According to the World Health Organization, cataract is the leading cause of blindness in the world. While not a common cause of blindness in the US, the prevalence of cataract is still significant and so are its economic and human costs. According to the National Society to Prevent Blindness, there are currently 24.4 million cases of cataract in the United States up from 20.5 million on the year 2000. Every year there are about 1 million surgeries for cataracts. It is estimated that the direct annual medical costs for outpatient, inpatient and prescription drug services related to the treatment of cataracts, total $6.8 billion.
In a recent British study,[i] there was a strong relation between cataract risk and diet group, with a progressive decrease in risk of cataract comparing high meat eaters to low meat eaters, fish eaters (participants who ate fish but not meat), vegetarians, and vegans respectively. After multivariable adjustment, the incidence rate ratios (95% CIs) were for moderate meat eaters (50–99 g meat/d), low meat eaters (<50 g meat/d), fish eaters, vegetarians, and vegans compared with high-meat eaters (≥100 g meat/d) were 0.96 (0.84, 1.11), 0.85 (0.72, 0.99), 0.79 (0.65, 0.97), 0.70 (0.58, 0.84), and 0.60 (0.38, 0.96), respectively (P < 0.001 for heterogeneity).
It’s important to notice the decline in the incidence of cataracts with the decline in the consumption of animal products. While studies focusing on individual nutrients are valuable for determining individual dietary components as risk factors, studies examining overall dietary patterns are also valuable for determining the effects of numerous dietary factors in concert. This study focused on overall dietary pattern instead of specific nutrients, and is notable for the large number of cases examined, and that the conclusion was based on a cohort of health-conscious British residents.
It is interesting to note that alcohol intake, body mass index, physical activity, education, socioeconomic status, and dietary supplement use were not associated with cataract risk. The incidence of cataracts in Britain has risen ten-fold in only 35 years. It may reasonably be suspected that increased levels of animal product consumption is either an etiologic or exacerbating factor. While the advantages of plant-based diets are often discussed in terms of diseases such as coronary artery disease, diabetes and essential hypertension, it should be remembered that diet affects a wider variety of diseases as well.
[i] Paul N Appleby, Naomi E Allen, Timothy J Key. “Diet, vegetarianism, and cataract risk” Am J Clin Nutr May 2011 vol. 93 no. 5 1128-1135