Food and Your Mood


New research focuses on how what you eat affects how you feel

Maybe it's not just the sunny climate, dazzling blue sea and bountiful beaches that make people living around the Mediterranean more cheerful. Prior research has shown that the lifetime prevalence of mental disorders is lower in Mediterranean countries than in northern Europe. Now a new Spanish study suggests that part of the explanation might be the so-called "Mediterranean diet."

It's the latest clue in unraveling the mystery of how food affects your mood. While scientists know, for example, that foods high in protein tend to make you more alert and carbohydrates can relax you — hence the term "comfort food" — most connections between what you eat and how you feel are less clear. Longer-term effects of diet on mental state, such as in the new Spanish research published in Archives of General Psychiatry, are particularly elusive.

Almudena Sánchez-Villegas, PhD, professor of preventive medicine at the University of Navarra, and colleagues studied 10,094 healthy Spaniards, initially free of depression. Participants reported their dietary intake on a 136-item food frequency questionnaire, used to calculate a 0 to 9 score for adherence to the "Mediterranean diet." Scores were based on nine components: high ratio of monounsaturated fats (such as in olive oil) to saturated fats; moderate intake of alcohol and dairy products; low intake of meat; and high intake of legumes, fruit and nuts, cereals, vegetables and fish.

After a median of 4.4 years of follow-up, 480 new cases of depression were identified. Participants with the highest "Mediterranean diet" scores, between 5 and 9, were 42% less likely to develop depression than those who scored 0 to 2. Overall, as scores dropped, risk for depression went up. The association didn't change when the results were adjusted for other markers of a healthy lifestyle.

To exclude potential pre-existing but undiagnosed depression, the researchers also analyzed the data without cases of depression diagnosed within the first two years. In that analysis, an even stronger inverse association emerged: Those with the highest scores were 58% less likely to develop depression and those in the next-highest group were at 50% lower risk.

Of the nine dietary components, consumption of fruits and nuts, legumes and monounsaturated fats was most closely related to reduced depression risk. Too much dairy and meat had the strongest association with increased risk.
This is your brain on food

How can food affect your mood, especially in chronic conditions such as depression? While the Spanish study was not designed to determine cause and effect, Sánchez-Villegas and colleagues took particular note of the findings about fats. Monounsaturated fats, like those in olive oil, might improve how serotonin — a neurotransmitter that helps bridge the gap (synapse) between nerve cells — binds to receptors in the brain.

Serotonin regulates mood, anger and aggression, appetite and even some cognitive functions. When serotonin is converted to the hormone melatonin, it helps you sleep. Most common antidepressants, such as Prozac and Zoloft, are selective serotonin reuptake inhibitors (SSRIs), which block the re-absorption of serotonin, leaving more at work in the synapses.

"The membranes of our neurons are composed of fat, so the quality of fat that you are eating definitely has an influence on the quality of the neuron membranes," said Sánchez-Villegas, "and the body's synthesis of neurotransmitters is dependent on the vitamins you're eating. We think that those with lowest adherence to the Mediterranean dietary plan have a deficiency of essential nutrients."

Vitamin B6 and folate, found in the vegetables, fruits and nuts, and legumes prevalent in the "Mediterranean diet," are especially crucial to healthy serotonin levels. The body needs these nutrients to convert tryptophan — found in dietary sources such as poultry, milk, bananas, oats and nuts — into serotonin. Studies have shown, for example, that psychiatric patients with depression are much more likely to be folate deficient, which causes serotonin levels in the brain to drop.

But serotonin is only part of the story. Sánchez-Villegas and colleagues suggested that B vitamins and folic acid may also counter depression through effects on the metabolism of two amino acids, methionine and homocysteine.

The "Mediterranean diet" might even improve mood in some of the same ways it's been shown to boost heart health. "Components of the diet may improve blood vessel function, fight inflammation, reduce risk for heart disease and repair oxygen-related cell damage, all of which may decrease the chances of developing depression," the researchers noted.

"However, the role of the overall dietary pattern may be more important than the effect of single components," they added, citing the "synergistic combination" of omega-3 fatty acids, other unsaturated fats, antioxidants, flavonoids and other phytochemicals, and natural folates and other B vitamins.
Fish-oil findings

Indeed, recent studies of individual nutrients' effects on mood have reported mixed results. In two earlier studies, for example, the omega-3s found in fatty fish (EPA and DHA) were found to significantly boost the effects of antidepressant medication among patients who were otherwise healthy. Such a combination makes biological sense, since omega-3s play a key role in the workings of neurons in the brain. And other research has found that people who seldom eat fish have an almost one-third higher incidence of mild to moderate depression than regular fish-eaters.

But a new clinical trial, published in the Journal of the American Medical Association (JAMA), failed to find a benefit for omega-3s among patients with depression plus coronary heart disease. Robert M. Carney, PhD, of Washington University in St. Louis, and colleagues split 122 patients into two groups: One group took an omega-3 supplement (930 mg EPA, 750 mg DHA), while the other got a placebo. All participants also received 50 mg of sertraline (Zoloft) daily. After 10 weeks, no significant difference was seen between the two groups on two standard tests for depression.

Despite the disappointing findings, Carney points out, "There have been about 20 studies of omega-3 and depression symptoms and about half have found a positive effect. It could be dose, duration or type of omega-3 (EPA or DHA) that determines the outcome."
Brewing a better mood

Like the "Mediterranean diet" and omega-3s, green tea has been associated with a wide range of health benefits — so it's not surprising that antioxidants in green tea might also affect your mood. In research recently published in the American Journal of Clinical Nutrition, Kaijun Niu, MD, PhD, of Tohoku University and colleagues compared green-tea consumption and symptoms of depression among 1,058 elderly Japanese.

Overall, about a third of the elderly participants had a mix of mild and severe symptoms, while about one in five had severe symptoms. After adjusting for other factors, those drinking four or more cups of green tea daily were 44% less likely to have mild and severe symptoms of depression than those drinking one cup or less per day. A similar relationship was seen for green-tea consumption and risk of severe depression.
The carb connection

But what about "comfort food"? While not a free pass to load up on buttery mashed potatoes or cheesy pasta, the role of carbohydrates in promoting relaxation — at least in part by enhancing serotonin levels — does suggest complex carbohydrates such as whole grains could be good for your mood.

One intriguing test of the "comforting" power of carbohydrates comes from the popularity of "low-carb" weight-loss plans such as the Atkins diet. Might dieters who are cutting back on carbs lose their sunny disposition along with pounds?

Australian researchers put this question to the test in a new study published in the Archives of Internal Medicine, Grant D. Brinkworth, PhD, of the Commonwealth Scientific and Industrial Research Organisation, and colleagues conducted a randomized clinical trial involving 106 overweight and obese participants, average age 50. While cutting calories equally, one group followed a very low-carbohydrate, high-fat diet, and the rest ate a high-carb, low-fat diet.

After one year, both groups averaged about 30 pounds of weight loss. But their moods differed as the study went on: Initially, after the first eight weeks, both groups experienced an improvement in mood as measured by scores on three standard tests. Only the high-carb group, however, showed lasting improvement on most measurements of mood, including hostility, confusion, depression and overall bad mood, while those on the low-carb diet returned to their baseline, more negative levels.

"This outcome suggests that some aspects of the low-carbohydrate diet may have had detrimental effects on mood that, over the term of one year, negated any positive effects of weight loss," Brinkworth and colleagues concluded. The difficulty of sticking to a low-carb diet may have been a factor in the group's negative moods, researchers speculated. But serotonin and proteins affecting neurons, they said, could play a part as well.

All these new studies about food and mood point to the importance of eating right to maintain a healthy outlook. The same nutrition-smart decisions you're already making for your body are likely to benefit your mental state, too. Now that's something to feel good about! ?

TO LEARN MORE: Archives of General Psychiatry, October 2009; abstract at . JAMA, Oct. 21, 2009; abstract at . American Journal of Clinical Nutrition, online before print . Archives of Internal Medicine, Nov. 9,2009; abstract at .
Put on Happy Plate

While many questions remain about the effects of food on mood, experts generally agree on these ingredients of a mentally healthy diet:

* Eating a healthy breakfast and occasional healthy snacks helps stabilize your blood sugar throughout the day, avoiding anxiety-producing "sugar drops."
* Foods high in complex carbohydrates such as whole grains, can increase serotonin levels and help keep you calm.
* Protein can boost alertness, as the body breaks it down into amino acids that serve as neurotransmitters.
* Get your daily dose of folate. Good sources include fortified cereals, baked goods, leafy vegetables (spinach, broccoli, lettuce), okra, asparagus, fruits (bananas, melons, lemons), legumes, mushrooms, orange juice and tomato juice. The adult RDA for folate is 400 micrograms-about the amount in a cup and a half of beans.
* Don't overdo alcohol, which is a powerful depressant and can damage the quality of your sleep.
* Caffeine really can perk you up, acting as an anti-depressant; too much, however, can cause anxiety in some people.
* Don't count on chocolate. Besides the short-lived boost of eating any candy containing sugar and fat, the evidence is mixed on whether chocolate has any special effect on mood. One 2007 study tested chocolate on people who watched sad, happy or neutral film clips: Only those depressed by the sad film got any boost from chocolate, and the effect was short-lived. A 2006 review suggested that people who are depressed may feel even worse after the initial mood improvement from chocolate wears off.

Share this with your friends