Pretty much what the title says. The research paper was on nutritional deficiencies in early modern China, and it made the comment in the section about scurvy in China. No sources were provided, and the author made the comment quickly and then went straight back to talking about China, so no other info was provided.
It was a scholarly paper though, so I’m assuming the author is correct and knew what they were talking about.
This is an interesting question, because it concerns some mysteries!
In January 1498, anchored off Mozambique, Vasco de Gama recorded that his sailors were beginning to show signs of scurvy after 5 weeks at sea.
Several weeks later, if I am looking at the entries correctly, de Gama and his crew arrived at Mombasa, and their condition had deteriorated markedly. Upon greeting the sailors, the King - or a member of his court - ordered that the crew should be fed with lemons and oranges, and their condition rapidly improved.
Almost a year later, de Gama arrived in Kenya again, at Malindi and the crew were in a bad way. They had sailed from India nearly 3 months earlier, and their journey had been a series of terrible ordeals. Men were dying of scurvy at this point. Several dozen died, in fact. Upon making landfall, the sailors, remembering their experiences in Mombasa the previous January, requested oranges and lemons. Some crew were too far gone, but the remainder recovered again.
As far as I am aware, that is the extent of our direct knowledge, which obviously raises an interesting question.
Did the Kenyans recognize scurvy and have cultural knowledge of it being tied to citrus fruits, or was it serendipity that they fed the men the cure to their disease?
To my knowledge, we don't have any direct attestations pertaining to the treatment of scurvy in East Africa, kn that era. It was also not uncommon for such fruits to be served to distinguished visitors.
But, obviously, it would be a pretty major coincidence for the King to order specifically that oranges and lemons be provided to the crew.
And that leads us to a related mystery: A year and a half earlier in July 1497, when de Gama sailed from Portugal, there is no record of their having carried citrus fruits or other vitamin C-rich foodstuffs. They struck out into the Atlantic before approaching the Cape, and made landfall in November, after 4 months at sea. Yet there are no reports of scurvy, which is not possible after 16 weeks of vitamin deficiency.
Eric Martini wrote an article published in the Lancet nearly 20 years ago in which he speculates that de Gama was lying about the length of his voyage, which has developed into the most viable explanation
As always, sources are available upon request.