"They are probably the hottest thing presently in terms of helping the brain heal and helping mood through eating properly," said George Pratt, a clinical psychologist in private practice at Scripps Memorial Hospital in LaJolla, Calif.
The body uses omega-3 fatty acids for building neurotransmitters like serotonin in the brain, and some studies have shown that eating plenty of these fats has depression-preventing qualities.
If fish is not part of your diet, you can find these nourishing oils in flaxseeds and walnuts.
In fact, countries where oily fish are a part of the diet, such as Japan, have lower rates of depression than other countries. These countries often have a healthier diet and lifestyle overall, but their omega-3 intake is higher as well.
So, depending on your mood, swallow that spoonful of cod liver oil, just as your grandmother said.
Milk. It does a body good.
This was the slogan for a 1980s ad campaign, urging kids and teens to drink milk to stay healthy. But the commercials, featuring sassy young kids growing up into handsome men and women, did not touch on how milk is good for the mind as well as the body.
Milk is rich in calcium and the amino acid tryptophan. Beyond its bone-building properties, calcium is known to calm nerves when feeling stressed or anxious. Tryptophan is important for producing serotonin, which elevates mood.
The U.S. Department of Agriculture recommends drinking three glasses of milk each day. If you can't stomach cow juice, however, some almonds, also rich in calcium and tryptophan, will do the trick when you feel stressed or down.
Coffee can boost mood on many levels. In the morning, the aroma of a rich Columbian roast can be enough to make you feel more alert. After two cups, the mind is alert, the eyes are bright, and the tail is bushy.
Of course, the sensory effects of coffee, and other warm beverages, like tea or cocoa, can lift your spirits. But the caffeine is the key ingredient when it comes to how a cup of java can affect your mood. The chemical can induce feelings of happiness and euphoria.
"A small amount of coffee or caffeine may help you feel more energized and alert," said the ADA's Sandon. "Too much may backfire, leaving you feeling more stressed and jittery."
Excess amounts of caffeine — say, more than four or five cups each day — can have effects on their own. The body becomes accustomed to the caffeine boost, and when it doesn't receive it, can go through withdrawal-like symptoms, which can lead to irritability and depression. Drinking caffeine after noon can interfere with sleep patterns, leading to further risk of fatigue and depression.
The effect of caffeine is magnified in people with an existing mental condition.
"A patient with bipolar disorder may react positively to coffee when depressed, where as mania could be exacerbated," said Carla Wolper, a nutritionist at the Obesity Research Center at St. Luke's Hospital in New York.
The expert verdict: A small amount of caffeine in the morning is permissible, beneficial, even. More than that, however, and your mood is at risk.
Of the five lucky children with golden tickets who made it into Willy Wonka's magnificent chocolate factory, only the hero was sweet tempered and happy. Perhaps he got started early on the promised lifetime supply of chocolate.