Are there any side effects for Vitamin B?

There are side effects to almost any vitamin if you ingest too much, but there are also side effects if you get too little. Side effects from high levels of B-vitamin, well above the RDA are very rare when taken orally. This is due to the fact that they are water soluble, which allows you to excrete excess amounts through urine. The B vitamins include: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (Pantothenic acid), B6 (pyridoxamine), folic acid (B9) and cobalamin (B12). Validated adverse reactions to B vitamins are generally confined to vitamins B3 (niacin), B6 and injections of B1 (thiamine), although rare.  These side effects can range from drops in blood pressure, disruption in nerve transmissions to rashes and skin flushing. In order to avoid side effects of B vitamins, make sure you stay within established safe/necessary ranges (see below) - especially when taking vitamins B3 and B6. The goal is to make sure you get proper daily amounts of the necessary B vitamins unless advised otherwise by a qualified physician. This goal is accomplished by taking a daily multivitamin and mineral formula that contains the necessary B vitamins shown below.

• B1: 2-30mg/day

• B2: 5-30mg/day

• B3 (Niacinamide): 30-50mg/day

• B6: 6-50mg/day

• Folic acid: 400-900mcg/day

• B12: 6-50mcg

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John
Dec 02, 2012, 06:20 AM
Thanks is very informative! Also I was wondering about niacin in real food. Today I consumed 55mg of niacin from my diet alone; not including the multivitamin. How harmful can this be? Am I okay to stretch this barrier? I just need to reduce my serving size of chicken is all.
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dotFIT Staff
Nov 20, 2012, 10:21 PM
There is no worry with Niacinamide at the levels in any of our multivitamin and mineral formulas (MVM) no matter what kind of diet you consume. Although the upper limit is set a 35mgs, that's truly only to safeguard for other forms of niacin that can cause harmless skin flushing. Niacinamide (nicotinamide) cannot produce these effects. In fact doses of Niacinamide used to lower cholesterol are commonly 200-250mgs daily with no side effects. Additionally 35mgs is the recommendation for pregnant or breast feeding adults.

Also see the Q&A from our Fitness Vault:
What is the difference between vitamin B3 and other B vitamins? http://www.dotfit.com/content-5751.html

What is the maximum dosage of B vitamins?
http://www.dotfit.com/content-35903.html


More info:
Niacinamide (also known as Nicotinamide) does not have the same pharmacological or toxicity effects as niacin (nicotinic acid) which is why the Lowest Observed Adverse Effect Level (LOAEL) is set at 1000mgs. Niacinamide does not have the vasodilator, gastrointestinal, hepatic, or hypolipidemeic effects of nicotinic acid. Nicotinamide does not produce the skin flushing, itching, or burning as when large doses of nicotinic acid are used. High-doses of nicotinamide are considered 3gms/day and at this level should be considered a drug and used under a doctor's supervision. Overall, however, it rarely causes side effects, and is considered generally safe as a food additive, and as a component in cosmetics and medication.
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John
Nov 20, 2012, 06:27 AM
According to the DRI the tolerable upper intake level of niacin b3 is 35mg and the dotfit mutivitamin I bought has like 75% of niacin daily value. Its going to be tough to budget less niacin since I need plenty of carbohydrates and niacin is found in like all grains!
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