Food for Thought
Eating for Your Eyesight
Age-related macular degeneration (AMD) is a progressive eye disease that affects the central macula of the eye, leaving sufferers with only peripheral vision. It is one is the most common causes of blindness in the over-50s in the Western world. As we age our risk increases: people in their 50s have around a 2% chance of suffering AMD which leaps to 30% by age 75. AMD Alliance International estimates that 25 to 30 million people are affected worldwide. It’s the macula (the central part of the retina where light sensitive cells send signals to the brain) that lets us to see fine detail and is critical to central vision helping us to recognise faces, drive a car, read a book or newspaper, or do close handwork. There’s no known cure. But there is something you can do.
‘Just as there are optimum ways of eating for a healthy heart, liver, skin, brain and kidneys, so there is one for the eyes,’ says nutritionist Catherine Saxelby. ‘The nutrients in orange, green and yellow produce – all antioxidants that belong to a large family of more than 600 carotenoids –can slow the progression of AMD. So can dark leafy greens that are rich in lutein and zeaxanthin, and egg yolks.’
A new study just published in the American Journal of Clinical Nutrition in April suggests that a low GI diet should also be a key part of your AMD prevention plans.
‘The retina has among the highest supplies of blood and nutrients, including glucose, and is dependent on adequate glucose delivery from the systemic circulation to maintain its physiologic function. Because glucose stores in the retina are negligible, it appears that glucose metabolism is efficient in the retina’ writes lead author Chung-Jung Chiu from Tufts University. To evaluate the association between ARM (age-related maculopathy) and dietary carbohydrate, researchers from Tufts and Harvard Universities followed 526 women (1036 eyes) without previous ARM diagnosis from the Nurses’ Health Study over ten years using validated food frequency questionnaires that the women completed an average of four times.
What they found was that ‘when total carbohydrate intake was held constant, there was a more than two-fold higher odds for ARM in participants with dietary GI in the highest versus lowest third of the study sample.’ Dietary GI has to be seen as a new risk factor according to Chung-Jung Chiu, and concludes that ‘Although our data cannot establish that the observed association is causal, they indicate a new direction for further studies. The results of such studies may prove helpful in preventing or delaying the onset of ARM and its related disability and costs.’
– Am J Clin Nutr 2006;83:880–6
8 Tips for Making Your Eyesight Last
Exactly what causes AMD is still not fully understood. But if you have a parent with AMD, you have a 50% risk of suffering from it yourself. Smokers have a four times greater risk than non-smokers, and those with high blood pressure, obesity or high cholesterol are also likely to suffer from it. Looking after yourself in your later years can have a significant impact on how long your eyesight lasts. According to Catherine Saxelby you should try to:
- Avoid smoking
- Maintain a healthy weight that’s right for you – neither too fat nor too thin
- Eat large serves of dark green vegetables and salad leaves as often as you can
- Enjoy different coloured fruits and vegetables for natural antioxidants
- Make the switch to low GI carbs (the smart carbs)
- Use oils rich in monounsaturated fat (olive, canola) or polyunsaturated fat (sunflower, grapeseed); limit intake of saturated fats (dairy, takeaway, deli meats)
- Enjoy fish twice a week
- Stay active to help manage your blood pressure and cholesterol
– Catherine Saxelby: www.foodwatch.com.au