While the jury is still out on which, if any, nutritional supplements can help with severe depression, there are many supplements that have shown promise with depression in its mild to moderate forms.
The herb St. John's Wort (Hypericum perforatum) has a long history of use as a treatment for sadness, worry, nervousness, and poor sleep. Today, the results of over 20 clinical trials suggest that St. John's Wort works better than a placebo and is as effective as prescription antidepressants for mild to moderate depression (though not effective against major depression), with fewer side effects.
Studies have linked depression with low dietary intake of Omega-3 fatty acids, a type of healthy fat needed for normal brain function. Because our bodies don’t make this essential compound on their own, we must get it from food or nutritional supplements. Cold water fish such as salmon, sardines and anchovies are the richest food sources of Omega-3 fatty acids. In countries with higher fish consumption, like Japan and Taiwan, the depression rate is 10 times lower than in North America. Post-partum depression is also less common in Japan and Taiwan.
For people who are already taking prescription anti-depressants: Studies suggest that Omega-3’s together with antidepressants may be more effective than antidepressants alone.
SAM-e, pronounced "sammy", is short for S-adenosyl-L-methionine. It's a chemical that's found naturally in the human body and is believed to increase levels of serotonin and dopamine—neurotransmitters that play important roles in mood. Several studies have found SAM-e is more effective than a placebo in addressing mild depression.
In North America, SAM-e is available as an over-the-counter supplement in health food stores, drug stores, and online. It should be enteric-coated for maximum absorption.
While all of these supplements are generally believed to be safe, be sure to discuss it with your health care professional before taking any of them, just to make sure they won’t work against any medications you are taking or exacerbate any other health issues you have.