Being the cornerstone of the Mediterranean-style diet, olive oil tastes great and offers a wide variety of health benefits. But that bottle that has been in your pantry for two years — not so much. As olive oil ages, it loses its nutritional potency. Researchers found that when stored for over six months, the antioxidants in olive oil decrease by about 40 percent. If you don't use much of the oil, buy smaller bottles to keep it antioxidant rich. Olive oil should be stored in a cool, dark space to help prevent oxidation, which not only compromises the taste of the oil but the nutritional benefits as well.