Not all leafy greens will build a super-nutritious salad.

In fact, iceberg lettuce (the nation's most-widely-used leaf) ranks the lowest in nutritional value across the board (96 percent water content will do that!). Turbo-charged spinach, on the other hand, boasts nearly twice the recommended daily value of vitamin K, half the recommended value of vitamin A, and oodles of calcium and iron (1). Clearly, Popeye was on to something. Historically, it has always been regarded as a plant with remarkable abilities to restore energy, increase vitality and improve the quality of the blood

Spinach is high in carotenoids, which the body converts into vitamin A in the liver. This little beauty acts as an antioxidant to combat cell damage done to the body through regular metabolism. In short, it help slows down the ageing of cells and helps rebuild them after exercise (2).

Free radicals are by-products of metabolism. They can cause oxidative stress, which triggers accelerated ageing. This also increases the risk of cancer and diabetes (3).

However, spinach contains antioxidants, which may fight oxidative stress and help reduce the damage it causes (4).

Several human studies link spinach consumption to a reduced risk of prostate cancer. Eating this leafy green may also help prevent breast cancer (5, 6).