Usually vitamin B is taken after meals, because vitamin B usually refers to vitamin B1, vitamin B2, vitamin B4, vitamin B6, vitamin B12 and other complex multivitamins, such vitamins are water-soluble vitamins, usually taken after meals will have relatively small effect on the mucosa of the gastrointestinal tract, reducing the stimulation of the gastrointestinal tract. These vitamins are basically acidic vitamins, acidic vitamins if eaten on an empty stomach will stimulate the gastrointestinal tract to release excessive gastric acid, gastric acid will play a certain comprehensive effect on the B vitamins, which will make the B vitamins secondary to failure, and also stimulate acid reflux. Long-term use of vitamin B on an empty stomach can cause dysfunction of the gastrointestinal tract, and also cause bile reflux gastritis, erosive and atrophic gastritis, and long-term use of gastric and duodenal ulcers, causing certain adverse consequences and adverse effects. Especially if you have previous gastric disease and gastric ulcer, you should eat within 30 minutes after meals to achieve the best absorption of B vitamins and not to produce side effects and stimulation of the gastrointestinal tract.