Passing gas between 14 and 23 times a day is completely normal. If you’re noticing it more than that, or it’s become disruptive, the cause is almost always traceable to what you’re eating, how you’re eating, or how your gut bacteria are processing food. Rarely, it signals a digestive condition worth investigating.
Where Gas Actually Comes From
Your body produces intestinal gas through two main routes: swallowed air and bacterial fermentation. Every time you eat, drink, or swallow saliva, small amounts of air travel into your digestive tract. Most of it comes back up as a burp, but some moves further down.
The bigger source of flatulence is your colon. When you eat carbohydrates that your small intestine can’t fully absorb, they pass into the large intestine, where trillions of bacteria break them down for energy. This fermentation process produces hydrogen, carbon dioxide, and sometimes methane as byproducts. Those gases have to go somewhere, and the exit is exactly what you’d expect.
The smell is a separate issue. Most intestinal gas is actually odorless. The rotten-egg quality comes from hydrogen sulfide, a pungent gas produced when certain gut bacteria break down sulfur-containing amino acids from protein-rich foods. Bacteria in the gut can also generate hydrogen sulfide by processing sulfate, a compound found naturally in various foods and drinking water. So volume and smell have different causes, and you can have a lot of one without the other.
Foods That Cause the Most Gas
Some foods are notorious gas producers because they contain short-chain carbohydrates that the small intestine absorbs poorly. These fermentable sugars, sometimes grouped under the term FODMAPs, are the primary dietary culprits. The biggest offenders include:
- Beans and lentils: loaded with a type of fiber that humans lack the enzyme to break down on their own
- Dairy products: milk, yogurt, and ice cream, especially if you have any degree of lactose intolerance
- Wheat-based foods: bread, cereal, crackers, and pasta
- Certain vegetables: onions, garlic, asparagus, and artichokes
- Certain fruits: apples, pears, cherries, and peaches
These foods aren’t unhealthy. They’re actually good for your gut microbiome. But if your body ferments them aggressively, the gas output can be significant. Cruciferous vegetables like broccoli, cauliflower, and cabbage are also common triggers because they contain both fermentable fibers and sulfur compounds, producing gas that’s both high in volume and strong in smell.
Habits That Make You Swallow Air
If your gas comes with a lot of belching or feels more like air pressure than deep intestinal rumbling, you may be swallowing more air than you realize. This is surprisingly common and tied to everyday habits: eating too fast, talking while eating, chewing gum, sucking on hard candy, drinking through straws, and drinking carbonated beverages. Smoking also increases air swallowing.
The fix here is straightforward. Slow down at meals, skip the gum, and cut back on sparkling water or soda for a week to see if the volume drops. These changes often make a noticeable difference within days.
Lactose Intolerance and Enzyme Deficiency
If dairy products consistently make you gassy, lactose intolerance is the likely explanation. Lactose, the sugar in milk, requires an enzyme called lactase to be digested in the small intestine. Most humans gradually lose the ability to produce lactase after infancy. This is actually the biological default: sustained lactase production into adulthood depends on a specific inherited genetic variant. People without that variant experience a steady decline in lactase activity as they age, which is why some people develop dairy-related gas in their twenties or thirties even though milk never bothered them as kids.
When undigested lactose reaches the colon, bacteria ferment it rapidly, producing a surge of hydrogen gas along with bloating, cramping, and sometimes diarrhea. If you suspect this is your issue, eliminating dairy for two weeks is a reliable way to test it. Over-the-counter lactase supplements taken before a meal can also help if you don’t want to cut dairy entirely.
Bacterial Overgrowth in the Small Intestine
In a healthy gut, most bacteria live in the large intestine. Sometimes, though, bacteria colonize the small intestine in unusually high numbers, a condition called small intestinal bacterial overgrowth, or SIBO. When this happens, food gets fermented earlier in the digestive process and more aggressively than normal, producing excess gas, bloating, and discomfort that can feel relentless.
SIBO is diagnosed with a breath test that measures hydrogen and methane levels after you drink a sugar solution. If the levels spike above a certain threshold, it suggests an overabundance of gas-producing bacteria. SIBO is treatable, typically with a course of targeted antibiotics followed by dietary adjustments, and it’s worth investigating if your gas is persistent, uncomfortable, and hasn’t responded to dietary changes on its own.
When the Problem Is Perception, Not Production
Here’s something that surprises most people: some individuals who feel excessively gassy are actually producing a normal amount of gas. The issue is how their body perceives it. A condition called visceral hypersensitivity lowers the pain threshold in the digestive organs, so normal amounts of gas, fluid, or food moving through the gut register as uncomfortable pressure, bloating, or cramping.
Your digestive tract has its own nervous system, sometimes called the “second brain,” with nerve endings in every layer of the intestinal wall. These nerves respond to stretch, bacteria, chemical signals, and the physical contents of the gut. When they become chronically overexcited, they can make ordinary digestion feel like something is wrong. This is common in people with irritable bowel syndrome and helps explain why some people feel constantly gassy even when their diet is clean and their gas output is within the normal range.
Practical Ways to Reduce Gas
Start with the simplest interventions. Eat more slowly, chew thoroughly, and reduce carbonated drinks. Keep a food diary for a week or two, noting what you eat and when gas is worst. Patterns usually emerge quickly, and you may find that one or two foods account for most of the problem.
If beans, lentils, or certain vegetables are your main triggers, over-the-counter enzyme supplements can help. Products containing alpha-galactosidase (the enzyme in Beano) break down the non-absorbable fibers in these foods before they reach the colon, preventing the fermentation that causes gas in the first place. More than 20% of the population experiences gas-related abdominal pain from these complex carbohydrates, so this is a common and well-studied solution. Take the supplement with your first bite of the problem food for best results.
If you suspect a broader issue with fermentable carbohydrates, a low-FODMAP elimination diet can help identify your specific triggers. This involves removing all high-FODMAP foods for two to six weeks, then reintroducing them one category at a time to see which ones cause symptoms. It’s most effective when done with guidance from a dietitian, since the elimination phase is restrictive and not meant to be permanent.
Persistent, severe gas that comes with vomiting, diarrhea, constipation, unintentional weight loss, blood in the stool, or heartburn warrants a medical evaluation. These symptoms can point to conditions beyond simple dietary intolerance, and a provider can run the appropriate tests to rule them out.