Passing gas 14 to 23 times a day is completely normal. If you feel like you’re always farting, you may actually be right in the middle of that range and just more aware of it, or you could be on the higher end due to diet, habits, or how your gut bacteria operate. Either way, the gas has to come from somewhere, and understanding the two main sources helps explain what’s going on.
Where the Gas Actually Comes From
Your body produces intestinal gas through two routes: swallowed air and bacterial fermentation. Every time you eat, drink, or swallow saliva, small amounts of air travel down into your digestive tract. Most of it gets burped back up, but some continues through to your intestines and eventually exits as flatulence.
The bigger contributor is your gut bacteria. Trillions of microbes live in your large intestine, and their primary job is breaking down whatever your small intestine couldn’t absorb, especially dietary fiber. When bacteria ferment these leftover food particles, they produce hydrogen, carbon dioxide, and sometimes methane as byproducts. The smell comes from a different process: when gut bacteria break down proteins instead of fiber, they produce hydrogen sulfide, the compound responsible for that rotten-egg odor. So a high-protein meal can make your gas smell worse even if the volume stays the same.
Foods That Cause the Most Gas
Certain carbohydrates are especially gas-producing because your small intestine literally cannot break them down. These molecules, sometimes grouped under the term FODMAPs, pass intact into your large intestine, where bacteria feast on them. Your small intestine even draws in extra water to help push them along, and the fermentation that follows produces both gas and fatty acids inside your gut.
The biggest offenders include:
- Beans and lentils: packed with oligosaccharides your body can’t digest on its own
- Onions and garlic: same category of hard-to-absorb sugars
- Wheat products: another common oligosaccharide source
- Dairy: the lactose in milk and soft cheeses ferments rapidly if you don’t produce enough of the enzyme to break it down
- Apples, watermelon, and stone fruits: high in fructose and sugar alcohols that ferment easily
- Sugar-free gum and candy: contain sugar alcohols (like sorbitol and xylitol) that head straight to your colon undigested
If you recently increased your fiber intake, that alone could explain the uptick. Your gut bacteria need time to adjust. Michigan Medicine recommends adding only about 5 grams of fiber per day and waiting two weeks before increasing again. Gas production rises at first but decreases as your microbiome adapts.
Habits That Make You Swallow Extra Air
You might be adding gas to your system without realizing it. Eating too fast, talking while you eat, chewing gum, sucking on hard candy, drinking through straws, and smoking all cause you to swallow more air than normal. This condition, called aerophagia, sends pockets of air past your stomach and into your intestines.
Carbonated drinks are a special case. The carbon dioxide in soda and sparkling water does expand in your stomach, but research shows it gets absorbed through the intestinal wall fairly quickly. Intestinal gas typically contains only about 9.6% carbon dioxide. So while carbonation can make you burp and feel bloated, it’s not a major driver of flatulence specifically. Your bigger concern with soda is the sugar or artificial sweeteners it contains, both of which can feed bacterial fermentation lower in the gut.
Lactose Intolerance and Other Sensitivities
If your gas kicks in reliably within a few hours of eating dairy, lactose intolerance is a strong possibility. It affects a large percentage of adults worldwide, and it happens because your small intestine doesn’t produce enough lactase to break down milk sugar. The undigested lactose moves to your colon, where bacteria ferment it rapidly, producing gas, bloating, and often diarrhea.
Fructose malabsorption works similarly. Some people absorb fructose poorly, so fruit, honey, and high-fructose corn syrup trigger the same fermentation cascade. Paying attention to timing is useful here. If you can connect your worst gas to specific meals or ingredients, you’ve likely found a sensitivity rather than a broader digestive problem.
When Excessive Gas Signals Something Else
Sometimes persistent, uncomfortable gas points to a condition worth investigating. Small intestinal bacterial overgrowth (SIBO) happens when gas-producing bacteria colonize parts of the small intestine where they don’t normally live in large numbers. The result is excessive bloating, gas, abdominal pain, and changes in your stool, including loose, oily, or unusually smelly bowel movements. A simple breath test that measures hydrogen and methane levels can confirm it, and unlike some gut conditions, SIBO is treatable once identified.
Irritable bowel syndrome (IBS) produces many of the same symptoms but is diagnosed differently. IBS is considered a functional disorder, meaning it’s identified when symptoms persist but tests don’t reveal a specific cause like bacterial overgrowth or inflammation. The overlap between the two is significant, which is why testing matters if your gas comes with other symptoms.
Red flags that warrant a medical visit include blood in your stool, unintentional weight loss, persistent diarrhea or constipation, and ongoing nausea or vomiting. Prolonged abdominal pain or chest pain alongside gas deserves prompt attention.
Practical Ways to Reduce Gas
Start with the low-effort changes. Slow down when you eat, close your mouth while chewing, and cut back on gum and carbonated drinks. These alone can meaningfully reduce the amount of air entering your system.
For food-related gas, an elimination approach works well. Pick the most common triggers (dairy, beans, onions, garlic, wheat) and remove one category at a time for a week or two. If your gas drops noticeably, you’ve found your culprit. You don’t necessarily have to avoid these foods forever. Smaller portions, different preparation methods (soaking dried beans overnight, for instance), or pairing them with other foods can reduce fermentation.
If you’re increasing fiber for health reasons, don’t give up on it just because of initial gas. The adjustment period is real, but it passes. Increase gradually, drink plenty of water, and give your gut bacteria a few weeks to catch up. The long-term benefits of fiber for digestion, blood sugar, and heart health are well established, and the gas does settle down.
Over-the-counter enzyme supplements exist for specific triggers. Lactase tablets taken before dairy can prevent lactose-related gas. Products containing alpha-galactosidase (the enzyme in Beano) are marketed for bean and vegetable gas, though clinical evidence for significant gas reduction is mixed. They’re safe to try, but results vary from person to person.