Can omega-3 fats increase IQ? The answer must be tentative, but the brain responds to the dietary omega-6/3 ratio: Gene expression and molecular composition of phospholipids in rat brain in relation to dietary n−6 to n−3 fatty acid ratio.
Rats were fed from conception till adulthood either with normal rat chow with a linoleic (LA) to linolenic acid (LNA) ratio of 8.2:1 or a rat chow supplemented with a mixture of perilla and soy bean oil giving a ratio of LA to LNA of 4.7:1. … There was an accumulation of docosahexaenoic (DHA) and arachidonic acids (AA) in brains of the experimental animals. … Twenty genes were found overexpressed in response to the 4.7:1 mixture diet and four were found down-regulated compared to normal rat chow. Among them were the genes related to energy household, lipid metabolism and respiration. The degree of up-regulation exceeded that observed with perilla with a ratio of LA to LNA 8.2:1 [Proc. Natl. Acad. Sci. U. S. A. 99 (2002) 2619]. It was concluded that brain sensitively reacts to the fatty acid composition of the diet. It was suggested that alteration in membrane architecture and function coupled with alterations in gene expression profiles may contribute to the observed beneficial impact of n−3 type polyunsaturated fatty acids on cognitive functions.
So, omega-3 fats in the diet change brain gene expression, and the fats accumulate in the brain, providing beneficial effects on cognition.
Now look at an article by Gottfredson, Miller, et al., Why is intelligence correlated with semen quality?
We recently found positive correlations between human general intelligence and three key indices of semen quality, and hypothesized that these correlations arise through a phenotype-wide ‘general fitness factor’ reflecting overall mutation load. In this addendum we consider some of the biochemical pathways that may act as targets for pleiotropic mutations that disrupt both neuron function and sperm function in parallel. We focus especially on the inter-related roles of polyunsaturated fatty acids, exocytosis and receptor signaling.
Further in the article:
Both neurons and sperm have high concentrations of PUFA relative to other body tissues. Specifically, the long chain PUFAs docosahexaenoic acid [22:6(n-3)] (DHA) and arachidonic acid [20:4(n-6)] (AA) are the dominant essential fatty acid components of the brain. They are concentrated at synaptic terminals and play a central role in neurodevelopment function1 and maintenance. Crawford2 and Broadhurst3 described the high degree of evolutionary conservation of DHA and AA in the brains of land mammals, including humans. While AA is readily available in the land-based food chain, DHA is available largely from the marine food chain, suggesting that hominids probably evolved with access to seafood in addition to hunted land animals.
Omega-3 fats are important to both brain and sperm, and IQ and sperm quality are correlated. Omega-3 fats could be the link.