Vitamin A is fundamental for healthy vision.
Vitamin A is a collection of fat-soluble organic compounds that are critical for proper cell growth and development. As such, it is extensively used to boost the immune system and combat various health complications with a particular emphasis on vision, including such potential benefits as:
- Enhancing light and dark sensitivity. Vitamin A seems to play a major role in photosensitivity and adaptation.
- Combating cataracts and dry eye. Consistent intake of the vitamin may reduce the risk of cataracts, dry eye, and blindness.
- Promoting good vision. The retinol present in vitamin A is key to healthy eye development.
When grouped together, the compounds retinol, retinoic acid, retinal, and various carotenoids make up the essential vitamin A. The fat-soluble vitamin assists in a plethora of fundamental bodily functions from helping cells multiply (which is essential for maintaining healthy skin and mucous linings as well as for growth) to enhancing the immune system.
It can be derived from two main dietary sources:
- Retinoids. Retinol is found in beef, chicken, eggs, dairy, and numerous other animal products.
- Carotenoids. Countless fruits and vegetables — especially ones colored dark-green. yellow, or orange — carry substantial quantities of carotenoids, notably beta-carotene.
Vitamin A deficiency is a well-known cause of vision problems, such as dry eye (xerophthalmia), age-related macular degeneration (AMD) and impaired night vision, which is why various health advocates consider the vitamin essential for healthy vision.
Currently, its supplemental use has only been proven for treating vitamin A deficiency, although it shows promise in ameliorating eye issues, preventing cataracts, and simply promoting sound vision.
How Vitamin A May Help With Vision
Developing Eye Structures
Vitamin A consists of a solid hodgepodge of chemical structures of which all-trans-retinol seems to be the stand out when it comes to promoting healthy vision. Particularly important for eye pigment formation is 11-cis-retinal.1
Sensing Light & Adapting to Darkness
Inside of the retina, 11-cis-retinal combines with opsin to convert into rhodopsin, which is the vision pigment that enables one to see in low-light. On top of that, the visual pigments that bind to 11-cis-retinol dehydrogenase (cRDH) are purportedly in charge of initiating visual excitation.2
The interplay between vitamin A and eye cells not only activates rhodopsin, which gives eyes the capacity to adapt to darkness3, but also triggers light sensors that are necessary to sense light4 and keep the corneal epithelial cells from drying out or ulcering.
While some of the details have yet to be fleshed out, the necessity of vitamin A in eye development speaks volumes to its significance for healthy vision.
Vitamin A Benefits & Uses for Vision
Vitamin A appears to play a central role in vision formation and maintenance. From as early as embryonic development, vitamin A – in the form of retinal – helps set up the framework of healthy eyes.5 Once all of the organs of the fetus are fully formed, one of the primary roles of retinol is to maintain suitable eye conditions.
Vitamin A seems to help out vision in a bunch of different ways:
- Facilitating visual pigment formation as 11-cis-retinal.6
- Improving light sensitivity.
- Enabling night vision.7
- Improving visual acuity.
- Expediting eye healing, both after eye surgery and injury.
- Reducing the risk of cataracts, dry eye, and developed blindness.8
Counteracts Vitamin A Deficiency
According to research conducted by UNICEF, vitamin A deficiency (VAD) is “the leading cause of preventable childhood blindness.” One of the immediate consequences of low levels of vitamin A is impaired vision because of how critical retinal is in sustaining healthy eyesight.
Missing out on sufficient amounts of vitamin A could lead to serious eye-related issues, such as9:
- Reduced night vision
- Xerophthalmia (dry eyes)
- Xerosis (conjunctiva)
- Bitot’s spots (eye plaques)
- Keratomalacia (damage to the cornea)
The good news is that vitamin A supplements may just be able to turn the tide and replenish depleting supplies in cases of vitamin A deficiency.
Research indicates that vitamin A plays a vital role in maintaining eye function by:
- Recovering visual sensitivity. Supplying vitamin A to retinoid-deprived animals restored rhodopsin levels and enhanced visual sensitivity at a markedly rapid rate.10
- Restoring visual pigment and dark adaptation. Salamander eye rods treated with 11-cis-retinoid solutions promoted the recovery of pigment regeneration and dark adaptation.11
- Sustaining daylight vision. Adding vitamin A to ground squirrel and chicken retinas facilitated the growth of opsin photopigments 20 times faster than in the normal cycle, which is responsible for sustained daylight vision.12
Clinical studies collectively highlight the ample potential benefits that vitamin A may offer to vision, from protecting against nuclear cataracts and dry eye to improved night vision and visual acuity.
In this population-based cross-sectional study, 2,900 adults between 49 and 97 years old living in an urban community near Sydney, Australia were given an assortment of nutrients, including vitamin A, and had their eye condition evaluated via lens photography. Vitamin A specifically seemed to reduce the risk of nuclear cataracts.
- The study concluded that “vitamin A, niacin, thiamin, and riboflavin protected against nuclear cataract.”13
In this randomized and controlled study, 150 patients with dry eye were given either artificial tears, cyclosporine, or vitamin A eye drops 4 times a day for 3 months. Compared to the control, vitamin A led to significant improvement in blurred vision, tear film, and dry eye syndrome.
- The study concluded that “vitamin A eye drops and topical cyclosporine A 0.05% treatments are effective for the treatment of dry eye disorder.”14
In this single patient case study, a 69-year old male with dry eye and night blindness was given high doses of vitamin A supplements for 1 month. Electroretinograms (ERG) confirmed that scotopic (dim-light vision) function was restored.
- The study concluded that “with high doses of oral vitamin A supplements…the patient reported that his visual function has significantly improved, while repeat ERG testing revealed that scotopic function has improved to normal levels.”15
In this randomized, double-blind investigation, 40 patients who had recently undergone photorefractive keratectomy (eye surgery to correct near-sightedness), were given 25,000 IU retinol palmitate and 230 mg of vitamin E or a placebo 3 times daily for 1 month and 2 times daily for 2 more months thereafter. Vitamin A supplementation resulted in significantly faster re-epithelialization, less haziness, more accurate myopic correction, and significantly better visual acuity.
- The study concluded that “high dose vitamin A and E oral supplementation may accelerate re-epithelialisation time and may reduce corneal haze formation after PRK.”16
In this cross-sectional investigation, 2873 adults between 49 and 97 years were given various vitamins, including vitamin A, over an extended period of time to determine their effect on cataracts. Vitamin A supplements protected against nuclear cataract (odds ratio 0.4).
- The study concluded that use of “vitamin A supplements was associated with reduced prevalence of either nuclear or cortical cataract.”17
Dosage for Vision
Vitamin A may be taken as:
- A supplemental capsule, 900 mcg (~5,000 IU, depending on the form of vitamin A)
- Liquid drops, 5,025 IU
- A topical cream or ointment, 0.025-0.05% retinol
The recommended dose for women is generally smaller (700 mcg) and even lower still for children due to average differences in size and processing.
Supplements in Review Says
- Vitamin A, 900 micrograms or 5,000 International Units
We recommend vitamin A for vision. Vitamin A is widely regarded as an essential component of natural eye development for its abundance of retinol. Its potential benefits include enhancing light sensitivity and adaptation as well as reducing the risk of vision complications, such as cataracts, dry eye, and blindness. Supplementation is highly recommended in cases of vitamin A deficiency.
The ideal way to take vitamin A is as a standardized 900 mcg pill supplement. Sufficient quantities of vitamin A can easily be consumed in the standard diet. Those concerned about vitamin A deficiencies or looking to enhance their vision, may turn to standardized nutrient supplementation to give them the extra stimulus they require.
- Byrne SM, Blaner WS. Retinol and retinyl esters: biochemistry and physiology. The Journal of Lipid Research. 2013 July;54:1731-43. ↩
- Chen P, Lee TD, et al. Interaction of 11-cis-retinol dehydrogenase with the chromophore of retinal g protein-coupled receptor opsin. J Biol Chem. 2001 Jun 15;276(24):21098-104. ↩
- Lamb TD, Pugh EN Jr. Dark adaptation and the retinoid cycle of vision. Prog Retin Eye Res. 2004 May;23(3):307-80. ↩
- Zhong M, Kawaguchi R, et al. Retina, Retinol, Retinal and the Natural History of Vitamin A as a Light Sensor. Nutrients. 2012 Dec; 4(12):2069-96. ↩
- Azais-Braesco V, Pascal G. Vitamin A in pregnancy: requirements and safety limits. Am J Clin Nutr. 2000 May;71(5 Suppl):1325S-33S. ↩
- Thompson DA, Gal A. Vitamin A metabolism in the retinal pigment epithelium: genes, mutations, and diseases. Progress in Retinal Eye Research. 2003 Sep;22(5):683-703. ↩
- Russell RM, Smith VC, Multak R, et al. Dark-adaptation testing for diagnosis of subclinical vitamin-A deficiency and evaluation of therapy. Lancet. 1973;2:1161-4. ↩
- Mayo-Wilson E, Imdad A, et al. Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis. BMJ. 2011 Aug 25;343:d5094. ↩
- Gilbert C. The eye signs of vitamin A deficiency. Community Eye Health 2013; 26(84): 66-7. ↩
- Katz ML, Chen DM, et al. Photoreceptor recovery in retinoid-deprived rats after vitamin A replenishment. Exp Eye Res. 1993 Jun;56(6):671-82. ↩
- Frederiksen R, Boyer NP, et al. Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods. J Gen Physiol. 2012 Jun;139(6):493-505. ↩
- Mata NL, Radu RR, et al. Isomerization and Oxidation of Vitamin A in Cone-Dominant Retinas: A Novel Pathway for Visual-Pigment Regeneration in Daylight. Neuron. 2002 Sep;36(1):69-80. ↩
- Cumming RG, Mitchell P, Smith W. Diet and cataract: the Blue Mountains Eye Study. Ophthalmology 2000;10:450-6. ↩
- Kim EC, Choi JS, et al. A Comparison of Vitamin A and Cyclosporine A 0.05% Eye Drops for Treatment of Dry Eye Syndrome. Am J Ophthalmol. 2009 Feb;147(2):206-13. ↩
- Anastasakis A, Plainis S, et at. Xerophthalmia and acquired night blindness in a patient with a history of gastrointestinal neoplasia and normal serum vitamin A levels. Doc Ophthalmol. 2013 Apr;126(2):159-62. ↩
- Vetrugno M, Maino A, et al. A randomised, double masked, clinical trial of high dose vitamin A and vitamin E supplementation after photorefractive keratectomy. Br J Ophthalmol 2001;85:537-9. ↩
- Kuzniarz M, Mitchell P, et al. Use of vitamin supplements and cataract: the Blue Mountains Eye Study. Am J Ophthalmol. 2001 Jul;132(1):19-26. ↩