Wednesday’s Ask Dr. Walt — Vitamin B-12

Dear Dr. Walt,

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

—Concerned in Oregon

Dear B-Keeper,

Many physicians recommend that all of their patients over the age of 50 take 1-2 mg (1000-2000 mcg) of vitamin B12 (cobalamin) per day. The reason is that many people at this age are less able to extract B-12 from food.

I also recommend B-12 for those who have a B-12 deficiency, for those:

  • taking medications that interfere with B-12 absorption,
  • for strict vegans or vegetarians,
  • for alcohol and drug abusers,
  • for people recovering from surgery or burns, and
  • for those with bowel or pancreatic cancer.

Although vitamin B-12 is generally considered to be safe, and no “Upper Tolerable Intake Level” has been established, there are some reports of higher doses causing outbreaks of acne and rosacea. In addition, in women who are pregnant, excessive blood levels of vitamin B-12 have been associated with an increased risk of autism. In general, I think it’s best to avoid excessive doses of any vitamin if it is not needed.

In addition, in women who are pregnant, excessive blood levels of vitamin B-12 have been associated with an increased risk of autism. In general, I think it’s best to avoid excessive doses of any vitamin if it is not needed.

In general, I think it’s best to avoid excessive doses of any vitamin if it is not needed.

In general, I also recommend that, when possible, vitamins be obtained from a healthy diet, and not supplement. But that can be a problem with vitamin B-12. 

Vitamin B-12 is naturally found in animal products, including fish, meat, poultry, eggs, milk, and milk products.

Vitamin B12 is generally not present in plant foods, thus the recommendation above concerning vegetarians/vegans, but fortified breakfast cereals are a readily available source of vitamin B12 with high bioavailability for vegetarians