Food and Mood

The relationship between food and mood is mediated by both psychological and physiological factors.

In the psychological realm, humans learn through reinforcement to expect palatable foods to positively influence mood states. Our emotional state can also influence the type and quantity of foods we consume.

In the physiological realm, the nutrients and food-based chemicals we consume can influence both the structure and function of our nerve cells (neurons) and the communicating chemicals (neurotransmitters) that make them work.

Psychological Aspects of Mood and Food

Based on feelings of pleasure and satiation, eating becomes an activity which not only supplies essential nutrients for our survival but also becomes psychologically reinforced. Consumption of highly palatable foods–fats and sugar in particular–becomes readily associated with a positive influence, albeit temporary, on mood states.

Through experience, eating foods we enjoy and find particularly tasty becomes associated with an expectation of mood elevation. The same is true of any pursuit of pleasure; with positive experience and the relief of discomfort there is repeated behaviour.

High-calorie fat and sugar-laden foods are associated with rewards throughout life. Birthday cake, holiday treats, candy, and sweets are associated with important occasions and rewards in childhood. This follows into adulthood so that the full-fat venti latte with extra syrup and whipped cream becomes the reward for a stressful day: birthday cake in a cup.

Stress-Related Eating

Given that highly palatable foods can influence mood states, it should be no surprise that both acute and chronic stress can influence the quantity and types of foods we choose. Research shows that snacking on high-fat and high-sugar foods as a way of coping increases during times of stress.

The first well-designed study, in Psychosomatic Medicine (1990), showed that in periods before major work deadlines employees make significant dietary changes. Intake of total calories, total fat, and overall percentage of calories from fat were significantly higher in the days leading up to work deadlines.

Further research in the British Journal of Health Psychology (1998) showed that daily stress increases the consumption of so-called comfort foods–in this case, fast foods and sweets. In teenagers, the periods before exams lead to higher intakes of total calories, and those reporting greater stress had higher overall fat intake and less consumption of fruits and vegetables.

In structured weight-loss programs, those reporting the highest levels of stress and depression at baseline are most likely to regain weight when followed for 18 months.

In a study in Preventive Medicine (2002) involving over 5,000 adults, researchers showed that stress-driven eaters have a higher body mass index and report a preference for foods rich in fat and sugar.

Depression and Obesity

A higher level of depressive symptoms would be expected in obese patients due to social pressure, body image, and discrimination. However, research indicates that depressive symptoms can pre-date many cases of obesity; and in fact, a number of those who are overweight may be turning to food in an inappropriate effort to medicate depressive symptoms.

In a group of almost 10,000 children, depression among seven- to 12-year-olds doubled the risk for developing obesity when assessed later. Separate researchers found a similar relationship between depression in childhood and adult obesity risk when children aged six to 17 were followed for 10 to 15 years.

Sleep Deprivation

Associated with both stress and depressive symptoms, sleep deprivation is linked to greater body fat in children and adults. In experimental studies, sleep deprivation alters appetite and increases food consumption by an incredible 250 percent.

Physiological Processes of Food and Mood

Modern science has shed significant light on the relationship between mood and food, which has been far from completely understood.

Cortisol

A common thread between chronic stress, sleep deprivation, and depression is an elevation in cortisol levels. This stress hormone increases the activity of the enzyme responsible for laying down abdominal fat and promotes fat storage and is also associated with increased body mass index and waist circumference.

Researchers have shown a relationship between abdominal weight gain and life stressors such as social isolation, divorce, and work or financial stress. In addition to choosing calorie-dense foods under stress, humans are more likely to store the calories as fat due to physiological changes brought on by stress.

Serotonin

Tryptophan, an amino acid essential for the manufacture of the mood-regulating neurotransmitter serotonin, gains access to the central nervous system most readily upon
consumption of sweets and other carbohydrates with low levels of dietary protein.

In addition, stress-prone individuals are protected against depressive symptoms and elevations of the stress hormone cortisol after consumption of a carbohydrate-rich and
protein-poor meal.

There is an abundance of experimental research which shows that low brain-serotonin and high stress-hormone levels enhance the intake of carbohydrates.

Ghrelin

Acute psychological stress raises blood levels of ghrelin, the hormone responsible for stimulating appetite, probably because the sympathetic, or stress branch, of the nervous system can directly stimulate ghrelin production. Since the consumption of highly palatable foods stimulates the area of the brain governing reward, physiological or chemical reinforcement to appetite stimulation and excess calories completes the stress-driven cycle.

Dietary supplements with 5-hydroxytryptophan and whey protein rich in alpha-lactalbumin have been shown to boost serotonin levels, help with sleep, and improve mood states.

Omega-3 Fatty Acids

Important for both brain cell structure and function, docosahexaenoic acid (DHA) omega-3 makes up a significant portion of the nerve cell wall, and eicosapentaenoic acid (EPA) omega-3 is responsible for communication within and between nerve cells.

Inadequate dietary intake of omega-3 fatty acids can have a profound influence on mood and cognition. Intervention studies using fish oil, EPA in particular, have shown that marine-derived omega-3 fatty acids improve depressive symptoms in those with treatment-resistant depression.

In addition, research in the European Journal of Clinical Investigation (2005) showed that one month of fish oil supplementation improved both mood and cognition in otherwise healthy adults.

Vitamins and Minerals

Low blood levels of zinc, selenium, and folic acid have all been shown (individually) to be related to low mood states in humans. A common thread: each of these nutrients helps to metabolize omega-3 fatty acids and boost omega-3 status.

Clinical trials have documented the benefit of just 25 mg of zinc and 500 mcg of folic acid in addition to antidepressant medications (versus placebo). At least two controlled studies also show that a daily multivitamin can improve cognition and mood in otherwise healthy adults, particularly in those who have a poor diet.

Dietary Antioxidants

Because they help preserve omega-3 fatty acids and prevent free radical damage to the lipid components within nerve cells, dietary antioxidants may not only prevent long-term cognitive decline later in life, but may also influence mental state and mood in day-to-day life at middle age.

Support for this hypothesis comes from a University of Toronto study which showed that when compared to a placebo, consumption of a green food supplement rich in antioxidants increased energy and vitality when taken for three months.

Energy

Human energy is a hot commodity in our modern society and energy levels have a tremendous influence on mood state. Caffeine (80 mg) and the amino acid taurine
(1,000 mg) have been shown in a number of studies to influence energy levels, cognition, and mood.

This combination is the basis of most commercially available energy drinks, although these beverages are not well-suited to health-conscious consumers because a small eight-ounce (250-mL) can contains close to 30 grams of sugar or a significant dose of brain-unfriendly aspartame.

It is clear that food can influence mood while mood can influence food choices. It is a complex relationship and one that is highly individualized based on taste, experience, expectations, culture, stressors, and nutritional status.

Based on the research, it is obvious that stress management should be a part of interventions designed to curb the consumption of calorie-dense foods. It is also important to ensure adequate nutritional intake through a balanced diet rich in whole grains, fruits and vegetables, lean meats, fish and seafood, and healthy oils. Supplementation with omega-3 fatty acids and a daily multivitamin-mineral may also be prudent as a nutritional insurance policy for mood support.

Food/Mood Relationships

• complex carbohydrates provide a steady stream of fuel for nerve cells
• amino acids from dietary proteins make up neurotransmitters which influence mood and behaviour
• fats make up the structural components of nerve cells
• vitamins and minerals run the brain machinery
• phytochemicals (natural plant chemicals), such as caffeine and polyphenols, protect nerve cells against oxidative stress and directly influence mood