Researchers asked kids to eat muffins and bread with extra flaxseed and found there was no change in their LDL, or "bad" cholesterol, compared to those who ate baked goods made without flaxseed. And their HDL, or "good" cholesterol, went down on the flaxseed diet.
"It didn't have any convincing benefit, and in fact there's some suggestion that it may have actually made (things) worse," said Dr. Brian McCrindle, who worked on the study at The Hospital for Sick Children in Toronto, Canada.
There's disagreement about whether drugs such as statins should be prescribed to children with high cholesterol, so doctors and parents often look for alternatives.
McCrindle said he and his colleagues have been asked about flaxseed by families who were aware of the cholesterol-lowering claims made about the food supplement - and based on their new findings, they won't be recommending it.
Flaxseed can be bought over the counter for about $10 for a month's supply. Some research suggests flaxseed - which is high in fiber and omega-3 fatty-acids - may help lower cholesterol in adults, although the data is mixed.
The seeds themselves can be sprinkled on or baked into food. Flaxseed oil can also be taken in capsule form.
For the new study, researchers split 32 youth between age eight and 18 with high cholesterol into two groups. The children in one group ate two muffins and one slice of bread fortified with 30 grams of flaxseed each day. Kids in the comparison group were given the same baked goods made with whole wheat flour instead of flaxseed.
LDL levels of 130 milligrams per deciliter and above are considered high for children under 20. Kids in the new study started off with a LDL of 135 to 193 milligrams per deciliter. Each also had a parent or sibling with high cholesterol.
After four weeks on the diets, there was no change in LDL or total cholesterol levels among kids eating flaxseed-rich snacks compared to the whole wheat group. However, the flaxseed group did see an average drop in HDL cholesterol of about 7 milligrams per deciliter, from a starting point of 53 milligrams per deciliter.
Young people in both groups gained weight during the study, the researchers reported Monday in JAMA Pediatrics.
"What they were supposed to do was use (the muffins and bread) to replace other foods in their diet, and I think all they did was add it," McCrindle told Reuters Health.
BETTER THAN A TWINKIE
Wendy Demark-Wahnefried, head of nutrition sciences at the University of Alabama at Birmingham, said recent research suggests that whether flaxseed is beneficial - for cholesterol-lowering or anything else - may in part depend on a person's genes.
"There may be some people that are able to metabolize the fatty acids that are in flaxseed a lot better than others," she told Reuters Health. But so far, doctors can't test for those flaxseed-metabolizing genes.
For now, she said taking flaxseed probably won't do kids much harm, but it's unclear whether it will help either.
"Flaxseed is a great source of B vitamins and fiber and that sort of thing, so as far as food value goes, it's certainly a heck of a lot better than eating a popsicle or Twinkie," said Demark-Wahnefried, who wasn't involved in the new research.
"I wouldn't be concerned if (children with high cholesterol) ate it or concerned if they didn't eat it," she said. "The most important thing is to make sure that their weight status is within normal range, and reduce their TV time and their computer time and get them out there and exercising."
