Eggs and Eye Health

Position Statement for Healthcare Professionals

Eggs and Eye Health

 

Updated June 2017

Age-related eye disorders have been reported as the leading causes of vision impairment and blindness in Australia1,2. These disorders include cataracts, age-related macular degeneration (AMD), diabetic retinopathy and glaucoma1, with age-related macular degeneration being the most common cause of blindness3.

The major risk factors for age-related eye disorders include smoking, family history and increasing age4,5. AMD also appears to be more likely in men than women6 although this differs between countries7. Given Australia’s ageing population, eye health will continue to be an important health issue to address. However, eye disorders are not only a problem for older adults - eye disorders are also among the most common long-term health problems experienced by Australian children8.

Evidence indicates that several dietary factors such as fruit and vegetable intake9, antioxidant intake10, fat types11, omega-3 intake12, glycemic index13 and adequate intake of key vitamins and minerals9 play an important role in the development and progression of some of these disorders including AMD and cataracts.

People with diabetes, in particular, have an increased risk of developing eye disease with an Australian study finding evidence of diabetic retinopathy in 16% of study participants14. Improved diabetes control, which ideally involves dietary and lifestyle modification, reduces the risk of developing, and the progression of, diabetic retinopathy15.

 

Antioxidants and Eye Disease 

Lutein and zeaxanthin (with their isomer meso-zeaxanthin) are the primary carotenoids found in the macular region of the retina16,17. Numerous studies have suggested lutein and zeaxanthin, (along with other nutrients such as omega-3), are essential components for eye health18-20. Current evidence from human studies, suggest dietary intake of lutein and zeaxanthin can lead to their accumulation in the retina, and as a result may provide protection against retinal degeneration21-23.

 

The Blue Mountains Eye Study (BMES) showed that older adults with the highest intake of dietary lutein and zeaxanthin, had a reduced risk of developing late AMD (RR 0.35)10. Similarly, a 2012 systematic review found that while dietary lutein and zeaxanthin were not significantly associated with a reduced risk of early AMD, these important antioxidants may protect against late AMD24. Studies published since then have also suggested that the benefits of these antioxidants may be limited to advanced (late) AMD25.

Further support for dietary lutein and zeaxanthin intake as a protective factor in AMD comes from the eye supplement trial, AREDS ((Age-Related Eye Disease Study) 26,27,28 which found the supplement lost its effectiveness if the background diet was sufficient in lutein and zeaxanthin.  

Individuals at high risk of AMD (ie, those genetically susceptible to AMD) appear to benefit from a high lutein and zeaxanthin intake29. Among participants with high genetic risk, the highest intake of lutein and zeaxanthin was associated with a >20% reduced risk of early AMD. No similar association was evident among participants with low genetic risk.

 

Bioavailability of Carotenoids in Eggs

Eggs contain both of the antioxidants lutein and zeaxanthin, with one serve* of eggs containing around 530µg. While this is lower than most plant sources of these carotenoids, a number of studies have demonstrated that the lutein and zeaxanthin in eggs is bioavailable while factors in plants may reduce the bioavailability from these sources30-32.

Egg consumption has been shown to be an effective vehicle for increased uptake of lutein and zeaxanthin, with results showing egg consumption effectively raises blood carotenoid levels33-35 and in some studies macular pigment optical density (MPOD)36,37. The level of increase differed in the studies dependent on level of egg consumption (1 to 4 eggs per day), duration of study and type of eggs used (regular verses lutein enriched). Furthermore, LDL cholesterol levels were not found to increase despite the increases in carotenoid levels with egg consumption33,36,37.

Due to both their high bioavailabilty and not being subject to seasonal variation, the consumption of eggs is a favourable source of lutein and zeaxanthin in the diet.

 

Recommended Level of Intake

Currently there is insufficient research to indicate an exact optimal level of intake of lutein and zeaxanthin for protecting against eye disease, although some researchers have recommended levels as high as 6mg per day38,39. Although more recent research suggests possible protective effects at levels considerably below the suggest 6mg per day10,40.

Overall, the research to date suggests that eggs are a highly bioavailable source of the dietary carotenoids, lutein and zeaxanthin, and that they are an effective vehicle for increased and site-specific antioxidant uptake. This in turn may have benefits for long term eye health given the data supporting the role of lutein and zeaxanthin. 

Omega-3 Fats and Eye Health 

The essential long chain omega-3 fatty acid docosahexaenoic acid (DHA) is a major structural lipid found in the photoreceptors of the retina and DHA deficiency is associated with alterations in the functioning of the retina and visual processing. Adequate intake of long-chain omega-3 can protect the eye from retinal damage caused by ischemia, oxidation, light, inflammation and age-associated diseases41. Some research has shown that lower intakes of saturated fat and higher intakes of omega-3 fatty acids are protective against the development of certain eye diseases12,42,43.

While individual studies have found associations between the consumption of omega-3 and/or omega-3 status and a reduced risk of AMD44-47, a 2015 Cochrane review found that omega 3 supplementation in people with AMD (who have had the disease for up to five years), does not reduce the risk of progression to advanced AMD or the development of moderate to severe visual loss.  The review concluded that current available evidence does not support increasing dietary intake of long chain omega 3 fatty acids for the explicit purpose of preventing or slowing the progression of AMD48.

Of note, in 2010, the European Food Safety Authority (EFSA) asserted that consuming 250mg of DHA per day (in one or more servings), can make an important contribution towards maintaining vision in the general population49

 

Other Nutrients in Eggs

In addition to omega-3, lutein and zeaxanthin, adequate intakes of vitamin A, other antioxidants and zinc are thought to reduce the amount of visual degeneration in older adults10,39,50.

For people aged 51 years and over, one serve of eggs* provides bioavailable vitamin A (34% RDI for women, 27% RDI for men), vitamin E (34% AI for women, 24% AI for men), selenium (68% RDI for women, 59% RDI for men), and zinc (6% RDI for women, 4% RDI for men).

Dietary and lifestyle effects on eye health

Studies have linked diet quality, glycemic index (GI) and body mass index (BMI) with eye health.  Studies using data from the BMES have shown older adults with higher diet quality (better compliance with dietary guidelines) also had healthier retinal vessels51 and a decreased long term risk of visual impairment52.  

Given the nutritional composition of eggs, they can make a valuable contribution to improved diet quality, help lower the GI of a meal/overall diet and may have a role to play in assisting weight management through appetite control.

Conclusion

Eggs contain a range of nutrients and antioxidants that have been shown to contribute to long-term eye health. Eggs can therefore be enjoyed regularly as part of a healthy lifestyle that also includes the following:

  • Smoking avoidance
  • Enjoying 1-2 fish meals per week
  • Eating other foods rich in carotenoids such as dark green and orange/yellow fruit and vegetables daily
  • Reducing dietary sources of saturated fat
  • Exercising regularly to control body weight and blood pressure
  • Reducing the glycaemic index of the diet
  • If overweight, aiming for weight loss to assist with controlling blood glucose levels and fat loss
  • For people with type 2 diabetes, achieving and maintaining optimal blood glucose and plasma lipid levels.

 

This statement is for healthcare professionals only.

 

*One serve = 2x60g eggs (104g edible portion)

 

RDI: Recommended Dietary Intake

AI: Adequate Intake

 

Useful links:

http://www.mdfoundation.com.au/

https://www.visionaustralia.org/learn-more/eye-conditions/age-related-macular-degeneration

 

 

References:

1.              AIHW. Australia's Health 2006: the tenth biennial health report.  (Australian Institute of Health and Welfare, Canberra, 2006).

2.              Welfare, A.I.o.H.a. A guide to Australian health data, 2nd edition (2009).

3.              Lim, L.S., Mitchell, P., Seddon, J.M., Holz, F.G. & Wong, T.Y. Age-related macular degeneration. Lancet379, 1728-1738 (2012).

4.              Cho, E., Seddon, J.M., Rosner, B., Willett, W.C. & Hankinson, S.E. Prospective study of intake of fruits, vegetables, vitamins, and carotenoids and risk of age-related maculopathy. Arch Ophthalmol122, 883-892 (2004).

5.              Ribaya-Mercado, J.D. & Blumberg, J.B. Lutein and zeaxanthin and their potential roles in disease prevention. J Am Coll Nutr23, 567S-587S (2004).

6.              Park, S.J., Kwon, K.E., Choi, N.K., Park, K.H. & Woo, S.J. Prevalence and Incidence of Exudative Age-Related Macular Degeneration in South Korea: A Nationwide Population-Based Study. Ophthalmology122, 2063-2070 e2061 (2015).

7.              Owen, C.G., et al. The estimated prevalence and incidence of late stage age related macular degeneration in the UK. Br J Ophthalmol96, 752-756 (2012).

8.              AIHW. Australia's Health 2008: the eleventh biennial health report.  (Australian Institute of Health and Welfare, Canberra, 2008).

9.              Raman, R., Vaghefi, E. & Braakhuis, A.J. Food components and ocular pathophysiology: a critical appraisal of the role of oxidative mechanisms. Asia Pac J Clin Nutr26, 572-585 (2017).

10.           Tan, J.S., et al. Dietary Antioxidants and the Long-term Incidence of Age-Related Macular Degeneration The Blue Mountains Eye Study. Ophthalmology (2007).

11.           Robman, L., et al. Dietary lutein, zeaxanthin, and fats and the progression of age-related macular degeneration. Can J Ophthalmol42, 720-726 (2007).

12.           Hodge, W.G., et al. The evidence for efficacy of omega-3 fatty acids in preventing or slowing the progression of retinitis pigmentosa: a systematic review. Can J Ophthalmol41, 481-490 (2006).

13.           Chiu, C.J., Milton, R.C., Gensler, G. & Taylor, A. Association between dietary glycemic index and age-related macular degeneration in nondiabetic participants in the Age-Related Eye Disease Study. Am J Clin Nutr86, 180-188 (2007).

14.           Tapp, R.J., Svoboda, J., Fredericks, B., Jackson, A.J. & Taylor, H.R. Retinal photography screening programs to prevent vision loss from diabetic retinopathy in rural and urban Australia: a review. Ophthalmic Epidemiol22, 52-59 (2015).

15.           Taylor, H.R. Diabetic retinopathy. Clin Experiment Ophthalmol33, 3-4 (2005).

16.           Pratt, S. Dietary prevention of age-related macular degeneration. J Am Optom Assoc70, 39-47 (1999).

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18.           Abdel-Aal el, S.M., Akhtar, H., Zaheer, K. & Ali, R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients5, 1169-1185 (2013).

19.           Schweigert, F.J. & Reimann, J. Micronutrients and their Relevance for the Eye - Function of Lutein, Zeaxanthin and Omega-3 Fatty Acids. Klin Monbl Augenheilkd (2010).

20.           Arnold, C., et al. Macular Xanthophylls and omega-3 Long-Chain Polyunsaturated Fatty Acids in Age-Related Macular Degeneration: A Randomized Trial. JAMA Ophthalmol, 1-9 (2013).

21.           Moeller, S.M., Jacques, P.F. & Blumberg, J.B. The potential role of dietary xanthophylls in cataract and age-related macular degeneration. J Am Coll Nutr19, 522S-527S (2000).

22.           Johnson, E.J. The role of carotenoids in human health. Nutr Clin Care5, 56-65 (2002).

23.           Renzi, L.M., Hammond, B.R., Jr., Dengler, M. & Roberts, R. The relation between serum lipids and lutein and zeaxanthin in the serum and retina: results from cross-sectional, case-control and case study designs. Lipids Health Dis11, 33 (2012).

24.           Ma, L., et al. Lutein and zeaxanthin intake and the risk of age-related macular degeneration: a systematic review and meta-analysis. Br J Nutr107, 350-359 (2012).

25.           Wu, J., Cho, E., Willett, W.C., Sastry, S.M. & Schaumberg, D.A. Intakes of Lutein, Zeaxanthin, and Other Carotenoids and Age-Related Macular Degeneration During 2 Decades of Prospective Follow-up. JAMA Ophthalmol133, 1415-1424 (2015).

26.           SanGiovanni, J.P., et al. The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report No. 22. Arch Ophthalmol125, 1225-1232 (2007).

27.           SanGiovanni, J.P., et al. w-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study. Am J Clin Nutr90, 1601-1607 (2009).

28.           Age-Related Eye Disease Study 2 Research Group. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA309, 2005-2015 (2013).

29.           Wang, J.J., et al. Genetic susceptibility, dietary antioxidants, and long-term incidence of age-related macular degeneration in two populations. Ophthalmology121, 667-675 (2014).

30.           Ghavami, A., Coward, W.A. & Bluck, L.J. The effect of food preparation on the bioavailability of carotenoids from carrots using intrinsic labelling. Br J Nutr107, 1350-1366 (2012).

31.           Riedl, J., Linseisen, J., Hoffmann, J. & Wolfram, G. Some dietary fibers reduce the absorption of carotenoids in women. J Nutr129, 2170-2176 (1999).

32.           van Het Hof, K.H., West, C.E., Weststrate, J.A. & Hautvast, J.G. Dietary factors that affect the bioavailability of carotenoids. J Nutr130, 503-506 (2000).

33.           Goodrow, E.F., et al. Consumption of One Egg Per Day Increases Serum Lutein and Zeaxanthin Concentrations in Older Adults without Altering Serum Lipid and Lipoprotein Cholesterol Concentrations. J Nutr136, 2519-2524 (2006).

34.           Curran-Celentano, J.M., Wenzel, A., Nicolosi, R.J. & Handelman, G.J. Evaluating the influence of egg consumption as a source of macular carotenoids and the impact on serum cholesterol risk ratios. Invest Opthalmol Vis Sci44, E-abstract: 403 (2003).

35.           Burns-Whitmore, B.L., et al. Effect of n-3 fatty acid enriched eggs and organic eggs on serum lutein in free-living lacto-ovo vegetarians. Eur J Clin Nutr64, 1332-1337 (2010).

36.           Vishwanathan, R., Goodrow-Kotyla, E.F., Wooten, B.R., Wilson, T.A. & Nicolosi, R.J. Consumption of 2 and 4 egg yolks/d for 5 wk increases macular pigment concentrations in older adults with low macular pigment taking cholesterol-lowering statins. Am J Clin Nutr90, 1272-1279 (2009).

37.           Wenzel, A.J., et al. A 12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women. J Nutr136, 2568-2573 (2006).

38.           Seddon, J.M., et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA272, 1413-1420 (1994).

39.           Rasmussen, H.M. & Johnson, E.J. Nutrients for the aging eye. Clin Interv Aging8, 741-748 (2013).

40.           Aronow, M.E. & Chew, E.Y. Age-related Eye Disease Study 2: perspectives, recommendations, and unanswered questions. Curr Opin Ophthalmol25, 186-190 (2014).

41.           SanGiovanni, J.P. & Chew, E.Y. The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina. Prog Retin Eye Res24, 87-138 (2005).

42.           Seddon, J.M., et al. Dietary fat and risk for advanced age-related macular degeneration. Arch Ophthalmol119, 1191-1199 (2001).

43.           Mitchell, P., et al. Nutritional factors in the development of age-related eye disease. Asia Pac J Clin Nutr12 Suppl, S5 (2003).

44.           Christen, W.G., Schaumberg, D.A., Glynn, R.J. & Buring, J.E. Dietary {omega}-3 Fatty Acid and Fish Intake and Incident Age-Related Macular Degeneration in Women. Arch Ophthalmol (2011).

45.           Delyfer, M.N., et al. Association of macular pigment density with plasma omega-3 fatty acids: the PIMAVOSA study. Invest Ophthalmol Vis Sci53, 1204-1210 (2012).

46.           Merle, B.M., et al. Circulating omega-3 Fatty acids and neovascular age-related macular degeneration. Invest Ophthalmol Vis Sci55, 2010-2019 (2014).

47.           Merle, B.M.J., et al. High Concentrations of Plasma n3 Fatty Acids Are Associated with Decreased Risk for Late Age-Related Macular Degeneration. J Nutr143, 505-511 (2013).

48.           Lawrenson, J.G. & Evans, J.R. Omega 3 fatty acids for preventing or slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev4, CD010015 (2015).

49.           European Food Safety Authority (EFSA). Scientific Opinion Docosahexaenoic acid (DHA) related health claims. EFSA Journal8, 1734 (2010).

50.           Vanden Langenberg, G.M., et al. Associations between antioxidant and zinc intake and the 5-year incidence of early age-related maculopathy in the Beaver Dam Eye Study. Am J Epidemiol148, 204-214 (1998).

51.           Gopinath, B., et al. Is quality of diet associated with the microvasculature? An analysis of diet quality and retinal vascular calibre in older adults. Br J Nutr, 1-8 (2013).

52.           Hong, T., et al. Adherence to dietary guidelines and the 10-year cumulative incidence of visual impairment: the Blue Mountains Eye Study. Am J Ophthalmol (2014).

 

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