Vitamin C for Eye Health


Vitamin C is one of the most well-known vitamins, commonly associated with scurvy prevention and immune system support. However, most of us are unaware that Vitamin C and eye health are closely related. The human eye is a delicate network of connective tissues, blood vessels, and nerve cells. One of the many reasons why vitamin C and eye care are connected is because Vitamin C is an important cofactor in collagen synthesis. Collagen is a fibrous protein found in all connective tissue, (including the cornea of the eye), and also supports healthy capillaries (blood vessels) in the retina. Interestingly, a 2011 study by scientists at Oregon Health & Science University found that nerve cells in the retina must be bathed in very high doses of vitamin C to perform their functions properly [1].

It is thought that one of the leading causes of cataracts, glaucoma, and macular degeneration is the generation of free radicals and the resulting oxidative damage to the eye lens. Existing scientific evidence proves that Vitamin C can protect eye tissue from oxidative changes that occur as we age, therefore, lowering the risk of degenerative eye disorders and vision loss.

Vitamin C Benefits in Cataracts


Cataracts, (a common age-related condition), cause cloudiness in the lens of the eye, leading to blurry or reduced vision, and are the biggest cause of blindness throughout the world.

The American Optometric Association says that “Numerous studies have linked Vitamin C intake and decreased risk of cataracts. In one study, women taking Vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing nuclear cataracts. Researchers estimate that by delaying the onset of cataracts for 10 years, half of cataract-related surgeries could be averted. Other research showed that women taking a daily supplement with a dosage of 364 mg experienced a 57 percent reduction in their risk of certain types of cataracts.” [1]

A 2015 meta-analysis summarized the evidence gathered from epidemiological studies of Vitamin C and age-related cataract risk. It found that higher Vitamin C and serum ascorbate intake could be associated with a lower risk of cataracts [3].

Ophthalmology also published a study in 2016 [4] finding that higher Vitamin C intake could protect the eyes against cataract progression. Participants who had a higher Vitamin C intake through their diet were found to have clearer lenses and a 33% reduction in risk of cataract production compared to those whose Vitamin C intake was low [5]. What’s more, the study found that genetic factors contributed to only 35% of the difference in cataract progression. The other 65% came down to diet and other environmental factors. Note that the study focused only on Vitamin C intake via foods, and not through dietary supplements. (Remember that nowadays there is less and less nutritional value and vitamin uptake from our diets due to land degradation, so vitamin supplementation – particularly with respect to Vitamin C – is essential.)

Our eye lenses are bathed in a fluid with a high concentration of Vitamin C, a powerful antioxidant thought to be crucial in the protection of the eye’s inner tissues against oxidative damage that causes a cloudy lens. This Vitamin C-rich fluid has many functions including providing oxygen and nourishment to eye tissues such as the lens and cornea (both of which have a lack of direct blood supply). The fluid also removes waste products from eye tissue and helps to maintain intraocular pressure (internal pressure) that keeps the eye in shape.

Vitamin C Benefits in Macular Degeneration


Macular degeneration is a condition that deteriorates the macula (the central part of the retina that is responsible for our central vision) and is one of the leading causes of vision loss in older people. However, taking vitamin c to prevent macular degeneration is a very smart move.

The National Eye Institute sponsored a clinical trial conducted to understand the effect of vitamin antioxidants and zinc on age-related macular degeneration (AMD) and cataracts. This significant Age-Related Eye Disease Study (AREDS) suggested that 500mg/day of Vitamin C, combined with beta-carotene, Vitamin E, and zinc supplements, can slow the progression of AMD and vision loss [6].

Results showed that participants at high risk of developing advanced AMD (those with intermediate AMD or advanced AMD in one eye) had a 28% lower risk of progressing to advanced AMD when they took antioxidant supplements, compared to participants who took a placebo.

Advancing age is an obvious factor behind an increased risk of cataracts and age-related macular degeneration. However, other factors include excessive sunlight exposure, smoking, obesity, statin drugs, diabetes, high blood pressure, excessive alcohol intake, genetic factors, previous eye surgery, and previous eye injuries. People with any of these conditions and factors should increase their intake of Vitamin C for eye health.

It cannot be argued that Vitamin C is essential for a healthy, well-functioning body – it is quite simply essential. There is plenty of scientific evidence proving that Vitamin C maintains our skeletal system, supports the growth and maintenance of connective tissues, seeks out damaging free radicals, and reduces the risk of cancer, arthritis, and heart disease. However, our body cannot produce Vitamin C on its own. What’s more, Vitamin C is water-soluble, meaning our body excretes excess Vitamin C through urine. Our body can’t simply store leftover Vitamin C for later. Therefore, we have to rely on a sufficient daily dose of Vitamin C through diet and high-quality Vitamin C supplementation to maintain sufficient levels for eye health as well as overall health and wellbeing.

References:

  1. OHSU scientists discover new role for vitamin C in the eye - and the brain. OHSU. 2011
  2. Vitamin C. American Optometric Association.
  3. Lin Wei, Ge Liang, Chunmei Cai and Jin Lv. Association of vitamin C with the risk of age-related cataract: a meta-analysis.  Acta Ophthalmologica. 2016.
  4. Ekaterina Yonova-Doing, Zoe A. Forkin, Pirro G. Hysi, Katie M. Williams, Tim D. Spector, Clare E. Gilbert, Christopher J. Hammond. Genetic and Dietary Factors Influencing the Progression of Nuclear Cataract. Ophthalmology. 2016.
  5. Increased vitamin C in the diet could help protect against cataracts. Science Daily. 2016
  6. 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. Jama Ophthalmology. 2001