Role of diet in cancer prevention

fruit and veg

As the link between diet and cancer becomes clearer, and studies show some links between certain foods and cancer, people are increasingly looking to nutrition as a way to prevent or even survive cancer. Today’s Miami Herald features an interesting story on the conflicting advice the public receives on what to eat or not eat to prevent cancer. While all are in agreement that there are  links between nutrition and cancer, some maintain a strict vegetarian diet, cutting out all meat and dairy products is the best way, others disagree.  

But the public, and cancer survivors in particular, say they are trying to educate themselves on how foods might relate to cancer after getting little information from their doctors on the matter other than general recommendations for an overall healthy diet. Part of the problem: there is little agreement on what actual foods comprise a cancer-preventative diet, with hundreds of studies for people to sift through, some with conflicting information. For example, soy-based products, which were touted as recently as last year as a potential tool for cancer prevention, have now been linked to certain types of breast cancer.

However, agreement has become fairly universal on some basic diet recommendations — among them, to eat more than five servings of varied fruits and vegetables a day (the more colorful, the better), choose fiber and multigrains, and eat lean meat such as chicken and fish. People are advised to reduce their consumption of red meat — beef, lamb and pork — as well as cured meat such as cold cuts and hot dogs, fat in general and alcohol.

Few studies have conclusively linked certain foods and drinks to cancer, but there are a couple. One food-cancer link involves cured meats such as cold cuts, which have been shown to cause colorectal cancer in several studies published in the Journal of American Medicine in 2005, the International Journal of Cancer in 2006 and others.

And alcohol has been linked to breast, stomach, esophageal and colon cancer in studies published in the Journal of the American Medical Association in 1998, the Annals of Internal Medicine in 2004 and the British Journal of Cancer in 2002. However, some medical researchers have speculated that red wine might actually protect women from breast cancer — basing their theory on studies on red wine’s positive effects on heart disease and prostate cancer risk. A 2006 study published in Cancer Epidemiology, Biomarkers and Prevention of 6,327 women with breast cancer and 7,558 healthy women concluded that neither red wine nor white wine had any effect on cancer risk. But it said women taking more than 14 drinks a week of any kind of alcohol had a slightly higher cancer risk.

Also, obesity in general has been linked to cancer of the breast for women who have gone through menopause, as well as colon, uterus, esophagus and kidney cancers. As a result, the American Cancer Society recommends a healthy, low-fat diet in general — the same basic prescription from other medical groups, such as the American Heart Association.

”When you look at all the evidence, it’s the mix of foods that people eat that offers the most protection, it’s the synergy of antioxidants and vitamins — not just one food,” said Colleen Doyle, director of nutrition and physical activity at the American Cancer Society. “A story will come out — eat blueberries and you won’t get cancer. There isn’t evidence that one food alone will prevent cancer.

”One of the key things to keep in mind is, even more than what foods people eat, it’s how much they eat,” she added. “People really need to watch their weight to reduce the cancer risk.”

Though its philosophy and advice to avoid meats and dairy products at all costs sometimes clashes with other groups such as the American Cancer Society, there is general agreement that fruits and vegetables are important parts of the diet.

”Diet is very individualized,” said Dee Sandquist, a dietician in Portland, Maine, and spokeswoman for the American Dietetic Association. “We look at the total diet approach — gradually increasing fruits and vegetables, adding in exercise. Everyone is genetically different. We certainly do need more research.”

(Adapted from Miami Herald – read article in full here)