VEGGIES. Eat lots of vegetables, fruits, and legumes every day. For examples there is strong evidence  that broccoli and other crucifers and tomatoes help protect against cancer and other diseases. 

FATS.

ANTI-OXIDANTS. Take adequate amounts of anti-oxidants such as Vitamins C and E, selenium, and others.

OTHER VITAMINS. Take adequate amounts of other vitamins such as the B's, D, K, etc.

MINERALS. Many people underrate the value of minerals. Most people don't get adequate amounts of calcium, potassium, magnesium, zinc, selenium, or trace minerals.  Deficiencies in any of these over a long period of time can have very serious consequences.

OTHER SUPPLEMENTS. There is research evidence supporting the use of other nutritional supplements.  Examples include milk thistle for a healthy liver, saw palmetto for a health prostrate, acidophilus and bifidus  for digestion, and glucosamine for healthy joints.

FIBER and PROTEIN.  Getting the proper amount of these each day is also important. Most Americans get enough protein, but many don't get enough fiber.