Marine n-3 Fatty Acids and Vitamin D Supplementation and Primary Prevention. Reply.

To the Editor: In their study of marine n–3 (also called omega-3) fatty acids, the VITAL (Vitamin D and Omega-3 Trial) Research Group (Jan. 3 issue)1 found that daily supplementation with 1 g of n–3 fatty acids had no cardiovascular or oncologic benefit. Although we were happy to see the citation of the n–3 index, this index is specific to red-cell membranes, not plasma.2 If these results are analogous, then the very low percentages suggest inadequate dosing, since n–3 fatty acids confer cardiovascular benefit when they compose 8 to 12% of red-cell membranes.3 The dose required to reach this level is 1800 mg.4 Thus, the null results of VITAL would be expected, since patients would have been underdosed.

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