Fats - quality more important than quantity?

By Stephen Daniells

- Last updated on GMT

Related tags Fatty acids Nutrition

Replacing unhealthy fats with healthy alternatives reduces risk
markers for cardiovascular disease (CVD) more than reducing the
quantity of fat, suggests new research from the US.

The study, by researchers from the University of Alabama at Birmingham, New York Obesity Research Center at St Luke's-Roosevelt Hospital, and Frito-Lay, could challenge the view that all high-fat products are unhealthy "The perception that all high-fat snacks are unhealthy may be wrong," wrote lead author Marie-Pierre St-Onge in the American Journal of Clinical Nutrition .

Clinical trials and observational studies have reported strong associations between dietary fat intake and a lowered risk of CVD, the causes almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169 billion ($202 billion) per year.

According to the American Heart Association, 34.2 percent of Americans (70.1 million people) suffered from some form of cardiovascular disease (CVD) in 2002.

The new study aimed to investigate if the type of fat could also impact on markers of CVD, by replacing low-fat and high-fat snacks with snacks rich in polyunsaturated fatty acids (PUFAs) and low in saturated and trans fatty acids.

The researcher recruited 33 volunteers and randomly assigned them to received snacks classified as low-fat (30.8 per cent of energy from fat, 5.2 per cent from PUFAs), high-PUFA (36.3 per cent from fat, 9.7 per cent from PUFAs), or high-fat (37.9 per cent from fat, 5.8 per cent from PUFAs).

After 25 days, participants crossed-over to consume one of the other snacks.

Three feeding phases were included in the study.

While each diet led to reductions in total and LDL-cholesterol levels, greater reductions were observed for the low-fat and the high-PUFA diets, compare dot the high-fat diet.

Specifically, LDL cholesterol levels were cut by 11.8 and 12.5 per cent for the low-fat and the high-PUFA diets, respectively, compared to an 8.8 per cent reduction following the high-fat diets.

Total cholesterol levels were cut by 10.5 and 10.7 per cent for the low-fat and the high-PUFA diets, respectively, compared to an 7.9 per cent reduction following the high-fat diets.

St-Onge and co-workers also reported that the high-PUFA diet led to a 9.4 per cent reduction in triacylglycerol concentrations, significantly greater than any reduction observed for the other diets.

"These data show that snack type affects cardiovascular health," wrote the authors.

"Consuming snack chips rich in PUFA and low in saturated or trans fatty acids instead of high-saturated fatty acid and trans fatty acid or low-fat snacks leads to improvements in lipid profiles concordant with reductions in cardiovascular disease risk," they concluded.

Numerous studies in the literature show that trans fatty acids raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation, can cause endothelial dysfunction, and influence other risk factors for CVD.

Source: American Journal of Clinical Nutrition June 2007, Volume 85, Number 6, Pages 1503-1510, "Snack chips fried in corn oil alleviate cardiovascular disease risk factors when substituted for low-fat or high-fat snacks" Authors: M.-P. St-Onge, I. Aban, A. Bosarge, B. Gower, K.D. Hecker and D.B. Allison

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