American Institute for Cancer Research
Newsletter 91, Spring 2006

Go Green Gradually

Adding more vegetables, fruits, whole grains and beans to your diet can help bolster your overall health and reduce cancer risk. To help your body adjust to a mostly plant-based diet that is high in fiber, starting slowly is key.

People who are eager to reap the health benefits of a high-fiber diet may try to do too much too soon. Similar to exercise, it’s wise to begin slowly when incorporating plenty of fruits, vegetables and whole grains into your diet for protection against cancer. “In my gastroenterology practice, I often see patients consuming fiber to excess,” says Antoinette Saddler, M.D., Assistant Professor of Internal Medicine at the University of Virginia Health System’s Digestive Health Center of Excellence in Charlottesville. “They ingest a huge amount of fiber, eating multiple bran muffins for breakfast, lots of broccoli and so on. You have to increase your fiber intake gradually so that your body can adjust.”

Gradually adopting a mostly plant-based diet will allow you to enjoy the many health benefits while preventing possible side effects.

Weeding Out Problems

Although a plant-based diet can help prevent many health problems, it can cause some discomfort if not adopted gradually. Gas is one of the most common types of distress.

“When you’re eating high-fiber foods, they pass into the colon where bacteria digest them. This process produces gas,” says Dr. Saddler. “People should introduce fiber slowly, chew their food well, minimize air swallowed and minimize how many carbonated beverages they consume.”

Enzyme supplements can help reduce intestinal gas that comes from fiber-rich foods. One very nutritious food that many people avoid for fear of developing intestinal gas is cooked dried beans. Unfortunately, they are missing out on a delicious, lowfat source of protein that also contains cancer-fighting folate and fiber, along with important minerals like potassium, magnesium and iron.

According to Registered Dietitian Karen Collins, gas forms in some people because their digestive enzymes do not break down certain complex carbohydrates in these foods. Therefore, the foods ferment excessively in the large intestine and emit gas. She suggests that people who develop gas after eating cooked dried beans and peas should look for supplements that contain the enzyme alpha-galactosidase.

“You need to consume the supplements just before or at the same time you eat the food,” says Collins. “They can’t be added to the food while it cooks. You also can lessen the gas produced by canned beans by rinsing them well. For dried beans, soak them several hours or overnight. Discard the water they soaked in before cooking them.”

Plant Foods and Digestive Illnesses

Some people associate consumption of certain vegetables with heartburn as well as intestinal gas. But other factors are often more to blame.

“A high-fat meal, swallowing larger chunks especially of meats, and some common foods like orange juice can lead to heartburn in some people,” says Dr. Elaine Feldman of the Medical College of Georgia. Caffeine, mints, garlic, alcohol and chocolate can cause heartburn and gastric distress too, as can lifestyle
factors such as smoking, stress, rushing through meals, or lying down too soon after eating. Sometimes acidic vegetables and fruits, such as citrus fruits and tomatoes, may contribute to heartburn. Feldman suggests cooking tomatoes, onions and garlic to help offset any discomfort these healthful plant foods may cause.

When you cook fruits and vegetables to ease digestion, use lowfat cooking methods (bake, broil, steam, stir-fry, or poach) and choose healthy fats (olive oil, canola oil, or another monounsaturated oil). Drink plenty of liquids including hot tea and fat-free, reduced-sodium broth. Last, but not least, exercise daily to help move waste through the system and prevent cancer.

As for conditions such as diverticulitis and ulcers, Dr. Saddler says, “People frequently confuse diverticulitis actual infection with diverticulosis, a condition of pockets in the bowel,” she explains. “Doctors may tell patients with diverticulosis to avoid small seeded items, but I have not seen definitive data that proves this prevents the condition. People with diverticulosis should eat a high-fiber diet to reduce developing pouches.”

She notes that a plant-based diet should have little or no impact on ulcers. “People have heard through the years that spicy foods and acidic foods will cause ulcers, but this is a myth,” Dr. Saddler explains. “They should worry more about the aspirin and ibuprofen they take rather than the pizza they ate.” (Most ulcers are caused by an infection of the bacterium Helicobacter pylori.) Fiber-rich foods also can relieve constipation. “One of the great things about a plant-based diet is that it helps with bowel movements,” Dr. Saddler says.

“There is a lot of constipation among older people because their colon motility slows down. They may have diseases or take drugs that cause constipation,” she says. “It is important to increase water when you increase fiber to help with constipation.” Older people should drink fluids before they become thirsty, because the sense of thirst decreases with aging.

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