Chia seed
 

Take the most nutritious food item you can imagine, and there’s a good chance it still pales in comparison to the tiny chia seed. Long heralded by indigenous South American peoples as a source of strength and energy, chia seeds are rich in omega-3 and omega-6 fatty acids, soluble fiber, potassium, and antioxidants. Toss them in a shake, or put it in a bowl of oatmeal.