Genes Steer Your Cholesterol Ship
Dec. 5, 2000 -- If you're like a lot of Americans, you probably
could stand to lower your cholesterol. A new study shows that the choice to do
so is up to you -- well, sort of. The researchers tell WebMD that genes may
have more power than sheer will in the fight against high cholesterol.
"We were looking into why people differ in their response
to cholesterol lowering diets," says study leader Margo A. Denke, MD,
associate professor of medicine at the University of Texas Southwestern Medical
Center in Dallas. "Some people try very, very hard on a diet, but can't
even budge their cholesterol levels. We were trying to determine how much of
that was due to genetics."
Between 1997 and 1999, 56 families -- 92 adults and 134
children -- in the Dallas-Ft. Worth area followed two special diets.
During the study, all members of a family got their fat --
20-25% of total calories -- in the form of either saturated fat-laden butter or
margarine with unsaturated fat. For each regimen, families were provided with
specially formulated breads, baked snacks, and spreadable fat for cooking.
After five weeks, they went back to their normal diet for a month, then
switched to the other diet for five more weeks. Cholesterol levels were
measured at different intervals during the study.
The research -- which, luckily for the study participants, was
halted between Thanksgiving and Christmas each year -- is published in the Dec.
6, 2000 issue of The Journal of the American Medical Association.
"In our study, 80% of people had lower cholesterol levels
when they consumed margarine compared to butter," Denke, who is also at the
UT Southwestern's Center for Human Nutrition, tells WebMD. Although the overall
trend was for cholesterol levels to drop with less saturated fat intake,
genetics definitely played a role. Parents who responded -- whose cholesterol
went up and down with diet -- had children who responded as well. "And if
the parents don't respond, neither do the children," she says.
People are powerless over their genes but one take home message
"is that margarine is a better choice than butter, which is one of the most
potent cholesterol-raising fats," says Denke. There is increasing evidence,
including a recent study looking at the blood vessels of children who'd died in
car accidents, that plaques that clog blood vessels begin forming much earlier
than previously thought. "What you eat really is very important," she
says, "and it is especially important to start out right. There will be big
pay-offs as you get older for learning a good diet when you're young."
The second, less obvious point, she says, is that heavier
people reap much less benefit from cholesterol-lowering diets than do thinner
folks. "A person who's overweight gets into trouble for two reasons. Being
overweight itself raises their cholesterol," she explains, "and even
when they try to lower cholesterol by diet, they won't get as much cholesterol