Pavy suggests that vegetables cause flatulence in 1869.
January 1, 1869
A treatise on the function of digestion; its disorders, and their treatment
The object to be attained in the treatment of flatulence is the improvement of the digestive energy and the muscular tone of the stomach. Digestive solution without spontaneous decomposition is what is wanted, and the muscular power should be such as to be capable of expelling by eructation whatever gas may chance to be produced, instead of allowing it to accumulate. The food should be easy of digestion, and taken at regular intervals. Vegetable articles, from their difficulty of digestion, are not unlikely to occasion flatulence with a weakened stomach.