Bruce Bistrian, M.D.

Harvard Health Letters

Q. In addition to a multivitamin, I've been taking vitamin B12 supplements (1,000 mcg) for a few years, hoping to increase my energy. My recent blood profile showed a high level of B12 (1,826 pg/ml). Should I stop taking B12? My energy is about the same.

A. Severe B12 deficiency usually occurs with a condition called pernicious anemia, an uncommon disorder that arises from the inability to absorb the vitamin from food because the stomach does not make enough intrinsic factor, a protein that facilitates B12 absorption.

A more common problem is chronic atrophic gastritis -- inflammation of the stomach lining that interferes with absorption of B12 from food, but not, as it turns out, B12 in pill form. Between 10 percent and 30 percent of people over age 50 have atrophic gastritis, so it's reasonable, but not imperative, for people in this age group to take a daily multivitamin that provides enough B12 so that they don't become deficient even if they have some gastritis.

Most of the over-the-counter multivitamins for sale in the United States provide 100 percent (and often more) of the Recommended Dietary Allowance (RDA) of B12, which is 2.4 micrograms (mcg) a day. So you can see that by taking a multivitamin and 1,000 mcg of B12 as a separate supplement, your daily intake is at least 400 times the RDA. Moreover, your B12 blood level of 1,826 picograms per milliliter (pg/ml) is more than ample. The normal range for that test is anywhere from 200 to 1,000 pg/ml. There's little, if any, chance you have pernicious anemia.

Are you maybe getting too much B12? Well, a safe upper limit for B12 intake hasn't been established because researchers haven't seen any adverse effects from consuming large amounts of the vitamin. At the same time, it's unlikely there's any benefit to maintaining higher than normal levels in the blood.

The bottom line is that your B12 status is excellent, so your flagging energy can't be blamed on that nor fixed by taking B12 in large amounts. In consultation with your doctor, who presumably is familiar with your medical history, you might wish to discontinue the 1,000 mcg of B12. There's no known medical risk to continuing, but doing so may be a waste of money.

I'd suggest sticking with the multivitamin. Some doctors and researchers are backing away from multivitamins, but I think they're a good insurance policy against nutritional deficiencies, especially as we get older.

So what can you do about your lack of energy? Many conditions cause fatigue -- heart disease, cancer, depression. If you have a sudden drop in energy, it's important to see a doctor.

But if your physician has found you to be basically healthy and your energy has declined gradually, then the answer may be as obvious as getting more and better sleep (granted, often easier said than done) or reducing stress.

Keep in mind that we all lose muscle with age, so even routine activity gets more tiring because there's less muscle to do the work. Exercise won't magically reverse age-related muscle loss but it can counteract it to a substantial degree. An exercise program, designed with the assistance of your physician and an exercise therapist, can be helpful in the ninth, even the tenth, decade of life.

 

Bruce Bistrian, M.D., Beth Israel Deaconess Medical Center, Boston, Massachusetts

 

Available at Amazon.com:

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No More Digestive Problems

 

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Health - Should I Stop Taking B12 Supplements?