Vitamin C is an important water-soluble antioxidant that serves many vital functions in the body’s cells. It is necessary for the synthesis of collagen, the most abundant structural protein in the body. Kale is much higher in vitamin C than most other vegetables, containing about 4.5 times much as spinach. A cup of raw kale contains even more vitamin C than an orange.
Cholesterol has many important functions in the body. It is used to make bile acids, which is are substances that help the body digest fats. The liver turns cholesterol into bile acids, which are then released into the digestive system whenever you eat a fatty meal. When all the fat has been absorbed and the bile acids have served their purpose, they are reabsorbed into the bloodstream and used again.
Substances called bile acid sequestrants can bind bile acids in the digestive system and prevent them from being reabsorbed. This reduces the total amount of cholesterol in the body. Kale actually contains bile acid sequestrants, which can lower cholesterol levels. This might lead to a reduced risk of heart disease over time.
According to one study, steaming kale dramatically increases the bile acid binding effect. Steamed kale is actually 43% as potent as cholestyramine, a cholesterol-lowering drug that functions in a similar way.
Kale is one of the world’s best sources of vitamin K. Vitamin K is critical for blood clotting, and does this by activating certain proteins and giving them the ability to bind calcium. The well-known anticoagulant drug Warfarin actually works by blocking the function of this vitamin. Kale is one of the world’s best sources of vitamin K, with a single raw cup containing almost 7 times the recommended daily amount.
The form of vitamin K in kale is K1, which is different than vitamin K2. It helps prevent heart disease and osteoporosis.
Kale has compounds that are believed to have protective effects against cancer. One of these is sulforaphane, a substance that has been shown to help fight the formation of cancer at the molecular level. It also contains a indole-3-carbinol, another substance that is believed to help prevent cancer.
Kale is high in beta-carotene, an antioxidant that the body turns into vitamin A.
Kale is a good plant-based source of calcium and magnesium. Eating plenty of magnesium may be protective against type 2 diabetes and heart disease. Kale also contains quite a bit of potassium, a mineral that helps maintain electrical gradients in the body’s cells. Adequate potassium intake has been linked to reduced blood pressure and a lower risk of heart disease.
One advantage that kale has over leafy greens like spinach is that it is low in oxalate, a substance found in some plants that can prevent minerals from being absorbed.
Lutein and zeaxanthin are carotenoid antioxidants that are found in large amounts in kale. Many studies have shown that people who eat enough lutein and zeaxanthin have a much lower risk of macular degeneration and cataracts.
Kale is very low in calories but still provides significant bulk that should help you feel full. Because of the low calorie and high water content, kale has a low energy density. Kale also contains small amounts of protein and fiber.