Can Vitamin D Really Improve My Eye Health
If you've ever searched for information on nutrients that can help keep your eyes healthy, you’ll know that finding trustworthy and reliable information can be difficult. One nutrient that falls under this category is vitamin D, because the information available can be confusing and often conflicting. To help provide some clarity, we’ve put together this guide to understanding vitamin D and the benefits it can have upon eye health.
The role of vitamin D in the body
Vitamin D has been researched extensively in relation to a number of general health benefits. It’s both a fat-soluble vitamin which your body needs to absorb calcium and a pre-hormone that is produced by your body when your skin is exposed to UV rays. According to the NHS, vitamin D also helps to control the amount of calcium and phosphate in your body, both of which are needed for healthy bones, teeth and muscles. It’s known that vitamin D plays an important role in the immune system, working to support immune function and reduce inflammation.i As such, its thought to be linked to a whole range of conditions, including high blood pressure, diabetes, cardiovascular disease and even depression.
Vitamin D and vision
Vitamin D has been linked to eye health in a number of ways. The anti-inflammatory properties of vitamin D have led experts to investigate the impact of vitamin D on eye conditions categorised by inflammation, such as age-related macular degeneration (AMD) and dry eye syndrome.
Age-related macular degeneration (AMD)
A common condition affecting the central part of your vision, AMD develops in the eyes as you age. While it’s not considered to be an inflammatory disease, experts now believe inflammation may play a role in its development.ii Several studies suggest there may be an association between vitamin D deficiency and AMD. One study found that vitamin D deficiency was associated with early AMD, which may have been caused by the lack of anti-inflammatory properties.iii
Research has also looked into the relationship between vitamin D and AMD in postmenopausal women. The study found that the women under the age of 75 who had a higher vitamin D intake were 59% less likely to develop AMD compared to those with the lower intakes.iv Additionally, one twin study found that siblings with the higher intake of vitamin D in their diet were less likely to develop severe AMD.v
Dry eye syndrome
If you regularly suffer from painful, irritated eyes, and you don’t produce a sufficient amount of tears to keep the surface of your eye moist naturally, then you could be experiencing dry eye syndrome.
Although the condition itself is most common in people aged over 50, exposure to blue light from tablet and smartphone screens is causing it to become increasingly common in young people too. There is some evidence to suggest that vitamin D deficiency can help to relieve dry eye syndrome as a result of its anti-inflammatory properties. In one study, researchers found that 52% of women with low vitamin D levels experienced dry eyes compared with just 4% of those with normal vitamin D levels.vii. Researchers concluded that this was because vitamin D enhances the tear parameters which in turn promotes lubrication and reduces surface inflammation.vi
Scientists believe that vitamin D deficiency may be linked to the development of glaucoma — a condition that causes damage to the optic nerve. Vitamin D deficiency has been linked to the development of primary open-angle glaucoma, the most common form of the condition which develops gradually.vii Experts have concluded that lower vitamin D levels are associated with a higher risk of glaucoma risk in women – although further research is needed to investigate the relationship thoroughly.viii
Diabetic retinopathy is a condition which damages the retina as a result of diabetes and can lead to partial or even complete vision loss. People who’ve had diabetes for a long time have a higher risk of diabetic retinopathy, although one study has also found vitamin D deficiency may play a part in retinopathy in young people with type 1 diabetes.ix The study found that the inflammation associated with vitamin D deficiency may lead to early damage of the retina, the thin layer of tissue that lines the back of the inside of the eye.ix Recent research has also discovered that people with diabetes naturally experience lower levels of vitamin D levels than those without diabetes, particularly in those with late-stage diabetic retinopathy.x
How to increase your vitamin D intake
Considering the important role vitamin D plays in the body — particularly in eye health— you should make sure that you are taking in enough to maintain normal functioning. Small amounts of vitamin D can be found in a range of foods including, liver, egg yolk, fortified cereals and oily fish such as salmon, sardines, herring, mackerel and fresh tuna.xi
However, since it’s difficult to get the recommended amount of vitamin D you need from diet alone, you should consider another form of intake. Since your body produces vitamin D when in contact with sunlight, you can take in some of vitamin D naturally during the spring and summer months by making sure you spend short periods outside in the sun with your forearms, hands or lower legs uncovered. The NHS also recommends boosting vitamin D intake through supplementation, suggesting that all adults and children take a daily 10mcg supplement, especially during the autumn and winter.xi We have a range of high-quality vitamin D supplements in various concentrations, should you consider supplementation.
Considering the research, vitamin D has been found to support overall eye health, and may even reduce the risk of a range of eye conditions. For more advice on how to improve your overall eye health, as well as specific information on a range of conditions, visit our Vision Health Hub.
Hoe, E., et al. Anti-Inflammatory Effects of Vitamin D on Human Immune Cells in the Context of Bacterial Infection. Nutrients. (2016 Dec). ;8(12): 806. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5188461
Yin, K., Agrawal, D.K. Vitamin D and inflammatory diseases. J Inflamm Res. (2014). ;7: 69–87. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4070857
Wang, Y., Wang, V.M., Chan, C.C. The role of anti-inflammatory agents in age-related macular degeneration (AMD) treatment. Eye (Lond). (2011 Feb) ;25(2):127-39. Available online: https://www.ncbi.nlm.nih.gov/pubmed/21183941
Parekh,, et al. Association between vitamin D and age-related macular degeneration in the Third National Health and Nutrition Examination Survey, 1988 through 1994. Arch Ophthalmol. (2007 May) ;125(5):661-9. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880532
Millen, A.E., et al. CAREDS Study Group. Vitamin D status and early age-related macular degeneration in postmenopausal women. Arch Ophthalmol. (2011 Apr) ;129(4):481-9. Available online: https://jamanetwork.com/journals/jamaophthalmology/fullarticle/427167
Seddon, J.M., Reynolds, R., Shah, H.R., Rosner, B. Smoking, dietary betaine, methionine, and vitamin D in monozygotic twins with discordant macular degeneration: epigenetic implications. Ophthalmology. (2011 Jul) ;118(7):1386-94. Available online: https://www.ncbi.nlm.nih.gov/pubmed/21620475
Yildirim, P., et al. Dry eye in vitamin D deficiency: more than an incidental association. Int J Rheum Dis. (2016 Jan) ;19(1):49-54. Available online: https://www.ncbi.nlm.nih.gov/pubmed/?term=Dry+eye+in+vitamin+D+deficiency%3A+more+than+an+incidental+association
Yoo, T.K., Oh, E., Hong, S. Is vitamin D status associated with open-angle glaucoma? A cross-sectional study from South Korea. Public Health Nutr. (2014 Apr) ;17(4):833-43. Available online: https://www.ncbi.nlm.nih.gov/pubmed/24476947
Kim, H.T., et al. The Relationship between Vitamin D and Glaucoma: A Kangbuk Samsung Health Study. Korean J Ophthalmol. (2016 Dec) ;30(6): 426–433. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5156616
Kaur, H., et al. Vitamin D deficiency is associated with retinopathy in children and adolescents with type 1 diabetes. Diabetes Care. (2011 Jun) ;34(6):1400-2. Available online: https://www.ncbi.nlm.nih.gov/pubmed/21515836
Payne, J.F., et al. Vitamin D insufficiency in diabetic retinopathy. Endocr Pract. (2012 Mar-Apr) ;18(2):185-93.
NHS. Vitamin D. (2017) Available online: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d