Mood Foods. Some foods just make you feel better

Some foods just make you feel better. But, is it just our perception that smooth, silky chocolate can calm us down after a bad day and caffeine makes us more alert, or can food-based compounds cause actual physiological changes to our state of mind?

A caffeinated world

Caffeine is perhaps the most widely used legal psychoactive agent (substance that affects brain functioning) in the world. Chemically speaking, caffeine is a xanthine alkaloid compound that is completely absorbed by our body within approximately 45 minutes after ingestion (European Journal of Clinical Pharmacology, 1981; 21:45-52). Caffeine binds to adenosine receptor sites in our central nervous system, leading to a decrease in adenosine activity. This decrease in adenosine activity results in an increase in dopamine, a neurotransmitter that stimulates the central nervous system (Pharmacology Reviews, 1999; 51:83-133).

If you think caffeine can help you get through that last hour of work, you aren’t imagining anything. Studies show that caffeine in doses of approximately 4 mg per kilogram of body weight can increase mental alertness and improve semantic memory, logical reasoning, free recall and recognition memory tasks (Appetite, 1994; 22(1):39-55). In addition, multiple small doses of caffeine given over a period of time seem to be equally as effective as a single large dose in improving alertness and performance on reactive and cognitive tasks (Psychopharmacology, 2002; 164:188-192).

Though the time it takes to eliminate caffeine completely from one’s body depends on a variety of factors, in general, half of caffeine consumed at any given time is eliminated in three to four hours (“Physician’s Drug Handbook,” 11th edition, 2005), which means that nighttime caffeine consumption could interfere with sound sleep.

Synthetic and natural sources of caffeine can be found in a variety of foods and beverages. Caffeine does more than just stimulate our central nervous system, it also lends a bitter flavor to foods and beverages, and may enhance sweet and salty tastes, as well (Journal of Sensory Studies, 2007; 15:449-457).

Theanine and tea

Tea is the most widely consumed beverage worldwide, trumped only by water—and with good reason. It is calorie-free, widely available and can both increase alertness and help us maintain focus (Nutrition Reviews, 2008; 66:82-90).

Tea’s unique relaxation and enhanced-concentration properties stem from its naturally occurring combination of caffeine and the amino acid l-theanine. Both caffeine and l-theanine stimulate areas of the brain that increase our alertness, and l-theanine increases alpha-brain-wave activity, which induces relaxation (Alternative Medicine Reviews, 2005; 10:136-138). Approximately 200 mg of l-theanine can reduce psychological and physiological stress (Biology and Psychology, 2007; 74(1):39-45), and l-theanine produces a dose-dependent relaxed, yet alert, state about 40 minutes after it is consumed (Alternative Medicine Reviews, 2005; 10:136-138).

Craving carbohydrates

Foods high in carbohydrates provide immediate energy and the preferred fuel source for our brain, glucose. Cut carbohydrates out of your diet, and your cognitive functioning, focus and memory may suffer (Psychopharmacology (Berl), 1999; 145:378-385; Appetite, 2009; 52:96-103).

In addition to affecting our cognitive functioning, carbohydrate consumption indirectly affects our mood. Carbohydrate increases the amount of insulin circulating in our bloodstream, and insulin increases the uptake of branched-chain amino acids in muscle tissue, thereby decreasing amino-acid competition across the blood-brain barrier. The amino acid tryptophan can then move more easily across the blood-brain barrier into the central nervous system, where it is converted to our feel-good neurotransmitter, serotonin.

Because we can manipulate our neurotransmitter production and, therefore, mood through carbohydrate consumption, one may wonder if people self-medicate through food. Indeed, many scientists believe that some people reach for carbohydrate-rich foods to make themselves feel better when they are experiencing a sour mood or depressed state of mind (Obesity Research, 1995; Suppl 4:447S-480S; Appetite, 1998; 11 Suppl 1:42-47). The link between using carbohydrates to enhance serotonin production is further amplified by the observation that prescription drugs that increase serotonin reuptake or transmission can lead to a decrease in carbohydrate consumption in some people (Journal of the American Dietetic Association, 1984; 84:1,004-1,007; Appetite, 1998; 11 Suppl 1:42-47). In fact, some physicians use selective serotonin reuptake inhibitors to help control binge eating, overeating and bulimia (Advances in Therapy, 2005; 22:278-283).

Serotonin needs vitamin B6

Because vitamin B6 is necessary for the conversion of tryptophan to serotonin, one might wonder if B6 is a rate-limiting substrate in this process, and if taking more can enhance serotonin production, making us feel happier and less depressed (“Modern Nutrition in Health and Disease,” 9th edition, 1999, 413-421). However, studies show that B6 supplementation does not relieve symptoms of depression in individuals suffering from depression (Contraception, 1997; 55:245-248).

Chocolate comforts

Commercials tell us that the smooth, creamy mouthfeel of chocolate will leave us feeling relaxed, without a care in the world. Is there any truth to these marketing messages? Some people crave chocolate and experience greater arousal and pleasure from just looking at images of chocolate (Biology and Psychology, 2005; 70:9-18). In addition to differences in chocolate cravings, those who are experiencing higher scores of depression reach for chocolate more often (Archives of Internal Medicine, 2010; 170:699-703). There’s a plausible reason for this: Eating chocolate can improve a negative mood, although it seems to have no effect on a positive or neutral mood (Appetite, 2007; 49:667-674).

Despite the immediate lift in mood some experience after eating chocolate, this elated state of mind is transitory (Journal of Affective Disorders, 2006; 92:149-59) and can immediately turn to feelings of guilt in those who believe certain foods will damage their efforts to lose or maintain weight (Appetite, 2006; 46:332-336).

Scientists believe that people use food to cope with stress and improve their mood. However, we vary tremendously in our cravings for certain foods, based on our state of mind and how we handle stress and our feelings. Emotional eaters actually have different responses in the feel-good sections of their brains to food, or even the anticipation of food, than non-emotional eaters (International Journal of Eating Disorders, 2009; 42:210-221), making fighting the urge to self-medicate potentially more difficult in emotional eaters.