<p>Everyone knows bananas are full of potassium, but what you may not know is that they also contain tryptophan, a brain chemical that helps to regulate mood, according to<a target="_blank" href="http://bottomlinehealth.com/feeling-blue-try-bananas/"> Dr. Ara DerMarderosian, research professor at University of the Sciences</a>. Bananas are also a good source of B vitamin folate, and having low levels of the vitamin has been linked to depression.</p><p>For recipes starring bananas, try <a target="_blank" href="http://www.delish.com/cooking/recipe-ideas/g2781/banana-ice-cream/">20 Crazy Twists on Frozen Banana Ice Cream</a>.</p>