Nutrition Plays a Critical Role in Mental Health

By Julia Turner

Mounting evidence suggests food may play an important role in the prevention of, progression and management of mental health disorders. This article addresses how food affects mood, energy and cognition, describes how to identify and correct underlying nutrition problems that may contribute to mental health disorders and outlines simple steps to promote optimal brain health and function.

Food and Mood

Food alters one’s mood by influencing the level of certain neurotransmitters—chemicals that allow brain cells to network and communicate.

The four neurotransmitters that are manufactured in the brain directly from food components are serotonin, dopamine, norepinephrine and acetylcholine. The levels and activity of these neurotransmitters are sensitive to food intake, and changes in dietary patterns can have profound effects on behavior, eating patterns, sleep and energy level.

Serotonin, often called the “feel good” neurotransmitter, is manufactured from the amino acid tryptophan, which is found in protein-rich foods (meats, dairy, eggs and legumes). Ironically, eating a protein-rich meal lowers brain tryptophan and serotonin levels, while eating a carbohydrate-rich meal has the opposite effect. Tryptophan competes with other amino acids for entry into the brain after eating a protein-rich meal, resulting in very little tryptophan getting through the blood-brain barrier, so serotonin levels do not rise appreciably.

In contrast, a carbohydrate-rich meal triggers insulin release. This causes most amino acids to be absorbed from the blood into the body’s cells (not the brain’s)—all except tryptophan, which allows free entry into the brain, with a resulting rise in serotonin levels. High serotonin levels increase feelings of calmness, improve sleep patterns, increase pain tolerance, and reduce cravings for food.

Dopamine and norepinephrine are manufactured from the amino acid tyrosine, also found in protein-rich foods. Unlike tryptophan, tyrosine levels rise after eating a protein-rich meal. This promotes levels of dopamine and norepinephrine to rise, which has the effect of increasing alertness and mental energy.

Acetylcholine is manufactured from the fatlike substance choline. Unlike amino acids, which must compete for entry into the brain, choline has no competitors. Acetylcholine is important in memory and in general mental function. Lowered acetylcholine levels, common with aging, results in memory loss and reduced cognitive function. Top food sources of choline include egg yolks, soybeans, beef liver, meats, nuts, flaxseeds, wheat germ and broccoli.

Underlying nutrition problems that may contribute to mental health disorders:

  1. Imbalanced gut flora:
    There is a strong connection between the gut and the brain; when there is an overgrowth of pathogenic bacteria and/or yeast, the by-products produced can contribute to mood disorders and depression, in addition to gastrointestinal symptoms like constipation and/or diarrhea.
     
  2. Food allergies or sensitivities:
    Either or both can contribute to symptoms of depression, schizophrenia and other mental disorders.
     
  3. Food opiates:
    Because of a lack of DPPIV enzyme, foods such as casein (milk) and gluten (wheat) may be only partially digested into opiate-like compounds that can influence mood and cognitive abilities.
     
  4. Nutrient deficiencies (select):
  •  Omega-3 fatty acids are essential for optimal brain function. They have been shown to benefit ADHD, autism, dyspraxia, dyslexia and aggression. For the affective disorders, meta-analyses have confirmed benefits in major depressive disorder (MDD) and bipolar disorder, with promising results in schizophrenia and initial benefits for borderline personality disorder. Lowered tissue levels of omega-3 fatty acids correlate with accelerated cognitive decline and mild cognitive impairment. Supplementation has improved cognitive function. Top food sources of omega-3 fatty acids include fatty cold-water fish (salmon), flax, hemp and chia seeds (and their oils), and omega-3 fortified foods.
  • Vitamin D may have protective benefits for the brain via several mechanisms. While low vitamin D levels have not been to shown to be a causative factor in depression, low levels may be related to the disorder. Evidence suggests that Vitamin D may have a positive effect on depression. Top food sources of vitamin D include cod liver oil, salmon, shrimp, sardines and mackerel. Vitamin D is also synthesized in the body during sun exposure.
  • Zinc is a trace mineral found in red meats, liver, eggs, dairy products, vegetables, and some seafood.  Among many other functions, zinc is involved in maintaining cell membranes and protecting cells from damage. Zinc deficiency can cause neurological impairment, influencing appetite, taste, smell and vision. Zinc deficiency has also been linked to ADHD, depression, apathy, irritability, jitteriness and fatigue.
  • B vitamins are essential for optimal central nervous system function. Depleted levels of B vitamins have been documented in many studies as being a contributing factor to mental illness, as well as poor memory and learning dysfunction. Top food sources of B vitamins include meats, dairy, eggs, whole grains, leafy greens, fortified cereals and bananas.
  • Antioxidants, including vitamins C and E, the mineral selenium and a wide array of other compounds from fruits and vegetables, act in ways to protect brain cells from damage and destruction. High levels of stress can significantly increase the need for antioxidants; antioxidant deficiency has been related to declining cognitive function.

The Role of Supplements

In a perfect world, food should provide all the necessary nutrients to support optimal brain health. Food contains bio-available vitamins, minerals, enzymes, co-enzymes, antioxidants and more—all in one complete package. Choosing whole, unprocessed, unrefined foods is certainly the goal but very often not the norm. Targeted, therapeutic supplementation of individual vitamins, minerals, trace elements, and other nutrients is often necessary for various mental health conditions and should be guided by an experienced nutrition professional, who can provide a comprehensive assessment and recommendations. Supplemental nutrients should consist of high quality bio-available forms and be free of unnecessary filler ingredients.

Nutrition Lifestyle Tips to Support Brain Function

  • Reduce or eliminate consumption of highly processed and refined foods containing unhealthy fats, refined sugars and chemical additives.
  • Improve intake of omega-3 fats (reduce the omega-6 to omega-3 ratio) by eating at least two servings per week of fatty fish like salmon. Choose grass-fed meats over those raised conventionally, and consume raw nuts, seeds, and their oils on a regular basis.
  • In an effort to maximize antioxidant and polyphenol intake, eat at least five (half cup) servings of vegetables and fruits each day. Including all the colors of the rainbow is a helpful guide. Ways to enjoy more vegetables: cook, puree and freeze then add to soups, sauces, meatloaf, smoothies and baked goods like muffins and pancakes.
  • Incorporate whole grains as another source of antioxidants, certain B vitamins, minerals and fiber.
  • Enhance the flavors of foods with spices and herbs, many of which are potent antioxidants.
  • Maximize overall nutrient intake by choosing locally grown organic meats, fruits and vegetables.
  • Balance blood sugar and neurotransmitter function by eating a balance of protein, fat, and carbohydrate at every meal and snack. For greater mental energy and alertness during the day, eat higher amounts of protein at breakfast and lunch.
  • Engage in regular physical activity.

Julia Turner, MMSc, R.D., L.N. is a registered dietitian and licensed nutritionist with a private practice based in Montana. She consults with clients nationally and internationally to address various health issues affecting all ages through nutrition intervention. She specializes in brain health nutrition, autism, ADHD and related disorders, food allergies-sensitivities and digestive disorders.

This article was brought to you by the editorial committee of ASA’s Mental Health and Aging Network (MHAN).