Winter 2008

A Balancing Act

What is good for the heart may also work against cancer





Dr. Alan Kristal isn’t thinking about antioxidants or omega-3s when he sits down to his dinner of pan-seared pork tenderloin.

As he savors some red wine and enjoys mixed greens tossed with a plethora of colorful, crisp vegetables, a bit of aged Parmesan, olive oil and balsamic vinegar, he’s simply taking pleasure in good food.

Though news headlines tout the food-as-medicine benefits of everything from blueberries to green tea, when it comes to cancer prevention, very little is known about food’s ability to stop cancer from occurring or recurring.

It’s not for lack of trying. But cancer—in all its types and stages—is a very complicated and diverse disease. And measuring people’s eating habits with precision is difficult and expensive. Researchers have found strong associations between diet and heart disease, but not cancer.

Kristal, a nutritional epidemiologist in the Cancer Prevention Program at Fred Hutchinson Cancer Research Center and a professionally trained chef, has conducted some of the most in-depth studies on the effects of certain foods on cancer risk. What we know for sure, he says, is that eating a diet that is good for your heart is likely to be good for warding off cancer.

There’s one certainty that has come out of research: obesity increases the risk of getting cancer, as well as many other diseases. For breast and prostate cancers, there’s also strong evidence that obesity increases the risk of dying from those diseases in people under 65.

But extreme diets aren’t necessary to maintain a healthy weight. Many studies of sustained weight loss show keeping active, consuming less fat and filling up on fruits and vegetables is the easiest way for people to stay slim for their entire lives.

Globally, many people hold mistaken beliefs about what causes cancer, tending to inflate the threat from environmental factors that have relatively little impact while minimizing the hazards of behaviors that have been well-documented as risk factors, a recent International Union Against Cancer survey found.

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Vegetables: The key to good health

The good news is that people have a lot of control over obesity.

“Obesity isn’t magic. It happens because you eat too much and exercise too little,” Kristal said. (See related article on page 12.)

Dr. Alan Kristal 
So if drinking gallons of pomegranate juice in the name of good health and worrying about environmental toxins more than your waistline is based on shaky science at best, how do you face the daunting task of navigating the 50,000 products carried by most United States’ supermarkets?

Kristal offers some common-sense suggestions for what to eat, based on strong scientific evidence.

He recommends consuming lots of vegetables, especially cruciferous ones like broccoli, Brussels sprouts, cabbage and bok choy. And eat a wide variety of veggies, from artichokes to yams.

“You should really eat a cup of vegetables at lunch and another cup at dinner, and if you can eat more, all power to you,” Kristal said. Vegetables make great between-meal snacks and can be mixed into other foods.

Research also shows great benefits of eating fish, particularly fatty species like salmon and albacore tuna.

“The oils change metabolic processes, leading to decreased inflammation and lowered risk of heart disease,” Kristal said. “Yes, there are some concerns about contaminants in fish, but that risk is small and the benefits are strong.”

Nutritionists recommend including plenty of filling fiber in your diet from whole-grain products like brown rice and whole-wheat cereal to pasta and bread. But Kristal—not personally a fan of whole-wheat pasta—absolves people from eating foods that taste bad to them. “You need to enjoy your food,” he said.

If you eat meat, choose lean cuts of meat and poultry, and limit yourself to a modest portion (under 6 ounces, preferably below 4 ounces). Be careful about the fat lurking under chicken skin; it’s good to remove the skin and cut off all the extra fat. Charbroiling meats (especially over charcoal) and browning meat in fat over high heat is known to produce cancer-causing chemicals, so eat charcoal-grilled and pan-seared meats no more than once a week.

Fruits also make the list of foods to eat, even though the cancer-prevention evidence is much stronger for vegetables.

“Still, if you’re eating fruit instead of having ice cream or a candy bar, that’s a very good choice,” Kristal said. Variety and regular consumption are key.

If you consume dairy products, Kristal urges choosing reduced-fat types. And when using fats and oils, do so sparingly.

But remember that fats also provide nutrients that are important to maintain normal metabolism. Canola and olive oils have high levels of monounsaturated fats, which can help reduce bad cholesterol levels in your blood and lower your risk of heart disease and stroke. Foods like avocados, peanut butter and many nuts and seeds are healthful foods, but should be enjoyed in moderation.

Along with the foods to choose, Kristal and other experts warn of some common dietary pitfalls to avoid.

If you drink alcoholic beverages, do so in moderation. This means no more than two to three drinks per day for men and one to two drinks daily for women. At these levels, alcohol decreases the risk of heart disease. But drinking more increases the risk of obesity, breast and oral cancers, and liver disease.

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Steer clear of fast food whenever possible

“Yes, fast food is cheap food and that’s part of its popularity, but it’s really expensive when you look at what it can do to your health,” Kristal said. “It’s not hard to get more calories in one fast food lunch than you need for the whole day.” For many families, cooking healthy meals at home saves a lot of money. If you must choose a meal on the go, there are healthier options, such as buying fast food that is fresh, not fried, and containing plenty of vegetables.

It’s not necessary to take vitamins and supplements, which Kristal calls “a huge industry built on nothing.” With the exception of moderate doses of vitamin E and selenium, there’s good evidence that vitamins and supplements don’t affect cancer or cardiovascular disease. In fact, taking large doses of vitamins and supplements—which some people do, believing “it can’t hurt”—can be harmful.

There’s much better evidence for getting benefits from foods themselves than from a concentrated extract, despite the many studies examining the effects of antioxidant compounds on cancer cells grown in test tubes. “It’s all very exciting in test tubes, but when you test these compounds in humans, it just falls apart,” Kristal said.

Foods that become the latest rage—think oat bran or goji berries—are usually good as part of the diverse range of foods you eat. But eating huge quantities of one item or trying to achieve the same result in pill form misses the point.

“When we pull one little thing out of food or concentrate on just one food, we lose the benefits of eating a mixture of healthy foods,” Kristal said. “Our chronic exposure to foods is much more important. And this ‘medicalization’ of foods is bogus.

“The smartest thing to do is eat foods that are optimal for your heart, which is probably also reducing your risk of cancer.”

With his culinary training, Kristal enjoys cooking and routinely prepares delicious food. He doesn’t follow his own advice all of the time, but instead advocates for balance, since food is as much about enjoyment as health.

“I use a little butter, and I brown foods often because it tastes good,” he said. “You take your risks. You can moderate your exposure and hope for the best.”

Keeping off the pounds and eating a heart-healthy diet are not guaranteed to keep you safe from disease, but they are excellent at putting the odds in your favor.

Learn more

When it comes to dietary health claims, be skeptical. Recommendations for further reading:

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