Nutrients for your mind (and your mood)

If you want to maximize your brainpower and happiness, your overall way of eating—not one or two "magical" foods or nutrients—yields the biggest benefits.

One way to accomplish this is to eat a Mediterranean diet, favoring fish, nuts, whole grains, olive oil, and red wine (in moderation), while limiting dairy, red meat, and refined carbohydrates. Several large studies have linked the Mediterranean diet to lower rates of Alzheimer's disease and depression in adults. The more closely the participants followed it, the better their chances were of staying mentally alert and emotionally stable over a subsequent period. In one study, those with the poorest adherence to the diet had a 40 percent greater chance of developing Alzheimer's disease.

The Mediterranean diet helps keep your arteries and heart healthier—which in turn helps keep your brain supplied with blood and oxygen. But at least one follow-up study concluded that the diet's benefits to the brain were independent of its vascular effects. Scientists think they might derive from some combination of these nutrients, all abundant in the diet:

• Omega-3 fatty acids. Found in foods including salmon, walnuts, soy, and flaxseed oil, omega-3s are one of the brain's basic building blocks. Some preliminary studies in animals have suggested that they aid in the function of the neurotransmitters dopamine and serotonin, which help govern mood. Researchers think omega-3s might have played a role in the study results described above. Increased omega-3 intake might also have contributed to the outcome of a small 2010 study, in which a group of women ages 19 to 30 who followed a Mediterranean diet for 10 days reported significantly higher levels of alertness, contentment, and vigor compared with a control group.
• Vitamins B6, B12, and folate. They might help to stave off depression, possibly by having an impact on serotonin levels. Low levels of B vitamins are associated with depression, and some studies have found that taking supplemental folate can help people with the condition respond better to antidepressant medications. Deficiencies in vitamin B12, which is found in eggs, fish, seafood, meat, milk, and poultry, can lead to memory loss. (That's why certain people who can't get enough of the vitamin from food, including older adults and strict vegetarians, are usually advised to take a modest B12 supplement.) Low levels of folate, found in beans, berries, leafy greens, oatmeal, and soybeans, have been linked to memory problems. (All three of those B vitamins can also be found in fortified breakfast cereals.)
• Magnesium. This mineral can help regulate the brain's serotonin levels and is found in beans, flaxseed, leafy greens like spinach or Swiss chard, nuts, potatoes (including sweet potatoes), and wheat germ. Low magnesium levels are linked to premenstrual syndrome and have also been implicated in treatment-resistant depression. Note that the most significant benefits seem to come from following the Mediterranean eating pattern as a whole. Clinical trials testing certain components of the diet in isolation, such as fish oil, have often turned up less-impressive results.