In Brain Food (part 2) I found that when I reduced my flaxseed-oil intake my sleep got worse that very night. (Presumably because I reduced the amount of omega-3 fatty acids in my diet and therefore my blood.) Several people, including me, have found that their sleep improved the night after taking more omega-3 — that is, hours later. For example, if the omega-3 was begun Monday afternoon, they slept better Monday night.
How could the effect turn on and off so quickly? An article in the current issue of Journal of Nutrition supplies an answer:
Of the lipids found in the brain, polyunsaturated fatty acids (PUFAs) play an important role, serving as a major component of the phospholipids that form cell membranes, being precursors of signaling molecules such as prostaglandins and leukotrienes, modulating gene expression through the activation of transcription factors, and forming the microenvironment around membrane-bound proteins.
In other words, omega-3 has several effects in the brain, with vastly different sensitivities to changes in omega-3 blood levels. Changes in cell membranes probably happen very slowly; changes in “the microenvironment around membrane-bound proteins” could happen very quickly.
That a necessary nutrient (omega-3) could have fast-acting changes (within hours) is counter-intuitive. It doesn’t agree with previous experience. Other necessary nutrients take much longer for a deficiency to become apparent. And it doesn’t agree with common-sense design notions. Evolution builds our bodies out of what is in our blood. Human design is quite different — cars are not built out of what flows around them (oil and gas). Nor is anything else. There isn’t a everyday analogy that shows that a deficiency of a construction element can have fast-acting effects. If all the raw metal in the world disappeared, your car would run fine for a long time. Nor does it fit with general trends in nutrition research. Nutrition researchers study the whole body, most of which changes slowly by comparison to the brain. Sure, food can change the brain — make you sleepy, make you alert (caffeine), but these are not changes that interest most nutrition researchers, who usually emphasize optimal functioning. During the Stone Age, our diets did not contain much caffeine so it is obviously not a necessary nutrient, even if it can improve memory. No dietician tells clients to consume more caffeine. There are hundreds of substances like caffeine that change mental functioning, of course, and with the right definition of improvement all of them can be considered to improve mental functioning. But none of them interest nutrition researchers, with the exception of Adelle Davis (fascinated by LSD). An experimental psychologist, on the other hand, . . .