Men who take a daily multivitamin over the long term may help reduce their risk of cancer, a large new U.S. study concludes.
The study, led by Boston researcher Dr. J. Michael Gaziano, follows other studies that have had mixed conclusions on whether multivitamins help cut cancer risk.
The study released in Wednesday's online issue of the Journal of the American Medical Association looked at 14,641 male physicians with an average age of 64 who were randomly assigned to take a multivitamin or placebo.
"In this large-scale, randomized, placebo-controlled trial among middle-aged and older men, long-term daily multivitamin use had a modest but statistically significant reduction in the primary end point of total cancer after more than a decade of treatment and followup," Gaziano, of Brigham and Women’s Hospital and Harvard Medical School in Boston, and his co-authors conclude.
"Although the main reason to take multivitamins is to prevent nutritional deficiency, these data provide support for the potential use of multivitamin supplements in the prevention of cancer in middle-aged and older men."
The 2010 Dietary Guidelines for Americans states that for the general population of healthy people, "there is no evidence to support a recommendation for the use of multivitamin/mineral supplements in the primary prevention of chronic disease," a conclusion supported by the U.S. National Institutes of Health's conference on the state of the science.
In the new study, multivitamins reduced the chance of developing cancer by eight per cent — less than a good diet, exercise and not smoking, each of which can lower cancer risk by 20 to 30 per cent, cancer experts say.
"This is a small, one could almost use the word tiny push in the right direction," said Dr. Michael Pollak, director of cancer prevention at the Segal Cancer Centre at the Jewish General Hospital in Montreal.
"It's probably that many people get no benefit but a subset of people get a big benefit," he said of the eight per cent risk reduction.
Cancer rates and deaths
The researchers said that while total cancer rates in the study were likely influenced by increased use of the prostate-specific antigen (PSA) test starting in the late 1990s.
About half of the confirmed cancers in the study were earlier stage cancers affecting the prostate. The researchers did not find a reduction in risk of prostate cancer, colorectal cancer or other "site-specific" cancers such as lung or bladder, but Gaziano told reporters that the study wasn't large enough to look for those.
There was no reduction in cancer death rates at a statistically significant level, that is, beyond chance alone.
The reduction in risk only appeared when total cancers were counted. During the course of the study, there were 2,669 cancer cases, including 1,373 prostate cases and 210 colorectal cases.
It’s not clear what components of the multivitamin made a difference. While the multivitamin used in the study stayed the same, vitamin makers have changed their formulations over time.
The researchers can't say whether the findings would apply to women, younger men, or those who were less healthy than the physicians participating in the study. About 40 per cent of them were former smokers, three per cent were current smokers and many were taking Aspirin as part of another study.
The Canadian Cancer Society cautiously welcomed the new research.
"Although the results from this study seem promising, more research about the potential benefits of multivitamins on reducing cancer risk is necessary since the findings of this study only show overall reduction in risk to be relatively small," the society said in an email.
"The society believes multivitamins should not replace other known ways of reducing one's risk of cancer, such as eating a diet that includes lots of fruits and vegetables (which are excellent sources of vitamins, minerals and phytochemicals), maintaining a healthy body weight, avoiding smoking and limiting your alcohol intake."
Dr. Ernest Hawk, vice-president of cancer prevention at the University of Texas MD Anderson Cancer Center and formerly of the U.S. National Cancer Institute also called it a "very mild effect."
"Personally, I'm not sure it's significant enough to recommend to anyone" although multivitamins are promising, added Hawk,, who reviewed the research for the American Association for Cancer Research.
The research was also presented on Wednesday at the U.S. group's Research Frontiers in Cancer Prevention Research meeting in Anaheim, Calif.
Dr. Howard Sesso, one of the study's authors and an associate epidemiologist at Brigham and Women's Hospital in Boston, cautioned consumers that studies have found that the contents of vitamins don't always match what it says on the label.
Side-effects were about the same in both groups although there were more rashes among those taking vitamins, the researchers said.
Pfizer provided the pills. BASF and DSM Nutritional Products provided packaging for the study that was funded by the U.S. National Institutes of Health and BASF Foundation.
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Sunlight spurs the body to make vitamin D. But because of the skin-cancer risk, there isn't an official recommendation to catch some rays. However, a small amount of sun exposure without sunscreen can do the trick. "If you're going to get it from the sun, about 20 to 25 minutes of exposure is helpful," says Stephen Honig, M.D., director of the Osteoporosis Center at the Hospital for Joint Diseases, in New York City. The sun is less likely to provide your daily needs at higher latitudes, in the winter, or if you're older or dark skinned (skin pigment blocks light and the process is less efficient with age). And FYI: Light through a window won't work. <strong>More from Health.com:</strong> <a href="http://www.health.com/health/gallery/0,,20506267,00.html" target="_hplink">Vitamins: What to Take, What to Skip</a> <a href="http://www.health.com/health/gallery/0,,20351257,00.html" target="_hplink">Foods to Boost Your Mood</a> <a href="http://www.health.com/health/gallery/0,,20503533,00.html" target="_hplink">Nutrition Needs That Change As You Age</a> <em>Flickr photo by <a href="http://www.flickr.com/photos/gcapron/6163186238/" target="_hplink">Guillaume Capron</a></em>
Fatty fish can be a good source of vitamin D. Common options include salmon, trout, mackerel, tuna and eel. A 3-ounce sockeye salmon fillet contains about 450 international units (IUs) of vitamin D -- a good portion of the 600 IUs that is the Institute of Medicine's recommended dietary allowance (800 IUs if you're over 70). And you get a bonus -- heart-healthy omega-3 fatty acids! <em>Flickr photo by <a href="http://www.flickr.com/photos/dongkwan/2963809313/" target="_hplink">BrownGuacamole</a></em>
Canned Tuna Fish
Fresh fish aren't the only way to boost your vitamin D intake; you can get vitamin D from a can, too. Canned tuna fish and canned sardines both contain vitamin D, and are usually less expensive than fresh fish. Plus, a longer shelf life makes the canned products easy to stock up on and use at your leisure. Canned light tuna has the most vitamin D -- about 150 IUs per 4 ounces -- while canned albacore tuna has about 50 IUs per 4 ounces, and canned sardines have a little more than 40 IUs per two sardines. <em>Flickr photo by <a href="http://www.flickr.com/photos/gezellig-girl/859232891/" target="_hplink">Kristen Bonardi Rapp</a></em>
Just like humans, mushrooms have the capacity to produce vitamin D when exposed to ultraviolet light. Mushrooms, however, are usually grown in the dark and don't contain the vitamin. Specific brands, however, are grown in ultraviolet light to spur vitamin D production. Check to see if vitamin D-rich 'shrooms, like Dole's Portobello Mushrooms, are available at a store near you. They're perfect for vegetarians looking for plant-based foods that contain the vitamin. Dole's portobellos will give you 400 IUs of vitamin D per 3-ounce serving (about 1 cup of diced mushrooms). <em>Flickr photo by <a href="http://www.flickr.com/photos/stevehopson/349974389/" target="_hplink">Steve Hopson</a></em>
Almost all types of cow's milk in the U.S. are fortified with vitamin D, but ice cream and cheese are not. In general, an 8-ounce glass of milk contains at least 100 IUs of vitamin D, and a 6-ounce serving of yogurt contains 80 IUs, but the amount can be higher (or lower) depending on how much is added. Some soy and rice milks are fortified with about the same amount, but check the label since not all contain vitamin D. <em>Flickr photo by <a href="http://www.flickr.com/photos/loop_oh/3030317020/" target="_hplink">loop_oh</a></em>
Some Types Of Orange Juice
Not a dairy fan? No problem. You can get vitamin D from fortified orange juice. One 8-ounce glass of fortified juice usually has around 100 IUs of vitamin D, but the amount varies from brand to brand. Not all brands are fortified, so check the label. Two fortified brands, Florida Natural Orange Juice and Minute Maid Kids+ Orange Juice, contain 100 IUs per 8-ounce serving. <em>Flickr photo by <a href="http://www.flickr.com/photos/poopface/2527944420/" target="_hplink">manwithface</a></em>
Vitamin D supplements can help you get your proper daily dose, and as Dr. Honig points out, you don't run into the issue of skin cancer as you might with UV rays. "And it's not like calcium," he says. "You don't have to split up your vitamin D dose; you can take it all at one time." Too much vitamin D can be toxic, however. The IOM sets the upper limit at 4,000 IUs for people aged 9 and older. That includes all sources -- food, sun, and supplements. Talk to your doctor before choosing a dosage.
Eggs are a convenient way to get vitamin D. They're popular in many breakfast, lunch, dinner and dessert recipes. Since the vitamin D in an egg comes from its yolk, it's important to use the whole egg -- not just the whites. One yolk will give you about 40 IUs, but don't try to get your daily vitamin D just from eggs. One egg contains about 200 milligrams of cholesterol, and the American Heart Association recommends consuming no more than 300 milligrams a day for heart health. <em>Flickr photo by <a href="http://www.flickr.com/photos/maryamandathompson/5322678053/" target="_hplink">mary_thompson</a></em>
If you're a vitamin D seeker looking for a crunch, look no further than fortified cereals. Choose a low-calorie fortified cereal like Multi Grain Cheerios to get part of your daily fill of vitamin D. You can pair it with fortified milk and a glass of fortified OJ too. A 1-cup (29 gram) serving of Multi Grain Cheerios with one-half cup of fortified milk is 90 IUs; add in an 8-ounce glass of fortified orange juice, and your total is close to 200 IUs. <em>Flickr photo by <a href="http://www.flickr.com/photos/nexus_icon/1350549141/" target="_hplink">Christian Cable</a></em>
Although it might not be the most appealing source, a 3.5-ounce serving of cooked beef liver contains about 50 IUs of vitamin D -- and several other nutrients. You'll also be getting vitamin A, iron and protein. However, beef liver is also high in cholesterol, so you might want to choose an oily fish instead.
Cod Liver Oil
While its name might suggest a less-than-savory flavor, cod liver oil is often flavored with mint or citrus, or comes in capsule form. One tablespoon contains about 1,300 IUs of vitamin D, which is more than twice the recommended dietary allowance of 600 IUs per day. That amount doesn't exceed the maximum upper-level intake of 4,000 IUs for people over 8 years old, but it exceeds the daily maximum for infants (1,000 IUs).
Ultraviolet Lamps And Bulbs
People at high risk of vitamin D deficiency may resort to UV-emitting lamps and bulbs. This includes people unable to absorb the vitamin (malabsorption) or those who can't get enough in winter months, says Michael F. Holick, M.D., a professor of medicine, sociology, and biophysics at Boston University Medical Center. These are similar to tanning beds, but smaller. "The lamp is only about 24 inches by about 16 inches," says Holick. These lamps carry the same skin-cancer risks and need for protective eyewear, so they're best for those with a doctor's recommendation. <strong>More from Health.com:</strong> <a href="http://www.health.com/health/gallery/0,,20506267,00.html" target="_hplink">Vitamins: What to Take, What to Skip</a> <a href="http://www.health.com/health/gallery/0,,20351257,00.html" target="_hplink">Foods to Boost Your Mood</a> <a href="http://www.health.com/health/gallery/0,,20503533,00.html" target="_hplink">Nutrition Needs That Change As You Age</a> <em>Photo from <a href="http://www.amazon.com/NatureBright-SunTouch-Plus-Light-Therapy/dp/B000W8Y7FY/ref=sr_1_1?ie=UTF8&qid=1342193526&sr=8-1&keywords=sun+lamp" target="_hplink">Amazon.com</a></em>