Some causes of smelly stomach gas include foods that generate gas, ulcerative colitis, and lactose intolerance, according to Healthline and WebMD. Foods that commonly create smelly stomach gas include beans, cabbage, onions, cauliflower, broccoli, high-fructose corn syrup products and dairy products, notes WebMD.
People generally have different food triggers when it comes to smelly stomach gas and WebMD recommends that patients keep a food journal to help identify food triggers. To help combat gas in general, patients can also stop eating gum and chew more slowly as swallowing lots of air can lead to additional gas. Drinking fizzy drinks and smoking cigarettes can also contribute to gas and avoiding these triggers can keep gas under control, according to WebMD.