Saturday, 19 November 2011
Tropical oils don`t boost some heart risk markers
Tropical oils may be sources of saturated fat, but a small study suggests that they do not boost certain markers of trouble in the blood vessels the way animal fats do.
In general, experts advise people to limit saturated fat in their diets because it raises blood cholesterol levels and has been linked to an increased risk of heart disease.
Meat and full-fat dairy products are probably the best-known sources of saturated fat, but certain vegetable oils -- like palm and coconut oils -- contain it too.
Different saturated fats are not exactly alike, however. And in societies where those tropical oils are used liberally, heart disease is less of a problem compared with Western countries, noted Phooi Tee Voon, a researcher at International Medical University in Kuala Lumpur, Malaysia, who led the new study.
In the study, Voon`s team followed 45 healthy Malaysian adults who spent five weeks on each of three diets: in one their main fat source was palm oil; in another it was coconut oil; in the third it was olive oil -- an unsaturated fat that`s considered heart-healthy.
The researchers found that regardless of the fat source, participants` blood levels of certain inflammatory proteins remained the same.
That`s important because at high concentrations, those proteins -- which include homocysteine, C-reactive protein and others -- are thought to damage the blood vessels and contribute to heart disease.
When it came to cholesterol, study participants showed no increase while on the palm-oil diet, but did see their numbers creep up while using coconut oil -- though that included an increase in "good" HDL cholesterol.
So should you feel free to swap your olive oil for the tropical versions?
"I`d say, hold the phone on that," said Roberta Anding, a registered dietitian and spokesperson for the American Dietetic Association.
A big limitation is that the study participants were on carefully controlled diets, explained Anding, who also directs sports nutrition at Texas Children`s Hospital in Houston.
The researchers supervised breakfast and lunch, and doled out packaged dinners. It was "very nicely controlled," Anding said, in order to isolate the effects of the different fats -- which is a good research design.
"But that`s not how people eat in the real world," Anding said.
In addition, people in the study followed a traditional Malaysian diet -- consisting of rice, chicken, fish and vegetables.
As part of a Western meat-and-potatoes diet already high in saturated fat and refined carbohydrates, palm and coconut oils might have quite different effects, according to Anding.
"I think if you were to keep eating your hamburgers and your fries, and then add coconut and palm oils, you could create the perfect storm," Anding said.
A study from Denmark published earlier this month also tested diets emphasizing palm oil, olive oil or lard, and found that the olive oil diet lowered cholesterol levels while palm oil and lard both raised cholesterol by about five percent. None of the fats influenced inflammatory proteins in that study.
The Malaysian study, which was funded by the Malaysian Palm Oil Board, appears in the American Journal of Clinical Nutrition.
Because it was limited to five-week diets, nothing can be concluded about the ultimate impact of the oils on people`s heart health.
But one thing the study does highlight is the fact that no single nutrient works in isolation, according to Anding.
"No individual dietary component can be labeled a demon," she said.
Eating a generally heart-healthy diet full of foods like fruits, vegetables, whole grains and fish is what`s key, according to Anding. So if you are cooking your vegetable stir-fry with some coconut or palm oil, then on balance, you are probably doing well, she said.
In general, though, many experts recommend limiting saturated fat. The American Heart Association says people should keep saturated fat (from all sources) to less than seven percent of your total daily calories. (That`s 140 calories if you eat 2,000 calories in a day.)
Instead, the heart association says, opt for unsaturated fat from vegetable oils and fish.
And if you`re overweight, Anding said, calories definitely count. "If you want to lose weight, you have to cut out calories."