“The anticataract effect of tocotrienol could be attributed to reduced lenticular oxidative stress and attenuation of nitrosative stress," concluded the researchers, led by pharmacologist Nafeeza Mohd Ismail of the Universiti Teknologi MARA, Malaysia.
The inhibition of cataract formation by annatto tocotrienol was dose-dependent, with low doses yielding the best protection, whereas a high dose may act as pro-oxidant.
Vitamin E is a family of eight separate but related molecules: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). While alpha-tocopherol is found in most multivitamins and is supplemented in foods, a growing base of evidence suggests that this popular vitamin E interferes with the uptake and function of tocotrienols. Tocotrienols are derived from three major sources, including rice, palm and annatto. Annatto is the only tocopherol-free source of tocotrienols. The recent study used the DeltaGold® branded annatto tocotrienol ingredient supplied by American River Nutrition, which typically contains about 90 percent delta- and 10 percent gamma-tocotrienol.
Clouding the lenses of affected individuals, cataracts are responsible for 51 percent of world blindness. As an age-related disease, the incidence of cataracts is expected to increase due to rapid population growth and greater longevity. Affecting approximately 22 million people in the United States, cataracts are responsible for an estimated national healthcare cost of $6.8 billion each year. Symptoms of the condition include cloudy or blurry vision, which can be attributed to stress, causing soluble proteins in the lens to congeal, become insoluble, and obstruct vision.
In the study, researchers tested the effects of annatto tocotrienol on cataract formation in a rat model. Results showed that tocotrienol slowed cataract onset and progression by reducing oxidative and nitrosative stress. Tocotrienol had a beneficial effect on lens antioxidant enzymes, including superoxide dismutase and catalase, both of which returned to normal levels with the topical treatment. Furthermore, tocotrienol significantly decreased malondialdehyde, a lipid peroxidation end product found to be high in cataracts, and restored the lens soluble to insoluble protein ratio to normal levels.
The study revealed that low doses of tocotrienol in a topical application were most effective, with best outcomes obtained at 0.03 percent or 300 ppm. A high dose of 0.2 percent or 2,000 ppm, on the other hand, may act as a pro-oxidant.
“While previous reports note that tocotrienols are absorbed in ocular tissue, this is the first study examining their beneficial effect on cataract," said Barrie Tan, president of American River Nutrition Inc. “Tocotrienol at low levels works both as a chemical and biological antioxidant in a dose-dependent manner, and its preventive application in topical eye formulas may be especially useful for our rapidly expanding aging population."