B-vitamins May Reduce Risk of Age-related Macular Degeneration (AMD)

James Meschino DC, MS, ROHP

A study published in the July 2013 issue of the American Journal of Clinical Nutrition has provided additional evidence to show that higher nutritional status of certain B-vitamins may be important in the prevention ofAge-related Macular Degeneration (AMD), which is the leading cause of vision loss in people over 55 years of age in the US and Canada (1). Previous studies have shown that taking certain antioxidant vitamins and minerals, as supplements (Vitamin E, Vitamin C, Beta-carotene, Selenium, and Zinc), at specific dosages, can slow the progression of AMD (2,3)

In the current study, known as The Blue Mountain Eye Study (Australia), serum folate (B-vitamin folic acid), vitamin B-12, and homocysteine were determined from blood samples drawn in 1997–1999 from cohort members aged ≥55 y.  AMD was assessed in 1760 survivors from retinal photographs taken in 2002–2004 and 2007–2009. Total intakes of folic acid and vitamin B-12 were assessed by using a food-frequency questionnaire.

Result showed that higher blood levels of homcysteine were associated with a significant increased risk of developing AMD, whereas higher serum levels of vitamin B12 were strongly associated with decreased risk of developing AMD. More specifically, data showed that increased concentrations of serum total homocysteine were associated with ∼30% increased odds of developing AMD over 10 y and increased concentrations of serum vitamin B-12 were associated with ∼30% reduced odds of developing AMD. Serum folate was less strongly associated, with an approximate reduced odds of 10% for development of AMD. People with folate or vitamin B-12 deficiency at the beginning of the study(baseline) were approximately twice as likely to develop AMD during the 10-yr study period (1).

Homocysteine is a toxic end-product of metabolism known to damage blood vessels and increase risk of cardiovascular disease. Studies continue to show that high serum levels of homocysteine also contribute to damage seen in AMD. The Blue Mountain Eye Study provides further evidence to support this hypothesis. What is important is that homocysteine levels are reduced via supplementation with, and dietary intake of, vitamin B12 and folic acid. These B-vitamins recycle homocysteine back to the non-toxic, and highly useful, amino acid known as methionine. This explains why high levels of serum homocysteine and low levels of vitamin B12 and folic acid are so strongly linked to the development of AMD, as confirmed once again in the Blue Mountain Eye Study (1).

Summary
It is thought that AMD is a highly preventable disease, which requires attention to various lifestyle behaviors. Extrapolating from what we know from experimental, observational and clinical studies, the following practices appear to be the best proactive strategies to prevent the development of AMD:

1. Don’t smoke
2. Protect your eyes for UV-light
3. Prevent the onset of type 2 diabetes, by remaining at your ideal weight, performing endurance and strength training exercises regularly, keeping your fasting glucose level below 5.0 mmol/L (90 mg/dL).
4. Eat a diet rich in brightly colored vegetables and fruit (dark green, yellow, orange, blue, purple, red).
5. Keep your cholesterol level low by also consuming foods low in total cholesterol, saturated fat and transfats.
6. Take a high potency multiple vitamin and mineral each day that contains the following dosages of antioxidants and B-vitamins:

Vitamin C- 1000 mg

Vitamin E – 400 IU

Selenium – 200 mcg

Zinc – 15 mg

Beta-carotene – 15,000 IU

Lutein powder – 6 mg

B-50 complex, including 400 mcg folic acid, 50 mcg vitamin B12 and 50 mg vitamin B6 (vitamin B6 also lowers homocysteine)

References:

1. Gopinath B, Flood VM, Rochtchina E, Wang JJ, Mitchell P. Homocysteine, folate, vitamin B-12, and 10-y incidence of age-related macular degenerationAm J ClinNutr 2013 98: 1 129-135;
2. Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev 2012;11:CD000254.
3. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol 2001;119:1417–36