Today CNN and some other sources around the web shared a story about too much junk food causing a teenager to go blind. The study was published in the Annals of Internal Medicine Letters (abstract here). A 17-year-old was diagnosed with nutritional optic neuropathy (blindness from permanent damage to the optic nerve) after years of eating almost exclusively potato chips, french fries, and white bread.
The teenager first visited the doctor at age 14 with a complaint of tiredness. His height and BMI (body mass index, a measure of body fat based on height and weight) were normal, he had no known health problems and wasn’t taking any meds. The doctors treated him with B12 injections and counseled him on nutrition based on a diagnosis of anemia.
A year later he returned with early vision and hearing loss, and by age 17 he was blind with deficient B12, D, copper, and selenium. His zinc levels were high (possibly contributing to the copper deficiency) and his bone density was low. (B12 works in the nervous system and is important in cellular DNA synthesis. Vitamin D builds the skeletal system. Copper and selenium are trace elements used in metabolism.)
The patient lives in the UK and his condition is rare in developed countries due to availability of a range of healthy foods. It’s usually seen only in people with decreased nutrient absorption from intestinal disease or some meds. In this case the blindness was potentially reversible if the dietary issues had been corrected earlier.
Nutritional optic neuropathy is also mentioned in a PubMed citation for a Polish optical journal: this case involved a young woman frequently following a water-only diet.
Low B12 is also a problem for some strict vegans. Study co-author Denize Atan, an ophthalmologist at Bristol Medical School and Bristol Eye Hospital, noted that today’s study suggests the incompleteness of BMI and caloric intake as indicators of health.
One criticism of today’s article is offered by Tom Sanders, a professor of nutrition and dietetics at King’s College London, who notes that the case relies on the patient’s own recall and reporting of his diet, and the teenager says he also occasionally ate small amounts of processed ham and sausage. We’ll update if further information becomes available.