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Cataract Researchers Say Vitamin E and B Good, Fat
Bad
Age-related cataracts in Baby Boomers and senior
citizens studied by nutritionist
Aug. 9, 2005 - Age-related cataract, the world's
leading cause of blindness, affects more than 20 million Americans over
the age of 40 years. Surgical correction is currently the only known
option for intervention, but new research says Vitamin E and B may help
but fat may increase the risk.
Researchers at the Jean Mayer USDA Human Nutrition
Research Center on Aging at Tufts University recently sought, in three
different studies, to determine if prevention is possible. Their
findings suggest that vitamins and polyunsaturated fatty acids--two
categories of nutrients believed to have health benefits--may both
affect cataract development, although not necessarily in beneficial
ways.
In one study, lead scientist Paul Jacques, DSc,
director of the Nutritional Epidemiology Program at the Center, and his
colleagues analyzed the diets and examined the eyes of a group of
Boston-area women over the course of five years.
Among the study participants, who were all members
of the larger Nurses' Health Study, women who reported supplementing
their diets with vitamin E (a powerful antioxidant) for 10 years or more
had significantly less progression of cataract development at the
five-year follow-up exam. A similar relative decrease in cataract
progression was seen in women who reported higher intakes of two of the
B vitamins, riboflavin and thiamin, when compared to women with lower
intakes.
"Our results," says Jacques, who is also a
professor at the Friedman School of Nutrition Science and Policy at
Tufts, "suggest that vitamin supplementation, particularly long-term use
of vitamin E, may slow down cataract development." These results build
upon some of Jacques' earlier work. In 2001, while examining the same
group of Nurses' Health Study members, Jacques and his colleagues found
support for a similar role for vitamin C in the prevention of cataracts.
"On the other hand," says Jacques, "the results
were not so clear when we looked at dietary fat." In the same population
of women, Jacques and his colleagues found that high dietary intake of
either or both an omega-6 polyunsaturated fatty acid (PUFA) found in
sunflower, safflower, corn, and soybean oils, and an omega-3 PUFA found
in canola, flaxseed, and soybean oils, may increase the risk of
developing cataracts in one of the three lens locations examined.
The results of this study, which were published in
the American Journal of Clinical Nutrition, are not consistent, however,
with findings of other studies on the relationship between PUFAs and
cataracts. In a study that was recently published in the American
Journal of Epidemiology, Jacques and colleagues observed that higher
overall fat intake increased the risk of cataract development or
progression, while omega-3 fatty acids, in particular the types found in
dark-fleshed fish, appeared to contribute to the prevention of cataract
formation.
"The results of these studies provide added support
for a relationship between nutrient intake and cataracts," says Jacques.
However, since there is inconsistency among studies of fat intake and
cataracts, he cautions that more research is needed. Jacques adds,
"finding ways to delay age-related cataract formation through diet, or
even through supplementation, would enhance the quality of life for many
older people, but many questions regarding the role of diet in cataract
prevention remain unanswered."
Source:
Jacques PF, Taylor A, Moeller S, Hankinson SE,
Rogers G, Tung W, Ludovico J, Willett WC, Chylack LT. Archives of
Ophthalmology. April 2005; 123:517-526. "Long-term Nutrient Intake and
5-Year Change in Nuclear Lens Opacities."
Lu M, Taylor A, Chylack LT, Rogers G, Hankinson SE,
Willett WC, Jacques PF. American Journal of Clinical Nutrition. April
2005; 81:773-779. "Dietary Fat Intake and Early Age-related Lens
Opacities."
Lu M, Cho E, Taylor A, Hankinson SE, Willett WC,
Jacques PF. American Journal of Epidemiology. May 15, 2005;
161(10):948-59. "Prospective study of dietary fat and risk of cataract
extraction among US women."
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