Recommendations by the Harvard School of Public Health for a Healthy Diet.

http://en.wikipedia.org/wiki/Healthy_diet

The Nutrition Source of Harvard School of Public Health makes the following 10 recommendations for a healthy diet:

• Choose good carbohydrates: whole grains (the less processed the better), vegetables, fruits and beans. Avoid white bread, white rice, and the like as well as pastries, sugared sodas, and other highly processed food.
• Pay attention to the protein package: good choices include fish, poultry, nuts, and beans. Try to avoid red meat.
• Choose foods containing healthy fats. Plant oils, nuts, and fish are the best choices. Limit consumption of saturated fats, and avoid foods with trans fat.
• Choose a fiber-filled diet which includes whole grains, vegetables, and fruits.
• Eat more vegetables and fruits—the more colorful and varied, the better.
• Calcium is important, but milk is not its best source. Good sources of calcium are collards, bok choy, fortified soy milk, baked beans, and supplements which contain calcium and vitamin D.
• Water is the best source of liquid. Avoid sugary drinks, and limit intake of juices and milk. Coffee, tea, artificially-sweetened drinks, 100-percent fruit juices, low-fat milk and alcohol can fit into a healthy diet but are best consumed in moderation.Sports drinks are recommended only for people who exercise more than an hour at a stretch to replace substances lost in sweat.
• Limit salt intake. Choose more fresh foods, instead of processed ones.
• Moderate alcohol drinking has health benefits, but is not recommended for everyone.
• Daily multivitamin and extra vitamin D intake has potential health benefits.

Other than nutrition, the guide recommends frequent physical activity (exercise) and maintaining a healthy body weight.