Cutting Back on Fat Is Safe for Kids

From the WebMD Archives

Feb. 5, 2001 -- Most experts agree that too much fat is bad for the heart and that many Americans need to cut back on their intake. But when it comes to children, adequate fat is essential for their growth. So are reduced-fat diets safe for children?

A new study in the February issue of Pediatrics answers that question by showing that cutting back on fat is not only safe for children, it also can help lower cholesterol in children whose levels already are elevated.

The researchers examined the effect that diet had on children with high levels of low-density lipoprotein, or LDL cholesterol. LDL cholesterol is what's called the "bad" cholesterol, the type that can help lead to heart disease. The study also looked at the overall safety of reduced-fat diets in children.

"The importance of this study shows that lowering saturated fat in the diet will lower cholesterol in children and that it's safe to do so," says the study's senior author Eva Obarzanek, PhD, RD, MPH, a nutritionist at the National Heart, Lung, and Blood Institute in Bethesda, Md. "We have a public health recommendation that says people should not get more than 30% of their calories from fat, and [in our study], we put the children on 28% fat."

For the research, more than 600 children were randomly assigned to either continue their usual diet or were placed on a reduced-fat diet. The children were between the ages of 8 and 10 at the beginning of the study, and their cholesterol levels, growth, and nutritional status were followed for seven years.

When the researchers assessed growth and nutritional status, they found that all of the children went through puberty with no difference between the two groups. Both groups also experienced normal growth and reached normal height and weight. The reduced-fat group also had the same levels of vitamin and mineral intake as the children eating an unrestricted diet.

In regards to cholesterol, after one year, the researchers found that the reduced-fat group had lower levels of both LDL and total cholesterol. The same was true after three years.

Things got a little murkier later on. At their five-year follow-up, the difference in cholesterol levels between the two groups seemed to level off. Both groups of children had lower levels of LDL and total cholesterol than when the study began, but now their levels were almost the same. And at the seven-year follow-up, LDL cholesterol had increased slightly, and again, the researchers found little difference between the two groups.

The results are still encouraging, though. The lack of difference at five and seven years may have been due to reduced compliance with the reduced-fat program, says Andrew Tershakovec, MD. "But when they looked specifically at a group of kids who really stayed with the program, then there was more of an effect."

He says that the unrestricted group had better cholesterol levels than expected, "which may have also accounted for the lack of difference at the last follow-up." Tershakovec, who was not involved in the study, is director of the Lipid-Heart Clinic at Children's Hospital of Philadelphia.

Obarzanek points out that going through puberty causes a natural decline in LDL levels. And the small increase at the end of the study may have been due to the adolescents entering adulthood.

The average age at the end of the seven years was 17, she says, and this is the beginning of their LDL level approaching adulthood levels. "We know that adult levels of LDL levels are higher than children's, so there will be a natural rise no matter what we do.

"But the idea is to make the rise a little bit smaller than what it would have been ordinarily," she says.

High-density lipoprotein or HDL cholesterol, the "good" cholesterol, remained similar between the two groups throughout the study. The lower-fat diet did not appear to affect its levels.

However, Gregory Miller, PhD, who is vice chairman of nutrition research at the National Dairy Council in Rosemont, Ill., is concerned about how these study results can be applied to real life.

"They say that it's safe to put kids on a low-fat diet when they're closely followed by pediatricians and nutritionists and are getting a lot of dietary advice on a regular basis," he says, "But this might not work in the real world.

"The children [in the study] were in a very controlled environment," Miller says, "But the reality is that in the real world, where people aren't nutritionists and they're not getting a lot of intervention from a dietician or nutritionist, they may not interpret [a reduced-fat diet] correctly." Miller was not involved in the study.

Tershakovec feels that the fear is unwarranted. He points out that there have been cases in scientific literature where reduced-fat diets caused problems in children, but it generally occurred when the family had gone overboard in restricting fat.

"One message that's important to get across," he says, "is that people who got into trouble are those who gave their child a diet that was inappropriately restrictive. They cut down too much on calories, nutrients, everything -- in addition to fat."

Obarzanek agrees. "There were cases where people just got overzealous. The incidences where we saw problems were where parents were starving their kids, or maybe the kids were doing it to themselves. It was more a calorie reduction rather than just fat reduction."

Parents should get some guidance before they start reducing calories and fat in children, Tershakovec says. "But this study shows that you can make the changes safely in children. Along with promoting a lower-fat diet, the hope is that you'll also be promoting a healthy lifestyle."