Age-related macular degeneration (AMD) is the most common cause of loss of vision in adults. Recently, I wrote about this condition, and offered some suggestions regarding the sort of supplements that appear to have promise in the management of this condition. Last year, I wrote about a study that found a link between eating a diet relatively disruptive for blood sugar levels (a high glycaemic index diet) and increased risk of AMD. The authors of this study concluded that eating a low GI diet would perhaps eliminate 20 per cent of cases of AMD. You can read about this study and some of the proposed mechanisms by which high GI foods may promote AMD here.
I was interested to read a recent study that has replicated this finding. This particular research was conducted in Australia, and assessed the relationship between dietary GI and risk of AMD over 10 years in a group of almost 2000 people . The results of this research showed that compared to individuals consuming diets of lower GI, those consuming the highest GI diets were at a 77 per cent increased risk of developing AMD. These findings are very much in line with those reported in the study from last year.
Eating a low GI diet basically means eating a diet made up of mainly meat, fish, eggs, nuts, seeds, green vegetables, beans, lentils and certain fruits such as apples and berries. My advice generally would be to limit grains in the diet, as some of these (such as most breads, and many breakfast cereals and forms of white rice) have relatively high GIs. They are particularly disruptive to blood sugar (and insulin) levels when eaten in quantity.
This recent Australian research also looked at the relationship between cereal fibre intake and intake of breads and cereals and AMD risk. As the intake of these foodstuffs went up, risk of AMD generally went down. However, even in the individuals eating the most, risk of AMD was not statistically significantly lower than those eating the least. This should not be too surprising given that many grains can be quite disruptive to GI, including some that are quite high in fibre (e.g. wholemeal bread).
There are plenty of good reasons for eating a diet of relatively low GI, including, most likely, a reduced risk of weight gain, type 2 diabetes, cardiovascular disease and maybe some forms of cancer too. We now have evidence that suggests a lower GI diet may help to protect against AMD and preserve vision as we age.
1. Kaushik S, et al. Dietary glycemic index and the risk of age-related macular degeneration. American Journal of Clinical Nutrition 2008;88(4):1104-1110