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when bad nutrition makes you blind

A junk food diet high in saturated fat and sugar causes severe damage to the retina.

A clinical case recently published in the Journal of the American College of Physicians reports an unusually early loss of vision in a 17-year-old Briton. Examination by an ophthalmologist revealed optic neuropathy (damage to the optic nerve) correlated with severe deficiencies of several nutrients, including vitamin B12, copper and selenium.

Investigations revealed that the teenager had been a “picky eater” for several years, consuming nothing but french fries, chips, white bread, sliced ​​ham and sausages. It is highly likely that the severe deficiencies in several nutrients caused by this type of exclusive intake in industrial foods, in particular the lack of vitamin B12, which is essential for the integrity of the nervous system, are responsible for this visual impairment.

In addition, taking dietary supplements to correct these deficiencies helped stabilize the young man’s residual vision. But without being able to reverse the damage done to the optic nerve.

First symptom: metabolic syndrome

Such a rapid and devastating effect of junk food is exceptionally rare. Nonetheless, it illustrates just how bad overeating ultra-processed processed foods can be for your health. It is well known that junk food plays an important role in the development of several serious metabolic disorders. Including obesity, insulin resistance, hypertension and dyslipidemia. A disorder of blood fat levels that accelerates atherosclerosis. Together, these abnormalities form what is known as the metabolic syndrome. A condition that greatly increases the risk of cardiovascular disease, type 2 diabetes and certain types of cancer.

AMD: Affects 35% of people over 75

It has also been reported that metabolic syndrome is associated with an increased risk of eye diseases. Including age-related macular degeneration (AMD). AMD is the leading cause of vision loss in developed countries. Up to 35% of people over the age of 75 are affected by this condition.
As the name suggests, AMD is a disease that affects the macula. It is a small structure (5mm in diameter) in the center of the retina. It is very rich in photoreceptors, the hyper-specialized cells that capture light. It therefore plays an essential role in the perception of details and colors.

During macular degeneration, these cells gradually stop working. There is then a gradual deterioration in vision. There are: difficulty reading or seeing at a distance, visual distortions (straight lines becoming curved), difficulty distinguishing colors, and finally the appearance of a dark spot in the visual center.

Junk Food: Damage to the retina that heralds AMD

To study how junk food and metabolic syndrome might accelerate this macular degeneration, Mayo Clinic researchers subjected two groups of animal models to a normal or junk-food-like diet (high in saturated fat, cholesterol, and fructose) that causes the onset caused by a Metabolic Syndrome.

After 9 months, the retinas were removed from the animals of both groups and examined by electron microscopy for AMD-typical changes. They observed variations in the thickness of Bruch’s membrane (structure located under the retina) and the number of cells present in the retinal pigment epithelium. They observed that animals fed excess fat and sugar developed metabolic syndrome. The retina showed thickening at several sites of Bruch’s membrane. As well as a conspicuous cell loss in the retinal epithelium.

Junk food related to AMD

These retinal changes are commonly seen during the development of AMD in humans. It therefore appears that the metabolic disorders associated with junk food contribute to the development of this disease.


Harrison R et al. Blindness from junk food diet. ann. Internal. Medical 2019; 171:859-861.
Bahadoran Z et al. Fast-food patterns and cardiometabolic disorders: a review of recent studies. health promotion. Outlook. 2015; 5:231-240.
Poh S et al. Metabolic syndrome and eye diseases. diabetes res. Clinical Prof. 2016:113:86-100.
Roddy GW et al. “Fast food” mimicking diets cause structural retinal changes relevant to age-related macular degeneration. act. eye res. 2020; 45:726-732.

* Presse Santé strives to convey health knowledge in a language accessible to all. In NO CASE can the information given replace the advice of a doctor.

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