Which supplement has been found to slow progression of RP?

• A. Vitamin A
• B. Vitamin C
• C. Vitamin E
• D. Omega-3 fatty acids

Answer: (A)

Supplementing with vitamin A palmitate has the strongest evidence for slowing progression in retinitis pigmentosa. The idea is that providing extra vitamin A supports the visual cycle and photoreceptor health, helping maintain rhodopsin function and delaying decline in vision. In long-term studies, a high daily dose of vitamin A palmitate produced a slower decline in both functional vision and electrophysiology measures compared with placebo, particularly in earlier stages of disease. However, safety is essential: high-dose vitamin A can harm the liver and is teratogenic, so it requires medical supervision with regular liver function monitoring and is not advised for pregnant individuals. Other supplements, such as vitamin E, have not shown consistent benefits and may even pose risks at high doses, while vitamin C and omega-3 fatty acids lack convincing evidence for slowing RP progression.