Dietary saturated fatty acids (12:0, 14:0, 16:0) differ in their impact on plasma cholesterol and lipoproteins in nonhuman primates

Article Abstract:

An elevated level of total blood cholesterol is well known as a risk factor for atherosclerosis. Decreasing intake of saturated fatty acid (chemically, fat components without double bonds) decreases blood cholesterol level more effectively than increasing intake of polyunsaturated fatty acids, molecular components of fat containing more than one double bond. Subjects with elevated cholesterol respond better to changes in dietary fatty acids than those with normal cholesterol levels. It is not clear whether all saturated fatty acids have the same impact on blood cholesterol levels, because results from previous studies have conflicted. To better distinguish among effects of saturated fatty acids with 12, 14, or 16 carbon atoms per molecule, (12:0, 14:0, and 16:0, respectively), the effects of these dietary fatty acids on the cholesterol response in three types of monkeys with varying susceptibility to atherosclerosis were evaluated. Five diets containing blends of oils but equal levels of total fat were used, with diet 1 containing chiefly saturated fats, while diet 5 contained roughly equal amounts of saturated and polyunsaturated fats and approximated American Heart Association dietary recommendations. When results from all monkey species were combined, there was a 25 percent decrease in blood cholesterol upon shifting from diet 1 to diet 5. As the content of 12:0 and 14:0 decreased and 16:0 increased, blood cholesterol measurably declined. This effect was not obvious when the decline in 12:0 and 14:0 was from 10 percent to 6 percent of total calories, but rather was only evident when these fatty acids were nearly absent. Similarly, substitution of 16:0 for some polyunsaturated fatty acids increased blood cholesterol insignificantly, while a similar substitution with 12:0 and 14:0 caused a significant increase in blood cholesterol. Similar but less predictable trends occurred in blood levels of triglyceride (fat). The different responses among varying monkey species are described. The study indicates that unsaturated fatty acids do not have equal effects on blood cholesterol and should be considered separately when studying the impact of dietary fat on risk for cardiovascular disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Fatty acids, Hypercholesterolemia

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Platelet aggregation in humans is affected by replacement of dietary linoleic acid with oleic acid

Article Abstract:

The typical US diet has a high level of saturated fatty acids, and this is thought to increase the risk of thrombosis (clot formation) in arteries. Increased thrombosis is thought to be related to increased aggregation of platelets, and a decrease in fat intake or replacement of saturated with polyunsaturated fatty acids can decrease platelet aggregation. However, previous studies of the effects of polyunsaturated fatty acids on platelet aggregation did not control the levels of total fat or saturated fat. In this study, levels of total and saturated fat were kept constant while dietary levels of linoleic acid (LA, a polyunsaturated fat) levels were changed for 80 days in seven healthy men. In addition, the effect of antioxidants, compounds such as vitamins E, C, and A, and selenium, which are needed to protect against harmful effects of LA, was studied. Platelet fatty acid composition changed in response to dietary manipulations. Platelet aggregation sensitivity to stimulation by either of two compounds decreased, after 63 days, in subjects given diets high in LA, while the low-LA diet had no effect. Blood levels of vitamins E and A did not change significantly during the study. The study suggests that modifications of dietary fat composition, without changes in consumption of total fat, may decrease the responses of platelets to factors which cause aggregation, implying a diminished risk for arterial clot formation. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors, Coronary heart disease, Linoleic acids, Linoleic acid

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Taurine modulates platelet aggregation in cats and humans

Article Abstract:

The relationship between taurine (amino acid in bile) and platelet (component of blood responsible for clot formation) function was explored in cats and humans. Under laboratory conditions, platelets from taurine-depleted cats were twice as sensitive to clotting as those from healthy cats. Platelets from healthy humans became 30 percent more resistant to clotting when subjects were given 400 milligrams of taurine per day, and 70 percent more resistant when subjects were given 1600 milligrams per day. Decreased clotting was associated with increased levels of taurine and glutathione (aids various chemical reactions in body) and decreased release of thromboxane (induces clotting) during blood clotting. This indicates that taurine stabilizes platelets against aggregation, so that a lack of taurine makes them clot too easily and an excess makes them clot less.

Blood clotting, Blood coagulation, Taurine

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