One nutrient that is essential but often overlooked when considering optimal brain health is water.

Research has shown that dehydration can impair several mental functions and cause fatigue and mood changes.

Recent studies using functional MRI scanning show that dehydration can make our brains less efficient because dehydrated neural circuits need to work harder to perform mental tasks.

A 2 percent decline in body weight resulting from dehydration caused by exercise or heat exposure has been shown to impair short-term memory and attention abilities.

Children and older adults are especially vulnerable to the mental effects of dehydration. A recent study of mildly dehydrated schoolchildren indicated that after they received adequate hydration, their short-term memory and verbal skills improved.

The Institute of Medicine recommends the following daily water intake for the average healthy person living in a temperate climate: about 12 eight-ounce glasses for men and 9 eight-ounce glasses for women.

To help ensure you get enough every day, drink a glass of water, tea, or other low-calorie beverage at every meal and between every meal, and be sure to drink water before, during, and after you exercise.