Mental health problems are believed to result from a combination of factors, including genetics, age, and environmental influences, but there is also increasing evidence that food and nutrition may play a role. Evidence suggests that food may contribute to the prevention, progression, and management of several mental health disorders, including depression, anxiety, schizophrenia, attention deficit hyperactivity disorder (ADHD), and Alzheimer's disease. Many people diagnosed with mental health conditions have been found to have low intakes of specific nutrients, but it is difficult to know whether these are causes or effects of the diagnoses. Research is ongoing, but while the role of nutrition in mental health has yet to be fully understood, it is generally accepted that diet has some influence on overall mood, brain function, and behavior.
Food plays an important role in physical and emotional well-being at every stage of life, and a number of anecdotal, clinical, and controlled studies highlight the importance of nutrition in maintaining positive mental health. Mental health may be influenced by several dietary factors, including overall intake of calories, macronutrients (proteins, carbohydrates, and fats), alcohol, and vitamins and minerals. Often deficiencies of multiple nutrients—rather than a single nutrient—are responsible for changes in brain functioning. In the United States and other developed countries, alcoholism is often the cause of nutritional deficiencies that affect mental functioning. Certain diseases can also result in nutritional deficiencies by affecting the absorption of nutrients into the body or by increasing nutritional requirements.
B vitamins (6, 12, and folic acid)
Asparagus, orange juice, spinach
Choline (B-complex vitamin)
Eggs, wheat germ
Improved memory, mood
Beans, starchy vegetables, whole grains
Promotes calmness, relaxation
Omega-3 fatty acids
Flax seeds, oily fish (e.g., salmon), walnuts
Supports cognitive functions, positive mood
Beans, dairy, eggs, lean meats and poultry
Improved concentration, energy
In addition to good nutrition, a well-balanced exercise program can improve general health, build endurance, and enhance emotional well-being.
The World Health Organization (WHO) estimates that approximately 450 million people have a diagnosable mental disorder, with many more experiencing mental problems. The number and type of mental illnesses reported vary from country to country depending on cultural, reporting, and intrinsic differences. Some statistics suggest that one in four people in the United States is likely to experience a mental health disorder at some point, with rates potentially higher in other countries.
Diagnosis of a mental health disorder is usually made by a trained clinician, such as a psychiatrist, psychologist, or family physician. Confirmation of a diagnosis usually is made following completion of standardized assessment tools and a full psychiatric assessment.
Energy, often referred to as the calorie content of a food, is derived from the carbohydrate, protein, and fat found in foods and beverages. Although vitamins and minerals are essential to the body, they provide no energy. The human brain is metabolically very active and uses about 20%–30% of a person's energy intake at rest. Individuals who do not eat adequate amounts of calories from food to meet their energy requirements will experience changes in mental functioning. Skipping breakfast is associated with lower fluency and problem-solving ability, especially in individuals who are already slightly malnourished. A hungry person may also experience lack of energy or motivation.
Chronic hunger and energy deprivation profoundly affect mood and responsiveness. The body responds to energy deprivation by shutting or slowing down nonessential functions and altering activity levels, hormonal levels, oxygen and nutrient transport, the body's ability to fight infection, and many other functions that directly or indirectly affect brain function. People with a consistently low energy intake often feel apathetic, sad, or hopeless.
Developing fetuses and young infants are particularly susceptible to brain damage from malnutrition. The extent of the damage depends on the timing of the energy deprivation in relation to stage of development. Malnutrition early in life has been associated with below-normal intelligence and functional and cognitive defects. Similarly, studies have shown that people suffering traumatic brain injury face the best chance of rehabilitation when placed on a high-calorie, high-protein diet.
Amino acids are the building blocks of protein. The human body can manufacture some of the amino acids, but there are eight essential amino acids that must be supplied in the diet. A complete or high-quality protein contains all eight of the essential amino acids in the amounts needed by the body. Foods rich in high-quality protein include meats, milk and other dairy products, and eggs. Dried beans, peas, grains, and nuts and seeds also contain protein, although the protein in these plant foods may be low in one or more essential amino acid. Generally, combining any two types of plant protein foods together will yield a complete, high-quality protein. For example, a peanut butter and jelly sandwich combines grain protein from the bread with nut protein from the peanut butter to yield a complete protein.
A bean and corn dish, such as refried beans in a corn tortilla, combines bean and grain protein for another complete protein combination.
The most widely researched amino acid is tryptophan, which is used by the body to produce the neurotransmitter serotonin. Serotonin plays a role in mood, eating patterns, and sleep patterns. One of the features of depression is a reduction in the amount of serotonin in the brain, though it is not known whether this decrease is a cause or effect of the condition. Tryptophan is found in many foods, including eggs, turkey, and beans. However, to convert tryptophan to serotonin, the body requires certain other enzymes, vitamins, and minerals. Absence of any of these essential components may affect the body's ability to manufacture serotonin.
Some diseases can cause a buildup of certain amino acids in the blood, leading to brain damage and mental defects. A buildup of the amino acid phenylalanine in individuals with a disease called phenylketonuria (PKU) can cause brain damage and intellectual disability.
Carbohydrates include starches, naturally occurring and refined sugars, and dietary fiber. Foods rich in starches and dietary fiber include grain products like breads, rice, pasta, and cereals, especially whole-grain products; fruits; and vegetables, especially starchy vegetables like potatoes. Carbohydrates significantly affect mood and behavior. Eating a meal high in carbohydrates triggers the release of a hormone called insulin in the body. Insulin helps let blood sugar (glucose) into cells, where it can be used for energy, but it also has other effects in the body. As insulin levels rise, more tryptophan enters the brain, resulting in higher levels of serotonin. The increase in serotonin in the brain enhances mood and produces a sedating effect, including feelings of relaxation and sleepiness. This effect is partly responsible for the drowsiness some people experience after a large meal.
ESSENTIAL FATTY ACIDS. Fat is essential for life. The brain is composed of a high percentage of fat, much of which comes from the essential fatty acids (EFAs) omega-3 and omega-6. These are called essential because they cannot be made in the body and must be obtained from the diet. These EFAs are a vital part of the structure of the brain cells and are important for promoting communication between the cells in the brain.
Studies suggest that omega-3 fatty acids may have positive protective benefits for the heart, and more recently researchers have become interested in the potential benefits of omega-3 in behavior and positive mental health. However, there has been wide variation in the outcomes of studies—some researchers who have reviewed the evidence suggest positive effects on mood, while others discount it. One study suggested that the levels of depression among people living in the Arctic and Subarctic regions rose at the same time that traditional diets, which were high in EFAs, were being replaced by more processed foods. However, many other factors, including cultural changes, could have played a role in this finding.
Other researchers have investigated a possible relationship between diet and Alzheimer's disease, schizophrenia, and other cognitive disorders. Research in this area is still new, and no definitive conclusions can be drawn. In one study, 53% of bipolar patients on placebo (olive oil) became ill again within four months, while none of the patients who were given 9.6 g daily of omega-3 fatty acids (as fish oil) did. A 25% decrease in schizophrenic symptoms was observed in patients receiving eicosapentaenoic acid (EPA), one of the omega-3 fatty acids contained in fish oil. However, some studies have indicated a relationship between higher intakes of fat and increased incidence of Alzheimer's disease. Other research suggests a possible link between lower levels of polyunsaturated fatty acids (PUFAs) and schizophrenia.
Sources of omega-3 include oily fish, such as mackerel, pilchards, sardines, fresh tuna, salmon, herring, anchovies, kippers, whitebait, and trout. Vegetable oils, including linseed, flaxseed, canola (rapeseed), and walnut oil, also contain omega-3, but it is not yet clear whether this form is as effective.
SATURATED FATS. Saturated fat and trans fatty acids (also called partially hydrogenated; fats or oils) have achieved notoriety for their apparent role in reducing levels of HDL cholesterol (the “good” cholesterol). These fats are considered to increase a person's risk of heart disease, atherosclerosis (clogged arteries), and other diseases. Atherosclerosis can decrease blood flow to the brain, impairing brain functioning. If blood flow to the brain is blocked, a stroke occurs.
Although numerous studies clearly document the benefits of a cholesterol-lowering diet for the reduction of heart disease risk, some studies suggest that reducing fat and cholesterol in the diet may deplete brain serotonin levels, causing mood changes, anger, and aggressive behavior. Some low-carbohydrate diets, such as the “South Beach Diet,” have achieved popularity in part because of their link with beneficial changes in cholesterol levels.
VITAMIN A. Vitamin A is a fat-soluble vitamin found in meats, fish, and eggs. A form of vitamin A, beta-carotene, is found in orange and green leafy vegetables, such as carrots, yellow squash, and spinach. Headache and increased pressure in the head are associated with both deficient and excess vitamin A intake. Among other effects, excess vitamin A intake can cause fatigue, irritability, and loss of appetite. Generally, doses must exceed 25,000 international units (IU) of vitamin A over several months to develop such symptoms.
VITAMIN E. Vitamin E is another fat-soluble vitamin found in plant oils, green leafy vegetables, and fortified breakfast cereals. Vitamin E deficiency is very rare, except in disorders that impair absorption of fat-soluble vitamins in the body, such as cystic fibrosis and liver diseases.
Vitamin E deficiency causes changes in red blood cells and nerve tissues, resulting in dizziness, vision and sensory changes, and muscle weakness. If left untreated, the nerve damage from vitamin E deficiency can be irreversible. Because it is an antioxidant, vitamin E has also been studied for treatment of neurological conditions, such as Parkinson's and Alzheimer's disease. Vitamin E and other antioxidants, such as vitamin C, had shown some promise in treating Alzheimer's, but larger analyses found no beneficial effect of vitamin E supplements. Research on vitamin E and other antioxidants is ongoing.
VITAMIN B6. Vitamin B6, also known as pyridoxine, is found in many plant and animal foods, including chicken, fish, pork, whole-wheat products, brown rice, and some fruits and vegetables. It is needed by the body to produce most of the brain's neurotransmitters and is also involved in hormone production. In healthy individuals, deficiency of vitamin B6 is rare, but certain drugs, including some antidepressant drugs, can induce vitamin B6 deficiency. Symptoms of vitamin B6 deficiency include mental changes, such as fatigue, nervousness, irritability, depression, insomnia, dizziness, and nerve changes.
Excess of vitamin B6 also causes mental changes. Vitamin B6 supplements are used by many individuals for a variety of conditions, including carpal tunnel syndrome, premenstrual syndrome, and fibrocystic breast disease. It is also included in excessive amounts in energy drinks and tablets. Doses of 500 mg per day or more can cause nerve damage, dizziness, sensory loss, and numbness.
FOLIC ACID. Folic acid is another B vitamin, found in liver, yeast, asparagus, dried beans and peas, wheat, broccoli, and some nuts. Many grain products are also fortified with folic acid. In the United States, alcoholism is a common cause of folic acid deficiency.
Folic acid is involved in protein metabolism in the body and in the metabolism of some amino acids, particularly the amino acid methionine. When folic acid levels in the body are low, methionine cannot be metabolized properly, and levels of another chemical, homocysteine, build up in the blood. High blood homocysteine levels increase the risk of heart disease and stroke.
Even modest folic acid deficiency in pregnant women causes an increased risk of neural tube defects, such as spina bifida, in developing fetuses. Folic acid deficiency also increases the risk of stroke. Some studies suggest that folic acid deficiency leads to a range of mental disorders, including depression, but this concept remains controversial. Folic acid deficiency can, however, lower levels of serotonin in the brain.
THIAMIN. Thiamin is a B vitamin found in enriched grain products, pork, legumes, nuts, seeds, and organ meats. It is intricately involved with metabolizing glucose. Glucose is the brain's primary energy source. Thiamin is also needed to make several neurotransmitters.
Alcoholism is often associated with thiamin deficiency. Alcohol interferes with thiamin metabolism in the body, and diets high in alcohol are often deficient in vitamins and minerals. Individuals with a thiamin deficiency can develop Wernicke-Korsakoff syndrome, which is characterized by confusion, mental changes, abnormal eye movements, and unsteadiness that can progress to severe memory loss.
NIACIN. The B-vitamin niacin is found in enriched grains, meat, fish, wheat bran, asparagus, and peanuts. The body can also make niacin from tryptophan. Niacin helps with the release of energy in the body from carbohydrates, proteins, and fats. Niacin deficiency is linked to many mental symptoms including irritability, headaches, loss of memory, inability to sleep, and emotional instability. Severe niacin deficiency progresses to a condition called pellagra, which is characterized by the “four D's”: dermatitis (a rash resembling a sunburn), diarrhea, dementia, and, ultimately, death. The mental symptoms in pellagra can progress to psychosis, delirium, and coma.
IRON. Iron is a trace mineral that is essential for formation of hemoglobin, the substance that carries oxygen to cells throughout the body. Iron is found in meat, poultry, and fish. Another form of iron that is not as well absorbed as the form in animal foods is found in whole or enriched grains, green leafy vegetables, dried beans and peas, and dried fruits. Consuming a food rich in vitamin C, such as orange juice, at the same time as an iron-containing plant food will enhance iron absorption from the food.
Iron deficiency can lead to anemia, which means that the ability of the body to transport oxygen around the body is compromised. This can result in fatigue, lethargy, and poor mood. Iron deficiency during the first two years of life can lead to permanent brain damage.
SELENIUM. Selenium plays a role in immune system functioning, reproduction, and thyroid hormone metabolism. Some research studies suggest that selenium may have a role in mood and energy levels, and that people with a low selenium intake are more likely to be anxious, depressed, and tired; however, it is not clear whether low selenium levels contribute to or are caused by these symptoms. Sources of selenium include walnuts and brazil nuts, seafood, chicken, beef, bran, broccoli, mushrooms, onions, wheat germ, and whole-grain products.
Although selenium deficiency is very rare, selenium toxicity has occurred in regions of the world with high selenium soil content. Selenium toxicity causes nervous system changes, fatigue, and irritability.
MAGNESIUM. Magnesium is found in green leafy vegetables, whole grains, nuts, seeds, and bananas. In addition to its involvement in bone structure, magnesium aids in the transmission of nerve impulses. Magnesium deficiency can cause restlessness, nervousness, muscular twitching, and unsteadiness. Acute magnesium deficiency can progress to apathy, delirium, convulsions, coma, and death.
MANGANESE. Manganese is a trace mineral found in whole grains, nuts, and (to a lesser extent) fruits and vegetables. It is involved in carbohydrate metabolism and brain functioning. Although very rare, manganese deficiency can cause abnormalities in brain function. Groups of miners of manganese in South America have developed manganese toxicity, with neurological symptoms similar to Parkinson's disease.
COPPER. The richest sources of the trace mineral copper in the diet are organ meats, seafood, nuts, seeds, whole-grain breads and cereals, and chocolate. In addition to other functions, copper is involved in iron metabolism in the body and in brain functioning. Deficiency of copper causes anemia, with inadequate oxygen delivery to the brain and other organs. Copper deficiency also impairs brain functioning and immune system response, including changes in certain chemical receptors in the brain and lowered levels of neurotransmitters.
ZINC. Zinc is found in red meats, liver, eggs, dairy products, vegetables, and some seafood. Among 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. It has also been associated with apathy, irritability, jitteriness, and fatigue.
Studies of schizophrenia suggest that people with schizophrenia many have lower than normal levels of antioxidants in the brain, indicating that their brain cells may be more vulnerable to oxidation and damage. However, further research is required before any correlations can be made. Similar research into the role of antioxidants in the prevention of Alzheimer's disease is also ongoing.
Water makes up more than three-quarters of the brain and is an essential element in ensuring the chemical processes in the body work efficiently. Water is lost daily through waste, sweat, and urine. Replacement of these fluids is essential. Average fluid requirements for adults are approximately 35 mL per kg (1.18 oz. per 2.2 lb.) per day. Signs of dehydration include tiredness, restlessness, irritable behavior, weakness, constipation, loss of concentration, and headaches. More severe symptoms can include low blood pressure, fainting, and, on rare occasions, heart failure.
High alcohol or caffeine intake can interfere with normal sleep patterns and affect mood. Alcoholism is one of the most common causes of nutritional deficiencies in developed countries. Alcoholic beverages provide energy but virtually no vitamins or minerals. A person who consumes large amounts of alcohol will meet their calorie needs but not their vitamin and mineral needs. In addition, extra amounts of certain vitamins are needed to break down alcohol in the body, further contributing to nutrient deficiencies.
A small number of mental health disorders are seen as relating directly to food and nutrition. The American Psychiatric Association recognizes seven disorders related to alcohol and caffeine intake: alcohol use disorder, alcohol intoxication, alcohol withdrawal, alcohol-induced disorder not elsewhere classified, caffeine intoxication, caffeine withdrawal, and caffeine-induced disorder not elsewhere classified.
Lifestyle factors, including exercise, are increasingly seen as first-line treatments for people with symptoms of depression, anxiety, and many other common mental health conditions. Interventions that include nutritional therapies often are undertaken in conjunction with more traditional treatments, such as cognitive behavior therapy (CBT).
While there is some evidence that good nutrition can help prevent some mental health problems, good nutrition is not in itself a treatment. Mental health disorders are caused by a complex interaction of factors, in which there is increasing evidence that nutrition is likely to play a role. Good nutrition can promote good physical health, which has also been linked to improved mental health outcomes.
Some changes in mental health may be caused by an underlying medical condition. People experiencing mental health–related symptoms should discuss all concerns with a doctor or psychiatrist.
Some researchers and many parents claim that a high sugar intake causes hyperactivity in children.
Carefully controlled studies do not support this conclusion. High sugar intake is associated with dental problems. Further, foods high in refined sugars are often low in other nutrients, making it prudent to limit their consumption.
Good nutrition is extremely important in helping school-aged children reach their academic potential; research studies suggest that when children are hungry, behavior problems increase. It has been suggested that ensuring good childhood nutrition can help reduce problem behaviors, such as fighting and class absences, while simultaneously increasing attention and focus in the classroom. One study has suggested that taking vitamin and omega-3 fatty acid dietary supplements can positively affect the behavior of adult offenders and reduce antisocial behavior; however, further studies are necessary to replicate these findings among the general population.
See also Anorexia nervosa ; Binge eating ; Body image ; Body mass index ; Bulimia nervosa ; Eating disorders ; Night eating syndrome .
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Academy of Nutrition and Dietetics, 120 South Riverside Plz., Ste. 2000, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600, email@example.com, http://www.eatright.org .
American Psychiatric Association, 1000 Wilson Blvd., Ste. 1825, Arlington, VA, 22209, (703) 907-7300, (888) 357-7924, firstname.lastname@example.org, http://www.psych.org .
Mental Health America, 2000 N. Beauregard St., 6th Fl., Alexandria, VA, 22311, (703) 684-7722, Fax: (703) 684-5968, (800) 969-6642, http://www.nmha.org .
National Institute of Mental Health, 6001 Executive Blvd., Bethesda, MD, 20892, (301) 443-4513, TTY: (866) 415-8051, (866) 615-6464, email@example.com, http://www.nimh.nih.gov .
Annette Dunne, MSc RD
Revised by Tish Davidson, AM