Making sense of nutrition 'sound bites'
Interview by Debra Ruder
Illustration by Lee Whale
Turn on the news or flip through a magazine, and you may very well hear about a new study claiming the benefits or drawbacks of a certain food or nutritional supplement. For patients, these media messages can be frustrating and confusing. But for Stacy Kennedy, MPH, RD, LDN, the changing landscape is exciting. "The ability to study how foods affect cancer risk, development, and progression is a relatively new science," she says, "and some of the inconsistencies are due to the fact that we're still learning."
Kennedy is one of seven full- and part-time registered dietitians staffing the Dana-Farber/Brigham and Women's Cancer Center (DF/BWCC) Nutrition Department, one of the largest outpatient oncology nutrition departments in the country. The team logged 5,200 adult visits last year, and there's a separate nutrition group for pediatric cancer patients seen in Dana-Farber's Jimmy Fund Clinic. Kennedy discussed the foundation of a healthy diet recently with Paths of Progress Editor Debra Ruder.
Paths of Progress (POP): We know that many cancers are preventable; according to the American Cancer Society, one-third of cancer deaths in the U.S. each year are related to poor diet, being overweight, and physical inactivity. [Tobacco use accounts for another one-third of cancer deaths.] What have we learned about the link between diet and cancer?
Kennedy: Diets lacking in plant-based foods, as well as those containing a lot of processed foods, tend to be connected to higher rates of cancer. So this is one area where people can take action to help reduce their risk. Many patients will say, "I've eaten healthfully my whole life, I've exercised, and here I am in this chair with cancer." We believe diet can influence when a cancer might develop and its aggressiveness, rather than determine whether or not someone will get cancer.
POP: What are the main steps you recommend?
Kennedy: The basic principles of healthy eating are very similar for cancer prevention, symptom management during treatment, and survivorship; it's really a matter of tweaking the details depending on your circumstances. The cornerstone is what we call a plant-based diet. It doesn't mean you have to become a vegetarian, but we encourage people to include more plant foods on their plates. That means fruits and vegetables, but also spices and seasonings like turmeric or parsley, soy foods, and nuts and beans/legumes – anything that comes from a plant. We also urge them to limit processed foods, which generally have higher levels of sugars, salt, trans fats, preservatives, and artificial flavors.
POP: So if you're planning to have a steak, have some broccoli or salad on the side?
Kennedy: Correct – and choose a lean cut and don't burn the steak. If your plate is a circle (see illustration above), half your plate should be from plants, one-quarter should be a lean protein source like fish, and one-quarter should be a carbohydrate, preferably a whole grain. Within a plant-based diet, you also want to choose a variety of foods. You can use color as a guideline; many of the phytonutrients [plant-based nutrients such as carotenes] are concentrated in the pigment or pungency. Even white plant foods like onion, garlic, and cauliflower have cancer-fighting properties. One interesting tidbit: If you crush or chop garlic, let it sit at room temperature for 15 minutes before cooking, as that enhances its anti-cancer potency.
POP: How do you know when something is whole grain?
Kennedy: You want the first ingredient on the list to say "100 percent whole _____," like wheat. A package might say, "made with whole grain" or "good source of whole grain," but that signifies a lower percentage of whole grain in a product – sometimes only 15-25 percent. Whole grains are less processed and refined, so the healthy nutrients naturally in them are left intact; you will get more fiber, minerals, and other vitamins important for keeping your immune system strong. Examples of whole grains are brown rice, barley, bulgur wheat, oats, and flax seeds.
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