Levels of the n-3 fatty acid eicosapentaenoic acid in addition to those of alpha linolenic acid are significantly raised in blood lipids by the intake of four walnuts a day in humans.

BACKGROUND AND AIMS: Ingestion of alpha linolenic acid (ALA), with the richest source among dry fruits such as walnuts, is associated with cardiovascular prevention. The aim of this study was to selectively evaluate the effects of moderate walnut consumption on the levels of ALA and its metabolic derivatives in human blood. METHODS AND RESULTS: After a 2-week run-in period, 10 volunteers consumed 4 walnuts per day (in addition to their habitual diet) for 3weeks. Fatty acid profiles, with special attention to levels of ALA and long chain polyunsaturated fatty acids (LC-PUFA), were assessed in blood drops collected from fingertips. The data indicate that the administration of a few walnuts a day for 3weeks significantly increases blood levels, not only of ALA (from 0.23+/-0.07 SD to 0.47+/-0.13 SD), but also of its longer chain derivative eicosapentaenoic acids (EPA) (from 0.23+/-0.37 to 0.82+/-0.41) with levels remaining elevated over basal values after washout. CONCLUSION: The findings of this pilot study indicate that plant ALA in appropriate food items favourably affects the n-3 LC-PUFA status.