If your B-complex contains 50,000% of the Daily Value (DV), which is 6 mcg for adults, then it has 3,000 mcg of B-12. For people without a severe B-12 deficiency, this is much more than necessary
. [Note: In 2016, the FDA lowered the Daily Value for B-12
to just 2.4 mcg for most adults, but this won't be reflected on all supplement labels until 2021. This means that your supplement actually provides 125,000% of the current
Although no "Upper Tolerable Intake Level" has been established, there are risks associated with getting too much B-12 from supplements. At a dose of 500 mcg (one-sixth the amount in your supplement), an increased risk of colorectal cancer
was reported in a placebo-controlled study of older people. Doses of just 20 mcg per day or higher have caused outbreaks of acne and rosacea
. A high-dose B complex supplement (with 1,000 mcg of B-12) hurt, rather than helped, people with type 1 or type 2 diabetes and advanced kidney disease
, resulting in a worsening of kidney function and an increase in the risk of heart attack, stroke and death.
In women who are pregnant, excessive blood levels of vitamin B-12 have been associated with an increased risk of autism
in their children.
Taking some B-12 is advisable for people over the age of 50 (when you're less able to extract B-12 from food), as well as for those taking medications that interfere with B-12 absorption, strict vegetarians, alcohol and drug abusers, people recovering from surgery or burns, and those with bowel or pancreatic cancer. But the amount needed to avoid deficiency is small and nowhere near the amount in the supplement you describe in your B-complex.
If you decide to take a B-12 supplement, you may want to choose one that has the right dose for you and has been tested and Approved by ConsumerLab.com
. Be aware that sublingual and dissolvable B-12 supplements
often contain sugar substitutes that can cause gas, bloating, and diarrhea in some people -- particularly if taking multiple pills. You can use the Ingredients
listings in CL's Review to spot and avoid these ingredients.
In general, it's best to avoid excessive doses of any vitamin if it is not needed.
Get more information, including the Recommended Daily Allowance for B-12 (by age and gender), differences in the forms of B-12, potential side-effects and drug interactions, plus ConsumerLab.com's tests of popular products, in the B Vitamin Supplements Review >>
You can check the recommended intakes of other vitamins and minerals here
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Learn More About B-12 Supplements:
Being over 50 years old, I'm looking to take a vitamin B-12 supplement. I see that many contain a form of vitamin B-12 called cyanocobalamin, yet I read on the Internet that this form is toxic. Should I be concerned? >>
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? >>
Is sublingual vitamin B-12 really better than the pill form? >>
I read on your website that some B-12 vitamins can cause diarrhea due to added sugar substitutes like sorbitol. I have had diarrhea and never thought it could be caused by my vitamin B-12 supplement, until I read your article and stopped taking the supplement. My diarrhea stopped immediately. Can you help me find a brand of B-12 that doesn't contain sorbitol or sugar substitutes that could cause this problem? >>
Which foods are a good source of B vitamins? >>
What B-vitamin complex do you recommend for older people? >>
Do vitamin B12 patches, like those from PatchMD, really work? >>
What's the best way to take vitamin B12? >>
Are B12 injections "better" than oral supplements? Are they necessary if I have a B12 deficiency? >>