Vitamin E Won't Help, May Hurt, Cancer Study Says
See comments by John Cartmell, MS, at end of article.
By Kyung M. Song
Seattle Times health reporter
Years of popping vitamins offer no protection from lung cancer, and taking vitamin E at high doses for a long time may even elevate the risk, according to a new study led by researchers in Seattle.
The researchers from the University of Washington and elsewhere tracked 77,719 Puget Sound-area adults age 55 to 76 for an average of four years to see whether multivitamins, vitamin C, vitamin E and folate reduced their odds of getting lung cancer, the leading cancer killer in the United States. The answer was no, regardless of how many vitamins they had taken during the previous 10 years.
The findings join growing evidence discounting the benefits of taking vitamins and minerals through pills instead of through food.
The study appears in the March 1 issue of American Journal of Respiratory and Critical Care Medicine.
Dr. Tim Byers, a professor of preventive medicine at the University of Colorado who wrote an accompanying editorial to the UW study, said it echoes two decades of research that packaged vitamins just can't mimic the beneficial properties of vitamins in foods.
"Are [supplements] doing much good biochemically? Probably not," said Byers, who was not involved in the study.
Dr. Christopher Slatore, the study's lead author and a senior pulmonary medicine fellow at the UW, said he was not surprised by the results.
In fact, current smokers who took the highest doses of vitamin E — at least 215 milligrams a day for 10 years — were 59 percent more likely to get lung cancer than those who did not take any, a difference that was unlikely to be due to chance.
Among everyone in the study, high vitamin E users had a lung-cancer rate of 209 per 100,000 people, compared with 189 for nonusers.
But even at high doses, the potential for harm from vitamin E paled in comparison to the risk from tobacco use alone. A current smoker in the study was 24 times more likely to get lung cancer than a nonsmoker. Cigarette smoking causes 90 percent of all lung cancers, according to the National Cancer Institute, which funded the study.
More than half of American adults take supplements, many in the belief that they help guard against chronic diseases or cancer. But Byers said little scientific evidence bears that out.
In fact, some vitamins may even be harmful. For instance, taking supplements of beta carotene, a compound found in many fruits and grains, has been shown to increase the chances of developing lung cancer. That's despite evidence that people who eat a lot of fruits are less likely to get the disease.
Byers said the paradox probably was because foods contain not only vitamins but other compounds that may somehow work to protect the body.
That's not to say that all supplements are ineffective, particularly when taken to correct deficiencies. Lack of vitamin D, for instance, may weaken the immune system. Folic acid reduces the risk of birth defects if taken by pregnant women, Byers said.
In addition, Byers said studies have suggested that selenium, a mineral with antioxidant properties, may help prevent prostate and lung cancer.
Still, Byers said, early hopes that supplements, including vitamin E, would reduce the risk of several types of cancer have not been definitively borne out by controlled trials.
So for lung cancer at least, UW's Slatore said, people should give up the notion of swallowing pills to better health.
"If you have $100, you'd be better off to spend it on nicotine patches," he said.
Kyung Song: 206-464-2423 or firstname.lastname@example.org
Copyright © 2008 The Seattle Times Company
John Cartmell, MS, comments
There are many variables that can affect the end results in any research study. Questions that one must consider in this study include:
- Were the subjects healthy and taking supplements to maintain health and prevent disease, or were they unhealthy and taking supplements in an effort to ensure nutritional adequacy to recover their health?
- What was the diet and lifestyle of the subjects like? Did they exercise, drink coffee or alcohol, smoke, get adequate rest or eat a diet rich in whole foods with a proper balance of protein, carbohydrates, fats, fluid and fiber?
- Did the subjects have nutritional deficiencies due to digestive disorders like Irritable Bowel Syndrome, where absorption of antioxidants and other nutrients might be impaired regardless of adequacy of the diet or supplement intake?
- Vitamin D deficiency is associated with increased risk of 18 different types of cancer. The main source of vitamin D is from sun-tanning. How many of the subjects (living in overcast Seattle) were deficient in vitamin D?
- How many of the subjects were taking prescription medications, commonly known to interfere with ingestion or digestion of food?
- How many of the subjects had a history of exposure to asbestos, known specifically to increase the risk of lung cancer?
- How many had diabetes or high blood sugar, known to suppresses the immune system and therefore increase the risk of cancer or infectious diseases?
- Who paid for this study?
A little information can be a dangerous thing.
The cases in this study were identified through the Seattle–Puget Sound SEER (Surveillance, Epidemiology, and End Results) cancer registry. http://ajrccm.atsjournals.org/cgi/content/abstract/177/5/524maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=vitamins&searchid=1&FIRSTINDEX=0&volume=177&issue=5&resourcetype=HWCIT.
This means a hundred percent of the subjects in this study had a history of cancer , and therefore had a higher risk of developing cancer in the future. It also means the apparent inability of vitamin supplements to decrease the risk of lung cancer in this group may not be relevant to normal, healthy people taking supplements to maintain health and prevent disease..
While there is no conclusive evidence that a healthy diet, or taking dietary supplements, is beneficial in treating cancer or preventing its reoccurrence, it certainly can be said that an unhealthy diet can increase the risk of cancer occurring or reoccurring. We can also say with certainty that a healthy diet is important for general health and well-being, and that you can't assume optimal health if nutrition in insufficient to support or maintain it. This is why adequate nutrition is important to maintain health and prevent cancer and other diseases. Vitamins and dietary supplements are a convenient, and relatively inexpensive way to assure nutritional adequacy. Something that medications cannot do.
In August of 2002, the Journal of the American Medical Association (JAMA) reversed their decades long stand against vitamin supplements stating, "Most people do not consume an optimal amount of all vitamins by diet alone. Pending strong evidence of effectiveness from randomized trials, it appears prudent for all adults to take vitamin supplements. We recommend that all adults take one multivitamin daily." (see http://jama.ama-assn.org/cgi/content/full/287/23/3127 )
To date, the AMA has not reversed this recommendation.
John W. Cartmell, MS
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