High fiber trumps low fat for teen diets

MICHIGAN STATE (US) — A diet high in fiber—but not necessarily one low in saturated fat or cholesterol—is tied to a lower risk of heart disease and type-2 diabetes in teenagers.

A new study published in Journal of the American Dietetic Association, suggests the best way to reduce metabolic syndrome—a collection of risk factors including high blood pressure and a large waistline—is to emphasize diets that include fiber-rich, nutrient-dense, plant-based foods rather than focusing on restricting foods high in cholesterol or saturated fat.

“What we found is that as fiber intake increases, the risk for metabolic syndrome decreases,” says dietitian Joseph Carlson, associate professor of Michigan State University‘s division of sports and cardiovascular medicine.


“High-fiber, nutrient-dense foods are packed with heart healthy vitamins, minerals, and chemicals that can positively affect many cardiovascular risk factors. It may be better to focus on including these foods than to focus, as is commonly done, on excluding foods high in saturated fat.”

The findings don’t mean that teens should have carte blanche in eating foods high in saturated fat and cholesterol, Carlson says. “It is well established that saturated fat can raise bad cholesterol. What this data suggest is the importance of including foods high in dietary fiber.”

With the high availability of processed foods today, it’s possible for teens to eat a diet that is low in saturated fat and cholesterol but that also is low in fiber and nutrient-rich, plant-based foods. Recent national data indicates up to 30 percent of teens’ dietary intake comes from beverages and sugar-rich snacks.

Because teens don’t eat a lot of fruits, vegetables, whole grains, and beans, their total dietary fiber intake is about 13 grams per day, well below the recommendation of 26 grams and 38 grams for female and male adolescents, respectively.

In addition, obesity and other key risk factors associated with metabolic syndrome are on the rise in youth; more than 70 percent of teens in the study had at least one of the five risk factors used to assess metabolic syndrome: high blood pressure, high levels of sugar and fat in the blood, low levels of good cholesterol and a large waistline (a person having three or more of the factors are classified as having the syndrome).

“One of the takeaways is that our study reinforced the current dietary recommendations for dietary fiber intake by including a variety of plant-based foods,” Carlson says. “A strategy of emphasizing fiber-rich foods may improve adherence to dietary recommendations.”

The next step is to figure out the best methods to boost dietary fiber intakes to levels that will improve or sustain a desirable cardiovascular risk factor status. For example, if a person daily has three servings of fruit and vegetables (12 grams of fiber), one serving of beans (seven grams), and three servings of whole grain, they will be at about 30 grams of dietary fiber.

“The trick is getting people in the groove finding the foods that they both enjoy and are convenient,” Carlson says.

As part of the cross-sectional study, the researchers focused on data collected as part of the National Health and Nutrition Examination Survey done from 1999-2002. They analyzed the diets of more than 2,100 boys and girls ages 12 to 19, looking at whether the teens had three or more conditions that make up metabolic syndrome.

The study found there was a three-fold increase in the number of children that had metabolic syndrome when the group of children receiving the least fiber was compared with the group receiving the most. There was not a significant relationship with either saturated fat or cholesterol intake.

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