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Question:
I thought the B vitamins were all water soluble and did not build up in the body, so you would not build up toxic levels. Am I wrong?

Answer:
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
B-3 (Niacin) Skin flushing/pain; liver toxicity; elevated blood sugar
B-6 Nerve damage, skin lesions
B-9 (Folate/Folic Acid) Kidney damage; masking of B-12 deficiency
B-12 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.

Also see related CL Answers:
I have been having neurological symptoms, and a blood test showed I have toxic levels of vitamin B-6. My multivitamin contains 75 mg of B-6, but this is below the upper limit of 100 mg per day. Could my vitamin contain more than it lists? >>

Can taking too much vitamin B-6 be dangerous? The label on my multivitamin states it contains 2000% the Daily Value! >>

Can taking too much vitamin B-12 be dangerous? The label on my B-complex states it contains 50,000% the Daily Value! >>

The maker of my multivitamin says it doesn't include folic acid because too much from supplements can be harmful. Is that true? >>

Is it possible to take too much vitamin C? >>


See other recent and popular questions >>
Comments
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Janice8014   October 18, 2015
there is something odd about B6- I know of several people who have had blood tests that showed elevated levels of B6- tested because of peripheral neuropathy symptoms- and were not taking any or lower dose B supplements. have others heard of this?

Stan13877   March 29, 2017
Natural food sources?

Marysue6882   July 23, 2015
What about the use of B 50 along with Biotin and D 3 for nails & hair?

ConsumerLab.com   July 31, 2015
Hi Marysue - Please see the information about biotin in the B Vitamins Review: https://www.consumerlab.com/reviews/_/bvitamins/#biotin. Also see the Encyclopedia article about Brittle Nails: https://www.consumerlab.com/tnp.asp?chunkiid=21425


sharon5845   July 8, 2015
I took 5000 B12 two times a day and developed hives on both arms. I was taking it for phantom pain. Hives disappeared when I stopped taking such a large dose.

Beth5839   July 5, 2015
I order a B complex that is called B natural complex. It is made up of all the B vitamins in the suggested daily dose.

The only one I have been able to find is by Nutrilite - sold by Amway.

Martha5838   July 5, 2015
I had a similar neurological reaction to too much B-6 and folic acid. You will slowly recoup your nerve function if you stop taking B vitamins and concentrate on just eating healthily. Check with your doctor to see if you have a genetic condition such as hemochromatosis. If you do - you can definitely take too much vitamin C. In this condition the liver hangs on to too much iron and seems to be more vulnerable to other toxicities. Some of us also have genes that require folate instead of folic acid - I am always searching for vitamins and foods that don't have folic acid added. I avoid most baked goods and bread for that reason. You are smart to be asking these questions

This CL Answer initially posted on 7/4/2015. Last updated 8/3/2017.

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