Eye health

Citation

Wells, D. (2002), "Eye health", Nutrition & Food Science, Vol. 32 No. 3. https://doi.org/10.1108/nfs.2002.01732cab.004

Eye health

Eye health

Roche Vitamins (UK) Ltd recently held a seminar to discover the links between nutrition and eye health. A number of interesting papers were given by leading researchers linking the relationship between cataracts and macular degeneration of the eye.

Dr Richard Wyse spoke about the health economics of eye health. In the UK some 19.5 million people are at risk of developing cataracts and their incidence starts to rise in the over 50s. By the age of 75 most people will have a cataract and about 50 per cent of those will have significant vision loss as a result of the condition. The direct surgery cost to the UK healthcare system of the 160,000 patients who have surgery is about £208 million. In addition, patients suffer substantial loss of quality of life, especially if both both eyes are affected. Prevalence of age-related macular degeneration increases rapidly in patients over 65, rising sharply in the over 75s and reaching approximately 50 per cent by 85 years of age. Unlike cataract treatment there is no definite treatment for macular degeneration (AMD). But a study in France has shown that the risk of AMD may be reduced by as much as 82 per cent in those with the highest levels of vitamin E.

At least 42 risk factors have been reported for AMD. As well as increasing with age, other risk factors include having a blue iris, decreased macular pigmentation, hypertension, sunlight, smoking, excess alcohol consumption, decreased consumption of fruit and vegetables, increased body mass index and family history (genetics).

Because of their direct exposure to light, ocular tissues are particularly sensitive to oxidative stress. It has been shown that there is a threefold increased risk in subjects living in North Africa in comparison with people living in the north of France. The fortification of food has the advantage of "passive" intervention and it can be quick and self-sustaining. Sugar fortification with vitamin A is already advanced in several countries in Central and South America and African countries are starting its implication.

Dietary measures to stop hypertension is an important component to prevent cataracts and AMD. Increased consumption of omega-3 fatty acids while decreasing the intake of total fats such as saturated fats, transfatty acids and increasing the intake of vegetable oils rich in linoleic acid is another way to prevent cataracts and AMD as well as cardiovascular diseases, reported Dr Steven Prattt. Nutrients which are associated with longevity also include vitamin C, vitamin E, lycopene, lutein, zeaxanthin and beta-carotene. Foods which have shown efficacy in protecting skin and ocular tissue from the adverse effects of sunlight include spinach, soy, broccoli, salmon, lycopene rich foods and sauces, green tea and berries.

Dr Richard Wyse reported that substantial protection against cataract onset can be conferred by vitamins C or E supplementation. Dr Cecile Delcourt's paper showed that oxidative stress results from an imbalance between the production of reactive oxidant species and their neutralisation by antioxidants. In the eye the exposure to sunlight is also an important source of reactive oxygen species and the accumulation of such oxidative damage appears to play an important part in ageing. Epidemiological studies have also suggested that high intakes of antioxidant micronutrients may reduce the risk for AMD. In particular three epimidiological studies have shown that there is a high reduction of at least 50 per cent of the risk for AMD in subjects with high plasma levels of vitamin E. Vitamin C, by contributing to vitamin E regeneration, may also be of importance.

Patients with cataracts and/or AMD are known to have a higher incidence of coronary heart disease and there is also an association of both ocular and cardiovascular disease with rheumatoid arthritis. The cost effectiveness in using vitamin supplementation to delay the onset of cataract and AMD may eventually have to include the additional clinical benefits afforded by their additional protection against a series of other expenses to treat diseases of the elderly.

The annual cost of 500mg vitamin C supplementation per day is between £15 and £30 and for 400mg vitamin E per day the annual cost is between £26 and £35 depending on the brands chosen. Vitamin prevention programmes can prove cost effective if they alleviate or treat long-term diseases of ageing.