Right now, there’s about a cup of orange juice in my gut, sloshing around and mingling with my stomach acid as it delivers all the vitamin C that I require for the day. I’ve got some major bruises on my knees, and so once the essential nutrient hits my body’s internal transport system, the orange juice that I just drank will play an important role in wound healing, preventing future capillaries from bleeding too easily, and with any luck helping me perform enough sweet, sweet collagen synthesis to make it look like I sleep regularly. Vitamin C may be the most important water-soluble antioxidant in human plasma, and is required for all plants and animals. But while most other animals can synthesize their own supply, humans — along with other primates, guinea pigs, capybaras, some fish, and some bats — have to get theirs elsewhere. Hence the orange juice.

The problem is that not everyone gets enough. And when vitamin C goes missing from a diet for long enough, the results can be explicitly unpleasant: scurvy.

We act like scurvy is long left behind, a throwback disease, forgotten and dust-covered and banished to antiquity. But this scourge of sailors is, in fact, not something that humanity has outgrown. It still happens, and probably more than you realize.

Scurvy, the most extreme result of prolonged lack of vitamin C, is, in a word, unpleasant. In three, it’s “fatal if untreated.” The disease kicks off with the universal symptoms of “ugh”: low-grade inflammation, fatigue, bleeding gums, and swollen joints. Vitamin C is absolutely necessary for healthy collagen, which matters greatly because it makes up one fourth to one third of all of the protein that makes up you. It’s in your skin, your tendons, your bones, your gut, and your blood vessels, just to name a few. Your body is forever making more of it, knitting yourself together with a kind of sticky meat yarn. Without enough vitamin C, the collagen is made poorly and is therefore unstable: capillaries burst, wounds remain open, and, since your body is constantly replacing the collagen in scar tissue, old scars can reopen. As the owner of a C-section scar, I find this possibility very distressing.

If you think of your body like a car or a building, collagen is doing a hell of a lot of the upkeep. But no vitamin C means no collagen, means no upkeep, means open, suppurating sores that will never heal, means the kind of sores that do not smell okay. Scurvy can also loosen the teeth, which is a literal nightmare I have at least twice a year.

A diet devoid of vitamin C is always fatal, if left untreated; without it, you basically just fall apart because your body can’t make the collagen that keeps you glued together.

The exact details of scurvy eluded explorers for centuries. It was hard to keep a boat full of sailors alive at sea by feeding them stale carbs, salted meat, and booze, but then again, it was pretty hard to keep a boat full of sailors alive in general. Of course, just because humans didn’t always fully understand the disease doesn’t mean they weren’t on the case. People had their suspicions regarding the correlation between the lack of fresh foods and withering sailors for centuries. By the late 1400s, the healing powers of citrus were known, but it wouldn’t be until the mid-18th century that medicine gave us definitive answers. In what is famously known as the first clinical trial ever (owing to his use of control groups), ship surgeon James Lind formally concluded that scurvy could be cured by citrus fruits, debunking the popular theory that it was caused by a lack of acids. Lind, however, waited to inform the British Navy about his findings because of citrus’s high price; it would be nearly 50 years before lemon juice would become a required ration in the Navy.

Yes, yes, but what does this have to do with me?

It’s true: Scurvy is not something that you will readily encounter in mainstream American life, since death from lack of vitamin C requires poor medical care and consistent and prolonged lack of access to fresh or fortified foods. It also often involves a cofactor such as alcoholism, being an elderly shut-in, or inadequate infant nutrition. But that doesn’t mean you’re off the hook: Like so many diseases with social roots, scurvy doesn’t come on like flipping a switch; it’s not as if one day you’re fine, and the next all your old scars are opening up and your tongue is covered in sores. This kind of malnutritive illness exists on a sliding scale of grays. Vitamin C deficiency is no joke, and acting like we don’t have to worry about historical diseases is arrogant and stupid. Here’s why.