the vitamin, which is prevalent in meat and dairy, is nontoxic. This renders overdose on the vitamin impossible.

Water-Solublility

In addition to being nontoxic, vitamin B12 is water-soluble. This means the body can relieve excess vitamin B12 through the renal system to prevent buildup. This also usually means that the vitamin requires relatively large doses per day to maintain adequate levels. However, because the body is capable of storing several years' supply of the nutrient, regimented consumption of the vitamin is unnecessary.

Bodily Storage

The body can store up to 6.3 years' worth of vitamin B12, according to a study in "The American Journal for Clinical Nutrition." Therefore, it is easy to maintain adequate levels of vitamin B12. This, in addition to its prevalence among common foods, is why deficiencies in the nutrient is rare. It also means that excess buildup due to kidney malfunction or renal failure is inconsequential.

Normative Consumption

For perspective, the National Institutes of Health's Office of Dietary Supplements indicates that a single serving of braised beef liver contains 48 mcg of vitamin B12, while breakfast cereals fortified with the vitamin contain 6 mcg. However, that same source states that adolescents above 14 and adults require 2.4 mcg per day, pregnant women require 2.6 mcg and lactating women require 2.8 mcg. Accordingly, it is common to consume much greater amounts than necessary.

Benefits

Vitamin B12, or cobalamin, is an essential daily nutrient the body uses for the growth and function of blood cells, the brain, the nervous system and other areas of the body. In addition to animal-derived foods such as fish and poultry, chemists can synthesize vitamin B12 in a laboratory. Uses for synthetic vitamin B12 include treating vitamin B12 deficiency, memory loss, mood retrogrades, concentration, immunity, pernicious anemia and age-related macular degeneration.

There is a long list of health complications and disorders for which some use vitamin B12 supplementation or treatments, but there is insufficient scientific evidence that these treatments can produce any benefit. This list includes Alzheimer's disease, shaky-leg syndrome, allergies, some cancers, eczema, chronic fatigue syndrome, diabetes, heart disease, memory loss, high cholesterol and multiple sclerosis. Treatments for skin ailments such as eczema often include the topical application of the vitamin. Some health clinics administer vitamin B12 intravenously to assist with weight loss, but there is no medical support for this practice, either. However, despite dosage or time frame of such treatments, all of them remain safe, as vitamin B12 is nontoxic.

Possible Side Effects

Side effects may occur after ingesting normal amounts of vitamin B12. These effects happen only in some people, but they range from mild to serious, including allergic reactions, blood clots, itching and diarrhea. For those who experience these effects, vitamin B12 dosage may not be a simple matter of amount. Correcting this problem may require medicines, herbal supplements, vitamin regimens and periodic vitamin B12 shots to bolster the body's stores.