Sailors got scurvy because their diet at sea contained virtually no vitamin C, and the human body can’t make or store it for long. After just one to three months without fresh fruits or vegetables, sailors’ bodies began breaking down at the cellular level. Between the time of Columbus and the rise of steam-powered ships in the mid-1800s, scurvy killed more than two million sailors, making it the single deadliest hazard of life at sea, responsible for more deaths than storms, shipwrecks, combat, and all other diseases combined.
What Sailors Actually Ate
A sailor’s daily ration was built entirely around foods that wouldn’t rot: about a pound of hardtack (a dry, dense biscuit), a pound of salt pork or salt beef, half a pound of hard cheese, and half a pound of dried peas or beans. On meatless days, they ate duff, a simple boiled flour pudding. The whole diet was designed for durability, not nutrition. Salt-curing, drying, and pickling kept food edible for months, but these preservation methods destroyed whatever vitamin C the ingredients originally contained.
Early in a voyage, ships sometimes carried live chickens or goats on deck, and a few vessels even maintained a small onboard greenhouse for growing greens. But these were stopgap measures. Once the fresh provisions ran out, typically within the first few weeks, sailors were left with nothing but preserved rations for the remainder of a journey that could last months or even years. Captains understood that “greenstuff” helped their crews stay healthy and tried to resupply with fresh food at port whenever possible, but on long crossings of the Pacific or South Atlantic, there was simply nowhere to stop.
What Vitamin C Does in the Body
Vitamin C is essential for building collagen, the protein that holds your connective tissues together. It works at a molecular level: your cells need vitamin C to properly assemble collagen fibers into their characteristic triple-helix structure. Without it, the collagen your body produces is unstable and weak. Your body also slows collagen production dramatically during deficiency, compounding the problem.
Collagen isn’t just skin deep. It’s the structural scaffold of blood vessels, gums, bones, tendons, and scar tissue. When collagen production fails, all of these systems start to deteriorate. Blood vessels become fragile and leak. Gums swell and bleed. Old wounds reopen. Bones ache. This is scurvy: not an infection or a poison, but your body literally falling apart because it can no longer maintain its own structure.
How Scurvy Progressed at Sea
The first symptoms appeared after 4 to 12 weeks without vitamin C. Sailors would feel an overwhelming fatigue and lose their appetite. These early signs were easy to dismiss as the ordinary misery of shipboard life. But within weeks, the disease became unmistakable. Gums swelled and bled, sometimes so badly that teeth loosened and fell out. Skin bruised at the slightest touch. Old scars from healed injuries broke open. Joints ached constantly.
In advanced stages, scurvy turned lethal. Internal hemorrhaging could occur anywhere in the body, including behind the eyes. Sailors became too weak to climb rigging or even stand. The disease moved through crews with devastating speed on long voyages. When British Admiral George Anson circumnavigated the globe in the 1740s, he lost nearly three-quarters of his roughly 2,000 men, most of them to scurvy. Shipowners and governments of the era routinely planned for a 50% death rate from scurvy on any major voyage.
Why No One Could Figure It Out
For centuries, doctors had no framework for understanding that a missing nutrient could cause disease. The dominant medical theories blamed scurvy on “humoral imbalance” or putrefaction of the blood, which led to treatments that were useless or actively harmful: bloodletting, purgatives, barley malt, and alcohol. One Dutch physician even proposed that scurvy was divine punishment for sin. As the Scottish naval surgeon James Lind wrote in 1753, the medical knowledge of his era was buried under “a veil of unmeaning, unintelligible jargon.”
The concept that food could contain invisible substances necessary for survival simply didn’t exist yet. Vitamins wouldn’t be identified until the early 20th century. So even when people noticed that fresh food seemed to help, they couldn’t explain why, and their observations competed with dozens of other theories that sounded equally plausible at the time.
Lind’s Experiment and the Long Delay
In 1747, James Lind conducted what is now considered one of the first controlled clinical trials in medical history. He selected twelve sailors with scurvy, matched them as closely as possible in severity, housed them in the same quarters, and fed them the same basic diet. Then he split them into six pairs, each receiving a different daily supplement: cider, dilute sulfuric acid, vinegar, seawater, two oranges and a lemon, or a paste of garlic, mustard seed, and dried radish root.
The results were dramatic. After just six days, one of the two sailors eating citrus fruit was well enough to return to duty. The other was recovering faster than anyone else in the trial. No other treatment showed meaningful improvement. The citrus supply ran out after six days, cutting the experiment short, but the evidence was clear.
What happened next is one of the great frustrations of medical history. Despite Lind’s findings, the British Admiralty did not officially mandate lemon juice for all naval voyages until 1795, nearly half a century later. The reasons for this delay are debated, but Lind himself never forcefully advocated for citrus to the Admiralty. It took Sir Gilbert Blane, who served as commissioner for sick and wounded sailors from 1795 to 1802, to push the reform through. Once the Navy began issuing lemon juice, scurvy rates plummeted almost immediately.
How Little Vitamin C It Takes
The cruel irony of scurvy is how little vitamin C is needed to prevent it. A landmark study found that as little as 10 milligrams per day can ward off visible signs of the disease. That’s the amount in a single tablespoon of fresh lemon juice, or a small bite of a bell pepper. A more recent analysis of the same study data suggests that about 95 to 100 milligrams daily is needed for full health, but the threshold to simply avoid scurvy is remarkably low.
This is why scurvy disappeared so quickly once navies adopted even modest dietary changes. Sauerkraut, which stores well for months on ships, contains enough vitamin C to keep crews healthy. The same goes for small amounts of citrus juice preserved in the daily rum ration, which became standard practice in the British Navy. Sailors didn’t need a dramatic dietary overhaul. They just needed one small source of a nutrient their preserved rations completely lacked.