Food for thought

If you think about it, it's heartening to realize that you can't easily influence your mood by a bagel or banana. (Kirk McKoy / Los Angeles Times)

"These nutrients are as effective as antidepressants in treating people with clinical depression," Hibbeln says. In fact, the American Psychiatric Assn. recommends that people with major depression consume a daily omega-3 supplement.

However, some nutritionists have gotten carried away by assuming that omega-3s can boost the spirits of people who are feeling just a little down. "When we give antidepressants to people who are a little blue, we see that placebos have an almost equal response," Hibbeln says.

For those with clinical depression, the recommended dose is three 6-ounce servings of salmon, tuna, herring or sardines each week. Mussels and trout are also good, but less so. If you can't stomach that much fish, take the equivalent in pure fish oil that contains DHA and EPA. Expect effects within a month, Hibbeln says.

Conversely, eating foods that inhibit omega-3s can make people feel worse. These include alcohol and foods high in omega-6 fatty acids, such as corn, vegetable and soy bean oils as well as the hydrogenated fats found in processed foods. Olive oil and saturated fats, such as butter, are considered neutral.

What you eat for lunch causes that 3 o'clock slump.

False

People often blame their lunch for making them feel lethargic in the afternoon. However, your reduced performance probably has more to do with your circadian rhythm than your diet, Kanarek says. A small snack at 3 p.m. can help get you through, but it's best to avoid simple carbs and sugar; Kanarek recommends an apple and some cheese.

If you're feeling cranky, drink water.

True

One of the first signs of dehydration is fatigue, which goes along with depression, Somer says. So tank up before you get dry.

Kristen E. D'Anci, a researcher specializing in nutrition and behavior at Tufts, found that even low levels of dehydration consistently had a negative effect on mood. "Not enough water made people feel irritable, less energetic and often brought on a mild headache," she says. She and her colleagues recommend people drink 2 liters of liquids per day — or more for those who engage in vigorous exercise or live in hot climates. Water is good, but almost any liquid, including caffeinated beverages, will do. Alcohol doesn't count.

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