The factors that cause cancer are still only vaguely understood in most cases. There is, however, increasing evidence of a relationship between diet and cancer; separate reports by the National Cancer Institute, the National Academy of Sciences and, just last month, the American Cancer Society have suggested that a diet high in Vitamins A and C and fiber and low in fats, alcohol and treated meat can reduce the likelihood that a person will develop at least some types of cancer. Now nutritionist Patricia Hausman, 30 (her master’s degree in nutrition is from the University of Maryland), offers more practical advice in her book Foods That Fight Cancer (Rawson Associates, $16.95). Hausman’s 1981 book Jack Sprat’s Legacy: The Science and Politics of Fat & Cholesterol was praised by a wide range of scientists. The fact that her own mother has had cancer for six years helped turn her research toward cancer’s relationship to nutrition. Foods That Fight Cancer includes recipes as well as Hausman’s analysis of research in the field. Over a glass of filtered tap water in her Silver Spring, Md. home, Hausman discussed cancer and nutrition with reporter Peggy Brawley.
What foods reduce the risk of cancer?
There are thought to be four protective nutrients: vitamin A, vitamin C, whole-grain fiber and the “inhibitors” in vegetables of the cabbage family. They’re the ones we know enough about to make recommendations. The other side of the story is things to cut down on: foods such as whole milk, butter and fatty red meat, alcohol, for those who drink large amounts, and cured foods such as smoked meats.
What’s so special about vitamin A?
The main form of vitamin A in fruits and vegetables is called beta-carotene. We find strong hints that carotene may lower the risk of cancers of the lungs, stomach and esophagus. Other studies show some evidence that carotene helps prevent bladder, mouth, colon and prostate cancer. Drinking combined with smoking produces a very high risk of cancers of the mouth and throat.
What are sources of carotene?
Mostly foods that are deep green, orange and yellow. We’re talking about romaine, spinach, kale, pumpkin, sweet potatoes—tomatoes too. Plant vitamin A is extremely tough stuff. It hardly matters how long you store it or how you cook it. Fruits include peaches, cantaloupes, mangoes and dried apricots.
Did the recent Harvard study that failed to find a relationship between vitamin A and cancer shake your convictions?
No. The researchers looked at total carotenoids and total cancer rates. They did not isolate carotene, for instance. And we’re talking about specific cancers, such as colon and lung.
What about vitamin C?
It’s not as stable as A. The longer it’s cooked or stored the more it’s destroyed. C is found in citrus fruits, of course, plus some green vegetables such as broccoli and brussels sprouts, and things that are red—red peppers, strawberries and raspberries. This vitamin is thought to protect the stomach and esophagus.
How does C work?
One thing it does is inhibit the conversion of nitrites—additives found in such pickled and salt-cured foods as ham, sausages, bacon and hot dogs—into nitrosamines, which may be cancer-causing chemicals.
What form should the C be in?
You might have noticed that some processed meats have small amounts of vitamin C added, but we don’t know whether this is enough to provide strong protection. I advise drinking orange, grapefruit or tomato juice whenever you do eat cured meats. Add a sliced green pepper or tomato to your sandwich.
Why is fiber important?
Studies show that a diet high in whole grains lowers the risk of colon cancer. One possibility is that fiber may get harmful chemicals out of the body sooner. Based on one study done last year, we think it’s possible that a high-fiber diet may also be linked to reduced breast cancer. Bran, oatmeal, shredded wheat, whole wheat and whole-wheat flakes—and beans—have the most fiber.
What other foods are related to breast cancer?
Diets high in fat have been linked by some people to hormone-related cancers such as breast and prostate cancer. We see this in Japanese families who move to the U.S. and shift from a low-fat diet to one high in fat. Except for infants, too much fat doesn’t do anything for anyone’s health. Of course, it provides flavor, and it’s unrealistic to think people will cut out all fats. It’s a question of not overdoing.
Cut back on fatty meat. Use low-fat milk, ice milk, low-fat yogurt and reduced-fat cheeses like part-skim mozzarella. We would like to see a cut in fat consumption of at least 25 percent.
After years of ingesting high-fat foods, does it make sense to switch?
Research with immigrants suggests that late-life changes influenced the rates of colon cancer and slowed other cancers.
How do cabbage family vegetables help?
Cauliflower, cabbage, broccoli, brussels sprouts and other members of the cabbage family contain inhibitors that appear to help strip dangerous chemicals of their ability to cause cancer in laboratory animals. We don’t know exactly how they work, but these inhibitors are called indoles. Research is so new that there are no tables ranking foods by indole level.
How much of your “cancer preventives” do you recommend eating?
For vitamins A and C, choose the foods you like best—and eat perhaps two servings per day. For fiber, also eat two or more servings a day. A serving is three quarters of a cup.
If these foods are good for you, is more always better than less?
No. Too much whole-grain fiber in a diet can interfere with the body’s ability to absorb minerals from food. Care should be taken with vitamin C supplements. High dosages can inter-react adversely with some prescription drugs and, in a few cases, speed formation of kidney stones.
Is food preparation involved in cancer?
Broiling meat appears guilty until proved innocent. Some scientists believe that charring meat, whether over charcoal or in the oven or frying pan, produces mutagens, which may increase the chances of cancer. And it’s not just meats. We’re looking into bread crusts, the whole browning reaction. It’s what happens when you heat protein. A related problem occurs when meat is surrounded by a lot of smoke. Chemicals form and appear to lodge on the surface. You shouldn’t eat meat raw, but it’s a good idea to cut down on broiling and instead bake, roast, stew and poach.
Can nutrients cure cancer?
Once the cancer is established and growing, how nutrition can affect it is pretty much unknown.
If your preventive plan is followed, how many lives could be saved?
Some cancers have never been linked to diet—Hodgkin’s disease, cancers of the brain, eye, thyroid, and lymphoma and leukemia, for instance. But British scientists Richard Doll and Richard Peto estimate that better nutrition could reduce colon cancer by 90 percent, breast cancer by 50 percent and lung cancer by 20 percent. Total reduction might reach 35 percent. That translates into about 150,000 lives a year, and that’s a lot of people.