Spinach is not the best tasting vegetable in the world but it packs a incredible amount of nutrients. Spinach is one of the richest sources of antioxidants. One cup of fresh spinach has over 3,600 IU of beta-carotene. Beta-carotene is one of the many carotenoids that are well known for their anti-cancer and anti-aging properties. Beta-carotene is also good for the heart because it prevents the LDL cholesterol from oxidizing which can have damaging effects on arteries.