Are there foods that can actually increase mental alertness?

Unfortunately, solid research in this area is a little tricky because it is difficult to measure mental alertness, but studies have pointed a definite finger at some diet dos. "Vitamin A plays an important ongoing role in brain function and in our ability both to learn and remember," says biologist Ron Evans, Ph.D., of the Salk Institute for Biological Research in La Jolla, California. "Most people have enough vitamin A in their diet to sustain learning and memory," says Evans, and when there's a deficiency, one can begin to experience cognitive problems. Conversely, there's no evidence that those with sufficient levels of the vitamin who take surplus amounts will see brain-bolstering effects. Foods high in vitamin A (and generally beta-carotene) include leafy green vegetables, yellow vegetables and fruits, egg yolk, milk, and fortified cereals. Evans says it's also important to have enough iodine (found in iodized salt and seafood). We need iodine for a healthy thyroid—closely linked to mental and cognitive functioning. An iodine deficiency is likely to have adverse effects. Research also shows that, as weight increases due to an excessive intake of fat or a lack of exercise, animals tend to become more sedentary and, ultimately, less alert. "To optimize your alertness, you want to stay as close to your natural weight (set point) as possible; limit your fat intake to unsaturated fats and be as active as you can be," says Evans.