"That is what happened to us, on the expedition," he says. "We had tinned food, but much of it was spoilt or tainted, and the preserved lemon juice loses efficacy over time. And so the men succumbed to scurvy—to say nothing of being poisoned by the lead from the tins. And—" an idea occurs to him, "perhaps there were other deficiencies of these—these nutrients as well. Good God."