Study: Vitamin A (2005) & Night Blindness
Learn more about night blindness.
Previous research has demonstrated that vitamin A supplementation can reverse the effects of night blindness. In this study researchers wanted to evaluted whether a diet contained small amounts of vitamin A would also have a beneficial effect.
The researchers compared supplementing with vitamin A in food sources versus supplementing with vitamin A, measuring the results by evaluating both dark adaption and plasma (blood) retinol levels in Napali women who suffered from night blindness.
The women were divided into six groups, receiving various forms of vitamin A in vitamin A–fortified rice, retinyl palmitate, amaranth leaves, goat liver, or carrots. They were evaluated weekly via degree of pupil dilation and blood reinol levels. The groups were also compared to women who were not experiencing night blindness.
The researchers found that night blindness diminished most in the group receiving goat liver compared to the vitamin A–fortified rice group. The blood retinol level change was greater in those receiving retinyl palmitate and liver groups than in the vegetable groups, and greater in the group receiving goat liver than in the group receiving vitamin A–fortified rice.
The researchers concluded that all of the methods decreased night blindness, and those methods with better results were not significantly so. Both dietary vitamin A and vitamin A supplementation were effective.
Researchers: Marjorie J Haskell, Pooja Pandey, Joanne M Graham, Janet M Peerson, Ram K Shrestha, and Kenneth H Brown
Published: Am J Clin Nutr February 2005 vol. 81 no. 2 461-471