Nutrition and the Eye, Part One
Nutrition & Diet

I have always had a keen interest in health, diet and nutrition and as these things are essential for good eye health, as well as general wellbeing, I wanted to write a post about nutrition and the eye.

The most recent statistics have reported that 67% of people in Ireland are overweight and approx. 1 in 6 people are diabetic. Most of these diabetics are type 2, which is related to diet and exercise, as opposed to type 1 diabetes, which is an autoimmune condition. Other health complications of being overweight that affect your eyesight include retinal vessel occlusions, diabetic eye problems and eye conditions related to strokes, all of which are potentially sight threatening.

Other lifestyle factors can have a significant impact on your eye health. Smoking, for example, can significantly increase your risk of developing age related macular degeneration. Even dry eye disease can be managed by changes to diet. To reduce your risk of developing these and other health issues it is essential to maintain a healthy weight, follow a healthy diet and exercise daily.

What is a healthy diet?

Carbohydrates
I often hear my diabetic patients talking about ‘cutting out the sweet stuff’. This of course is important but so is reducing carbohydrate intake. Carbohydrates should make up approx. 1/3 of our calorific intake, but choose wholegrain or wholemeal varieties, such as wholemeal bread, brown rice and wholemeal pasta. Make sure to manage portion sizes. If you like potatoes, keep the skins on to get the extra fibre these provide.

Protein
Protein is essential for growth and repair of the body and is a good source of vitamins and minerals, such as iron, zinc and B Vitamins. I have become a pescetarian in the past year and I now get my protein from a wide range of sources such as tofu, soya, eggs, beans, lentils and of course fish. Choose lean protein and low fat dairy. Take care when buying some low fat products, such as yoghurts, which can have a high sugar content. If you don’t eat meat you may need to take B12 supplements.

Fruit and Vegetables
You see a lot written about your ‘5 a day’ and I sometimes wonder about this. Of course 5 a day is better than 2 a day or none but there are other countries that suggest significantly more. My advice is eat plenty of vegetables either fresh or frozen and do not overcook them. Eat fruit in moderation due to the higher natural sugar content. We are all being encouraged to switch to plant based diets for the good of our health and the environment and we do need to take heed of this advice.

Sugars
Check the label! There is added sugar in almost everything, so know your RDA.

  • AGE 4 – 6 years 19g
  • AGE 7 – 10 years 24g
  • AGE 11 – Adult 30g

Most breakfast cereals contain over 14G of sugar per 100g, meaning a small bowl can contain almost the full RDA of sugar for a child. Know the names of sugars which can be hidden, such as sucrose, fructose, glucose, corn syrup, and fruit concentrate etc. There are also many foods that now contain low carbohydrate sugar alcohols or polyols which are commonly found in protein bars. Sugar can provide approx. 4 calories per gram whereas polyols range from 0 calories per gram (erythritol) to 2.6 calories per gram (sorbitol). So take care what you eat and be informed. Hidden sugar is everywhere!

If you consume excessive amounts of carbohydrate it causes insulin to be secreted twice as insulin is based on the carb levels of previous meals. Excessive carbohydrates mean excessive insulin production. The insulin converts the excessive carbohydrate to glucose, the surplus of which is transported to the liver where it’s turned into fatty acids and stored as body fat.

Fats
It is important to reduce consumption of foods high in saturated fats. For example sausages, cakes, pies and butter as these can increase the level of LDL or “bad” cholesterol, whereas foods containing saturated fats such as olive oils, nuts, seeds, oily fish and avocados can reduce cholesterol levels.

Omega 3 Vs Omega 6
We all know the benefits of Omega 3 in our diet but are less aware of the role of Omega 6. Omega 6 fatty acids help with brain function, muscle growth and hormone production but they also cause inflammation in the body and they compete with Omega 3 to be absorbed by the body. The ideal ratio of Omega 6 to Omega 3 in the diet should be 4:1, however, due to the excessive amounts of processed foods consumed in western diets the ratio can range from 12:1 to 25:1!!

Omega 6 oils, such as corn oil, soybean oil and sunflower oil, among others, are cheap to produce but many are genetically modified and produced with toxic solvents. Cooking these Omega 6 oils at high heats oxidizes the fats in the oils and this oxidized Omega 6 damages DNA, causes inflammation of the heart and raises the risk of several types of cancer, including breast cancer. Furthermore the hydrogenation of these fats in packaged foods takes these already harmful fats and converts them into trans fats which are worse again.

As I write this I see that the ratio of Omega 3: Omega 6 in pumpkin seeds is 1:54, I will be ditching these from my breakfast cereal forthwith!

Omegas 3’s on the other hand are an integral part of cell membranes and affect the cell receptors in these membranes. They are also involved in the production of hormones that regulate blood, heart and genetic function. Studies have shown that they help prevent heart disease and strokes and may protect against inflammatory conditions and cancer.

Sources of Omega 3 include oily fish, cauliflower, flaxseed and some nuts. You can optimise Omega 3’s through taking supplements like krill oil.

So, for optimal health, it is essential to maximise Omega 3 intake and minimise Omega 6 intake. It is important if you are taking Omega 3 supplements along with other medication, or if you have liver or kidney problems, that you consult your GP, as you may be unsuited to Omega 3 supplements.