Can brain foods make you smarter?

To function at its very best, the brain needs fat and sugar. That may sound surprising, given how often we're warned away from those two substances. However, the brain is the only organ that draws nearly all its energy from glucose. It's also the body's second-highest deposit of fat, after fatty tissue itself (such as the butt and the gut) [source: Aaronson].

It's not just any fat and sugar that the brain is after, though. Trans fats and saturated fats, such as those found in fast food and junk food, can decrease cognitive ability [source: UCLA]. One study found that rodents who were given the equivalent of rat junk food couldn't navigate mazes or remember the solutions to problems they'd solved previously [source: Douglas et al.]. Those kinds of fats harden brain cells.

Your brain cells crave polyunsaturated fatty acids, which you may know by the names omega-6 and omega-3. We typically get enough omega-6 acids throughout the day thanks to their presence in soy and corn oils, but most people need to consume more omega-3 fatty acids. These acids appear to strengthen the brain's synapses, which provide the pathways for neural communication. Omega-3s also appear to help molecules on the synapses directly related to learning and memory. In an Australian study, children who drank a beverage with omega-3 fatty acids received higher scores on tests of verbal intelligence and memory compared to children who didn't have the drink; results were evident after just six months [source: UCLA].

­Omega-3 fatty acids are found in some nuts, such as walnuts and hazelnuts, flaxseed, kiwi and most importantly, fish. Researchers aren't sure why exactly fish are so helpful to brain cells, but there's plenty of evidence showing that it might be the ultimate brain food. In one study, elderly people who ate fish at least once a week slowed cognitive decline about 10 percent compared to those who didn't chow down on fish, and the fish-eaters also performed better on tests of memory and mental sharpness [sources: O'Connor, Bakalar]. In rodents, omega-3 deficiency has led to learning impairments, while the consequences of a deficiency in humans include brain disorders such as dyslexia and schizophrenia [source: UCLA]. One physiologist even speculated that fish consumption by early man is what spurred the human brain to get so big in the first place [source: Binns].

To read about the sugar your brain needs and to learn whether too much brain food is a bad thing, swim on over to the next page.

We mentioned on the last page that your brain needs glucose to function properly. The glucose supply should be steady, so that means no skipping meals. It also means you should avoid a cheap source of glucose, like a candy bar. Candy will give you a quick high and a plummeting low in terms of glucose levels, and if you've ever experienced a sugar crash, you know what that can do to your body. To provide a steady stream of glucose, you should look for food that slowly releases carbohydrates into the bloodstream, which include most fruits and vegetables, milk and breads with lots of grains. Foods such as candy and white bread just give you the sugar rush.

Glucose is essential for keeping the neurotransmitters in the brain at peak levels, but is there anything else you can eat besides oatmeal and salmon? Yogurt also aids the production of neurotransmitters thanks to its amino acids [source: Douglas et al.]. Choline, a nutrient found in eggs and soybeans, produces a neurotransmitter called acetylcholine; abnormally low levels of acetylcholine have been found in people with Alzheimer's disease, so you know you want to keep yours up [source: Aaronson]. Folic acid, essential for brain function, can be found in spinach and orange juice. And don't be afraid of spicing it up a bit; curcumin, a spice used in curries, may be one reason why India has such a low incidence of Alzheimer's [source: UCLA].

But don't go too crazy with all these brain foods. When you consume too many calories, you can undo the positive brain effects. In the process of converting glucose to energy, extra oxygen is created as unstable molecules called free radicals. Free radicals in turn cause oxidative stress by destroying brain cells they come in contact with. Not only does this oxidative stress force the brain's synapses to work harder, it's also a major factor in many diseases, which is why you so often hear about the benefits of antioxidants.

Fruits and vegetables are full of the antioxidants that can fight those free radicals. Load up on a salad of spinach, broccoli, carrots and onions, and don't forget to throw some berries on top. If you're more in the mood for a beverage, you can drink your antioxidants in the form of concord grape juice, which has the total antioxidant level of any fruit, vegetable or juice tested [source: Flora]. Green tea also provides antioxidants to the brain.

Keeping your brain running smoothly by means of fueling it with the right energy is just one step to increasing your smarts, though. Eating the right food will clear the pathways for knowledge to zoom around the brain, but you'll have to put it there. For some true food for thought, go to the next page and load up on more information about the brain.