Cancer and the Nutrition Connection

MADISON – There is no single, magical food proven to prevent or cure cancer. No vitamin or supplement is a magic pill. And no single study offers the magic bullet to ward off cancer.

When it comes to nutrition and cancer prevention, there's really nothing magical about it.

• The food you eat can increase your body's ability to fight cancer and survive after a diagnosis 
• The food you eat can decrease your risk of developing cancer in the first place 
• And it makes sense that what you eat to prevent cancer may help reduce your risk of cancer recurrence

"The best strategy for preventing cancer in general is not to place one's faith in any one particular nutrient or one supplement or one food, but to eat a whole variety of foods rich in healthful nutrients," Weihofen said.

Fruits and Vegetables

Although there are several controversies about food and cancer, Weihofen says there is "total agreement" that fruits and vegetables are the leading cancer fighters.

"So do anything you can to eat a whole variety," says Weihofen, RD, MS, whose work includes nutritional counseling for patients at the UW Carbone Cancer Center.

The most colorful fruits and vegetables tend to have the highest amounts of cancer-fighting phytonutrients, including antioxidants, vitamins and minerals. Among the highest in antioxidant power are:

• Blueberries, blackberries, strawberries, oranges, cranberries, grapes, cherries, apples and melons
• Broccoli, spinach, asparagus, peppers, peas, beets, tomatoes, carrots, squash, pumpkin, sweet potatoes, cabbage, onions and garlic

Quercetin is a type of plant-based chemical (phytochemical) known as a flavonoid, which Weihofen said appears to have powerful anti-inflammatory and cancer-fighting properties. Quercetin is found in apples, cranberries, raspberries, blackberries, black currants, lingonberries, onions, tea and red wine.

Berries have shown particular cancer-fighting promise in recent studies, including a 2007 University of Pittsburgh study in which researchers exposed human leukemia cells to the red pigment in strawberries, raspberries, grapes and cherries. The study showed that the pigment induced "cellular suicide" in certain leukemia cells but had no toxic effects on normal blood cells, Weihofen explained.

The "humble cabbage" is another vegetable that shows promise, Weihofen said. Fermenting cabbage produces isothiocyanates, a class of cancer-fighting compounds.

"Sauerkraut is the new health food – can you believe it?" Weihofen said, joking that researchers haven't yet studied pairing sauerkraut with Wisconsin brats.

Onions and garlic may also be linked to lower risks of certain types of cancers, including colon, ovarian, oral, breast, prostate and kidney, Weihofen said.

Alcohol

The jury is still out about alcohol's connection to cancer, but the general rule is to avoid alcohol in large amounts – even red wine, Weihofen says.

Though some studies have shown increased breast cancer and colon cancer risk associated with moderate drinking, the connection may not be directly related to alcohol. In a 2001 study, postmenopausal women who had one drink per day and had low intakes of folate were 59 percent more likely to develop breast cancer than those who did not drink alcohol and had high intakes of folate. When folate levels were adequate, however, moderate drinking did not increase breast cancer risk.

"When they had enough folate in their diet, (alcohol) wasn't a factor," Weihofen said.

In another colon cancer study, men who drank more than 2 drinks per day doubled their risk of colon cancer – but this may not be directly linked to alcohol. Since alcohol reduces the absorption of folic acid, colon cancer risk may increase as folic acid levels fall, Weihofen explained.

"This was mainly men who didn't have folate in their diet and then they drank, too," Weihofen said. "It's a man who would go out to dinner and order a steak, a baked potato and a brandy manhattan, and then not eat his broccoli."

Red wine is a source of quercetin and may have some health benefits, but Weihofen said nutritionists do not advocate drinking lots of wine to reduce cancer risk.

"We do have to watch the research as this develops," she said. "We do not have the bottom line on how much alcohol affects cancer."

Vitamins and Supplements

Generally, people who take a daily multivitamin have less risk for certain types of cancers, Weihofen says. But excessive vitamin intake may actually be toxic and increase one's cancer risk, she added.

"We don't think these high-dose single supplements are good," Weihofen said. "The bottom line is, vitamins are great, but you really need to choose food over supplements. So, do eat a variety of foods and not rely just on the vitamin."

Calcium and vitamin D supplements are important for those who do not eat dairy products regularly, Weihofen said. However, she stressed that people should check with their physician or nutritionist before taking any herbal supplements.

"There are a lot of them on the market. They come in fancy bottles and they promise you everything from calm sleep to male fuel," Weihofen said. "We have no basis for some of them… the clerks in the stores are not your health providers."

Coffee and Tea

Weihofen encourages drinking lots of non-alcoholic fluids to help reduce cancer risk. She added that multiple studies have shown that tea has special characteristics that decrease the risks of some cancers and possibly slow some cancer cell growth.

"If you want to drink something really healthy, every time we turn around there is something good about tea," Weihofen said, stressing that herbal teas such as chamomile do not have the high-antioxidant activity of green, white and red teas.

Coffee may have a bad reputation, but Weihofen jokes that coffee is "still looking for a disease."

"It will not raise your cholesterol, it's not related to any cancers, it won't give you Alzheimer's disease," Weihofen says. "It's a plant food and it actually is a source of good antioxidants in your diet. So if you enjoy your coffee, you can definitely keep drinking it."

Omega-3

Weihofen encourages finding ways to increase essential omega-3 fats in one's diet. Omega-3 fats act as an anti-inflammatory agent, reduce blood clot formation and lower blood pressure, Weihofen explains.

"We don't make these (fats) in our bodies – we need to eat them," Weihofen said. Omega-3 fatty acids are abundant in oily fish (especially salmon; tuna, sardines, herring, mackerel and trout are also good sources). Other healthy fats include olive oil, canola oil, walnuts and flax seeds.

Fiber and Whole Grains

Hundreds of studies have shown strong links between high-fiber diets and reduced cancer risk, Weihofen says, adding that a good goal is 25-30 grams of fiber per day. Fruits and vegetables provide some fiber, and other high-fiber foods include:

• Breads and cereals made with whole grains, nuts and seeds 
• Beans and legumes (red, white, black and kidney beans)

Exercise

"You cannot talk about a healthy lifestyle, food and nutrition without including exercise," Weihofen said, citing a 2003 report from the national Women's Health Initiative study of 74,000 women ages 50-79. The study showed that those who engaged in 1¼ - 2½ hours of moderate exercise weekly had an 18 percent lower risk of breast cancer than inactive women.

Another 2007 study showed that housework cut breast cancer risk in both pre- and post-menopausal women, Weihofen said.

Recipes

View recipes and tips by Donna Weihofen in the Donna's Recipes section of Channel3000.com.

Date published: 11/6/2007 (updated 06/08/2008)