2005 Volume 54 Issue 12 Pages 617-625
Platelet hyper-aggregation is a serious manifestation of type 2 diabetes and a precipitating factor in the most frequent cause of death in patients with type 2 diabetes-myocardial infarction. Consumption of flaxseed oil as a dietary supplement containing alpha-linolenic acid (ALA, 18:3 n-3) through its metabolism to eicosapentaenoic acid (EPA, 20:5 n-3) and subsequent production of antiaggregatory eicosanoids may reduce such aggregation in vivo. Lipoprotein(a) (Lp (a)) may also influence platelet aggregation in vivo. Furthermore, serum Lp(a) concentrations are increased and bleeding time is decreased in patients with type 2 diabetes, presenting an enhanced risk of myocardial infarction. It was hypothesized that Lp(a) and bleeding time would be correlated due to the considerable molecular homology between apolipoprotein(a) and plasminogen, which should decrease bleeding time. Bleeding time is an excellent measure of in vivo platelet aggregability. The purpose of this study was to determine, if as the result of flaxseed oil consumption, Lp(a) influences the mechanism of any change in bleeding time. A secondary purpose was to determine if gender differences exist in the response of bleeding time to Lp(a) in flaxseed oil consumers. Subjects (n = 40) were randomized to treatment with flaxseed oil (n = 20) or a safflower oil placebo (n = 20). Each of groups contained equal numbers of males (n = 10) and females (n= 10). Some subjects dropped from the study due to reasons not related to treatment side effects. Subjects came for three visits, each three months apart. On each visit, age, gender, and BMI were recorded, bleeding time was performed, and serum Lp(a) concentrations were determined. At the completion of visit 2, subjects were randomized to 1 g of oil per 10 kg body weight each day for three months. Compared with pretreatment measurements, there was a statistically significant increase in bleeding time in the flaxseed oil group among both males and females posttreatment. In contrast, there was no change in the safflower group regardless of gender. Males had a statistically shorter bleeding time pretreatment while males and females showed no difference posttreatment with flaxseed oil consumption. Pretreatment values for Lp(a) and bleeding time showed a nonsignificant correlation among males and a statistically significant correlation among females. A statistically significant correlation also held when all males and females in the study were combined though at a lower value than in females. Significant correlations were lost and/or maintained upon administration of flaxseed oil and safflower oil, respectively. It is also concluded that serum Lp(a) concentrations remain unchanged following flaxseed oil consumption; thus, at least in part diminishing the correlation of Lp(a) with bleeding time. These findings suggest that other factors such as EPA derived eicosanoids mediate the prolonged bleeding time in flaxseed oil consumers.
