Protein–energy malnutrition
Protein–energy malnutrition, sometimes called protein-energy undernutrition, is a form of malnutrition that is defined as a range of pathological conditions arising from coincident lack of dietary protein and/or energy in varying proportions. The condition has mild, moderate, and severe degrees.
for protein–energy malnutrition per 100,000 inhabitants in 2004.
Types include:
- Kwashiorkor
- Marasmus
- Marasmic kwashiorkor
Note that PEM may be secondary to other conditions such as chronic renal disease or cancer cachexia in which protein energy wasting may occur.
Protein–energy malnutrition affects children the most because they have less protein intake. The few rare cases found in the developed world are almost entirely found in small children as a result of fad diets, or ignorance of the nutritional needs of children, particularly in cases of milk allergy.
Prenatal protein malnutrition
Protein malnutrition is detrimental at any point in life, but protein malnutrition prenatally has been shown to have significant lifelong effects. During pregnancy, one should aim for a diet that consists of at least 20% protein for the health of the fetus. Diets that consist of less than 6% protein in utero have been linked with many deficits, including decreased brain weight, increased obesity, and impaired communication within the brain in some animals. Even diets of mild protein malnutrition have been shown to have lasting and significant effects in rats. The following are some studies in which prenatal protein deficiency has been shown to have unfavorable consequences.- Decreased brain size: Protein deficiency has been shown to affect the size and composition of brains in rhesus monkeys. Monkeys whose mother had eaten a diet with an adequate amount of protein were shown to have no deficit in brain size or composition, even when their body weight amounted to less than one-half of that of the controls, whereas monkeys whose mothers had eaten low-protein diets were shown to have smaller brains regardless of the diet given after birth.
- Impaired neocortical long-term potentiation: Mild protein deficiency in rats has been shown to impair entorhinal cortex plasticity, noradrenergic function in the neocortex, and neocortical long-term potentiation.
- Altered fat distribution: Protein undernutrition can have varying effects depending on the period of fetal life during which the malnutrition occurred. Although there were not significant differences in the food intake, there were increased amounts of perirenal fat in rats that were protein-deprived during early and mid pregnancy, and throughout pregnancy, whereas rats that were protein-deprived only late in gestation were shown to have increased gonadal fat.
- Increased obesity: Mice exposed to a low-protein diet prenatally weighed 40% less than the control group at birth. When fed a high-fat diet after birth, the prenatally undernourished mice were shown to have increased body weight and adiposity, while those who were adequately nourished prenatally did not show an increase in body weight or adiposity when fed the same high-fat diet after birth.
- Decreased birth weight, and gestation duration: Supplementation of protein and energy can lead to increased duration of gestation and higher birth weight. When fed a supplement containing protein, energy, and micronutrients, pregnant women showed more successful results during birth, including high birth weights, longer gestations, and fewer pre-term births, than women who had consumed a supplement with micronutrients and low energy but no protein.
- Increased stress sensitivity: Male offspring of pregnant rats fed low-protein diets have been shown to exhibit blood pressure that is hyperresponsive to stress and salt.
- Decreased sperm quality: A low-protein diet during gestation in rats has been shown to affect the sperm quality of the male offspring in adulthood. The protein deficiency appeared to reduce sertoli cell number, sperm motility, and sperm count.
- Altered cardiac energy metabolism: Prenatal nutrition, specifically protein nutrition, may affect the regulation of cardiac energy metabolism through changes in specific genes.
- Increased passive stiffness: Intrauterine undernutrition was shown to increase passive stiffness in skeletal muscles in rats.
Epidemiology
Although protein energy malnutrition is more common in low-income countries, children from higher-income countries are also affected, including children from large urban areas in low socioeconomic neighborhoods. This may also occur in children with chronic diseases, and children who are institutionalized or hospitalized for a different diagnosis. Risk factors include a primary diagnosis of intellectual disability, cystic fibrosis, malignancy, cardiovascular disease, end stage renal disease, oncologic disease, genetic disease, neurological disease, multiple diagnoses, or prolonged hospitalization. In these conditions, the challenging nutritional management may get overlooked and underestimated, resulting in an impairment of the chances for recovery and the worsening of the situation.PEM is fairly common worldwide in both children and adults and accounts for 6 million deaths annually. In the industrialized world, PEM is predominantly seen in hospitals, is associated with disease, or is often found in the elderly.
Co-morbidity
A large percentage of children that suffer from PEM also have other co-morbid conditions. The most common co-morbidities are diarrhea and malaria. However, a variety of other conditions have been observed with PEM, including sepsis, severe anaemia, bronchopneumonia, HIV, tuberculosis, scabies, chronic suppurative otitis media, rickets, and keratomalacia. These co-morbidities tax already malnourished children and may prolong hospital stays initially for PEM and may increase the likelihood of death.The general explanation of increased infectious comorbidity in malnourished people is that the immune system is what prevents such diseases from being more widespread in healthy, well-nourished people and malnutrition stresses and diminishes immune function. In other words, malnutrition tends to cause immunodeficiency, eroding the barriers that normally keep infectious diseases at bay. For example, this reversal is well established regarding the variable natural history of tuberculosis in the pre–TB drug era. Epidemiologically, there are also associations between malnutrition and other health risks via the common underlying factor of poverty. For example, condoms can reduce spread of HIV, but impoverished people often may not have money to buy condoms or a nearby place to buy them. Also, once a poor person has any particular infection, they may not have access to optimal treatment of it, which allows it to get worse, present more chances of transmission, and so on. Even when a developing country nominally/officially has national health insurance with universal health care, the poorest quarter of its population may face a de facto reality of poor health care access.