Abdominal Bloating: Causes and What Your Microbiome Reveals

Abdominal bloating is one of the most common digestive symptoms: it is estimated that between 15% and 30% of the population suffers from it regularly. That feeling of a swollen belly, pressure in the abdomen or clothes that feel tight even though you have not overeaten always has a cause — and very often, that cause lies in your gut microbiota. In this article we explain why it happens, the most common causes and how to find out exactly what is going on inside your gut.

What exactly is abdominal bloating?

Abdominal bloating, also called abdominal distension, is the feeling that your belly is fuller, tighter or larger than usual. It can be accompanied by gas and flatulence, bowel noises (borborygmi), pain or pressure in the abdomen, a feeling of heavy digestion and mild nausea. It is important to distinguish between functional bloating (with no apparent organic cause) and bloating caused by a specific condition. Most cases are functional — and in those cases, the gut microbiota plays a central role.

The most common causes of abdominal bloating

1. Intestinal dysbiosis: an imbalanced microbiome

The number one cause that scientific studies link to chronic bloating is intestinal dysbiosis: an imbalance in the composition of the bacteria living in your gut. When there is an excess of gas-producing bacteria (such as certain Firmicutes) or a lack of beneficial bacteria (such as Lactobacillus or Bifidobacterium), food fermentation produces more gas than normal. The result: abdominal distension after eating, even with light meals. A microbiota analysis like VitalOme identifies exactly which bacteria you have in excess or in deficit, and gives you personalized recommendations to rebalance your flora.

If you want to compare the options available in Spain before deciding, check out our comparison of microbiota tests.

2. Undiagnosed lactose or gluten intolerance

Many people live for years with bloating after eating without knowing they have a food intolerance. The most common: lactose intolerance (gas and distension between 30 minutes and 2 hours after consuming dairy) and non-celiac gluten sensitivity (bloating, fatigue and digestive discomfort without confirmed intestinal damage).

3. Irritable Bowel Syndrome (IBS)

IBS affects 10-15% of the population and abdominal bloating is one of its most characteristic symptoms, especially in women. It is characterized by alternating constipation and diarrhea, abdominal pain that improves after a bowel movement and bloating that worsens throughout the day. Recent studies show that people with IBS have a significantly different microbiota composition than healthy people.

4. Chronic constipation

When intestinal transit is slow, food waste stays longer in the colon, where bacteria ferment it and produce more gas. The result is persistent abdominal bloating, especially at the end of the day.

5. A diet high in FODMAPs

FODMAPs are fermentable carbohydrates that some people digest poorly: wheat, onion, garlic, leek, apple, pear, mango, legumes and dairy with lactose. A low-FODMAP diet reduces bloating in 75% of people with IBS, according to clinical studies.

6. Swallowing air (aerophagia)

Eating quickly, talking while eating, chewing gum or drinking through a straw increases the amount of air you swallow. It is a very common cause, especially in people with high stress levels.

7. Stress and the gut-brain connection

The gut-brain axis is bidirectional: stress affects intestinal motility and alters the composition of the microbiota. Prolonged stressful situations reduce bacterial diversity and increase intestinal permeability — more bloating, more gas and worse digestion.

Abdominal bloating in women: why is it more common?

Abdominal distension disproportionately affects women. The reasons: the hormonal cycle (progesterone slows transit during the luteal phase, before menstruation), greater visceral sensitivity and a higher prevalence of IBS (twice as common in women as in men). If you notice that your bloating follows a cyclical pattern related to your menstrual cycle, this is an important diagnostic clue.

How to find out your specific cause?

The VitalOme test by GenBiome uses NGS sequencing to analyze the bacteria in your gut and identifies which bacterial species you have and in what proportion, specific imbalances associated with bloating and slow digestion, your microbial diversity index and personalized dietary recommendations for your specific microbiota. Instead of following a generic diet that works for others but maybe not for you, you get a map of your gut and an action plan designed specifically for your bacteria.

What to do meanwhile: 5 science-backed changes

1. 1Eat slowly and chew well — 20 chews per bite reduces swallowed air and helps enzymatic digestion.
2. 2Increase fiber gradually — going from little to a lot of fiber at once worsens gas. Do it little by little over 2-3 weeks.
3. 3Stay hydrated — at least 1.5-2 liters of water a day supports transit.
4. 4Reduce stress — 10 minutes of diaphragmatic breathing a day has a proven effect on intestinal motility.
5. 5Move your body — a 20-minute walk after eating speeds up gastric emptying and reduces distension.

When to see a doctor

• Unintentional weight loss
• Blood in stool
• Bloating that does not subside in days
• Fever accompanied by severe abdominal pain
• Sudden change in bowel habits in people over 50

Conclusion

Abdominal bloating almost always has an identifiable cause. In most cases, that cause is directly related to the state of your gut microbiota: which bacteria you have, which ones you are missing and how your flora responds to what you eat. Knowing your microbiota is not just interesting — it is the most direct way to stop guessing and start acting with real data about your own body.

Article reviewed by GenBiome's scientific team. Last updated: August 2026.