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High Trans Fatty Acid Intake Linked To Coronary Heart Disease

A high intake of trans fatty acids contributes to an increase in risk of coronary heart disease, Dutch research shows.

A relative risk of coronary heart disease (CHD) was increased by around 25 percent for a two percent increase of intake of trans fatty acids at baseline, find researchers led by Dr. Claudia Oomen and colleagues from the National Institute of Public Health and the Environment, Wageningen University, The Netherlands.

Trans fatty acids are mainly present in solid fats produced by part hydrogenation of oils, and are naturally found in products originating from ruminant animals.

Current trans fatty acid intake contributes between 0.5 percent and 2 percent to energy intake in western Europe, and an estimated 2 percent of energy intake in Canada and the United States.

However, evidence on the relation between trans fatty acid intake and CHD is scant. Previous studies in the US showed a detrimental effect of trans fatty acids on low-density lipoprotein and high-density lipoprotein cholesterol.

Evidence that intake of trans isomers affects the rate of CHD is derived from population-based studies in other US studies. Until now, a fairly small number of observational studies have focused on the health effects of trans fatty acids in Europe, with weak or equivocal results.

The Dutch researchers investigated a Dutch population with a fairly high trans fatty acid intake, including trans fatty acids from partly hydrogenated fish oils. Making up the cohort were 667 men of the Zutphen Elderly Study, from the town of Zutphen, who were first studied in an epidemiological study of CHD in 1960. They were aged between 64 and 84 and did not have CHD at baseline.

Dietary surveys were used to establish the participants' food consumption patterns. Information on risk factors and diet was obtained in 1985, 1990, and 1995.

After ten years of follow-up from 1985-95, there were 98 cases of fatal or non-fatal CHD, the investigators found. Between 1985 and 1995, average trans fatty acid intake decreased from 4.3 percent to 1.9 percent of energy.

When investigators adjusted for age, body mass index, smoking and dietary factors, trans fatty acid intake at the start of the study was positively associated with a ten-year risk of CHD. The relative risk of CHD was increased by around 25 percent for each 2 percent increase in trans fatty acid intake at baseline.

"A high intake of trans fatty acids (all types of isomers) contributes to the risk of coronary heart disease," the researchers declared. "The substantial decrease in trans fatty acid intake, mainly due to industrial lowering of trans contents in Dutch edible fats, could therefore have had a large public-health impact."

The decrease in trans fatty acid intake of 2.4 percent of energy could have contributed to about 23 percent fewer coronary deaths, that is about 4,600 of 20,000 coronary deaths in the Netherlands per year. Possibilities for further industrial reductions in trans fatty acid contents in The Netherlands are now restricted to bakery products and fast foods.

Investigators conclude that "the substitution of trans fatty acids requires further attention, because in the current manufacturing process trans fatty acids are partly replaced by saturated fatty acids."
Lancet 2001;357:746-51. "Association between trans fatty acid intake and 10-year risk of coronary heart disease in the Zutphen Elderly Study: a prospective population-based study"

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