Why Do Bellies Bloat? – Jesse Santiano M.D.

Have you ever wondered why your abdomen bloats after eating?

It was a puzzle for me for several years and I could not find a reason for “benign belly-bloating”. There are medical conditions that can make an abdomen large like bowel obstruction and ascites and they have to be ruled out.

While at work in the ER, I often see a haziness on the visceral fat while looking at abdominal CT scans. That haziness usually means inflammation but they are mostly incidental findings.

Then I came across a talk by Dr. Alessio Fasano on Youtube. I was quite impressed with his lecture and credentials being an expert and founder of the Massachusetts General Hospital’s Center for Celiac Research and several published research about gluten. So I bought his book, Gluten Freedom.
Gluten Freedom talks about how gliadin loosens the tight junctions in the inside lining of the intestines, thus allowing microscopic intestinal contents to pass through. But before we go any further, lets us define some terms

What is Gliadin?

Gliadin is the central part of gluten. Gluten is the protein in wheat, it is also seen in wheat, rye, barley, bulgur, couscous, farina, matzo, graham flour, Kamut, semolina, spelt, and triticale. In contrast, corn, millet, rice, and sorghum do not contain gluten.

Gluten makes the dough stretchable, making it possible for the bread to be formed into different shapes. It is broken down into gliadin, and gliadin can make the intestines more permeable.

How Can Gliadin Make the Intestines More Permeable?

The food that we eat is not sterile and contains many germs. The undigested food becomes fecal material. To prevent unwanted intestinal contents from going get out of the abdominal cavity, the cells in the inner lining of the intestines have tight junctions. Tight junctions are multi-protein complexes between cells that allow some ions and water but no solid particles.

In the human body, there is a protein called zonulin that can open the tight junctions. The presence of gliadin can release zonulin making the intestines more permeable to whatever is inside the intestinal lumen. According to Fasano, the zonulin production as a response to the presence of gliadin applies to everybody and not only to patients with celiac disease and gluten-intolerance.

So the next valid question is, If bad stuff can go thru the gut, why is it that we don’t sick? That is because there are protective mechanisms right in the visceral fat just outside the intestines.

The Visceral Fat

Visceral fat is the fat that is inside the abdomen. It surrounds the intestines and other solid organs like the liver, pancreas, and kidneys. Visceral fat also contains monocytes, which are a type of white blood cells. Monocytes, like other white blood cells, are there to guard against unwanted molecules, bacteria, viruses, or fungi that may cross the intestinal barrier.

Monocytes can turn to Macrophages

Imagine a sweet, smiling, and friendly security guard with a badge but no gun. He is there just to let everybody know that there is “security” around. That guard is like a monocyte.

At the first sign of serious trouble, the same security guard puts on a SWAT outfit complete with an AR-15, 9 mm semi-automatic pistol, spare magazines, flash-bang grenades, bulletproof vest, helmet, and goggles. That is the macrophage. Like the SWAT guy with many weapons, the macrophages have their own armaments called pro-inflammatory cytokines.

Pro-Inflammatory Cytokines

Pro-Inflammatory Cytokines are always mentioned on this website because they are involved in many diseases. But what are cytokines? Cytokines are proteins that are secreted by different cells, including the macrophages. Many different things can go thru that intestine, which is why many different types of cytokines are made. Some of them are the interleukins (IL-1), IL-12, and IL-18, tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFNγ), and granulocyte-macrophage colony-stimulating factor (GM-CSF).

Therefore, when anything awful shows up in their jurisdiction, these SWAT guys are called into action, and firefight happens. Now you have probably seen a post-firefight scene before. There is a lot of carnage. Inside the belly, it is called inflammation. That is why the cytokines mentioned above are called pro-inflammatory cytokines. Those cytokines promote inflammation. The bloated belly is a sign of the body protecting itself.

Swelling is made of Water

Think about a time when you had a skin infection. The inflamed area is red, swollen, hot, and painful. The swelling is called edema and is from the additional water that is drawn in that is typical in inflammation. The only difference is that the pain is not felt with that type of abdominal swelling.

In Summary

Ingested gluten gets digested to gliadin. Gliadin triggers zonulin production. Zonulin opens the tight junctions leading to the passage of intestinal contents towards the visceral fat.

The monocytes in the visceral fat recognize the unwanted intruders and become macrophages and release the pro-inflammatory cytokines. The inflammation draws water in and makes the abdomen swell up and look big. And that is how the belly gets bigger disproportionately after eating.

Variables

The summarized situation may not apply to all. A more considerable visceral fat, coupled with gluten and other food ingested, leads to more significant swelling.

If there is less visceral fat and little or no gluten is ingested during a meal, then the abdominal girth may only change minimally.

How do Cytokines Contribute to Disease?

Overweight and obese people have excessive visceral fat. The CDC defines obesity according to the Body Mass Index or BMI. More than 25 to 30 is overweight, and >30 is obese. Obesity and the waist circumference is a measure of visceral fat and the number of pro-inflammatory cytokines.

The excess pro-inflammatory cytokines can enter the blood circulation and spread all over the body. More substantial visceral fat and frequent meals produce higher and constant large amounts of pro-inflammatory cytokines. As mentioned earlier, there are many cytokines with different functions.

Some can promote cell-growth, control the immune response, cell death (apoptosis), atherosclerosis, and cancer. Thus, cytokines can cause uncontrolled cell growth, hyperimmune reaction, gene changes, and persistence of old useless cells.

The cytokines can also interact with the commonly present high blood sugar (hyperglycemia) and free radicals associated with high carbohydrate intake and produce diseases.

That is why obesity or metabolic syndrome is associated with different kinds of maladies that may seem unrelated to each other. Therefore, no connection is made. The usual thinking is that diseases are age-related or it runs “in the family,” or it is just a fluke of circumstance. There is more to visceral fat than just plain fat.

Strategies to prevent a bloated belly

Avoid gluten. Here is a list from Drperlmutter.com
Eating a low carbohydrate diet, especially sweets because carbs become fat. Low carb is low gluten. The low carbohydrate content is one of the main reasons that several diets work. Like the Ketogenic diet, Paleo diet, Atkins diet, Low Carb, High-Fat Diet or LCHF, Eco-Atkins, Zero Carb, and the Mediterranean diet.
Intermittent Fasting is a good way to use the available visceral fat.

Try an experiment. Compare meals with gluten and without gluten and look at your belly in the mirror after the meals.

Two years of intermittent fasting made me lose 35 lb. My waist is four inches smaller. I don’t get that bloated belly anymore. My desire to eat bread has reduced and all my metabolic profiles are better. There is no turning back.
Note: This article is written to inform and not to make a diagnosis. If you have any concerns about your abdomen, consult your physician. Not all diseases are associated with metabolic syndrome, some may have a familial basis.

Further recommended reading:

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References:

Fasano Alessio. Gluten Freedom: The Nation’s Leading Expert Offers the Essential Guide to a Healthy, Gluten-Free Lifestyle
Wouters K, Gaens K, Bijnen M, et al. Circulating classical monocytes are associated with CD11c+ macrophages in human visceral adipose tissue. Sci Rep. 2017;7:42665. Published 2017 Feb 15. doi:10.1038/srep42665
Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Ann N Y Acad Sci. 2012;1258(1):25–33. doi:10.1111/j.1749-6632.2012.06538.x
Fasano et al. Gliadin, zonulin, and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines. Scandinavian journal of gastroenterology. 41. 408-19. 10.1080/00365520500235334.
Wouters K, Gaens K, Bijnen M, et al. Circulating classical monocytes are associated with CD11c⁺ macrophages in human visceral adipose tissue. Sci Rep. 2017;7:42665. Published 2017 Feb 15. doi:10.1038/srep42665
Marette, A. Molecular mechanisms of inflammation in obesity-linked insulin resistance. Int J Obes 27, S46–S48 (2003) doi:10.1038/sj.ijo.0802500

Image Credit

Tight Junctions By Mariana Ruiz LadyofHats – I did the diagram myself using the information found here:[1], [2], [3], [4], [5], [6], [7], [8] and [9]. Image renamed from File: Cellular tight junction.SVG, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6178606