RESUMEN
Walnut consumption produces beneficial cardiovascular effects. The aim of the present study is to compare the effects of meat enriched in walnut paste (WM) and low-fat meat (LM) consumptions on platelet aggregation, plasma thromboxane A2 (TXA2, measured as TXB2), prostacyclin I2 (PGI2, as 6-keto-PGF1alpha) and the thrombogenic ratio (TXB2/6-keto-PGF1alpha) in volunteers at high CVD risk. Twenty-two adults were placed on a random, non-blinded crossover study involving two test periods (five portions WM/week for 5 week; five portions LM/week for 5 week) separated by a 4- to 6-week washout period. The participants were asked to complete a diet record throughout the study. Platelet aggregation, plasma TXB2, 6-keto-PGF1alpha production and the TXB2/6-keto-PGF1alpha ratio were determined at baseline and at weeks 3 and 5 for the two dietary periods. The WM diet contains a lower SFA content, a higher concentration of PUFA and a more favourable n-6/n-3 ratio than the LM diet. Significant time x treatment interactions were observed for TXB2 (P = 0.048) and the TXB2/6-keto-PGF1alpha ratio (P = 0.028). The WM diet significantly increased the level of 6-keto-PGF1alpha (P = 0.037) and decreased the TXB2/6-keto-PGF1alpha ratio (P = 0.048). At week 5, significant differences (P < 0.05) between treatments were found for maximum aggregation rate, TXB2 values and the TXB2/6-keto-PGF1alpha ratio. The effects on TXB2 and the TXB2/6-keto-PGF1alpha ratio were time-course dependent (P = 0.019 and 0.011, respectively). The WM and LM diets reduced TXB2 levels most (P = 0.050) in obese individuals, while the TXB2/6-keto-PGF1alpha ratio decreased most (P = 0.066) in volunteers whose serum cholesterol levels were > or = 2200 mg/l. The WM diet should be considered a functional meat because it improves the thrombogenic status mainly in individuals with high-cholesterol levels or high BMI.