Margarines are a healthy choice according to a CSIRO study.
The study, published recently in the American Journal of Clinical Nutrition, indicated that the benefits of polyunsaturated margarines are enhanced when they are also low in trans fatty acids, substances which raise total blood cholesterol.
Clinical trials conducted at CSIRO Human Nutrition in Adelaide, compared the effects of four types of margarine on blood cholesterol. The margarines were polyunsaturated or monounsaturated, with or without trans fatty acids. Thirty eight men and women with mildly elevated cholesterol took part in the feeding trial, lasting 11 weeks.
The results of the study showed that, compared to saturated fat spreads, any of the four margarines reduced the level of LDL (bad) cholesterol in the blood by 11 - 15 per cent. This corresponds to a fall in the risk of heart disease of approximately 20 - 30 per cent. HDL (good) cholesterol was unchanged. In an unexpected finding, the margarine high in polyunsaturates and low in trans fatty acids produced a greater fall in blood LDL-cholesterol than the other margarines.
"The margarine high in polyunsaturates and low in trans fatty acid lowered LDL-cholesterol a further 6 per cent compared to other margarines, a statistically significant difference", said CSIRO researcher Manny Noakes.
"Based on our data, the fall in heart disease risk could be reckoned to be 13 per cent greater with the polyunsaturated margarine without trans fatty acids than a similar spread with trans fatty acids."
Trans fatty acids are a minor class of fats found in small quantities in certain animal products. They used to be present in moderate quantities in margarines. However, there has been an international trend to reduce levels of trans fatty acids in margarines.
Approximately half the margarines on the Australian market do not contain trans fatty acids.