If you think about it, it's heartening to realize that you can't… (Kirk McKoy / Los Angeles…)
You've heard the claims: Chocolate evokes that loving feeling. Eating fish makes you smarter. Pure carbs calm you down. If you are what you eat, as they say, then it certainly stands to reason that food can influence mood and brain power.
The theory behind these supposed connections seems plausible. Certain neurotransmitters do affect the brain and, consequently, our dispositions in measurable ways. For instance, high levels of serotonin are associated with being calm, happy and relaxed, while low levels are linked to depression and aggression. Dopamine and norepinephrene are reward chemicals released by the brain in response to pleasure.
Particular foods have been shown to boost the production of these neurotransmitters but usually not by enough to make a perceptible difference in the brain. In fact, science has shot down most of the food-mood links accepted as conventional wisdom and perpetuated by self-proclaimed nutrition experts.
Which is a good thing. If you think about it, it's heartening to realize that you can't easily influence your mood by a bagel or banana.
"If food were designed to take mood way up or way down, we'd be in big trouble," says John Fernstrom, a professor of psychiatry and pharmacology at the University of Pittsburgh School of Medicine.
Still, people have an insatiable craving to believe that eating certain things will boost mental focus, attitude or energy. And believing may just be the best shot at a food-mood connection.
"Our perceptions about food and what it will do for us are very strong and can create a self-fulfilling prophecy, even if no physiological evidence exists," says psychologist Robin Kanarek, who directs the nutrition and behavior laboratory at Tufts University in Medford, Mass.
Although much remains to be studied, here's what scientists currently believe to be true and false with regard to the relationship between the belly and the brain:
Sugar makes kids hyperactive.
We've heard for years that sugar gets kids all wound up at birthday parties or on Halloween, but it's really just the excitement and unstructured environment surrounding the festivities, Kanarek says. She cites an authoritative analysis published in the Journal of the American Medical Assn. in 1995 that examined the effect of sugar on the behavior or cognition of children. Researchers crunched through the data from 16 published studies in which neither kids nor their adult observers knew who got real sugar and who got an artificial sweetener. The surprising result was that sugar had nothing to do with how the children behaved.
The fact that parents expect their kids to bounce off the walls after they eat sweets is what perpetuates the behavior, Kanarek says. Moreover, many parents don't realize that the body can't tell the difference between the sugar in a glass of apple juice or the sugar in a large cookie.
Coffee improves energy and mental performance.
This claim has been supported in numerous studies which have consistently shown that caffeine — the ingredient that gives coffee its kick — improves focus, attention, mood and energy, says psychiatrist Joseph Hibbeln, acting chief for the Section on Nutritional Neurosciences at the National Institute on Alcohol Abuse and Alcoholism. "Caffeine creates a more perfect association of ideas," he says.
An irrational fear of caffeine addiction turns some people against coffee, says Marcia Pelchat, a food researcher at Monell Chemical Senses Center in Philadelphia. "It's harmless because the amount people use is self limiting," she says. "People back off when they feel jittery."
Carbohydrate snacks make you feel calmer and happier.
Some nutrition experts still perpetuate the outdated theory that a high-carb snack will boost mood. The reasoning went like this: Carbohydrates boost serotonin, which makes you feel calm and relaxed, so eating carbohydrates also makes you feel calm and relaxed. The problem is that a lot happens between the mouth and the brain. For instance, if you have any protein within 12 hours of a carb snack, the protein will block the brain's uptake of serotonin and the snack will have no effect on your mood, Fernstrom says.
In an experiment with lab rats, researchers found that for the animals to experience any serotonin boost from carbs, they had to put two to four hours between the all-carb snack and a protein meal — and their metabolism rates are about five times higher than those of humans. So if you had one slice of bacon at 8 a.m., then nothing but pure carbohydrates all day, at 8 p.m. you might feel a little boost.
Ironically, preliminary research suggests that some dietary protein — such as that from eggs — may have a bigger effect on mood than carbohydrates, Fernstrom says.
Sugar takes the edge off pain.