Dr. Susan M. Kleiner is a renowned authority on eating for strength, endurance, power and speed, and the co-founder and co-CEO of Vynna®, LLC, an evidence-based, female-centric performance nutrition brand. She is an international columnist and speaker, and has consulted with professional teams, Olympians and elite athletes in all sports. Dr. Kleiner has been a faculty member at several esteemed universities, authored numerous academic chapters, articles and scientific manuscripts, and penned seven books, including the bestselling POWER EATING, 4th Edition (Human Kinetics, 2014).
Food Chemistry Meets Brain Biochemistry: The Top 7 Food Factors That Influence Mood
I remember the moment when the phone rang and the strength and conditioning coach on the other end of the line asked me to work with an All Star NBA player who was struggling with his weight. At our first meeting, it was very clear that he wasn’t only struggling with weight—he was depressed, possibly clinically depressed. I lobbied for him to receive mental health counseling, but to no avail. It would be my job to get him back to his fighting weight and back on the court—and the team gave us just nine weeks to do it.
Proceeding as any good sports nutritionist would, I collected the athlete’s diet and training record. It quickly became clear that he was under-eating, fearful that any bite he took would add pounds to the scale or fat weight to his body composition. Ironically, in an athlete, under-fueling leads to an exchange of fat for muscle as energy wanes and training intensity and duration decreases. This is exactly what was happening, and he was spiraling into disordered eating as well as depression.
I knew how to adjust his diet to alter his body composition, but what would it take to improve his mental state, focus and mood? This was years before fish and blueberries began appearing in the daily news cycle, so I dove into the research literature to study the neurobiology of food. Taking on the role of the practitioner with a goal, rather than the scientist following scientific methodology, I put into his diet plan every food that had potential from very early research studies on animals and humans.
Shockingly, it worked. Within the proscribed period of time, his body weight shifted to the desired goal. That only happened because he was now getting out of bed, eating his meals and showing up to train. The strength coach and I knew this wouldn’t last forever, but it was amazing how well it worked for nearly a year. I was convinced that food could absolutely influence the brain in affecting our moods, mental focus and mental energy.
Today, we have numerous research studies to support the foods that I included in the diet of my athlete, and many more studies with new data on other foods and supplements. Here is a list of some of the most potent and well-documented foods, nutrients and supplements that influence how we feel.
There is no other nutrient, food or supplement that will affect the brain more profoundly than water. The brain of an adult human is approximately 78 percent water, and water participates in every biochemical reaction that occurs there. A loss of only 1 to 2 percent of body weight as fluid leads to reductions in the subjective perception of alertness and ability to concentrate and to increases in self-reported tiredness and headache (Maughan, 2003).
Daily fluid intake recommendations are 9 to 12 cups of fluid per day for a sedentary individual in the form of fluids, non-alcoholic beverages, soups and foods. An additional 2 cups per day should be added for the following factors: illness, weight-loss dieting, activity, hot, dry or humid environments, high altitude, travel, pregnancy and lactation. Two hours prior to rigorous activity, drink about 2.5 cups of fluid. During moderate exercise, individuals may drink according to thirst. However, during high-intensity training and competitions, athletes need to be more focused on a personalized hydration plan. After exercise, replace every pound lost during exercise with 3 cups of fluid (Kleiner, 1999).
Carbohydrate and Protein
The amino acid tryptophan is a building block for serotonin, the calming, feel-good brain chemical. Typically, unless you are on a protein-restricted diet, you have enough tryptophan circulating to raise serotonin levels. A lack of carbohydrate in the diet, which initiates the cascade of biochemical events that allow tryptophan to cross the blood-brain barrier and enter the brain, is the most common dietary reason for low levels of serotonin. Serotonin is also responsible for helping the body prepare for rest and sleep. Therefore, it is a combination of protein and carbohydrate that enhances mood, alertness, rest and relaxation.
Research has found that diets that include less than 40 percent of total calories from carbohydrate can increase the risk of depression in depression-prone subjects (Soenen et al., 2012). Furthermore, anecdotal reports of low mood and sleep disturbances are frequently reported by individuals on very-low-carbohydrate diets. When managing a carbohydrate-controlled diet, maintain total carbohydrate at or above 40 percent of total calories from carbohydrates.
Fish Oils: DHA and EPA
Fish oils may help ease symptoms of depression. While research has not been done on individuals with severe depression, those with mild-to-moderate symptoms have benefited from fish oil treatment. Daily supplement doses of at least 1000 mg of DHA plus EPA have typically been used in studies with successful outcomes (Grosso et al., 2014). Eating three to five 4-ounce servings of fatty fish per week is also highly recommended. Fish high in oils include sardines, salmon, herring, trout, black cod, shellfish and canned tuna that contains the original fish oils.
The role of vitamin D in depression is well documented, as vitamin D plays an important part in maintaining levels of dopamine and serotonin in the brain. Vitamin D deficiency is now a global public health problem, affecting a billion people worldwide. Studies utilizing good research methodology have shown in meta-analysis that vitamin D supplementation (≥800 IU daily) was somewhat favorable in the management of depression in studies that demonstrate a change in vitamin levels (Spedding, 2014). Because most adults spend the majority of their time inside, our summers are fairly brief in the northern hemisphere, and the liberal use of sunscreens block the ultraviolet rays from the sun that convert vitamin D to its active form, a daily supplement of vitamin D-3 of 800 to 1,000 IU may be a useful strategy for helping to maintain a good mood. Good food sources of vitamin D include fortified milk and fatty fish.
Choline, found most prominently in egg yolks, has been shown to be significantly lacking in the diets of Americans. Choline, a B vitamin, is half of the neurotransmitter acetylcholine, which acts every time we think or move. Choline is half of the phospholipid, phosphotidylcholine, which is required for the creation of channels in the brain cell membrane to allow nutrients into and toxins out of brain cells. Low choline levels have been associated with increasing incidence of anxiety in one study, and may also be linked to depression (Demirkan et al., 2013).
Because there is no association between egg yolks consumption and blood cholesterol levels, the most efficient way to add choline back to the diet is to eat one to two whole eggs per day. That strategy alone will increase choline consumption by 50 percent. The recommended Adequate Intake is 425 mg/day for adult women and 550 mg/day for adult men.
A Plant-rich Diet
The brain is a highly metabolic organ, and research is beginning to indicate that many of the phytochemicals in plants act as powerful antioxidants and anti-inflammatory agents, protecting brain cells from injury and reducing inflammation. These actions have the potential to promote memory, learning and cognitive function. Fruits and beverages such as tea, red wine, cocoa and coffee are major dietary sources of polyphenols, which have been identified as having potent neuroprotective actions. A specialized group of polyphenols, the flavonoids, are found in a variety of foods and beverages, including parsley, celery, citrus fruits, oregano, wine, soy and soy products, onions, leeks, broccoli, green tea, red wine and chocolate. Another group of polyphenols come from berries, kiwis, plums and apples. A fourth type comes from grapes, wine and peanuts (Meeusen, 2014).
As you can see, eating a diet rich in a full variety of plant foods will support the kind of nutritional intake that will keep you healthy AND happy, functioning at optimal levels throughout your lifetime.
Demirkan, A. et al. (2013). Plasma phosphatidylcholine and sphingomyelin concentrations are associated with depression and anxiety symptoms in a Dutch family-based lipidomics study. Journal of Psychiatric Research, 47, 3, 357-362.
Grosso, G. et al. (2014). Role of omega-3 fatty acids in the treatment of depressive disorders: A comprehensive meta-analysis of randomized clinical trials. PLoS One, 9, 5, e96905.
Kleiner, S.M. (1999). Water: An essential but overlooked nutrient. Journal of the American Dietetic Association, 99, 200-206.
Maughan, R.J. (2003). Impact of mild dehydration on wellness and on exercise performance. European Journal of Clinical Nutrition, 57, Supplement 2, S19–S23. DOI:10.1038/sj.ejcn.1601897
Meeusen, R. (2014). Exercise, nutrition and the brain. Sports Medicine, 44, Supplement 1, S47-S56.
Soenen, S. et al. (2012). Relatively high-protein or 'low-carb' energy-restricted diets for body weight loss and weight maintenance? Physiology and Behavior, 107, 3, doi: 10.1016/j.physbeh.2012.08.004.
Spedding, S. (2014). Vitamin D and depression: A systematic review and meta-analysis comparing studies with and without biological flaws. Nutrients, 6, 1501-1518.