We’ve all heard the saying, “An apple a day keeps the doctor away.” But maybe, in this patient’s case, an apple a day could’ve kept blindness away.

Earlier this week, the story of a 17-year-old boy who went blind after religiously adhering to a diet of French fries, Pringles, white bread and processed ham and sausage since elementary school dominated news headlines. Although rare, blindness is just one of many consequences of a poor diet.

The patient first visited a doctor when he was 14 years old, complaining of tiredness. He wasn’t taking any medications, had a normal BMI and height and showed no visible signs of malnutrition. After discovering low vitamin B12 levels and anemia, his doctor treated him with vitamin B12 injections and offered dietary advice. One year later, he showed signs and symptoms of hearing and vision loss with no identified cause.¹

By the time the patient turned 17, researchers from the University of Bristol found that his vision had worsened to the point of blindness due to nutritional optic neuropathy, a dysfunction of the optic nerve only rarely caused entirely by a poor diet in developed countries. He had vitamin B12 deficiency, low copper and selenium levels, a high zinc level and reduced vitamin D and bone density levels.²

While the researchers currently suspect the teen’s permanent vision damage was solely linked to a poor diet and lack of nutrient intake, it could’ve also been due to genetic defects or environmental exposures, according to a professor of nutrition and dietetics at King’s College London.³

The researchers recommend doctors encourage patients to follow a more balanced diet and ask them about their dietary history as part of routine clinical examinations to catch nutritional optic neuropathy early, as it is reversible if detected right away.²