Albumin and transthyretin as risk factors for cataract: the POLA study

To assess the associations of markers of protein nutrition (plasma albumin and transthyretin) with cataract.

The Pathologies Oculaires Liées à l'Age (POLA) Study (1995-1997) is a population-based study on age-related eye diseases, performed in 2584 residents of Sète (South of France), aged 60 to 95 years. Cataract classification was based on a standardized lens examination at slitlamp according to Lens Opacities Classification System III.

After multivariate adjustment, the risk for cataract (any type) was increased by about 50% in the lowest quintile of plasma albumin concentration (<38.28 g/L) and transthyretin concentration (<0.21 g/L) (odds ratio [OR], 1.49 [95% confidence interval (CI), 1.04-2.14]) and OR, 1.48 [95% CI, 1.03-2.13], respectively). The associations were stronger with mixed cataract (OR, 1.87 [95% CI, 0.95-3.68] and OR, 2.37 [95% CI, 1.22-4.59] for albumin and transthyretin levels, respectively) and nuclear cataract (OR, 2.39 [95% CI, 1.20-4.76] for low transthyretin levels). There were no significant associations with the other types of cataract. There were no associations of cataracts with high-sensitivity C-reactive protein and orosomucoid levels.

This study is suggestive of an association of protein undernutrition with increased risk of cataract. Low protein intake may induce deficiencies of specific amino acids that are needed to maintain the health of the lens, or other nutritional deficiencies, particularly niacin, thiamin, and riboflavin.