...Indeed, our findings suggested an additive benefit, in that those with highest levels of both linoleic acid and n-3 PUFA had the lowest risk of total and cardiovascular mortality (figure 3, supplement figure 2). This important finding would have been obscured using an analysis based on the n-6/n-3 ratio. The conceptual and biologic flaws of the n-6/n-3 ratio have been described. A key flaw is the inability to discern very different conditions of dietary intake or underlying physiology: e.g., a ratio may be identical when consumption and circulating levels of both n-6 and n-3 are high or when both are low, two very different circumstances. In addition, the ratio cannot distinguish increases in the n-6 PUFA vs. decreases in n-3 PUFA. Finally, the conceptual basis of the ratio depends on the notion that n-6 PUFA and n-3 PUFA have opposing effects. However, substantial evidence indicates that both are beneficial;6 indeed, a recent meta-analysis found that individuals with higher circulating levels of arachidonic acid, the prototypical n-6 PUFA thought to be pro-inflammatory and harmful, had lower risk of coronary disease. Given these considerations, we agree with Dr Lucas that existing evidence suggest beneficial effect of dietary linoleic acid for cardiovascular outcomes, not harm, and use of the n-6/n-3 ratio is unlikely to impart meaningful information over and above assessment of the individual fatty acids alone.

PMID 26195495

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