When we think of fitness, we typically consider our physical condition, but optimal brain health is also an important aspect of being fit for duty and for life. Furthermore, as officers with demanding careers and busy lives, we commonly experience psychosocial stress, which may impair cognitive function1. Therefore, it is important to be aware of how we can optimize brain function and selecting a nutritious diet is one way to do this.

Most research about the effect of nutrition on cognitive function has been performed using either animal models or cell cultures, thus more human studies are needed in this area. However, there are very compelling data and hypotheses about mechanisms that support a strong role of nutrition in optimizing brain health.

Antioxidants
Oxidative stress results from environmental exposures and routine metabolic activities in the body. Because the brain is highly metabolically active and because it is rich in lipids, which are susceptible to peroxidation, the brain is particularly at risk for oxidative damage2. Fortunately, the body has systems in place to protect against damage and to repair damage due to oxidation. This is done through the use of antioxidants2.

Selenium, copper, manganese, and zinc serve as cofactors to enzymes with antioxidant functions2. These minerals are founds in meats, fish, oysters, nuts, seeds, beans, whole grains, and wheat germ3. Vitamins A and E help prevent peroxidation of lipids and vitamin C scavenges reactive oxygen species, which are unstable molecules that start a chain reaction of damage at the cellular level2. These vitamins are founds in fruits, vegetables, nuts, seeds, and the oils of nuts and seeds3.

Furthermore, there are thousands of phytochemicals, called phenols or polyphenols, which are widespread in plants, such as fruits, vegetables, legumes, grains, nuts, tea, red wine, olive oil, herbs and spices that serve as antioxidants2. Examples of these compounds include resveratrol in red grape skin, carotenoids, such as lycopene and lutein, curcumin (found in turmeric) and compounds in green tea2. These compounds primarily act as scavengers of reactive oxygen species, but there is some evidence that they may also have a role in decreasing inflammation in the brain2.

Brain-Healthy Fats
Our serum cholesterol profile is not the only thing to consider when choosing the types of fats to consume. Docosahexaenoic acid (DHA) is an omega-3 fat that is highly concentrated in the brain and serves as one of the major structural components of the cell membranes of neurons2. DHA is converted in our body from alpha-linolenic acid (ALA). The typical U.S. diet contains inadequate ALA, which is found in flaxseeds, chia seeds, walnuts, the oils of these foods, and canola oil as well as processed foods that use these oils3. Furthermore, the efficiency of conversion from ALA to DHA in the body is thought to be poor1,2. In addition to being converted from ALA, DHA can be consumed directly in the form of fatty fish such as sardines, salmon, mackerel, herring, and tuna 3. There are likely physiologic regulatory measures in place that dictate the amount of DHA that will be used by the brain independent of diet, but it is still important to meet the needs of the brain with dietary intake2.

High concentrations of DHA in the neuron cell membrane increase the fluidity of the membrane, which can improve the function of enzymes and proteins in the cell membranes1,2. Furthermore, DHA may play an important role in the development of new neurons, increasing the number of neurons, creating synaptic proteins, and protecting against neuronal loss2. Choline (found at high levels in egg, poultry, pork, fish, beef, beans, and milk) and uridine are also important in some of these processes2,3. The long-chain omega-3 fats, such as DHA and eicosapentaenoic acid (EPA), may have an anti-inflammatory role and having insufficient levels may adversely affect neurotransmission2. Given these various important functions, it is not surprising that DHA supplementation was shown to improve cognitive function and to possibly prevent cognitive decline in people with mild cognitive impairment2.

B Vitamins
Subclinical deficiencies of vitamins B6, B12, and folate can lead to high levels of homocysteine, which is not only a marker for cardiovascular risk, but may also adversely affect the microvasculature of the brain, potentially affecting memory and learning2. Homocysteine causes oxidative stress in the brain and may also be directly toxic to neurons, causing DNA damage and apoptosis2. Vitamin B6, B12, and folate act by lowering homocysteine levels, and thereby mitigate its potentially harmful effects2. Vitamin B12 and folate also are required for synthesis of neurotransmitters2. These B vitamins are founds in beans, fortified cereals and grains, seeds, nuts, green leafy vegetables, animal products, and wheat germ3.

Eating a balanced and varied diet can provide the nutrients our brains need to thrive. Supplementation with some nutrients missing from the diet may be effective. However, it is important to keep in mind that nutrient roles in brain health are highly complex and still not fully understood. In some cases, the correct proportion of nutrients may be important. Supplementing with one nutrient could potentially upset a delicate proportion or lead to a deficiency in a non-supplemented nutrient. When nutrients are obtained in a varied and balanced diet, important nutrients are likely to be present in amounts that promote the right balance. Plus, diet is the best source of the numerous polyphenols that are widespread in a variety of foods.

Overall, a diet rich in the nutrients discussed above may optimize cognitive function. When we choose a diversified, colorful diet that has a wide variety of whole foods, such as vegetables, fruits, legumes, nuts, seeds, whole grains, fatty fish, and lean meats, we are not only decreasing our risk of chronic disease, we are helping our brain to function at its best.

References:
1) Dauncey, MJ. New insights into nutrition and cognitive neuroscience. Proceedings of the Nutrition Society. 2009, 68:408-415.
2) Parletta, N, CM Milte, BJ Meyer. Nutritional modulation of cognitive function and mental health. Journal of Nutritional Biochemistry. 2013, 24: 725-743.
3) U.S. Department of Agriculture, Agricultural Research Service. 2013. USDA National Nutrient Database for Standard Reference, Release 26. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl. Accessed March 29, 2014.