You really should eat your carrots. And kale. The parents of an 11-year-old boy in Canada learned that the hard way after doctors solved the mystery behind their son's serious vision loss. Toronto doctors who examined the boy spotted a buildup of Bitot's spots on his corneas, Live Science reports. The foamy patches, caused by severe dryness, were a tip-off that malnutrition may be the cause. One point was crystal clear: eight months after symptoms began, the boy could only see hand motions 12 inches from his face. Writing in JAMA, the doctors say blood tests found the boy to be severely deficient in vitamin A, with 14.33 micrograms per deciliter, well below the normal range of around 26 to 49 micrograms. With multiple food allergies and eczema, the boy was on a restrictive diet to prevent outbreaks.
It turns out that pork, lamb, apples, and Cheerios are not the stuff of a balanced meal, even if you add potatoes and cucumbers. None of those foods—all the boy ate—were a good source of vitamin A, which keeps the corneas moist and feeds photoreceptor cells that detect light, per Science Alert. Without these foods on his dinner plate, the boy was slowly going blind. Rare in developed countries, "vitamin A deficiency is very common in poorer parts of the world, where it is a leading cause of blindness," the boy's doctor, Eyal Cohen, tells Live Science. After six weeks of megadoses of vitamin A, the boy's sight was vastly improved, but doctors say he may never fully recover. (Italy considered jailing parents of vegan kids.)