Active adults have lower risk of cataracts
March 25, 2009
The incidence of age-related cataracts is significantly lower among active adults, compared to age-matched controls, according to the National Runners' Health Study.
The study included over 29,000 men and nearly 12,000 women. All participants were non-smokers, and 80 percent of them were followed for up to seven years.
During the 7-year follow-up period of the study, cataracts were reported by 733 men (2.5 percent) and 179 women (1.5 percent).
BMI and cataracts
The risk for cataract increased with body mass index (BMI) among the study participants.
BMI measurements are calculated based solely on a person' height and weight. According to the U.S. Department of Health and Human Services, the current BMI categories are as follows:
- BMI less than 18.5 = Underweight
- BMI 18.5 to 24.9 = Normal weight
- BMI 25 to 29.9 = Overweight
- BMI 30 or higher = Obese
- Under these BMI guidelines, a 6-foot tall man would be classified accordingly, based on his weight:
- Under 136 pounds = Underweight
- Between 137 and 183 pounds = Normal weight
- Between 184 and 220 pounds = Overweight
- Over 220 pounds = Obese
In this study, the risk for cataracts among men with a BMI greater than 27.5 was 88 percent higher than the risk for cataracts in men with a BMI less than 20.
More miles and better fitness also lowers cataract risk
Men’s cataract risk declined significantly in relation to running distance, even when adjusted for BMI. Men who ran 40 or more miles per week had 35 percent lower risk for cataract than those who ran less than 10 miles per week. (When adjusted for BMI, the risk was 28% lower.)
In addition, men with greater cardiorespiratory fitness were at significantly less risk for development of cataract than were the least fit men, independent of running distance or BMI. Compared with the least fit men, those who ran faster than 10.6 miles per hour had 50 percent lower risk for cataracts (43 percent lower when adjusted for running distance per week and BMI).
Other study results
The study also showed that running greater distances reduces age-related weight gain and reduces the incidence of Type 2 diabetes.
Cataracts that occurred among study participants were more common among older subjects, heavier men and both men and women who reported running shorter distances per week.
Oxidation, inflammation associated with cataracts
Oxidation and systemic inflammation are associated with the development of age-related cataracts, according to the study authors. High-density lipoproteins (HDL), sometimes called "good cholesterol," reduce oxidation and inflammation, and a number of training studies show that routine exercise increases blood levels of HDL, they point out.
The researchers also noted that previous studies have linked low HDL levels to cataract formation.
The study appears in the January 2009 issue of Investigative Ophthalmology and Visual Science.