Its not the alchahol that wards off scurvy its vitiman C rich fruits and veggies.
Scurvy can be prevented by a diet that includes certain citrus fruits such as oranges or lemons. Other sources rich in vitamin C are fruits such as blackcurrants, guava, kiwifruit, papaya, tomatoes, bell peppers, and strawberries. It can also be found in some vegetables, such as carrots, broccoli, potatoes, cabbage, spinach and paprika. Some fruits and vegetables not high in vitamin C may be pickled in lemon juice, which is high in vitamin C. Many animal products, including liver and oysters, contain vitamin C. Though redundant in the presence of a balanced diet, various nutritional supplements are available that provide ascorbic acid well in excess of that required to prevent scurvy, and even some candies and most soft drinks contain vitamin C as a preservative.
So make sure you have a lime in your gin n' tonic