New evidence reveals that many eye conditions of older age may be caused by a highly processed
For eight years, Chung-Jung Chiu, a scientist at Tufts University, has been quietly working away on a theory that could change everything we think about ageing and eye health.
Chiu's explosive research reveals that diminishing eyesight has little to do with age and a great deal to do with what you put in your mouth. The amount of quick-sugar foods you eat isn't just bad for your waistline; it could also be contributing to losing your sight.
The flip side of that risk is prevention: just a few changes in your lifestyle, such as simply eating a low glycaemic diet and getting regular exercise, could stave off most of the eye problems, long supposed to be a normal part of the ageing process, that eventually rob millions of good vision in their later years.
One of the medical myths we live with is the notion that eye disease arises as an inevitable consequence of growing older-as inevitable in the over-50s as the sprouting of grey hairs.
A measure of how much this is ingrained in our thinking is the terminology used by conventional medicine, which applies adjectives like 'age-related' and 'senile' to macular degeneration (AMD) and cataracts, respectively, and considers diabetic retinopathy a virtually inevitable complication of diabetes.
At the moment, medicine can only offer surgery to replace lenses in cataract sufferers, and it continues to explore alternatives for AMD and diabetic retinopathy-everything from retinal cell transplants, laser surgery and new drugs to computer chips in the eye to boost vision.
But the orthodox view is not keeping up with nutritional research, which firmly places the cause of all three conditions at the foot of the processed-food industry. Chiu, the lead scientist at the Jean Mayer United States Department of Agriculture (USDA) Human Nutrition Research Center on Aging at Tufts University in Boston, Massachusetts, has been involved in numerous studies, including most recently the Nutrition and Vision Project, a subsidiary study of the long-term, ongoing, Nurses' Health Study. While studying patients who eventually developed cataracts, diabetic retinopathy or AMD, he found that all three had a single thing in common: a diet high in processed sugar.
In one of his earliest studies, Chiu recruited some 400 nurses in the Boston area, aged between 53 and 73, whose diets had been tracked by the Nurses' Study over 14 years. He and his colleagues then assessed the eyes of their participants for cortical opacity, using the Lens Opacity Classification System III (LOCS III). The researchers discovered that those with the highest intakes of carbs (more than 200 g/day) were two and a half times more likely to develop opacities than those eating the least carbs.
In this instance, the quality of carbs was immaterial; it was the amount of carbs eaten (and so a smaller amount of other macro nutrients, like protein and fats) that was the major determinant of early lens cortical opacities.1
Chiu's findings were bolstered by an Australian study, where researchers examined in depth the dietary habits of some 1,000 Australian patients aged 49 or older with no history of cataracts after five and 10 years. The participants then had their eyes photographed and assessed according to a well-accepted standard for assessing cataract development.
An amazing connection emerged. After controlling for such factors as diabetes and age, every significant increase in the glycaemic index (GI), or sugar contents of the food consumed, predicted the incidence of cataracts. Those with the highest GI and poorest-quality carb diets had a 77 per cent greater risk of developing cataracts than those who ate low GI foods.2
While hyperglycaemia, or having high levels of sugar in the blood, has always been considered a risk factor, few scientists had made the connection between a diet high in processed carbs and cataracts. With their study, the Australian researchers had shown that the quality of the carbs we eat plays a part. Previously, an earlier Harvard School of Public Health study had come to a similar conclusion: even in non-diabetics, "cataract may be mediated at least in part by glucose intolerance and insulin resistance".3
It's well known that diabetics and those consuming high GI diets are more prone to developing cataracts because high blood sugar levels lead to glycation-the binding of sugars to proteins in the eye lens, so modifying their structure-causing the lens to become cloudy and vision to blur. Proteins in the eye lens are particularly susceptible to this kind of damage.4 But even in people without diabetes, elevated blood sugar can cause oxidative stress and glycation throughout the body. In fact, one study found that people older than 49 with a fasting glucose level above 108 mg/dL (6 mmol/L; within the range of prediabetes) had a 79 per cent greater risk of developing cataracts over the next decade compared with those with glucose levels below 106 mg/dL (5.9 mmol/L).5 And for every 18 mg/dL (1 mmol/L) increase, the risk of developing cataracts increased by up to 25 per cent.
Chiu and his colleagues went on to do a similar study with women at risk of developing AMD, pulling from the same pool of Nurses' Study volunteers, this time some 500 women of the same age without a history of eye disease, and assessed their likelihood of developing AMD. Again, the researchers compared the results with the dietary information collected for over a decade in the Nurses' Health Study, and again a connection was made with high-sugar foods. Those whose diets were highest on the GI-a system that ranks carbs according to how quickly they are digested and so how rapid a rise in blood sugar levels in the body-were nearly three times more likely to have abnormalities in the macular pigment of the eye, an early indicator of macular degeneration.6
When Chiu and his colleagues rolled out their research, recruiting more than 4,000 participants-this time both men and women-to take part in their Age-Related Eye Disease Study (AREDS), they discovered a 49 per cent increase in the risk of advanced AMD in those with a GI higher than average.7
Other studies show that those in the highest fifth of dietary GI have a higher risk of progressing to advanced AMD. In fact, the authors of the AREDS calculate that one-fifth of all AMD cases could be eliminated if people consumed a low-GI diet; even small shifts in controlling the consumption of processed carbs would eliminate some 100,000 cases of AMD in five years.7
Chiu's work has been corroborated by the Blue Mountains Eye Study of more than 3,600 participants, which showed that those with a dietary GI in the highest fourth were at an increased risk for early AMD, while those consuming the largest amounts of cereal fibre and grains had a reduced risk of the eye abnormalities heralding early onset of AMD.8 The evidence was clear that it was not total carb intake, but only high-GI foods converting to sugar easily that increased the risk.
Other research reveals that following a low-GI diet and getting your blood sugar under control can significantly lower the risk of developing diabetic retinopathy. In one study of 1,441 people with type 1 (insulin-dependent) diabetes, those who kept their blood sugar well under control reduced their risk of developing retinopathy by 76 per cent over the six and a half years they were followed. And those who already had a mild form of the condition at the beginning of the study were able to reduce its progression by 54 per cent, just by keeping their blood sugar under control.9
All these studies suggest that these three conditions have one common risk factor: a highly processed diet that persistently causes hyperglycaemia, or high blood sugar. Now Chiu and his colleagues believe they know the reason for the connection. The eye has a highly active metabolism determined not only by glucose, but also oxygen. In Chiu's theory, when you eat too much sugar, it leads to the expression of genes relating to hypoxia (too-low oxygen levels) and ends up bombarding the eye with too much sugar while depriving the eye of necessary oxygen.10
Besides high-glycaemic foods, links have also been made between eye disease and the amount and type of fats you consume. Researchers from the Harvard School of Public Health found that AMD patients consuming high levels of vegetable fats nearly quadrupled their risk of disease progression, while high intakes of processed foods laden with any type of processed fats (animal, saturated, monounsaturated and polyunsaturated fats) doubled the risk of its progression. This suggests that too-high levels of omega-6 fatty acids, found abundantly in most processed foods, can contribute to the oxidative damage seen with age-related eye disease.11
More recent studies show that other kinds of fats, such as fish and nuts, both rich in omega-3 fatty acids, can protect against these eye conditions so long as your intake of the usual omega-6 fatty acids is low.
In one study, eating fish at least once a week reduced the risk of early macular degeneration by 40 per cent in those over age 49, while those who ate fish three or more times a week lowered their risk of late AMD by a whopping 75 per cent.12
In fact, most studies have shown that the most protective effects of omega-3s are those found in fish , which have abundant concentrations of DHA and EPA; plant-based omega-3s, on the other hand, are rich only in alpha-linolenic acid.13
Besides fish, a diet rich in fruits and vegetables can guard against all three conditions. Various studies have shown that high intakes of fruit (at least three portions a day) can reduce the risk of AMD and cataracts by about a third, and lower risk of diabetic retinopathy by more than half in type 2 diabetics.14 One of the most powerful dietary regimens of all is a Mediterranean diet rich in fruits, vegetables, whole grains, fish, beans and olive oil.
Another often overlooked risk factor of late-stage eye disease is a sedentary lifestyle. People who exercise for just seven hours a week lower their risk of AMD by two-thirds, while running and even moderate walking can cut the risk of cataracts significantly.15 And studies of those with diabetic retinopathy show they are more likely to be couch potatoes who are far less likely to meet the very minimum recommendation of 2.5 hours of moderate exercise per week plus resistance training, as suggested by the NHS in the UK, the US Department of Health & Human Services, and the Diabetes Supplement to the US Health and Retirement Study.16
The evidence unearthed by Chiu and his colleagues shows that cataracts, AMD and diabetic retinopathy are not diseases of old age so much as diseases of our modern industrialized age. All three diseases are close cousins of other degenerative diseases like hypertension, vascular diseases, Alzheimer's and diabetes, and each of these conditions shows evidence of raised homocysteine, an amino acid derived from the normal breakdown of proteins.17
High levels of homocysteine are caused by inadequate levels of B vitamins and chromium.18 Although natural sugars and grains contain enough chromium to support the metabolism of high-carbohydrate foods, most, if not all, B vitamins and chromium are removed during the refining process of the sugars and processed foods that now make up our typical Western diet.
Cataracts, AMD and even diabetic retinopathy are not inevitable features of growing old, but yet another symptom of modern Western malnutrition. They can be prevented, halted -or even reversed-by adopting a Mediterranean diet rich in fruits, vegetables, whole grains and fish, while limiting sugar, adding regular exercise to your daily life and taking a variety of supplements.
All of this evidence suggests that the eyes are not simply a window into your soul, but a window into your lifestyle. The most powerful prescription a doctor might write these days to prevent all the eye issues of older age consists of three simple words: Cook from scratch.
Spot the difference
As we age, we're more prone to suffer a number of eye problems that potentially cause blindness. These include:
Cataracts: cloudiness that develops in the crystalline lens of the eye or lens capsule. Varying in degree from slight to complete opacity obstructing the passage of light, cataracts are the leading cause of blindness in the underdeveloped countries. At this time, some 11 million Americans have cataracts, as do one in three Britons.
Age-related Macular Degeneration: gradual destruction of the macula (the central pigmented area of the eye retina) leading to loss of the fine-detail, 'straight-ahead' and colour vision needed for activities like reading and driving. Official diagnoses of the condition, which afflicts actress Judi Dench, have increased by 30-40 per cent over the last few decades; some 500,000 people have AMD in the UK, 11 million in the US, and three-quarters of all people in industrialized countries over age 75. AMD is the leading cause of sight loss in people aged over 60.
Diabetic retinopathy: damage to the tiny blood vessels of the retina brought on by diabetes. Currently, according to diabetes associations, nearly all patients with type 1 diabetes will develop some form of this after 20 years, and more than a fifth of those with type 2 diabetes already have it when diagnosed or will go on to develop it.
A diet for sore eyes
The following diet and supplement plan has been shown to slow or prevent the formation of cataracts, AMD and diabetic retinopathy.
Eat a Mediterranean diet rich in fresh, organic fruits and vegetables, olive oil, legumes and fish. Whenever possible, cook fresh food from scratch.
Consume enough protein. British ophthalmologist Dr Stanley Evans spent 40 years studying cataracts and other eye disease in Africans. In many cases, the patients were highly deficient in protein. Evans routinely advocated a minimum intake of 70-80 g/day.
Stop smoking. It's not only bad for every other part of you, but it's especially bad for the eyes.1 The cadmium in cigarettes, which settles in the lens, is probably the most responsible.
Eat spinach, kale, cooked collards and cabbage, which are all rich in lutein, the most effective carotenoid antioxidant for the eye.2 Other important lutein-rich foods include kiwi fruit, grapes, corn and egg yolk.
Think pink with seafood. Crab, lobster, shrimp, salmon and other red-coloured seafood are rich in astaxanthin, another potent antioxidant. Just 6 mg/day can improve visual acuity, say several Japanese studies.3
And think blue too. Blue and purple fruits and veg like blueberries, bilberries, red and purple grapes, and blackberries contain anthocyanins, shown to promote production of a particular retinal pigment crucial for seeing in waning light.4
Do indulge, but drink with moderation. In the Australian Blue Mountains Eye Study, those who had one or two drinks a day lowered their risk of developing cataracts by 50 per cent compared with those who had more than two drinks a day or abstained altogether.5
Avoid lead exposure, which has been linked to cataracts.6
Wear sunglasses. Studies in Japan and other countries conclude that exposing your eyes to high levels of sunlight (and ultraviolet radiation) result in the highest incidences of cataracts.7
Get moving. Exercise can lower the risk of all eye problems, even myopia. Get off your sofa and work it.
Steer clear of certain drugs. Statins, aspirin, steroids, sulpha-based drugs, antidepressants, anticoagulants, antihistamines and antacids all are known to cause eye problems. NSAIDs (non-steroidal anti-inflammatory drugs) can also increase the risk of cataracts by as much as 44 per cent, and antibiotics, phenothiazine antipsychotics, antidopaminergics (for motion sickness) and antihypertensives like beta-blockers have also been associated with AMD.8 Plus two-thirds of those taking Viagra have 'blue vision'-abnormal blue-tinged vision-for at least four hours after taking the drug.
The following supplements have been found to maintain eye health.
Carotenoid combos that include lutein, meso-zeaxanthin and zeaxanthin, all found in abundance in the eye, can help minimize oxidative damage
Vitamins A, C and E are all antioxidants proven to help eyes
Suggested daily dosage: 5000 IU vitamin A, 1-3 g vitamin C, 400 IU vitamin E
Fish oils Suggested daily dosage: at least 1,400 mg EPA and 1,000 mg DHA
A good vitamin B complex including B1, B2, B6 and B12
Suggested daily dosage: a B-100 complex
Folate (l-methylfolate, not folic acid-see page 21)
Suggested daily dosage: 1,000 mcg
Alpha-lipoic acid Suggested daily dosage: 150 mg
Chromium Suggested daily dosage: 200 mg
Magnesium Suggested daily dosage: 400 mg
Can eye disease be reversed?
Taking high dosages of certain supplements orally or as eye drops directly into the eye may be able to reverse the damage.
Zinc. AMD patients given supplements of 25 mg twice a day reported significantly improved vision.1
Eye drops containing N-acetylcarnosine (NAC). Carnosine is a potent antioxidant that helps stop glycation and improve vision in people with cataracts.2 One available brand with evidence of effectiveness is Can-C. After six months of twice-daily Can-C use, patients reported that 90 per cent of NAC-treated eyes improved in visual acuity and 89 per cent improved in glare sensitivity.
Combo vitamins. AMD patients given vitamins A, C and E, beta-carotene, zinc, taurine, EPA, DHA and copper, lutein and zeaxanthin showed significantly improved visual acuity compared with a placebo.3
Bilberry (European blueberry) extract. A 200-mg dose of Vaccinium myrtillus extract given alone or in combination with beta-carotene leads to significant improvements in night vision, quicker adaptation to the dark and more rapid restoration of sight after a bright light flash. As it inhibits angiogenesis, it's effective against retinal diseases involving abnormal blood vessel growth.4 It can also reduce permeability and haemorrhages in diabetic retinopathy.5
Suggested daily dosage: 180 mg twice daily, standardized to 25 per cent anthocyanosides6
Pycnogenol (PCG). Comprising the bark of French maritime pine tree and grape seed extract (GSE) from Vitis vinifera grapes, PCG contains vitamin-C-like flavonoid nutrients shown to improve night vision and after glare.7
Suggested daily dosage: 150-300 mg
Ginkgo biloba.This herb can increase the blood supply to the eyes in elderly patients, and bring about significant long-term improvements in patients with senile macular degeneration.8
Suggested daily dosage: 120 mg
Curcumin. Patients with diabetic retinopathy given a patented form of curcumin showed significantly less swelling (oedema) and improved blood flow in the retina as well as better vision.9
Suggested daily dosage: 200 mg twice a day
The success stories
British ophthalmologist Stanley Evans developed his nutritional approach to treating vision problems over 50 years, 17 of them spent in Africa on an extended research programme into the causes and prevention of blindness.
Here are a few cases of the hundreds of cataract patients in Britain and Africa successfully treated by Dr Evans with nutritional therapy.
Cataracts had begun to develop in a 32-year-old manthree weeks before his first consultation with Evans. His vision in his right eye had fallen to 20 per cent of normal, while the vision in the left eye was 200 per cent of normal.
The opacity in the right eye was "milky" as is so often the case with rapid developing cataract. After four weeks of nutritional therapy, the vision in the left eye had improved to 100 per cent of normal. The ophthalmoscope revealed that the media in the right eye was clear.
An 80-year-old man had a full aperture cataractin each eye, resulting in a vision in each eye of 10 per cent normal. Two weeks of nutritional therapy raised the vision in each eye to 50 per cent of normal.
A 60-year-old man could only count fingerswith his right eye, while his left eye had 10 per cent of normal vision. A full aperture cataract covered each eye. Two weeks of nutritional therapy raised the visual acuity in the right eye to 20 per cent of normal and 30 per cent of normal in the left eye.
A 55-year-old woman had vision in the right eye that was 60 per cent of normal,and was only able to count fingers with the left eye. An ophthalmoscope revealed a central opacity in the right eye, while the left eye was totally clouded.
After one month of nutritional therapy, the vision in the right eye had improved to 150 per cent of normal (still abnormal but much improved) with the media completely clear. Vision in the left eye had improved to 15 per cent of normal.
The GI list
The glycaemic index (GI) is useful tool for weight loss or maintenance. You're allowed carbs, but only in their natural, unrefined state.
Researchers at Oxford University developed the scores listed here by measuring blood sugar levels two hours after consuming specific foods. Glucose was allocated the number 100. All other foods (besides beer) absorb more slowly; the slower the response, the lower the number. Generally speaking, the foods with a glycaemic index under 50 are the best to choose. The way that you prepare foods greatly influences how fast its carbs enters your bloodstream, since heat and processing raises a food's GI. Raw carrots have a GI of 30; boiled carrots, a GI of 85.