High-dose omega-3 fatty acids have no effect on platelet aggregation or coagulation measured with static and flow-based aggregation instruments and Sonoclot; an observational study in healthy volunteers.

The effect of omega-3 fatty acids on platelet aggregation and coagulation is highly unclear. Studies both support and refute the impacts of omega-3 fatty acids on prolonged bleeding time and platelet inhibition as well as its purported positive effects on cardiovascular disease. In a previous pilot study we suggested an inhibition of platelet aggregation measured with multiple electrode aggregometry. Following on that, the aim of the present study was to investigate the effects of supplementary high doses of omega-3 fatty acids on platelet aggregation and coagulation in a sample-size calculated number of healthy volunteers using Sonoclot, multiple electrode aggregometry, and flow-based Cellix instruments after 10 days of omega-3 fatty acid intake. Twelve healthy human volunteers ingested 2520 mg of supplementary omega-3 fatty acids per day for 10 days. Venous blood was sampled and platelet aggregation and coagulation were measured before and after the treatment period. The viscoelastic test instrument Sonoclot, multiple electrode aggregometry, and flow-based Cellix instruments with collagen-coated channels were used to evaluate platelet aggregation and coagulation. There were no differences in any of the measured variables after the treatment period as compared to before. In this well-powered study on healthy volunteers, no effects of high doses of omega-3 fatty acids after 10 days of intake could be demonstrated, either on coagulation or platelet function. Further studies are needed to clarify whether omega-3 fatty acids have a role in the regulation of the putative complex processes in vivo.

Effects of naturopathic medicines on Multiplate and ROTEM: a prospective experimental pilot study in healthy volunteers.

BACKGROUND: Of patients undergoing surgery, 22 to 57% have been reported to be using naturopathic medicines. Several of these medicines have been reported to increase bleeding or enhance the effect of other drugs that increase bleeding. The Swedish Medical Products Agency recommends cessation of the use of the naturopathic medicines echinacea, fish oil, ginkgo biloba, ginseng, St. John's wort, valeriana and garlic 2 weeks before surgery. The aim of this pilot study was to examine the effects of these 7 naturopathic medicines in healthy humans by utilising multiple electrode aggregometer (Multiplate) and viscoelastic rotational thromboelastometer (ROTEM) to obtain data for sample size calculation before a larger trial. METHODS: Thirty-five healthy volunteers ingested one of the listed naturopathic medicines for 7 days. Each naturopathic medicine was taken in a recommended standard dose by 5 volunteers. ROTEM clot initiation (CT), clot formation (CFT), α-angle (AA) and clot structure (MCF) were analysed with tissue factor activated (EXTEM) and native (NATEM) assays. The Multiplate platelet aggregation area under curve (AUC) was measured with adenosine diphosphate (ADP), collagen (COL) and arachidonic acid (ASPI) assays. RESULTS: Multiplate with ADP agonist decreased from 73 ± 8.7 AUC to 60 ± 5.9 AUC (P = 0.003, 95% confidence interval (CI) -19.2 to -7.6) after medication with fish oil, but fish oil had no effect on COL or ASPI reagents. None of the other naturopathic medicines had any effect on Multiplate aggregometry. ROTEM NATEM-CFT increased from 217 ± 32 s to 283 ± 20 (P = 0.009, 95% CI 26.8 to 107), and NATEM-AA decreased from 52 ± 3.9° to 44 ± 2.3° (P = 0.009, 95 % CI -12.0 to -3.2) after medication with fish oil. There were no significant changes in the other NATEM or EXTEM parameters. The other naturopathic medicines had no significant effects on ROTEM or Multiplate aggregometry. CONCLUSIONS: We have demonstrated that a recommended standard intake of 1260 mg Ω-3 polyunsaturated fatty acids (fish oil) daily - but not echinacea, ginkgo biloba, ginseng, St. John's wort, valeriana or garlic - may decrease platelet aggregation and clot formation. A larger trial in this setting would be meaningful to perform. TRIAL REGISTRATION: Trial registration ISRCTN78027929. Registered 19 May 2015.