Are black or green olives more healthy for you? Many people assume the answer is black, given that darker fruits often correlate with higher anthocyanin content (a class of polyphenols which produce purple pigments, among others). Though in the case of olives, it's actually the green which have more antioxidants versus black. This is primarily because the color in the black is not coming from anthocyanins.
Testing results can vary greatly among cultivators and processing techniques, but it's not uncommon to see an ORAC value for green olives which is twice that of the black variety. The most common type of antioxidant in green olives (and all varieties for that matter) is hydroxytyrosol. In terms of fighting free radicals, the scientific committee of the European Food Safety Authority (EFSA) notes that it may offer a more rare health benefit of specifically protecting blood lipids against oxidation. The sample used in this ORAC test was Olymp brand. It was purchased in Norway but the country of origin was Greece. The olives were without their stone, or pitted.
Which type of olive is healthiest? If you're going off of total antioxidant content as measured by the ORAC scale, then the answer would be the Kalamata.
Research Support, Non-U.S. Gov't: Carlsen MH, Halvorsen BL, Holte K, et al. Nutrition Journal NIH Jan 2010