Nutrition for Cancer Prevention

It’s a known fact that fruits and vegetables are essential to a healthy diet, because they are filled with antioxidants: substances or nutrients in our foods that can prevent or slow damage to our body. When our cells use oxygen, they naturally produce free radicals, by-products which can cause damage. Antioxidants act as "free radical scavengers," preventing and repairing damage. Health problems such as cancer are caused by oxidative damage. Researchers are busy discovering the hardest working antioxidants in our foods and how they work.

Green Tea
In the last 15 years, tea has become one of the most studied foods. Researchers believe tea’s health benefits are due to polyphenols, which are potent antioxidants. Flavonoids, one type of polyphenol, are the most effective, and catechins, a type of flavonoid, play a role in cancer prevention. All types of tea, including decaf, as well as tea consumed hot or cold, have these substances, but the amounts vary by type of tea and how strongly a cup is brewed. Another antioxidant in green tea, EGCG, has been shown to latch onto a protein in tumor cells and inhibit the cells’ growth. The amount of green tea used in the study wasn’t even a lot—it was comparable to the amount found in your body after drinking two cups.

While both green and black tea offer health benefits, green tea packs more punch. All varieties of tea are derived from the same plant. The difference is in how the leaves are processed after they are picked. For black tea, fresh leaves are rolled and then allowed to wither indoors, which causes most of the active substances to oxidize. For green tea, the leaves are steamed to preserve the natural active substances, thereby yielding more antioxidants. In fact, based on invitro studies, the flavonoids in a cup of green tea have a greater antioxidant effect than single servings of broccoli, carrots, apples, or grapes.

Green tea is also a more healthful beverage than coffee or alcohol. Fresh brewed green tea is all-natural, and contains no fat, calories, alcohol, or sugar (if left unsweetened and without milk.) A cup of green tea has about half the caffeine found in a cup of coffee.

Citrus Fruits
Eating just one orange per day will cut your chances of certain types of cancer in half. Oranges contain over 170 antioxidants, and sixty of them are flavonoids. Citrus fruits also strengthen the immune system, which inhibits tumor growth and normalizes tumor cells.

Tomatoes
Tomatoes are colored by lycopene, which has been shown to be particularly helpful in lowering men’s chances of prostate cancer. In fact, researchers have recommended lycopene supplementation be used as an adjunct to standard prostate cancer treatment, alongside surgery, chemotherapy, and radiation. Lycopene has also been shown to limit the DNA damage that may precede prostate cancer in African-American men.

If you want the most anti-cancer benefits from tomatoes, cook them. Heat processing actually increases the amount of lycopene that can be absorbed by the body, as well as increasing its antioxidant activity.

Other Fruits and Vegetables
Americans who do eat enough fruits and vegetables tend not to go for much variety. Iceberg lettuce, corn, apples, potatoes, and bananas don’t carry much cancer-fighting punch. In order to capture health benefits and reduce disease risk, we must eat more variety. Cauliflower, dark lettuces (i.e. romaine or red leaf), spinach, broccoli, Brussels sprouts, carrots, squash, sweet potatoes, cantaloupe, red peppers, and strawberries are all high in antioxidants and have been shown to have disease-prevention properties.

Selenium
The mineral selenium has been found to slow esophageal, skin, rectal, and prostate cancer. Scientists studying blood levels of selenium found that people with less selenium were up to three times more likely to have precancerous growths than those with more selenium. They believe that selenium inhibits the growth of abnormal cells, preventing genetic damage and helping the body kill off cells that might otherwise become tumors. Foods with selenium include tuna, oysters, shrimp, salmon, Brazil nuts, liver, pork, and turkey.

Less Meat, Dairy, and Alcohol
Scientists have found that premenopausal women who ate the most fatty red meat and milk had a 54% higher chance of developing invasive breast cancer than those who ate less meat. The researchers believe that eating more saturated fat from meat increases hormone levels that boost the chances of breast cancer.

A 2003 study also showed that post-menopausal women who averaged two alcoholic drinks per day raised their risk of breast cancer by 80%. Again, the researchers believe that alcohol affects the levels of hormones that influence cancer.

References:

Menendez, Mary. “Eat to Live.” Energy Times, May 2004.

Milling, Marla Hardee. “Green Light for Green Tea.” Aurora Healthcare Your Health Newsletter, Nov 2004.

“Tea’s Ties to Better Health.” HealthNews, Oct 2001.

Zangwill, Monica, MD, MPH. “Reducing Your Risk of Prostate Cancer.” Aurora Healthcare Your Health Newsletter, Nov 2004.