Boost your mental performance with better nutrition

Have you ever felt tired, sluggish, or foggy after eating a big meal? Have you seen how kids (and kids at heart) get hyper or seem like they’re not thinking straight after a candy binge? Then you probably know that what you eat affects how you feel.

In a state of optimal nutritional fitness, what you eat supports healing and your immune system, helps prevent injury, improves energy levels, and allows you to achieve optimal emotional, cognitive, and physical performance. When you eat right, you’re likely to feel more energized, less fatigued, and have better focus, judgment, accuracy, and reaction time. The opposite is true when you fuel your body improperly. Whether you’re at home or deployed, follow these tips to help you to stay alert, focused, and performing at your best.

Mental performance nutrition tips

To achieve nutritional fitness, focus on a balanced diet rich in whole foods, with plenty of fruits, vegetables, whole grains, low-fat dairy, and lean meats. Read more on the recommended diet for Military Service Members.

  • Boost your intake of magnesium. Magnesium is important to regulate muscle and nerve functions, blood sugar levels, and blood pressure. It also helps make protein, bone, and DNA. Nearly half of all Americans over age one are deficient in magnesium, and the deficiency is even greater for some gender and age groups. Foods high in magnesium include legumes, nuts, seeds, whole grains, green leafy vegetables (such as spinach), fortified breakfast cereals, milk, and yogurt.
  • Eat plenty of foods high in B vitamins. These nutrients support metabolism, brain development, blood and nerve cell health, DNA production, and the development of serotonin, which impacts mood, memory, and emotions. Foods high in B6 include poultry, fish, organ meats, potatoes and other starchy vegetables, and noncitrus fruits. Foods high in B12 include beef, liver, clams, fish, poultry, eggs, milk and other dairy, and fortified breakfast cereals. Foods high in folate include asparagus, brussels sprouts, spinach, oranges, nuts, beans, peas, and grains. Food is the best source of most vitamins, but supplements can help if you’re unable to eat some of these foods.

“We don’t eat nutrients, we eat food.”

Paul Jacques and Katherine Tucker,

Tufts Human Performance Research Center on Aging


  • Fuel your body consistently. Eat meals regularly to maintain blood glucose (sugar) and muscle glycogen (stored energy) levels throughout the day. Balance meals and snacks with whole grains, lean protein, fiber, and healthy fats to help keep your blood sugar steady. Avoid skipping meals, too much sugar, and imbalanced meals that are mainly refined flours (carbohydrates). Dips and spikes in your blood sugar can make you feel tired, shaky, or less focused. If you skip meals or don’t eat enough, your blood sugar can drop, resulting in hypoglycemia (low blood sugar) and a decline in performance. Symptoms of low blood sugar include headache, dizziness, blurred vision, weakness, fatigue, sweating, confusion, and fainting. You don’t actually need to have full-blown hypoglycemia to begin feeling these effects.
  • Rethink your meal choices on the night shift. At night, your body’s metabolic processes slow down. Eating at night has been shown to be bad for your health, including an increased incidence of obesity, diabetes, cancer, cardiovascular disease, and infections. But for night-shift workers, it can mean the difference between staying alert—or not—on the job. The right type and amount of foods and beverages can help keep up your blood sugar to stay alert.
  • Get a caffeine boost, but not too much. Caffeine improves alertness, vigilance, attention, and reaction time when taken in small to moderate amounts. Caffeine can also help mental performance in sleep-deprived situations. But dose and timing matter;  refer to Operation Supplement Safety for more information.
  • Drink enough water. Water is the most abundant component of the human body—around 50–70% of your weight—so your body needs fluids regularly to function properly. Performance can start to decline once you’ve lost as little as 2% of your body weight. Even mild to moderate dehydration can reduce alertness and cause fatigue, tension, and difficulty concentrating. Carry a water bottle with you and refill it throughout the day. Aim to drink half your body weight in water each day to stay hydrated (e.g. 100 oz if you weigh 200 lbs). And don’t rely on thirst as a good indicator of your fluid needs. By the time you feel thirsty, you’re already a little dehydrated.

Bottom line

Mental performance is just as important as physical performance. Fortunately, proper nutrition can help with both.

References

Berry, K., & Deuster, P. A. (Eds.). (2017). Nutrition Reviews (Vol. 75) (suppl_2): Oxford University Press.

Feldman, J., & Barshi, I. (2007). The effects of blood glucose levels on cognitive performance: A review of the literature. Retrieved from https://ntrs.nasa.gov/search.jsp?R=20070031714

Grant, C. L., Dorrian, J., Coates, A. M., Pajcin, M., Kennaway, D. J., Wittert, G. A., . . . Banks, S. (2017). The impact of meal timing on performance, sleepiness, gastric upset, and hunger during simulated night shift. Industrial Health, 55(5), 423–436. doi:10.2486/indhealth.2017-0047

Masento, N. A., Golightly, M., Field, D. T., Butler, L. T., & van Reekum, C. M. (2014). Effects of hydration status on cognitive performance and mood. British Journal of Nutrition, 111(10), 1841–1852. doi:10.1017/s0007114513004455

McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine’s effects on cognitive, physical, and occupational performance. Neuroscience & Biobehavioral Reviews, 71, 294–312. doi:10.1016/j.neubiorev.2016.09.001