Researchers with the Age-Related Eye Disease Study (AREDS)  first made its recommendations for a precise balance of antioxidants and zinc that supplements should contain to reduce progression of certain ocular diseases public in 2001.1 The research was followed by additional investigations — especially, AREDS2 in 2013 — into the clinical use of vitamins to prevent or slow the progression of vision loss resulting from diseases such as age-related macular degeneration (AMD).2 As the research developed, manufacturers began providing vitamin supplements that conformed to the group’s recommendations — many of them labeled AREDS, or later AREDS2. New research published by investigators associated with the University of Louisville in Kentucky asks if the top brands and generics on the market are, in fact, all following the formula prescribed in the same way.3 

Specifically, the new study published in the American Journal of Ophthalmology analyzed the concentrations of vitamin C, vitamin E, zinc, and copper in four national brands of dietary supplements recommended for patients at risk for macular degeneration to determine if the vitamin content on each supplement’s label was accurate.3 They found that, although all the national brand name vitamins — both tablet and gel capsule formulations — and generic brands in tablet form were “relatively accurate” in their product labeling, most had lower concentrations than the recommended AREDS2 dosage.3 

The AREDS2 investigation had recommended a daily dosage of 500mg vitamin C, 400 IE vitamin E, 4 5 80m zinc oxide, 10 mg lutein, 2 mg zeaxanthin, and 2 mg copper oxide.4 “Four of the 5 products we tested had a lower dosage than the recommendations of the AREDS2 group,” the investigators said.3 They added that the “dosage of these products is not suitable to treat patients with higher risk factors for AMD.”3


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The investigators also noted that some generic gel capsules lacked labeling and, therefore, they could not perform comparative analysis for labeling or comment on the accuracy of their vitamin and mineral contents.3

The comparative analysis of the vitamin content was performed by gas chromatography-mass spectrometry, and the zinc and copper content was analyzed by atomic absorption spectroscopy.

The vitamin and supplement market in general has broad variability. In fact, 73% of dietary supplement manufacturers inspected by the US Food and Drug Administration failed to adhere to 1 or more regulations.4 The investigators of the American Journal of Ophthalmology study suggest that the reasons that many of the same products may not be equivalent in composition, strength, or bioavailability is because the different manufacturers set their own standards and also are not required to confirm the identity of ingredients supplied to them.3,6

With that in mind, the researchers suggested that physicians may recommend national brand names vitamins and generic brands in tablet form to their patients with some confidence, but that the content may have some inaccuracies in its labeling.

References

  1. 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(10):1417-1436
  1. Age-Related Eye Disease Study Research Group. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA. 2013;309(19):2005-15.
  1. Fleissig E, Apenbrinck E, Zhang X, Barr C. Vitamin analysis comparison study. Am J Ophthalmol. Published online August 20, 2020. doi: 10.1016/j.ajo.2020.08.028
  1. Age-Related Eye Disease Study Research Group. Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. JAMA Ophthalmol. 2014;132(2):142-9. doi: 10.1001/jamaophthalmol.2013.7376. 
  2. United States. Government Accountability Office. Dietary supplements: FDA may have opportunities to expand its use of reported health problems to oversee products. Published March 18, 2013. Accessed September 25, 2020.
  3. Miller R, Celestino C, Giancaspro G, Williams R. FDA’s dietary supplement cGMPs: standards without standardization. Food Drug Law J. 2008;63(4):929–942.