The Fiber Crunch
How much is enough?
A few months ago my 70-year-old father, who looks deceptively young for his age, left his doctor’s office with a simple prescription: eat more fiber—30 grams per day. My mother, the food buyer and chef of the house, asked me, despair in her voice, “How can Dad get that much fiber in a day?”
Like the average American, my father was consuming only about 14 grams of fiber per day, far below the 21 to 38 grams recommended for healthy adults. A routine test detected diverticular pockets developing in his intestine, a condition that can lead to inflammation and infection and that can be the result of inadequate fiber. But 30 grams of fiber sounds like a lot, especially when you realize that white bread has only 0.6 gram per slice. Surely, the solution is not to eat 50 slices of white bread a day.
Although adequate fiber is crucial for colon health and preventing constipation, research is now revealing even more compelling reasons to increase dietary fiber: the prevention of cardiovascular disease, type 2 diabetes and a number of cancers, including rectal, breast, prostate, laryngeal and ovarian.
The human gastrointestinal tract lacks the enzymes to digest fiber, found in structural components of plant cells. Some fibers are soluble in water, while others are not. It is the soluble fibers that have been found to offer health benefits related to cardiovascular disease and diabetes prevention. In one recent review of studies from the United States and Europe, Mark Pereira, an epidemiologist at the University of Minnesota, found that “every time you add 10 grams of fiber, there is a 14 percent reduction for all risks [of coronary heart disease] and a 27 percent reduction in risks for coronary heart disease mortality.”
Insoluble fibers add bulk, which not only promotes a feeling of fullness (aiding in weight loss) but also increases intestinal transit time, reducing the risk of certain cancers. “Fiber found in whole grains and vegetables appears to be most important in reducing the risk of rectal cancer,” says Marty Slattery, professor of health and preventive medicine at the University of Utah. Both soluble and insoluble fibers in foods reduce the meal’s glycemic load.
After listening to the doctor, my father, who for the past 20-odd years has breakfasted on one cup of coffee and two slices of white toast smeared with butter and jam, started eating whole-grain cereals topped with nuts and fruit. It’s the first step in his fiber reform, and he and my mother, who has also benefitted from the changes, are determined to reach the goal.
Any foods high in fiber contain both the soluble and insoluble kind and are often rich in other micronutrients. Look for 3 grams or more of fiber per serving. It helps to keep a bowl filled with fresh fruit on the countertop and nuts readily available.
|Fruit juices||Whole fruits|
|White bread||Whole-grain bread|
|White pasta||Whole-wheat pasta|
|White rice||Brown rice, barley|
|Meat||Beans, lentils, whole grains|
|Meat stews||Bean chilis|
|Cream soups||Lentil soups|
|Chips, crackers||Raw vegetables, nuts|
|Cake or pie||Fresh fruit|
The Age of Fiber
Depending upon your age, fiber requirements vary:
“After age 50, the typical person eats fewer calories, so they also need less fiber,” explains Joanne Lupton, Texas A&M nutrition professor who chaired the Dietary Reference Intakes panel.
If Henry VIII Had Only Had a Cow
Drink more than two glasses of milk a day and your chances of getting gout, an arthritis that typically attacks men, may be cut in half. Researchers suspect that the protein in dairy products may dismantle the chemicals that cause the joint inflammation.
N. Eng. J. Med 350, March 2004.