Gilbert Blane and Thomas Beddoes, highly esteemed authorities on scurvy in the 18th century, rightly doubted that there was any antiscorbutic virtue in malt. Thomas Trotter, another expert, thought sauerkraut and portable soup were 'mere placebo'. They stated what Lind had already experimentally deduced - that fresh vegetables and citrus juice are the only substantial sources of vitamin C. https://www.bbc.co.uk/history/british/empire_seapower/captaincook_scurvy_01.shtml

Treatment for scurvy had been demonstrated by James Lind in his Treatise of 1754.

Thomas Trotter (1760 – 1832) was a Scottish naval physician and author who was a leading medical reformer in the Royal Navy and an ardent critic of the slave trade. In England, while in private medical practice at Wooler in Northumberland, he wrote up his notes on scurvy to order, and published them as Observations on the Scurvy (1786; 2nd edit., much enlarged, 1792). Trotter corroborated Lind's thesis by extensive observations. Wikipedia

In 1795, through Sir Gilbert Blane, the Admiralty endorsed the general use of lemon juice.

An Act to amend the Merchant Shipping Act, 1854. [20th August 1867.] Lime or Lemon Juice and other Anti-scorbutics to be provided and kept on board certain Ships.

Merchant Shipping Act 1894 UK Public General Acts 1894 c. 60 FIFTH SCHEDULE The anti-scorbutics shall be served out to the crew so soon as they have been at sea for ten days; and during the remainder of the voyage, except during such time as they are in harbour and are there supplied with fresh provisions. The lime or lemon juice and sugar shall be served out daily at the rate of an ounce each per day to each member of the crew, and shall be mixed with a due proportion of water before being served out.

Vitamin C was discovered in 1912, isolated in 1928, and in 1933, was the first vitamin to be chemically produced. Partly for its discovery, Albert Szent-Györgyi was awarded the 1937 Nobel Prize in Physiology or Medicine.

Anson circumnavigation 1741; While the crew, weakened by typhus and dysentery, fought gale-force winds and huge seas, scurvy broke out. What little useful information available on its prevention was ignored and it is unlikely that the navy could have procured sufficient vitamin C for 1,000 men even if it had recognized the need. Hundreds of men died of disease in the weeks during and immediately after battling around the Horn. (Wikipedia)

Franklin expedition 1845; Russell Taichman, the Major Ash Collegiate Professor of Periodontics and Oral Medicine, said that historians and researchers for decades have speculated on several generally accepted causes of death: exposure, scurvy, lead poisoning, botulism, tuberculosis and starvation. But Taichman and colleagues now believe that tuberculosis resulting in adrenal insufficiency, or Addison’s disease, also contributed to the demise of the crew. Their findings were published in the journal Arctic earlier this year. (University of Michigan 2017)