If you're snapping at co-workers or feeling anxious about an upcoming social event or just plain cranky, it could be something you ate. Or didn't eat. Food can have a direct effect on your stress levels: With the right diet you can manage the challenges that come your way; the wrong one can leave you defenseless. According to a March 2008 study, women with high levels of the "stress hormone" cortisol tend to eat more calorie-dense sweet foods and far less fresh vegetables. A survey launched by the U.K.'s Food and Mood Project in 2001 showed that people who consumed more sugar, caffeine, alcohol, and candy felt more stress, while those who ate more vegetables, fruit, and oil-rich fish, felt the least stressed.
But it's not just a matter of what you eat. It also matters how much and how often. Calorie restriction can lead to fatigue, depression, irritability, and lethargy, according to Gary Taubes, author of Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease (Knopf, 2007). Nutritionists recommend eating every four hours, and including foods high in protein, B vitamins, antioxidants, calcium, and other stress-fighting nutrients.
Berries: The antioxidants in blueberries and raspberries can help prevent oxidative stress, which is linked to chronic diseases and aging. Berries also satisfy a sweet tooth better than a candy bar—you won't crash half an hour later.
Citrus: Both grapefruit and oranges contain high amounts of vitamin C, which is involved in the production of adrenaline, says Jack Challem, author of The Food-Mood Solution: All-Natural Ways to Banish Anxiety, Depression, Anger, Stress, Overeating, and Alcohol and Drug Problems—and Feel Good Again (Wiley, 2007). Vitamin C deprivation, according to Challem's research, can result in fatigue and irritability.
Herbs: "Oregano tops the list of herbs in terms of antioxidants," reports Miami-based dietitian Betsy Klein, R.D., L.D., "followed by dill, thyme, and rosemary." Another bonus: "The flavor boost you get from herbs means you can use less salt," says Klein.
Nori: This roasted or dried seaweed is the richest source of iodine you can find. "You need iodine to make thyroid hormones, and that's a natural upper," says Challem. "Fish and seaweed are a great stress-busting combo."
Shellfish: Crab, lobster, and shrimp are low in calories and saturated fat. They're also flavorful and full of high-quality protein, B12 and B6, selenium (an antioxidant), and zinc, which helps speed the metabolic process of proteins. "Zinc, like magnesium and calcium, helps antioxidants do their job, shuttling free radicals out of your system," says Challem.
Spinach: Full of iron, a one-cup serving of spinach also provides 40 percent of our daily requirement of magnesium, a mineral shown to lower stress levels. Deficiencies can cause migraine headaches, fatigue, and general irritability.
Turkey: Like lean beef, turkey contains calming tryptophan. But turkey goes beef several better: It has more protein, fewer calories, and much less saturated fat.
Whole Grains: "Buckwheat, farro, cracked wheat, and other whole grains positively affect serotonin production in much the same way that exercise and certain antidepressants do," says Betsy Klein. The fiber in whole grains also helps regulate blood sugar.