Dietary Oils May Help Some Fight Fat
THURSDAY July 16, 2009 -- For certain people, dietary oil supplements could help ward off unwanted fat, according to a new study.
Obese older women with type 2 diabetes who added safflower oil or conjugated linoleic acid (CLA) supplements to their diet either decreased their body mass index or boosted their muscle mass, researchers found.
"I don't think it's a magic bullet, but I think it could have enhancing effects," said the study's lead author, Martha A. Belury, the Carol S. Kennedy professor of human nutrition at Ohio State University in Columbus. The study appeared online in the American Journal of Clinical Nutrition.
Belury, who received no funding from the supplement industry, compared the effects of the two oils in 55 obese, postmenopausal women with type 2 diabetes. Their average age was 60. Each woman tried both oils, one at a time, during two 16-week periods separated by a four-week period when they took neither oil.
Participants took eight dietary oil capsules a day, two at each meal and another two at night, for a total of eight grams of added oil per day. In all, 35 women finished both study periods. They didn't change their diet or exercise patterns, although they kept diet and exercise diaries so the researchers could account for any change in energy output and calorie consumption.
Safflower oil is a common cooking oil. CLA, an omega-6 fatty acid, is found in trace amounts in lamb, beef and milk, but researchers prefer to study the commercial CLA supplements, because the concentration in food is too small to have much fat-lowering ability, Belury wrote. Both oils are considered "good" fats when consumed in proper amounts.
The women who took the CLA had a significant decrease in their body mass index (BMI) -- about half a point on average. Their total body fat declined by about 3.2 percent.
The safflower oil did not affect total body fat, but did decrease the trunk, or belly fat tissue, by 2.6 to 4.2 pounds. It also boosted muscle mass by 1.4 to 3 pounds.
The safflower oil also lowered fasting blood sugar levels by 11 to 19 points. Average levels after 16 weeks of safflower oil supplements were 129 to 148, still high but significantly improved, Belury said. (Below 110 milligrams per deciliter is normal).
Belury stressed that the oil supplements could be added to other efforts to reduce weight and tighten diabetes control. "Using one or both of these oils could work into all the other things, such as diet and exercise," she said.
While her study included only women, previous studies have found that CLA lowers fat in men, she said.
How the oils affect fat loss and muscle mass is still unclear. Belury said it may be related to changes in the functioning of adipose tissue, where fat is stored.
Despite Belury's enthusiasm, another expert who reviewed the study was underwhelmed by the findings. "Although the study appears to be fairly well done, there are a lot of limitations and concerns for applying this information to anyone other than postmenopausal, obese women with type 2 diabetes," said Lona Sandon, an assistant professor of nutrition at the University of Texas Southwestern Medical Center at Dallas, and a spokesperson for the American Dietetic Association.
One issue, she said, is the dropout rate, with 20 of 55 women not completing the study. Also, "participants were asked to take eight capsules per day," Sandon noted. "This is a lot of extra pills for women who are already trying to manage diabetes," she said.
Instead of spending money on supplements, Sandon recommends eating a balanced diet that includes heart-healthy polyunsaturated fats and monounsaturated fats and getting regular exercise.
Posted: July 2009