Complex carbohydrates: Many people crave carbs when they're depressed -- especially when they're struggling with wintertime SAD. Whether it's a chemical cause or a learned behavior is unclear, but there's something about a big piece of chocolate cake that promises sweet relief. Carbs affect the body's serotonin levels, which makes you feel good. But be careful with the foods you choose -- simple carbs can cause a spike in blood sugar and then a crash. Complex carbs keep things nice and steady, so stick to foods like oatmeal and whole-wheat bread [source: WebMD].
Omega-3s: Researchers have been investigating the connection between omega-3 fatty acids and heart health, but there have been some interesting studies on omega-3s and depression, as well.
There are different types of omega-3 fatty acids. Your body can't make its own -- you have to know what to put in your mouth to get them. The two omega-3 fatty acids with the biggest health benefits are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in fish such as sardines, salmon and halibut.
What do omega-3s do? Among several other important functions, such as keeping blood from clotting too much, omega-3s help with brain and behavioral function [source: University of Maryland Medical Center]. People with an omega-3 deficiency exhibit poor memory, poor concentration, mood swings, fatigue and depression. So if depression is a symptom of deficiency, researchers thought these fatty acids could be a possible cure for it.
If you look at the studies examining the role of omega-3s in improving depression symptoms, you won't find a clear answer. Some studies have found that omega-3 supplements in addition to medications help people with depression and bipolar disorder. But those findings aren't consistent [source: University of Maryland Medical Center]. If you decide to take a supplement, pick one with mostly EPA -- a meta-analysis showed that to be the most effective [source: Raison].
Vitamin D: Without vitamin D, your bones get soft and weak, your immune system falls apart and your muscle strength is reduced. Vitamin D deficiency may also be linked to depression in older people [source: WHFoods].
One way we get vitamin D is from fortified foods, such as milk and cereal -- few foods contain it naturally, although salmon and tuna are good bets (get your omega-3s and vitamin D in one sitting!). The other way we get it is from the sun.
Exposure to the sun's UVB rays triggers your body to produce vitamin D, but it's not a perfect system. People with dark skin don't make the same amount of vitamin D, for example, and neither do people who live far away from the equator. Overweight and older people also have lower levels of vitamin D [source: Harvard School of Public Health].
Since seasonal affective disorder is thought to be connected to a lack of exposure to light, researchers are interested in the vitamin that's made from sunlight. Like with omega-3s, there isn't conclusive evidence indicating that eating foods high in vitamin D will help symptoms of seasonal affective disorder. But the research is promising, and there's a good chance you're deficient anyway, according to the Harvard School of Public Health.