The Scoop - October 2011

Study Shows Increased Prostate Cancer Risk From Vitamin E Supplements

The Selenium and Vitamin E Cancer Prevention Trial (SELECT), a study of over 35,000 men age 50 and older that was sponsored by the National Institutes of Health (NIH), showed that men who took 400 international units (IU) of vitamin E daily for several years had more prostate cancers compared with men who took a placebo. The findings showed that per 1,000 men, there were 76 cases of prostate cancer in men who took only vitamin E supplements versus 65 in men taking a placebo over a 7-year period. This represents a 17 percent increase in prostate cancers in men who took vitamin E compared with those who took a placebo, a difference that was statistically significant and therefore not likely due to chance. Some men in the study took both vitamin E (400 IU/day) and selenium (200 micrograms [mcg]/day). These men were also more likely to develop prostate cancer than men who took a placebo, but those increases were small and possibly due to chance. “SELECT has definitively shown a lack of benefit from vitamin E and selenium supplements in the prevention of prostate cancer and has shown there is the potential for harm,” said Lori Minasian, M.D., study co-author and acting director of the NIH National Cancer Institute’s Division of Cancer Prevention. “Nevertheless, this type of research has been critically important to understanding the potential benefits and risks from supplements.” The results of this study appeared October 12, 2011, in the Journal of the American Medical Association. The National Cancer Institute has more information on the results of the SELECT trial.

Saw Palmetto: No More Effective Than Placebo for Urinary Symptoms

Saw palmetto, a popular herbal dietary supplement used by some men, does not reduce urinary problems associated with prostate enlargement any better than a placebo, according to research recently published in the Journal of the American Medical Association. Prostate enlargement, also called benign prostatic hyperplasia (BPH), can cause frequent urination (especially at night); a hesitant, interrupted, or weak urine stream; urgency and leaking or dribbling; and an inability to empty the bladder completely. More than half of men in their 60s, and up to 90 percent in their 70s and 80s, have symptoms of BPH. The study was a randomized, double-blind, placebo-controlled clinical trial involving 369 men age 45 years or older with symptoms of BPH. The men took either saw palmetto (at daily doses that increased during the study from 320 milligrams (mg) to 640 mg and finally 960 mg) or a placebo for 72 weeks. At the end of the study, the men who had taken saw palmetto had no greater improvement in urinary symptoms associated with BPH than those taking the placebo. The study was funded by NIDDK, NCCAM, and ODS, all part of NIH. For more information, see the NCCAM Research Spotlight article about this study.

Soy Isoflavone Supplements and Menopause/Bone Health Research

Soy isoflavone supplements—a popular alternative to hormone replacement therapy during menopause—may be no better than a placebo in preventing menopausal symptoms or bone loss, according to a study published in the August 2011 issue of the Archives of Internal Medicine. Isoflavones are compounds found in some plants such as soy that are believed to have mild estrogen-like effects in the body. In the study, 248 women between the ages of 45 and 60 and within 5 years of menopause, took either 200 mg of soy isoflavones or placebo pills daily for 2 years. The researchers measured changes in bone density in the spine, hip, and neck, as well as hot flashes and other menopausal symptoms. Compared with placebo, taking soy isoflavones did not significantly affect bone mineral density and actually increased hot flashes and constipation. The researchers concluded that a daily soy isoflavone supplement is no better than a placebo in preventing menopausal symptoms or bone loss.

I try to eat right, but sometimes I don't succeed. How do I know if I should take a multivitamin supplement, especially since I've heard that they might be harmful?

It’s always best to get nutrients from food first, if you can, before taking supplements. Multivitamin/mineral supplements (MVMs) cannot take the place of eating a variety of foods that are important to a healthy diet. But people who don’t get enough vitamins and minerals from food alone, are on low-calorie diets, have a poor appetite, or avoid certain foods (such as strict vegetarians and vegans) might consider taking an MVM. Health care providers might also recommend MVMs to patients with certain medical problems.

We have just published a fact sheet on MVMs that we encourage you to read. It discusses what types of MVMs are available and possible effects of MVMs on health, and provides guidance on which kind of MVM to choose. There’s also a more detailed version if you’re looking for more comprehensive information.

Most research suggests that getting recommended intakes of vitamins and minerals from food—and dietary supplements as needed—promotes health. Our fact sheet points out that some people might benefit from taking certain nutrients found in MVMs. For example:

• Women who might become pregnant should get 400 mcg/day of folic acid from fortified foods and/or dietary supplements to reduce the risk of birth defects of the brain and spine in their newborn babies.
• Pregnant women should take an iron supplement as recommended by their health care provider.
• Breastfed infants should receive vitamin D supplements of 400 IU/day until they are weaned. After weaning, infants should drink about 1 quart per day of fortified formula or whole milk.
• In postmenopausal women, calcium and vitamin D supplements may increase bone strength and reduce the risk of fractures.
• People over age 50 should get recommended amounts of vitamin B12 from fortified foods and/or dietary supplements because they might not absorb enough of the B12 that is naturally found in food.

Keep in mind that manufacturers add some of the vitamins and minerals found in dietary supplements to a growing number of foods, including breakfast cereals and beverages. As a result, you may be getting more of these nutrients than you think, and more might not be better. Taking more than you need is always more expensive and can increase your risk of side effects.

You may have read about a recent study suggesting that taking an MVM—or nutrients such as folic acid, copper, and iron—is linked to an increased risk of death. Calcium was the only nutrient in the study that reduced the risk of death. Because the participants in the study were almost all white postmenopausal women, the results cannot be applied to men, younger women, or to people of different ethnicities or races. In addition, the study was not a cause and effect study, so it cannot prove that taking supplements results in dying earlier. Most other studies don’t find a link between taking an MVM or other nutrient dietary supplement and increased risk of death.

To get a personalized list of your nutrient needs, you can use the interactive dietary reference intake tool from the U.S. Department of Agriculture (USDA).

I recently heard that people can get too much zinc from using denture creams. Is that really possible?

Yes. Zinc is present in some denture cream adhesives. Using large amounts of zinc-containing denture creams (well beyond recommended levels) could lead to excessive zinc intake. Too much zinc can cause copper deficiency and nervous system problems, such as numbness and weakness in the arms and legs. The safe upper limit for zinc is 40 mg per day. Many denture creams have been reformulated so that they don’t contain zinc, but check product labels to be sure. Have more questions? See our fact sheets on zinc.

I get colds a lot, and I've thought about trying echinacea. Since it's a natural herb, it should be safe. Right?

Not necessarily. Even though herbal products, such as echinacea, are "natural," that doesn't mean that they are always safe or good for you. The safety of an herbal supplement depends on many things, such as its chemical makeup, how it works in the body, how it's prepared, and how much you take. Many supplements contain active ingredients that can have strong effects in the body and can interact with certain prescription drugs in ways that might cause problems.

Always be alert to the possibility of unexpected side effects, especially when taking a new product. Echinacea does not usually cause serious side effects, although it sometimes causes nausea, stomach pain, diarrhea, or vomiting, and allergic reactions can occur.

Unfortunately, study results on echinacea are mixed, so it is not clear at this time whether echinacea prevents or treats upper respiratory tract infections, such as the common cold.

Have more questions? See our background fact sheet on botanical dietary supplements and a fact sheet on echinacea from NCCAM.