It is often said that we are what we eat. The food we eat is used not only to fuel our body, but also to build it. This applies to the brain as well. Food choices can influence our brain functions in both positive and negative ways. The right food may enhance brain functioning and ameliorate the cognitive decline associated with aging. In addition, some foods can improve our emotional status and prevent conditions like depression.

Lipids are good for brain—myth or reality?

It is a fact that some lipids, including unsaturated fatty acids, are necessary for brain development and functioning. This is not surprising if we consider that the brain is the second richest organ in lipids. Approximately 50–60% of the brain is made of lipids. But not all the fatty acids are equally good for the brain. Omega-3 fatty acids found in fatty fish (salmon, mackerel, herring) and seafood are essential for the brain. These fatty acids constitute brain cell membranes. Also, they are main compounds of myelin, a fatty coat that insulates neurons (brain and ensures transmission of signals.

Omega-3 fats play vital functions in improving cognitive functions, providing proper neuronal communication and securing adequate attention. Interestingly, consumption of just one fish meal per weak is believed to decrease the risk of Alzheimer’s disease by up to 60%. Human clinical trials showed that supplementation with omega-3 fatty acids might improve mood, cooperation and cognitive score in subjects with dementia. Omega-3 fatty acids are extremely important for neonatal development as well. A deficit in these fats in pregnant and breastfeeding women, as well as in early childhood, may lead to conditions like autism and attention deficit hyperactivity disorder (ADHD).

Polyunsaturated (omega-3) and monounsaturated fatty acids also regulate the brain’s dopamine system. This is how they improve levels of dopamine and serotonin—the chemicals that make us feel happy. This is why diets with high fish consumption are associated with a low prevalence of depression. Cross-national analyses declared Japan as a country with the highest fish intake on the one hand and the lowest depression score on the other.

Apart from fish meals, walnuts (and nuts in general) are rich sources of omega-3 fatty acids. They contain essential alpha-linolenic fatty acids that cannot be synthesized inside our body and need to be obtained from our diet. Flaxseed and flaxseed oils are other valuable sources of this fatty acid.  In addition to omega-3 fats, walnuts contain potential brain antioxidants—vitamin E and polyphenols.

Olive oil is an especially rich source of monounsaturated fatty acids, with oleic acid as the main representative. Like omega-3, monounsaturated fatty acids help to improve cognitive functions and prevent age-related cognitive decline. These fats are also found in avocados. This is why avocado is commonly labeled as a brain superfood. It is assumed that eating just a quarter or half of a avocado daily can help maintain brain health.

Antioxidants: food for thought

Brain membranes are rich in polyunsaturated fatty acids that are highly susceptible to oxidation. The oxidation of fatty acids leads to changes in membrane structure that can jeopardize brain functioning. When fatty acids are oxidized, membranes are damaged or even ruptured. This makes the intake of nutrients into brain cells quite difficult. The lack of nutrients stops normal functions of brain cells and eventually causes their death.

Oxidation of brain lipids occurs when the production of free radicals is greater than their removal by antioxidants present in the body. Thus, the adequate intake of antioxidants can prevent oxidation of brain lipids and slow down the loss of brain functions. This is why berries and fruits with high antioxidant potential are often recommended as good foods for the brain. Some findings suggest that high intake of blueberries and strawberries can halt the onset of age-related cognitive decline by up to 2.5 years. What makes berries powerful antioxidants is the presence of polyphenols, chemicals that give color to these fruits. Berries can decrease aging-related vulnerability to oxidative stress. These decrease further manifests with improvements in behavior. Human trials in people with mild cognitive impairments suggested the positive impact of berries on verbal memory performance. Apart from combating oxidative stress in the brain, polyphenols can also improve microcirculation. By enhancing blood flow, polyphenols help the proper nourishment of the brain that is important for its functioning.

Another food rich in polyphenols (more precisely epicatechin) that is believed to enhance cognition is dark chocolate. It is assumed that by decreasing oxidative stress and inflammation, dark chocolate improves memory and confers neuroprotection. Still, human trials are required to establish if dark chocolate can be considered as a brain superfood.

Curcuminoids are phenolic compounds from turmeric (popular curry spice) that can enhance memory and protect from neurodegenerative diseases, like Alzheimer’s. Although this opinion is mostly based on animal studies, it is likely that prevalence of Alzheimer’s disease in India is very low due to the common consumption of curry.

A diet rich in vitamins, minerals, and antioxidants, such as polyphenols and their subclass flavonoids, is assumed to suppress the incidence of Alzheimer’s disease. One of the foods containing all of these components is spinach. Spinach, like other leafy green vegetables, contains folic acid and vitamin K that are believed to help keep the brain sharp. Although vitamin K is important for producing myelin, the substance that insulates neurons, the effects of dietary vitamin K supplementation on the function of brain myelin have not been tested so far.

Other cognitive enhancers

Another possible brain stimulator representing one of the most popular drinks worldwide is tea. An interesting study in Chinese adults tracked the association between tea consumption and cognitive decline. The higher tea intake was associated with lower prevalence of cognitive impairments, suggesting that regular tea consumption may slow down cognitive decline. Interestingly, the association was most evident for black tea. The same study showed no association between coffee intake and cognitive status.

Extracts from herb Ginkgo biloba have been traditionally used for memory and concentration problems, but also for dealing with depression and anxiety. A recent meta-analysis found no impact of ginkgo on cognitive functions in healthy subjects, suggesting that the effects of Ginko may be rather minor. Nonetheless, some earlier studies showed that ginkgo together with ginseng may acutely enhance memory in a dose-dependent manner. Unlike ginkgo, human trials with ginseng showed that its consumption can improve working memory performance and mood in terms of calmness.

Although further clinical trials are needed to confirm the cognitive enhancement by many foods, it is evident that diet represents a promising tool for maintaining and improving brain health.

References

Muldoon, M.F., Ryan, C.M., Sheu, L., Yao, J.K., Conklin, S.M., Manuck, S.B. (2010). Serum phospholipid docosahexaenonic acid is associated with cognitive functioning during middle adulthood. Journal of Nutrition. 140(4): 848-853. doi: 10.3945/jn.109.119578

Terano, T., Fujishiro, S., Ban, T., Yamamoto, K., Tanaka, T., et al. (1999). Docosahexaenoic acid supplementation improves the moderately severe dementia from thrombotic cerebrovascular diseases. Lipids. 34 Supplement: S345-S346. PMID: 10419198

Gómez-Pinilla, F. (2008). Brain foods: the effects of nutrients on brain function. Nature Reviews. Neuroscience. 9(7): 568-578. doi: 10.1038/nrn2421

Joseph, J.A., Shukitt-Hale, B., Willis, L.M. (2009). Grape juice, berries, and walnuts affect brain aging and behavior. Journal of Nutrition. 139(9): 1813S-1817S. doi: 10.3945/jn.109.108266

Ahmed, T., Enam, S.A., Gilani, A.H. (2010). Curcuminoids enhance memory in an amyloid-infused rat model of Alzheimer’s disease. Neuroscience. 169(3): 1296-1306. doi: 10.1016/j.neuroscience.2010.05.078

Ng, T.P., Feng, L., Niti, M., Kua, E.H., Yap, K.B. (2008). Tea consumption and cognitive impairment and decline in older Chinese adults. American Journal of Clinical Nutrition. 88(1): 224-231. PMID: 18614745

Laws, K.R., Sweetnam, H., Kondel, T.K. (2012). Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis. Human Psychopharmacology. 27(6):527-533. doi: 10.1002/hup.2259

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