Teens who eat little fiber in their diet tend to have bigger bellies and higher levels of inflammatory factors in their blood, both major risk factors for developing diabetes and heart disease, according to a study by Georgia Health Sciences University.

University researchers studied 559 Georgia teens ages 14 to 18 and found that only about 1 percent met the recommended daily fiber intake of 28 grams for females and 38 grams for males. They consumed about one-third of recommended levels on average.

The researchers also found that female teens with a low-fiber diet tended to have higher levels of overall body fat. They did not find the same true in males. Meanwhile, males seemed to reduce their general body fat while on a high-fiber diet.

“The simple message is adolescents need to eat more fruits, vegetables and whole grains,” said Dr. Norman Pollock, bone biologist at the Medical College of Georgia and the Institute of Public and preventive Health at Georgia Health Sciences University.

Researchers know that increasing fiber intake may be challenging, since teens are drawn to processed foods that are notoriously low in fiber. Teens may also be put off by the side effects of eating lots of fiber, which may include intestinal gas, bloating and diarrhea.

The research team hopes to secure funding to develop convenient and palatable forms of fiber. This includes fiber that could be sprinkled on the low-fiber foods that adolescents tend to consume regularly.

How fiber works
The researchers do not fully understand exactly how fiber combats high body fat and inflammatory factors. They hypothesize that increased bulk in the stool causes digested food to spend less time in the gastrointestinal tract.

Another theory is that fiber improves insulin sensitivity and may potentially reduce visceral adiposity.

Fiber tends to speed satiety and may help decrease total food consumption and calorie intake. Finally, fiber may also help absorb and eliminate inflammatory factors.

Fiber performs several key functions in the human body, according to the American Academy of Pediatrics. It is a natural laxative that keeps food moving through the intestinal tract. It may also lower the concentration of cholesterol in the blood.

Getting more fiber
Foods rich in fiber include grains like wheat germ, wheat bran, whole-wheat bread, oat bran, brown rice and barley.

Legumes are also rich in fiber. They include kidney beans, navy beans, pinto beans, black beans, lima beans, lentils and chickpeas.

Fruits and vegetables are also good sources. Some examples include cauliflower, broccoli, celery, potatoes, peas, beans, carrots, apples, oranges, blackberries, tomatoes, dates and raisins. Uncooked vegetables have higher fiber than cooked vegetables.

To increase a teen's intake of fiber, the American Academy of Pediatrics recommends serving uncooked vegetables as snacks. Serve fruits and vegetables with edible skins left on. Serve cooked vegetables while still crisp to retain fiber content.

Garnish salads with seeds and add dates and raisins to snacks and cereals. Substitute whole-grain bread for white bread, and eat plenty of dried beans, peas and legumes. Finally, serve popcorn with little butter and salt for a healthy high-fiber snack.

The study may be the first to correlate dietary fiber intake with inflammatory markers in adolescents. It was published in the Journal of Clinical Endocrinology and Metabolism.