Health Aid Halibut Liver Oil Capsules are a natural source of Vitamin A & Vitamin D. Both vitamins play a large role improving weak eyesight & resistance to infections such as respiratory infections, as well as helping to reduce age spots & keep tissues & organs healthy. Both vitamins are therefore vital to general health & well-being. Vitamin A in particular plays an essential role in the maintenance of healthy eyes, hair, skin & bones & teeth, while also enhancing immunity, protecting against various infections & skin diseases. Vitamin D helps to control calcium & phosphate levels within the body & build & maintain strong bones & teeth. It is also essential for helping to protect against muscle weakness, maintain a healthy heart, glandular & nervous system, & regulate metabolism.