The secret to adding years to your life: Eat the rainbow. Colorful fruits and veggies are full of antioxidants — powerful compounds that block dangerous free radicals — and the more variety you get, the better. People who consume many different types of antioxidant-rich fruits and veggies, even in small amounts, reap greater health benefits than those who eat fewer types, according to a Colorado State University study. For maximum longevity, add the proven powerhouses below to your shopping list.

Grapefruit: The antioxidant behind this citrus fruit's bitter taste could help treat diabetes. A 2010 study found that naringenin can help the liver break down fatty acids the way some diabetes drugs do.

Cranberries: Studies have shown that the phytochemical antioxidants in this superfood may have antimicrobial properties (meaning they protect you from infections), reduce the risk of atherosclerosis (plaque buildup in the arteries), and even help prevent the growth of certain cancers.

Garlic: It may give you killer breath, but thanks to its high levels of allicin, garlic has been shown to lower blood pressure. Plus, studies find that it can prevent certain cancers and reduce lipids and "bad" LDL cholesterol levels in the bloodstream, lowering your risk of heart disease.

Coffee: Your daily brew gives you more than an energy boost — it's also packed with polyphenols. A recent study looking at more than 400,000 people found that drinking coffee daily (up to 5 cups) was associated with less risk of dying of health problems such as diabetes, heart disease or infections.

McClatchy News Service