Olive oil, nut oils, fish oils, flaxseed and avocados contain heart-healthy mono-unsaturated omega-3 and omega-9 fats. Twenty-five percent of daily calories should be healthy fats.
RealAge Difference: 3.4 years younger
It's something we hear or read a lot: Certain foods can help your immune system. But what does that really mean? And is there any science behind it?