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How does protein-energy malnutrition affect the immune system?

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rickets, a nutritional disease — nutritional disease Children with rickets. The disease, which most commonly strikes children, causes bone deformities such as bowlegs. Rickets is caused by a lack of vitamin D or calcium.

Protein-energy malnutrition (PEM) is a significant cause of immune deficiency, particularly in children whose diets lack sufficient protein and energy. This condition severely impairs both antibody responses and cell-mediated immunity.1

The underlying mechanism for this impairment is often the atrophy of the thymus, which leads to a deficiency of helper T cells. As a result of this weakened immune state, individuals—especially children—become highly susceptible to infectious diseases, such as measles and diarrhea. In cases of marasmus, the body’s profound weakness and inability to resist infection create a dangerous cycle that can lead to severe illness or death.12

It is a fundamental ethical imperative to address malnutrition globally, as it is a preventable condition that causes immense human suffering. Fortunately, the damage to the immune system is not always permanent; the thymus and the broader immune system can often recover completely if adequate nutrition is restored in a timely manner.12