Changing dietary fats could reduce disease risk: Study

21-Oct-2009 - Last updated on 22-Oct-2009 at 14:53 GMT

Related tags Nutrition

Consuming a diet rich in monounsaturated fats could lower the risk of metabolic syndrome – even without weight loss, says a new study.

Metabolic syndrome is a condition that encompasses a number of risk factors for overweight and obesity, such as a large waistline, hypertension, high blood pressure, and low levels of HDL (high-density lipoprotein) cholesterol – so-called ‘good’ cholesterol. This latest study, published in the American Journal of Clinical Nutrition, adds further weight to the idea that monounsaturated fat can help reduce LDL (‘bad’) cholesterol while diets high in saturated fat are linked to higher rates of tissue inflammation.

Inflammation related to obesity is known to contribute to the development of a range of disorders, including type-2 diabetes, heart disease, insulin resistance, and fatty liver disease.

“Several studies have show increased inflammation in adipose tissue of obese subjects and revealed its possible role in the development of insulin resistance,” the authors wrote. “Our study suggests that the type of dietary fat is an important component in the cause of adipose tissue inflammation.”

Dietary composition

The Dutch researchers selected twenty ‘moderately overweight’ subjects for the study on the basis of a body mass index (BMI) of 25 or over, or a waist circumference of at least 80cm for women and 94cm for men. All subjects consumed a diet rich in saturated fat for a two-week ‘run-in period’ and then ten continued on this diet for a further eight weeks, while ten received a diet rich in monounsaturated fats, mainly in the form of refined olive oil.

The diets were similar in terms of total fats, protein, carbohydrates and dietary fiber, but the saturated fat diet contained 19 percent saturated fatty acids (SFAs) and 11 percent monounsaturated fatty acids(MUFAs), while the monounsaturated fat diet contained 11 percent SFAs and 20 percent MUFAs. The researchers monitored weight and adjusted energy intake in order to prevent weight changes.

Monounsaturated fat, reduced cholesterol

The researchers found that the MUFA diet led to reduced total and LDL cholesterol, but did not affect insulin sensitivity, although they hypothesized that the intervention period may have been too short to observe changes in insulin sensitivity.

However, they noted that it was difficult to distinguish whether the beneficial effects of the MUFA diet were due to higher levels of monounsaturated fat or lower levels of saturated fat. “It could be a combination of both,” they wrote.

Source: American Journal of Clinical Nutrition

Published online ahead of print

“A saturated fatty acid–rich diet induces an obesity-linked proinflammatory gene expression profile in adipose tissue of subjects at risk of metabolic syndrome”

Authors: Susan J van Dijk, Edith JM Feskens, Marieke B Bos, Dianne WM Hoelen, Rik Heijligenberg, Mechteld Grootte Bromhaar, Lisette CPGM de Groot, Jeanne HM de Vries, Michael Müller, and Lydia A Afman.