Our ancient ancestors ate lots of green plants, grazing meat animals and fish, all of which are good sources of a class of fats called Omega-3s that are essential for the health of our hearts and our brains. But the processed food and grain-fed meat we eat today gives us a lot fewer Omega-3s. Instead, we're eating a lot more of a class of fats called Omega-6s that may be interfering with Omega-3s.