There are four eye disease in the US that accounts for 75% of the cases for blindness and 85% of cases of visual impairment for adults 40 years and older in the US. 1
- age-related macular degeneration (AMD)
- diabetic retinopathy – blood vessels in the retina leak fluid or bleed caused by diabetic complications
- glaucoma – slow clogging of the drainage canals which results in increased eye pressure
The presence of drusen under the retina increases the risk of a person developing age-related macular degeneration (AMD). Drusen are yellow deposits under the retina that are composed of lipids.
Carotenoids are a group of phytonutrients (phyto = plants) with at least 600 different compounds. They impart colours ranging from pale yellow, orange, pinks and reds to fruits and vegetables. The autumn colours of leaves, the pink of salmon flesh and flamingo feathers are also created by carotenoids. The green pigment of chlorophyll masks reds of carotenoids in leafy green vegetables. Carotenoids are only produced by plants.
Lycopene, β-carotene, α-carotene, lutein, β-cryptoxanthin and zeaxanthin are the most common in the US diet. 2
|Green peas, cooked||1690|
As well as leafy green vegetables, carotenoids are also found in Einkorn, Khorasan and durum wheat and corn.
Astaxanthin and fucoxanthin are abundant in green and brown algae, respectively, which are eaten by fish.
Capsanthin is found in peppers. Beta-cryptoxanthin is a vitamin A precursor. It is most abundant in corn, oranges, peaches, papaya and watermelon but is also found in many fruit and vegetables. 3
Lycopene, lutein, and zeaxanthin are powerful antioxidants. They contribute to the prevention of damage to light sensitive organs such as eyes and skin.
Nuclear cataracts are the most common form of cataracts that are caused by the hardening and yellowing of the lens. For nuclear cataracts, the odds ratios were 0.67 for every 1 mg increase in the daily lutein and zeaxanthin intake. 4
That is, for every 1 mg increase per day in lutein and zeaxanthin the incidence of cataracts is reduced by a third. One cup of cooked kale (which is only 250 ml – which is not very much) contains 6 mg of lutein and zeaxanthin.
Despite the Australian Eggs website 5 claiming that eggs are a great source of lutein and zeaxanthin, one normal 50 g egg only contains 0.25 mg of lutein and zeaxanthin. One cup of cooked kale contains 24 times more. 6
The POLA (Pathologies Oculaires Liées à L’Age) Study is a study of cataract and age-related macular degeneration that was performed in Sète, a French city on the Mediterranean coast. 2,584 participants aged 60-95 years participated in the study.
The purpose was to assess the associations of carotenoids on the risk of age-related maculopathy (ARM) and cataract formation. 7
|Plasma Carotenoid||µg||Odds ratio|
|0.18 - 0.41||0.45|
|0.04 - 0.09||0.76|
|0.25 - 0.56||0.48|
|0.22 - 0.71||0.9|
Each nutrient is listed according to the amount found in the blood – the lowest third, the middle third and the highest third. In the above table, the odds ratio (OR) compares the incidence of AMR in lowest third with the middle and highest levels of the nutrient.
The carotenoids were obtained from the diet – not from supplements. It is probably significant that Sète is in the Mediterranean region which has a higher consumption of fruit, vegetables, pasta, legumes and olives and less poultry, seafood and dairy than the general French population. 8
According to a 2011 paper, cataract surgery is the most common surgical procedure in developed countries. This paper also states that lutein and zeaxanthin are the most powerful retinal anti-oxidants and absorb the harmful blue light and that their depletion induces the development of the lens opacification-cataracts. The development of cataracts reduces the retinal oxidative stress, which causes a reduction of the probability to develop AMD. 9
Restoring the anti-oxidative capabilities of the retina by increasing intake of lutein and zeaxanthin reduces the likelihood of AMD and cataract.
Most studies examine isolated components such as lutein and zeaxanthin, beta-carotene, vitamin E, vitamin C or vitamin D on an isolated health outcome such as AMD, breast cancer, prostate cancer or heart disease.
Lutein, zeaxanthin, lycopene, quercetin, beta-carotene and vitamin C as well as a multitude of other micronutrients work synergisticly to provide a far greater response than consuming isolated supplements. 10
For the final paper, let’s examine data from the EPIC study which studied 27,670 participants aged at least 40 in the United Kingdom. Below is the incident ratio of cataracts associated with four different dietary groups. As the diets become more vegetarian, the incidence of incidence of cataracts decreased. The men, women and 65+ vegans had an incident rate of cataracts of 39%, 73% and 57% respectively compared with the meat-eating group. 11
|Diet Group||Men||Women||65 years
|Dairy & Eggs||0.56||0.75||0.54|
- Rein, D. B. (2006) The Economic Burden of Major Adult Visual Disorders in the United States. Archives of Ophthalmology. 124 (12), 1754.
- Rao, A. & Rao, L. (2007) Carotenoids and human health. Pharmacological Research. 55 (3), 207–216.
- Abdel-Aal, E.-S. et al. (2013) Dietary Sources of Lutein and Zeaxanthin Carotenoids and Their Role in Eye Health. Nutrients. 5 (4), 1169–1185.
- Vu, H. T. V. et al. (2006) Lutein and Zeaxanthin and the Risk of Cataract: The Melbourne Visual Impairment Project. Investigative Opthalmology & Visual Science. 47 (9), 3783.
- Australian Eggs (2017) Egg Nutrition: What’s In An Egg? [online]. Available from: https://www.australianeggs.org.au/nutrition/ (Accessed 24 November 2017).
- U.S. Department of Agriculture (n.d.) USDA Food Composition Databases NDB No 01131
- Delcourt, C. et al. (2006) Plasma Lutein and Zeaxanthin and Other Carotenoids as Modifiable Risk Factors for Age-Related Maculopathy and Cataract: The POLA Study. Investigative Opthalmology & Visual Science. 47 (6), 2329.
- Kesse, E. et al. (2005) Regional dietary habits of French women born between 1925 and 1950. European Journal of Nutrition. 44 (5), 285–292.
- Wegner, A. & Khoramnia, R. (2011) Cataract is a self-defence reaction to protect the retina from oxidative damage. Medical hypotheses. 76 (5), 741–744.
- Liu, R. H. (2003) Health benefits of fruit and vegetables are from additive and synergistic combinations of phytochemicals. The American Journal of Clinical Nutrition. 78 (3), 517S-520S.
- Appleby, P. N. et al. (2011) Diet, vegetarianism, and cataract risk. The American Journal of Clinical Nutrition. 93 (5), 1128–1135.