The good fats aren't only good for your heart; new studies show they're also good for your brain, especially polyunsaturated fats containing omega-3s. In one recent study, girls who ate omega-3s actually outsmarted girls who ate higher amounts of omega-6 fatty acids. And scientists believe that women of childbearing age and pregnant and breastfeeding women who store and continue to eat omega-3s supply nutrients that are critical to fetal and early infant brain development. But pregnant and breastfeeding women should continue to balance the need for omega-3s with the risk of eating fish containing mercury.

Omega-3s have also been shown to help people with depression. One 2007 study out of Norway showed that nearly 22,000 people with depressive disorders who took daily doses of cod liver oil, which is high in omega-3s, experienced less depressive symptoms. Another study found depleted levels of omega-3 fatty acids in people with severe depression. And researchers suspect that women who have low levels of omega-3 during pregnancy may be more prone to pregnancy-related depression.