What Happens If You Take Too Much Vitamin B12?

Vitamin B12 is a water-soluble vitamin that is crucial in human body for various functions. It plays a vital role in cell growth and reproduction, protein and tissue synthesis and blood formation. The human body does not produce it, so it has to be absorbed from foods and supplements. Although the human body requires small amount of vitamin B12 for its normal and adequate functioning. Mostly individuals above the age of 50 and those who consume vegetarian diet are deficient in this vitamin. Generally, a healthy diet rich in meat, fish and dairy products provide a natural source of vitamin B12 required for the body, but it may be deficient in vegetarians and vegans.

What Happens If You Take Too Much Vitamin B12?

Daily Requirement of Vitamin B12

The daily requirement of vitamin B12 varies according to age and is same for both genders, but it increases in pregnant and breastfeeding women, being 2.6 mcg and 2.8 mcg respectively. Infants (up to the age of 6 months) require 0.4 mcg, babies (from 6 to 12 months) require 0.5 mcg, children (between the age of 1 to 3 years) require 0.9 mcg, children of 4 to 8 years of age require 1.2 mcg, children of 9 to 13 years of age require 1.8 mcg and individuals above 14 years of age require 2.4 mcg.

Symptoms of Vitamin B12 Deficiency

Vitamin B12 deficiency can affect nervous system, gastrointestinal system, cardiovascular system as well as bone health. The deficiency symptoms include weakness, numbness, tingling, dizziness, memory loss, depression, balance problems, confusion, dementia, fatigue, palpitations, tachycardia, shortness of breath, nausea, lack of appetite, weight loss, diarrhea, constipation, soreness and redness in tongue with loss of papillae, difficulty walking, muscle weakness, irritability, and/or vision loss.

What Happens If You Take Too Much Vitamin B12?

Although, vitamin requirement in the body is sufficed with foods rich in animal sources including meat, fish, poultry and milk and other dairy products. However, strict vegetarians, adults and people with certain medical conditions require supplements in vitamin B12 deficiency. Most of the vitamins when taken in excess can cause toxicity in the body, but not vitamin B12 as it is a water-soluble vitamin. Body uses the amount that is required and excretes the rest of it; however, vitamin supplements in the form of injections and nasal gels and sprays when taken in excess can cause some side effects, which include the following.

Dermatological Effects: If too much vitamin B12 is used in the form of nasal gel or spray or is injected then there might be certain dermatological side effects. These include mild to severe acne on face including folliculitis. It is also associated with severe flare-ups of rosacea, as well as mild symptoms of rash in the body with or without pruritis (itchiness).

Cardiovascular Effects: The side effects of vitamin B12 injection include congestive heart failure, peripheral vascular thrombosis (clot formation in a peripheral blood vessel), or pulmonary edema. The symptoms of these conditions include shortness of breath, pain, and numbness in the extremities.

Other side effects of taking too much vitamin B12 include headache, dizziness, diarrhea, indigestion, nausea, vomiting, back pain, joint pain, swelling, anxiety, nervousness and lack of coordination.

There is also risk of contamination with the supplement of this vitamin. The additives that may be found in it are iodine and sorbitol, which some people may have a reaction to. Iodine could cause upset stomach, burning sensation in the mouth while sorbitol could cause allergic reactions, dry mouth and blood in stools.

Hence, vitamin B12 supplements should always be taken after consultation and prescription from a health care professional. Since there is no upper tolerable limit of this vitamin established as of yet, it is difficult to determine how much is too much for the body to process. Supplementation of 2000 mcg per day for up to 2.5 years has been considered safe for individuals deficient in vitamin B12, but it is always important to consult with a doctor prior to starting the treatment.

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Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:November 29, 2023

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