Glaucoma damages the optic nerve in the eye and is one of the leading cause of blindness in the US. Millions of people are affected by the disease; and though it can be treated, it’s incurable. The risk of developing glaucoma may soon be lessened, a new study suggests, thanks to one of the B vitamins.

Glaucoma begins gradually, and there are no warning signs, so vision changes may not occur until the disease is advanced. It can occur at any age, but it is most often seen in older people. Some people lose vision completely, while others lose it only partially. Any vision lost is lost forever.

Young mice who received extra B3 had a significantly lowered risk of developing the disease later in life, and it prevented further damage in mice who were already showing early signs of glaucoma.

Researchers found that the degeneration of the optic nerve seen in glaucoma is linked to low levels of a precursor to vitamin B3, or niacin.

With this in mind, the scientists gave mice bred to be susceptible to glaucoma oral doses of vitamin B3 to see if it would help to prevent the development of the disease. Young mice receiving extra B3 had a significantly lowered risk of developing the disease later in life, and it prevented further damage in mice who were already showing early signs of glaucoma.

Among mice given B3 as a preventive measure, 93 percent did not develop optic nerve damage, the distinguishing characteristic of glaucoma.

Therapeutic levels of niacin should only be taken under the guidance of a physician.

The recommended amount of vitamin B3 is 14 milligrams a day for adult women and 16 milligrams for adult men. It is found in green vegetables, eggs, meat, fish and poultry, and many food products are fortified with it.

Vitamin B3 is used to lower blood cholesterol and triglyceride levels and reduce the risk of cardiovascular disease. The doses needed for such benefits are high, however, and can cause serious side effects and harm the body.

So even though the benefit of taking niacin to prevent glaucoma appears promising, keep in mind that this study was performed in mice; and animal studies do not always lead to the same results in humans. Therapeutic levels of niacin should only be taken under the guidance of a physician.

The study is published in Science.