Kim is an RN and author of the book "360 Health: Your Guide to Cancer Prevention, Healing Foods, & Total Body Wellness."
Avocados are filled with an abundance of vitamins and minerals, making them an antioxidant-rich superfood. Perhaps the most important element of the avocado is its rich monounsaturated fatty acid (MUFA) profile. The MUFAs in this special fruit enhance the absorption of fat-soluble vitamins and carotenoids. Interestingly, its MUFAs, especially oleic acid, provide optimal absorption not only of the inherent carotenoids in the avocado itself, but also the carotenoids found in other foods eaten at the same time. Carotenoids are the plant pigments responsible for eye health, and research shows that the more carotenoids one eats, the more protection from eye disease one receives.
Nutrient Content of 1 Avocado
|Vitamin/Mineral||Amount||% Daily Value|
Importance of Carotenoids
In addition to the above vitamins and minerals, one avocado contains 13.5 grams of fiber. It consists of 71% monounsaturated fat, 13% polyunsaturated fat, and 16% saturated fat.
Avocados also contain nine carotenoids. Two are especially helpful for healthy eyesight -- lutein and zeaxanthin. These carotenoids are taken up into the macula of the eye where light is focused. The macula is the central area of the retina and has a yellowish tint. Lutein and zeaxanthin are responsible for giving the macula its color. These antioxidants also help filter out blue light which can damage the eye, and they help protect and maintain healthy cells in the eyes.
In humans, the macula is the place in the back of the eye where light is focused by the cornea and lens, both in the front of the eye. The macula provides us with the ability to read and see in great detail. When someone develops age-related macular degeneration (AMD), they lose the ability to focus their central vision which affects ability to read, drive a car, recognize faces or colors, and see objects in fine detail. AMD involves the deterioration of the central portion of the retina, but the exact cause is unknown. Likely, hereditary and environmental factors come into play. More than 10 million people in the United States are affected by some form of the disease.
A study published in the journal Nutrients found that eating one avocado per day for six months increased serum lutein levels by 25%. In contrast with the control group, those eating avocados experienced significant increases in macular pigment density (MPD). Interestingly, the same research team found that avocado consumption more than doubled the MPD compared to a lutein/zeaxanthin supplement. This suggests that the fatty acids (MUFAs) in avocado significantly increase absorption of these key carotenoids over and above a supplement.
Researchers have found that high MPD is connected to retention of visual acuity, suggesting that macular pigment may retard age-related loss of visual function. MPD correlates with preservation of clarity of the lens as well as health of the retina.
The avocado intervention increased MPD by more than double that of the supplement, with only a small fraction of the amount of lutein. This suggests that other components in avocado are particularly effective in the enrichment of neural lutein. The most likely components are monounsaturated fatty acids.
— 2016 study, Nutrients Journal
A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. Most cataracts are related to aging, although smoking and diabetes can be contributing factors. Cataracts are very common in older people. According to the National Eye Institute, by age 80, more than half of all Americans either have a cataract or have had cataract surgery.
The lens focuses light onto the retina at the back of the eye, where an image is recorded. It also adjusts the eye's focus, allowing things to be seen clearly both up close and far away. With age, some of the protein in the lens may clump together and start to cloud a small area. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see.
Oxidation and free radical damage of the lens is a major cause of cataracts. This is why antioxidant intake likely plays a role in reducing their occurrence. Avocados are rich in vitamins C and E and in the mineral zinc, all of which can decrease the risk for developing cataracts. And, of course, avocados' remarkable levels of lutein and zeaxanthin are beneficial.
The famous Nurses' Health Study found that people taking high amounts of lutein and zeaxanthin had a reduced need for cataract surgery. The five-year follow-up to the Beaver Dam Eye Study showed that people with the highest intakes of lutein and zeaxanthin had a significantly lower risk for developing new cataracts than those with the lowest intakes. And a study published in the Archives of Ophthalmology in March 2008 found that women with high dietary intakes of lutein and zeaxanthin had a 23% lower risk of nuclear cataracts than women with low levels of these carotenoids.
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The main finding ... was that high lutein intake in the distant past significantly reduced the risk of incident cataract by 50%. High intake of lutein at baseline reduced risk of incident cataract by 60% among subjects under 65 years. High intake of greens (with high lutein content) was also found to reduce risk of incident cataract. The authors concluded that nutrient intake in middle age may influence development of cataracts far into older age.
— 1999, Beaver Dam Eye Study
Newer research shows that lutein and zeaxanthin may also play a role in helping preserve visual acuity and contrast. The following studies make mention of supplementation, but remember that lutein from avocados is even better absorbed and may have similar benefits.
A 2009 study published in the British Journal of Nutrition found that participants who received lutein supplements during a 12-week trial period experienced a significant improvement in visual performance. The study followed three groups of Chinese individuals with long-term computer display light exposure. Each day for the 12 weeks, one group received 6 mg of lutein, another received 12 mg of lutein, and the third group received a placebo. Those who were given 12 mg of lutein per day saw the most improvement in visual acuity and contrast sensitivity.
Visual function in healthy subjects who received the lutein supplement improved, especially in contrast sensitivity, suggesting that a higher intake of lutein may have beneficial effects on the visual performance.
— 2009 study, British Journal of Nutrition
Another study, which was a randomized, double-blind, placebo-controlled intervention trial, published in the Journal of Ophthalmology, investigated the eye-health benefits of MacuView, a dairy-drink product from Newtricious (a company in the Netherlands). The product is a buttermilk drink containing egg yolks enriched with lutein, zeaxanthin, and omega-3 DHA. After one year, compared to the placebo group, the MacuView group (who drank 80 ml daily) experienced a significant improvement to MPD, visual acuity, and plasma lutein concentrations. The company's CEO stated, "We’re pleased these results demonstrate that MacuView improves macular pigment optical density and sharpness of vision contribution to healthy vision."
It appears that the avocado's unique combination of antioxidants and monounsaturated fatty acids make it a powerful healing agent for the eyes. Daily consumption may improve vision or delay onset of age-related eye conditions. For more information on the benefits of avocados and avocado oil, see the article "Five Health Benefits of Avocado Oil."
Video: Benefits of Daily Avocado Consumption
Video: Benefits of Lutein and Zeaxathin for the Eyes
Crane, Michael. "Lutein-Enhanced Dairy Drink Improves Visual Acuity and Macular Pigment Optical Density in Study," 2 May 2016, Nutritional Outlook, http://www.nutritionaloutlook.com/science/lutein-enhanced-dairy-drink-improves-visual-acuity-and-macular-pigment-optical-density-study.
"Avocado: A Superfood with Many Health Benefits," Heal With Food, https://www.healwithfood.org/health-benefits/avocado-superfood.php.
Downey, Michael. "Avocados Super-Enhanced Carotenoid Absorption," October 2015, Life Extension, http://www.lifeextension.com/magazine/2015/10/avocados-super-enhanced-carotenoid-absorption/page-01.
Watson, Tracy. "Avocados Found to Improve Eye Health in Aging Adults," 17 September 2017, Natural News, https://www.naturalnews.com/2017-09-17-avocados-found-to-improve-eye-health-in-aging-adults.html.
"Daily Avocado Supports Eye Health and More," 6 September 2017, Natural Health News, https://www.naturalhealthnews.uk/food/2017/09/daily-avocado-supports-eye-health-and-more/.
"Nutrition and Cataracts," American Optometric Association, https://www.aoa.org/patients-and-public/caring-for-your-vision/nutrition/nutrition-and-cataracts.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
Kim Maravich (author) from Pennsylvania on March 30, 2018:
Dora, As always, thank you for reading and for your kind comments!
Dora Weithers from The Caribbean on March 19, 2018:
Very educational and helpful article. Heard that avocado has good nutritional benefits, but was not aware of how beneficial it is to the eyes. Thank you.