Objectives: In two studies we have compared the effects of four different saturated fat diets (medium chain fatty acids (MCFA), and lauric, myristic and palmitic acids) with those of a monounsaturated oleic acid diet on in-vitro whole blood aggregation in healthy women and men.
Design: Study 1 had a cross-over design with three diet periods of each six weeks, and studied the effects of diets enriched in lauric, palmitic or oleic acids. Study 2 had a parallel design. After a three week oleic acid run-in diet, three groups of subjects were formed which consumed either an MCFA, myristic acid or oleic acid rich diet for six weeks.
Subjects: Eighteen women and 14 men in Study 1 and 37 women and 23 men in Study 2. All subjects were healthy and were aged 20-60 y.
Interventions: The experimental diets were the same in nutrient composition except for on average 8 En% (Study 1) or 10 En% (Study 2) which was provided by either MCFA, lauric acid, myristic acid, palmitic acid or oleic acid. Blood samples were taken at the end of each dietary period. Whole blood platelet aggregation, anticoagulated with recombinant hirudin was assessed after administration of collagen (final concentration (fc): 0.38 microgram/mL) in Study 1 and collagen (fc: 0.22 microgram/mL) or ADP (fc: 1.25 mumol/L) in Study 2. Collagen-induced formation of thromboxane (Tx)A2, measured as thromboxane (Tx)B2, was evaluated in Study 1 only.
Results: The aggregation velocity between the saturated fatty acid diets and the monounsaturated fatty acid diet did not differ. TxB2 concentrations measured in collagen activated blood samples, which correlated significantly with aggregation velocity, did not differ between the lauric or the palmitic compared with the oleic acid diet. A stepwise regression analysis indicated that collagen-induced aggregation was negatively correlated with the number of red blood cells. ADP-induced aggregation also correlated negatively with red blood cell count, and positively with platelet count.
Conclusions: The exchange of 7-10 En% from oleic acid for MCFA, lauric, myristic or palmitic acid does not affect in-vitro whole blood aggregation induced by collagen. ADP-induced aggregation is not affected when 10 En% from oleic acid is exchanged for MCFA or myristic acid.