A study published in the American Journal of Clinical Nutrition in May 2013 reports that low levels of vitamin B12 and folate and elevated homocysteine are associated with age-related macular degeneration. Homocysteine is a naturally occurring amino acid, and elevated levels are linked to cardiovascular disease. Age-related macular degeneration affects more than 1.75 million adults in the United States. With the rapid aging of the U.S. population, it is estimated that this number will increase to almost three million by 2020.
Researchers measured serum folate, vitamin B12 and homocysteine in subjects 55 years of age or older in 1997-1999. The investigators evaluated 1,790 subjects for age-related macular degeneration using retinal photographs in 2002-2004 and 2007-2009. The subjects completed food-frequency questionnaires to assess vitamin B12 and folate intake. The researchers also collected data including age, sex, current smoking, white cell count and fish consumption to adjust the data for potential confounding factors.
The investigators found that for each 1-standard deviation increase in serum homocysteine, there was a 33 percent increased risk of developing early or any age-related macular degeneration. The subjects with vitamin B12 deficiency (less than 185 pmol/L) showed a 58 percent increased risk of early age-related macular degeneration and a 156 percent increased risk of developing late age-related macular degeneration.
The investigators also determined that the subjects with folate deficiency (less than 11 nmol/L) had a 75 percent increased risk of early age-related macular degeneration and an 89 percent increased risk of late age-related macular degeneration. Furthermore, the researchers found that subjects who reported supplementary vitamin B12 intake had a 47 percent reduced risk of developing age-related macular degeneration.
The researchers concluded, “Elevated serum total homocysteine and folate and vitamin B12 deficiencies predicted increased risk of incident age-related macular degeneration, which suggests a potential role for vitamin B12 and folate in reducing age-related macular degeneration risk.”
Gopinath B, et al. Am J Clin Nutr. 2013 May 1. [Epub ahead of print.]