Here is the first half of an excellent article by Elizabeth Landau, from CNN.com, analyzing the conflicting breast cancer/vitamin research results we have been discussing the past few days:
(CNN) — To take the multivitamin or to not take the multivitamin: That is the question researchers are still trying to answer.
New research on vitamins has offered conclusions that weren’t crystal clear. But researchers generally recommend getting vitamins from foods, not supplements, to boost your health.
Vitamin supplements and cancer
A study done on women in Puerto Rico, presented Sunday at the American Association for Cancer Research, found that multivitamin and calcium supplements have a protective effect against breast cancer. But a large Swedish study in the American Journal of Clinical Nutrition found that taking multivitamin supplements may increase the risk of breast cancer.
The Puerto Rican study, which was not published in a peer-reviewed journal, looked at the capacity of DNA to repair itself in the face of damage. A low DNA repair capacity has previously been linked to cancer risk, said Jaime Matta at the Ponce School of Medicine. Researchers surveyed 268 breast cancer patients and 457 healthy controls and took samples from them to analyze their DNA repair capacity.
They found that participants who took multivitamin supplements reduced the odds of having breast cancer by 30 percent, and those who took calcium had a 40 percent decreased risk. Statistical analysis suggested that the calcium effect could be explained by the DNA repair capacity, but the vitamin effect was independent. Taking supplements of individual vitamins such as A, C and E had no effect, Matta said.
The Swedish study, which looked at more than 35,000 Swedish women, found that those who reported taking multivitamins were 19 percent more likely to develop breast cancer than those who said they didn’t take them.
Both studies should be looked at in the broader context of research on the subject, which has consistently found no association between multivitamins and cancer, said Joanne Dorgan, epidemiologist at Fox Chase Cancer Center in Philadelphia, Pennsylvania.
A 2009 study of more than 160,000 women in the U.S. Women’s Health Initiative found no link between multivitamin use and the likelihood of developing cancer or cardiovascular disease, or of dying. Other large-scale studies similarly have not found connections between breast cancer and multivitamin use.
Don’t take all of these multivitamins with the intention that it will decrease breast cancer risk. The Swedish study, which also has a large sample, should be followed up, Dorgan said.
Although the Puerto Rican study is small, it generates a useful hypothesis about DNA repair capacity that should be looked into also, said Dr. Banu Arun, professor of medicine at University of Texas M.D. Anderson Cancer Center. It is important to explore why some people may benefit from vitamin intake more than others, and DNA repair capacity is a possible factor in that, she said.
Arun’s bottom line: “Don’t take all of these multivitamins with the intention that it will decrease breast cancer risk. Getting the vitamins and minerals from natural sources — food source — is the best.” Those with deficiencies because of genetics or chronic illnesses should compensate with supplements, she said.
Go to CNN.com-Studies clash on vitamin benefits to read more.
I was thinking about all of this last evening as I ate a bowl of low carb ice cream. Not a horrible choice–I ate at least ten servings of vegetables yesterday–but I could have eaten some fresh strawberries that were left over from the weekend instead. That would have been a better, more effecient use of those calories, don’t you think?
Feel good and keep smiling! Pat