Eye Health and your diet
Updated: May 2, 2021
In the human body there are some blood vessels that are very tiny, particularly in our extremities and in the brain, kidneys and the eyes. Some of these blood vessels are even smaller than the red blood cells (erythrocytes or RBC) that are circulating carrying oxygen to your whole body. So how do these areas get nourished with a regular supply of oxygen and removal of carbon dioxide?
In order for the red blood cells to get into these areas, they must deform to squeeze through these tight spaces. After deforming and providing needed oxygen, they must reshape themselves back to continue on their journey through your blood vessels. This it seems is quite simple for healthy red blood cells and so long as they continue to do this, your extremities and particularly your eyes, brain and kidneys continue to be nourished and healthy.
Cholesterol is a major component of our cell walls and these cells have the ability to deform as required. However when we eat certain plant foods that have significant quantities of plant sterols (phytosterols), then this plant “cholesterol” can replace some of the natural animal “cholesterol” in our cell walls. It is this replacement of cholesterol by phytosterols that is touted by some food manufacturers as a positive mechanism to lower the overall level of cholesterol in your body.
But plant cell walls composed of plant sterols (phytosterols) have cell walls that are much stiffer and more rigid than animal cell walls. I guess this is not surprising as plants need this rigidly to give them strength and shape as they have no bone structure. We have discovered that red blood cells with high levels of phytosterols can not deform to the normal level and as a result may be unable to reach some of these tiny extremities and provide the necessary oxygen. The result could be macular degeneration and may also increase risk of stroke.
Research has now established that your LDL cholesterol level has almost zero impact on the risk of heart disease, so I have decided to avoid food with plant sterols. This includes Canola oils and some margarines. So what you eat is clearly important to your eye health and despite claims that these phytosterols are safe, not everyone agrees. I don’t wish to take the chance with my eyes or increase stroke risk.
When we have a continuous high level of blood sugar for long periods then an effect called glycation can occur in our blood. This is where the sugar molecules bind with fat or proteins creating what is known as Advanced Glycation End products (AGE’s). These AGE’s are linked to atherosclerosis and type-2 diabetes. This reaction is exactly the same as the reaction causing browning of food (maillard reaction) when it is cooked.
Damage by glycation can lead to stiffening of the collagen in your blood vessel walls, leading to higher blood pressure, especially in diabetes. It can also weaken the collagen in blood vessel walls, which may lead to micro- or macro-aneurysm; (localized enlarging of the blood vessel) this may cause strokes in the brain.
Research has identified that AGE’s can sensitize the eye lens to damage by photo-crosslinking and oxidation, leading to damage to eye proteins in the lens resulting in early macro degeneration of sight. This can apparently induce protein misfolding and triggers what is called the “unfolded protein response”, which is implicated in the death of retinal neurons and vascular cells in patients with diabetes. Autophagy apparently helps reverse this, but in people with high and constant insulin presence, autophagy is suppressed. Some researchers are now suggesting that this mechanism could be behind an increase in strokes and increase in macular degeneration.
Retinal eye disease is a common complication of diabetes. 90% of type 1 diabetics and over 60% of type 2 diabetics will suffer from this condition in the first twenty years of the disease’s progression. Twenty percent of type 2 diabetic patients are already affected by this at the time of their diagnosis
The natural dipeptide carnosine may assist. Carnosine which is found mainly in meat, not only inhibits the formation of AGEs, it can also protect normal proteins from the toxic effects of AGEs that have already formed. Carnosine is claimed to be the safest and most effective natural anti-glycating agent. Studies have shown that carnosine can stop protein damage from spreading to healthy proteins. It also found evidence that carnosine reacts with and removes the carbonyl groups in glycated proteins.
George Elder, Author, "Take Back Your Health", Amazon $3.99.