Curry… brain food?

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are one of the most well-studied dietary supplements, usually in the form of fish oil. Examine.com’s fish oil page boasts one of the highest citation counts out of all the entries in the database, with over 700 studies cited. Two of the main n-3 PUFAs of interest are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

DHA is considered essential for brain function. Deficiency is linked to various maladies, including Alzheimer’s disease, schizophrenia, psychosis, and anxiety.

Vegetarians have lower circulating DHA, compared to omnivores. This is not surprising, as DHA is not often found in plant-based food. However, alpha linolenic acid (ALA) is a readily available plant-based n-3 PUFA. The caveat is that humans must convert it to DHA before it can be utilized, as shown in Figure 1. This conversion rate may not be ample^[1] enough to provide a person with enough to satisfy the recommended amount, though.

Figure 1: ALA to DHA conversion

Sources: Burdge, Curr Opin Clin Nutr Metab Care, 2004 Burdge, Wootton, Br J Nutr, 2002.

It is, however, entirely possible to thrive on a vegetarian diet. Part of this may be due to dairy and eggs being a possible source of DHA. But there is also a question as to whether or not something in the vegetarian diet increases the conversion efficiency of ALA to DHA.

As it turns out, curcumin is a component of turmeric, a frequently used spice in Indian populations, many of whom are vegetarians. Since these populations do not experience noticeable declines in cognitive abilities, a couple of research groups in California teamed up to determine if curcumin consumption could be one of the factors that increases the DHA conversion rate. Curcumin is a heavily researched dietary supplement on its own and boasts a plethora of potential benefits. Examine.com has over 200 cited publications on their curcumin page. Combining both biochemical assays and cognitive testing, rats were studied to determine if curcumin affected DHA levels (and DHA-converting enzymes), and if there was any significant impact on perceived anxiety.

While vegetarians have a lower intake of DHA due to its relative absence in non-animal based foods, they do not suffer from many of the problems linked to low DHA levels. Researchers investigated whether something in their diet attenuates the signs of DHA deficiency.