Cancer is constantly in the news, it seems-and no wonder, since its re-cently overtaken heart disease as the leading cause of death in the US. Youre bombarded with information, myths and hopeful guesses about what might protect you against cancer and what might raise your risk. Your lifestyle really can affect your risk-but whats fact and whats sheer speculation?Thats where science can help you take a step back and evaluate the on-slaught of cancer dos and donts. Not that science has all the answers-far from it. But the ongoing process of sci-ence involves constantly reviewing and testing to learn what we really know, what we dont know yet, and what we suspect but still dont know for sure.Take the much-touted power of fruits and vegetables to protect against cancer, for instance. Science has al-ready established many good reasons to eat fruits and vegetables. In fact, the updated federal Dietary Guidelines for Americans to be released later this year are likely to recommend moving toward a more plant-based diet for everybody. But can eating plenty of produce help reduce your risk of cancer, specifically?A large new study suggests that the answer is yes-but theyre just a start. Paolo Boffetta, MD, of Mount Sinai Medical Center in New York City, and colleagues noted that no prior study has conclusively demonstrated that high intakes of fruits and vegetables combat cancer. Most studies have focused on protective benefits against specific types of cancer. The handful that examined fruits and vegetables and overall cancer risk have produced mixed results.So Dr. Boffetta and colleagues looked at nearly nine years of data from the European Prospective Investiga-tion into Cancer and Nutrition (EPIC) on almost a half-million people, ages 25 to 75. Participants represented 10 different Western European countries, with a wide range of fruit and vegetable consumption. During the follow-up period, more than 30,000 participants were diagnosed with cancer.Our study supports the notion of a modest cancer preventive effect of high intakes of fruits and vegetables, and we can exclude chance as a likely factor, they concluded, writing in the Journal of the National Cancer Institute. Never-theless, the observed association of can-cer risk overall with vegetable and fruit intake was very weak, and we cannot entirely rule out the possibility of residual confounding by these or other factors.Overall, eating about 7 ounces more fruits and vegetables daily was associated with a 3% lower risk of any cancer. As consumption increased from 8 ounces or less on the low end to 22.4 ounces or more on the upper end, a significant trend for reduced cancer risk was observed in both men and women.Eating 3.5 ounces more vegetables per day was linked to a 2% reduced risk; analysis by gender found this beneficial association was limited to women. Total fruit intake was not as-sociated with any significant difference in cancer risk. Greater fruit and veg-etable intake had a stronger connection with reduced cancer risk among heavy alcohol drinkers, but only for cancers linked to alcohol and smoking.Given the small magnitude of the observed associations, researchers concluded, caution should be applied in interpretation of the results.Joel B. Mason, MD, director of Tufts HNRCA Vitamins and Carcino-genesis Laboratory, commented, I am hesitant to give people the message that fruits and vegetables only help to a very small degree. The very nature of the design of studies such as EPIC tends to attenuate the degree of protection that can be detected. Also, many of us in the field suspect that a diet high in fruits and vegetables effectively pushes out other detrimental items in the diet such as animal meat, saturated fat, etc., so there is a multiplier effect that occurs. This is not taken into account by a study such as EPIC, since these detri-mental items are statistically eliminated from the equation.In any case, the answers to all your cancer worries cant be found in the produce section. So what else can you do to help protect yourself? A flurry of new studies, including research present-ed at the recent American Association for Cancer Research (AACR) annual meeting, offer additional clues:Zinc associated with prostate-cancer survival: Men who consume plenty of zinc in their diet now-primarily from grains, meat and dairy-may be thankful later, if theyre diagnosed with early-stage prostate cancer. Research presented by Harvard doctoral candi-date Mara S. Meyer, MS, at the AACR meeting showed that men with the highest zinc intake were 74% less likely to die from prostate cancer than those with the lowest zinc consumption.Meyer and colleagues examined data on 525 Swedish men with con-firmed prostate cancer diagnoses in 1989-94 who completed food-frequency questionnaires; 218 men subsequently died of the cancer and 257 from other causes. Zinc intake was primarily from food, as use of dietary supplements was negligible. Men in the top group of zinc intake averaged 15.7 milligrams or more daily, while those in the bottom group consumed 12.8 mil-ligrams or less. (One cup of oat cereal provides about 4.5 milligrams of zinc.)The study also showed an associa-tion between survival and intake of the omega-3 fatty acid DHA from fish, with the highest DHA group 30% less likely to die than the lowest group. No link was seen between survival and con-sumption of saturated, monounsatu-rated or omega-6 polyunsaturated fats.Aspirin and other anti-inflammatory drugs dont protect against ovarian cancer: In another study presented at the AACR meeting, regular use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) didnt reduce the risk of ovarian cancer. Self-reported daily use of acetaminophen, however, almost doubled risk of ovarian cancer among more than 100,000 California school employees over about 12 years. Over-all, 402 participants were diagnosed with invasive epithelial ovarian cancer.The study, by Lei Duan, PhD, of City of Hope in Duarte, Calif., and col-leagues, sought to test the notion that if inflammation plays a role in tumor development, anti-inflammatory drugs might have a protective effect.Higher Vitamin K2 intake linked to lower cancer risk: In a study recently pub-lished in the American Journal of Clinical Nutrition, intake of one form of vitamin K was associated with lower risk of dying from cancer. Vitamin K comes in two main types-K1, found in leafy green vegetables and some vegetable oils, and K2, found in meat and cheese. In the study of 24,430 Ger-man adults, ages 35 to 64, those with the highest intake of K2-mostly from cheese-were less likely to die of cancer, especially prostate and lung cancer. No such link was seen for vitamin K1.Jakob Linseisen, MD, of the Ger-man Cancer Research Center, and col-leagues noted that vitamin K has been shown to inhibit cancer-cell growth in the lab and that a previous study as-sociated it with lower prostate-cancer risk. Their study was not, however, designed to show cause-and-effect; its possible some other component in cheese is related to lower cancer risk.Eating right, drinking less, really does pro-tect against breast cancer: Another new pooled analysis of previous studies supports the importance of a healthy diet and reducing alcohol consump-tion to reduce the risk of breast cancer. You cant change your family history, researchers noted, but you can modify what you eat and drink. Previous stud-ies have focused on individual dietary components, but since foods arent consumed in isolation, researchers reasoned it might be more illuminating to combine this data.Sarah Brennan of Queens University Belfast in Northern Ireland, and col-leagues pooled 18 studies involving more than 400,000 women. A prudent diet was defined in part as one high in whole grains and vegetables; women sticking most closely to this goal were 11% less likely to develop breast cancer than those eating the least-prudent diet. Surpris-ingly, however, no such association was observed for high and low adherence to a Western diet. Higher consumption of alcohol was linked to a 21% increased risk, as seen in previous studies; post-menopausal women who drink more alcohol have higher levels of estrogen, thought to be a factor in breast can-cer. The findings were published in the American Journal of Clinical Nutrition.Multivitamin use associated with greater breast-cancer risk: Could multivitamins, which millions of women take daily as insurance for a healthy diet, actu-ally increase the risk of breast cancer? Thats the suggestion of a large new Swedish study published in the Ameri-can Journal of Clinical Nutrition-though researchers were quick to cau-tion that their observational study cant show a cause-and-effect relationship. If there were such a link, they added, the additional risk for any individual woman would be small.Susanna C. Larsson, MD, of the Karolinska Institute, and colleagues followed more than 35,000 older women (ages 49 to 83 at baseline) over an average of 10 years, during which 974 participants were diagnosed with breast cancer. A little over a quarter of the women reported regularly taking multivitamins at the start of the study. After adjusting for known risk factors, multivitamin users were 19% more likely to develop breast cancer.While theres no way to know if the supplements actually contributed to the cancers, researchers said such an effect is biologically plausible and further investigation is warranted. In any case, the Swedish team added, If you eat a healthy and varied diet, there is no need to take multivitamins.
| What Can You Do NOW? To reduce your risk of cancer, the American Cancer Society recommends: Maintain a healthy weight. Be more active. Eat at least five daily servings of veg-etables (including legumes) and fruits each day, especially those with the most color (a sign of high nutrient content). Aim for at least three servings of whole grains each day. Cut back on processed meats like hot dogs, bologna and luncheon meat, and red meats like beef, pork and lamb. |
Soda and coffee cleared as colon-cancer culprits: While sugary soft drinks pres-ent plenty of other health problems, a new study says at least they wont in-crease your risk of colon cancer. Neither will coffee, although heavy tea con-sumption was associated with a 28% increased risk. Researchers cautioned, though, that only 3% of their study population were heavy tea drinkers, so those results could be due to chance.Xuehong Zhang, MD, ScD, of Harvard, and colleagues combined data from 13 North American and European studies totaling 731,441 people. Over 6 to 20 years, a total of 5,604 cases of colon cancer were diagnosed among the studies participants. Researchers found no increased risk of colon cancer associated with drinking up to six cups of coffee daily or up to 18 ounces of soda per day. Nor was there any link between caffeine intake and increased risk. Only a small percentage of the participants drank the highest amounts of soft drinks, so the study may have been underpowered to draw conclu-sions about downing more than 18 ounces of soft drinks a day.The findings were published in the Journal of the National Cancer Institute.TO LEARN MORE: Journal of the National Cancer Institute, online before printjnci.oxfordjournals.org/cgi/content/abstract/102/8/529 (fruits and vegetables); jnci.oxfordjournals.org/cgi/content/abstract/djq107v1(beverages). American Association for Cancer Research www.aacr.org. American Journal of Clinical Nutrition, May 2010, www.ajcn.org/cgi/content/abstract/91/5/1348 (vitamin K); www.ajcn.org/cgi/content/abstract/91/5/1294(breast cancer); www.ajcn.org/cgi/content/abstract/ 91/5/1268 (multivitamins).