What is the cause of a protuberant belly in kwashiorkor?

Question

Kwashiorkor is a PEM (Protein–energy malnutrition) usually characterised by a pot belly. Why is there a pot belly in the case of a malnutrition? I have found contradictory reasons. This paper says that it is due to a fatty liver. This website says it is due to excess fluid accumulation in the tissues.

I noticed that these children have very skinny limbs. When I pointed that out to my teacher a few years back, she told me that the subcutaneous fat from the thighs accumulates under the belly. I can find no source confirming that, though.

So, what is the cause of the pot belly?

Answer 1

The Gastroenterology paper you cite doesn't mention distended bellies at all. There is no dispute that fatty liver is a symptom of kwashiorkor. But the Wikipedia article makes it quite clear that the cause of the distended belly is edema.

The extreme lack of protein causes an osmotic imbalance in the gastro-intestinal system causing swelling of the gut diagnosed as an edema or retention of water.[4]

And:

Compromised fluid recovery results in the characteristic belly distension observed in highly malnourished children.[14]

Here's another source:

To understand the reasoning for this, it is important to know that in malnourishment, the rounded abdomen is not due to fat accumulation. Instead, the water retention and fluid buildup in the body cause the abdomen to expand. This results in a bloated, distended stomach or abdominal area.

The rest of the article goes into more detail on the phenomenon and mechanism of action.

This source seems less authoritative, but also suggests that weakened abdominal muscles (due to protein deficiency) also play a role:

The swollen belly is the result of not only that enlarged liver, but also the loss of muscle mass, which leads to weak abdominal muscles. Together with a weakened lymphatic system that is unable to keep up with the body’s liquid wastes, when those wastes accumulate in the abdomen, the belly becomes distended.

So the author suggests that fatty liver contributes to belly distension, but is not a sole cause. None of the sources I looked at mentioned fat accumulation as a contributor, but rather eliminated it.

Answer 2

Abdominal distension is common in kwashiorkor, and many reasons have been proposed for it [1,2]:

• Dilated bowel loops (because of gas produced by bacterial overgrowth),
• An enlarged liver (because of steatosis, i.e. fat accumulation),
• Ascites, i.e. excess fluid in the peritoneal cavity (as part of the generalised oedema of kwashiorkor), and
• Weakness of the abdominal wall muscles.

But these are merely guesses. It is difficult to pinpoint one particular cause, since no studies have been done on this. Possibly, each of them contributes to some extent.

Now it is true that children with kwashiorkor have skinny limbs, but it would not be correct to say that their fat has 'moved' to their bellies. They are skinny because they are not getting enough nutrition to make up for their fat and muscle breakdown. The liver fat accumulation, on the other hand, is because the liver too is diseased. It is unable to metabolise lipids as it normally does [3].

References

1. Klein S. Protein-energy malnutrition. In: Goldman L, Schafer AI, editors. Goldman's Cecil medicine. 24th ed. Philadelphia: Elsevier Saunders; c2012. p 1388–90.
2. Ashworth A. Nutrition, food security and health. In: Kleigman RM, Stanton BF, St Geme JW, Schor NF, editors. Nelson textbook of pediatrics. 20th ed. Philadelphia: Elsevier; c2016. p 295–306.
3. van Zutphen T, Ciapaite J, Bloks VW, et al. Malnutrition-associated liver steatosis and ATP depletion is caused by peroxisomal and mitochondrial dysfunction. J Hepatol. 2016;65(6):1198–1208. https://doi.org/10.1016/j.jhep.2016.05.046