Understanding What Individuals Are at Risk for PEM?

October 12, 2025 •

4 min read

According to the World Health Organization, nearly half of deaths among children under five years old are linked to undernutrition. This highlights the critical importance of understanding what individuals are at risk for PEM, or protein-energy malnutrition, which can have devastating health consequences.

Quick Summary

This article explores the key demographics and underlying health and socioeconomic conditions that place people at high risk for protein-energy malnutrition (PEM). It outlines primary and secondary causes and distinguishes between different forms of severe malnutrition.

Key Points

Children are at the highest risk: Rapid growth and immature immune systems make children, especially those under five, the most vulnerable group for PEM.
Older adults are highly susceptible: Elderly individuals, especially those in institutionalized care or with chronic health issues, frequently suffer from PEM due to reduced appetite and absorption.
Chronic illness is a major driver: Medical conditions such as cancer, liver disease, and inflammatory bowel disease can lead to secondary PEM by increasing metabolic demands or impairing nutrient absorption.
Socioeconomic factors amplify risk: Poverty, food insecurity, and poor sanitation in developing countries are major contributors to widespread PEM.
PEM exists in different forms: Marasmus involves severe protein and energy deficiency leading to wasting, while Kwashiorkor is characterized by protein deficiency with edema.
Prevention requires targeted action: Addressing PEM involves targeted nutritional support for high-risk groups, alongside interventions to tackle socioeconomic and environmental causes.

Protein-energy malnutrition (PEM), also known as protein-energy undernutrition (PEU), is a serious condition that arises from a severe deficiency of protein, energy, or both. While often associated with poverty and resource-limited regions, PEM affects vulnerable populations globally, including those in developed countries, due to a complex interplay of factors. Understanding the specific groups at risk is the first step toward effective prevention and intervention.

Who Is Most Vulnerable to PEM?

Children and Infants

Children are particularly susceptible to PEM because of their high energy and protein requirements for rapid growth and development. The most critical period is from conception to a child's second birthday, and malnutrition during this time can have irreversible physical and cognitive effects. The risk increases significantly during weaning, especially if new foods are inadequate in nutrients or contaminated. In developing countries, PEM is the second most frequent cause of death in children under five. Even in developed nations, factors like rare fad diets, severe food allergies, or child abuse can lead to severe PEM in children.

Older Adults

Elderly individuals are another major high-risk group for PEM, both in community and institutional settings. The prevalence of PEM can be as high as 50% for older patients hospitalized in acute care units. Reasons for increased vulnerability include:

Geriatric anorexia: A natural loss of appetite that can lead to decreased food intake.
Chronic illness: Many chronic conditions common in older age, such as heart failure, cancer, or kidney disease, interfere with appetite or nutrient metabolism.
Physical limitations: Difficulties with cooking, chewing, swallowing, or accessing nutritious food.
Social and psychological factors: Isolation, depression, and dementia can all contribute to inadequate nutritional intake.

Individuals with Chronic or Critical Illnesses

Many diseases and medical conditions can cause secondary PEM, where the underlying illness, rather than simply inadequate intake, drives malnutrition. Chronic inflammatory states, wasting disorders, and conditions that increase metabolic demands are all major contributors.

Common conditions that increase the risk of PEM include:

Gastrointestinal disorders: Conditions like inflammatory bowel disease (IBD), celiac disease, or pancreatic insufficiency can lead to malabsorption and nutrient loss.
Liver cirrhosis: Malnutrition is a common complication, with reported prevalence rates as high as 65.5%, leading to increased catabolism.
Cancer and HIV/AIDS: These wasting disorders cause cachexia, a complex metabolic syndrome that leads to muscle and fat loss.
Kidney disease: Patients on long-term hemodialysis are at risk for PEM.
Infections: Acute and chronic infections, fever, burns, and trauma significantly increase the body's metabolic requirements.

Socioeconomic and Environmental Drivers of Risk

Beyond individual health, broader social and economic issues are fundamental drivers of PEM, especially in low-income and resource-limited regions.

Key socioeconomic risk factors include:

Poverty: Limited financial resources restrict access to adequate and varied food.
Food insecurity: Insufficient access to affordable, nutritious food.
Limited education: A lack of maternal education is often linked to higher rates of childhood PEM.
Poor sanitation and hygiene: Contaminated water and unhygienic conditions increase the risk of gastrointestinal infections, which can trigger PEM.
Conflict and displacement: Famine and displacement due to regional conflicts can disrupt food supplies, as seen in some parts of Africa.

Marasmus vs. Kwashiorkor: Two Forms of Severe PEM

Severe PEM manifests in two primary forms, each with distinct features. Marasmus is a severe deficiency of both calories and protein, while Kwashiorkor is predominantly a protein deficiency despite relatively adequate calorie intake. Many patients can exhibit features of both, known as marasmic kwashiorkor.


Feature	Marasmus	Kwashiorkor
Primary Deficiency	Energy (calories) and protein	Protein predominantly
Appearance	Wasted, emaciated with skin and bones visible; 'old man face'	Swollen abdomen and extremities (edema); 'moon face'
Body Fat	Markedly depleted	Maintained or increased
Muscle Wasting	Severe and evident	Present but often masked by edema
Hair Changes	Thinning, brittle hair	Sparse, brittle hair with potential color changes
Apathy and Irritability	Irritable at first, can become apathetic	More prominent apathy
Occurrence	Most common form of PEM in children globally	Less common, often confined to specific regions with low-protein staple diets

Addressing the Risk of PEM through Nutrition

Mitigating the risk of PEM requires a multi-faceted approach focused on providing adequate nutrition for vulnerable populations. This includes targeted nutritional support for children, especially during the critical first two years of life, and for older adults who may face mobility or health-related eating challenges. For those with chronic diseases, nutritional management is a crucial part of treatment to combat secondary PEM. Addressing the underlying socioeconomic drivers, such as poverty and food insecurity, is also vital for long-term prevention. Ultimately, a balanced, nutrient-dense diet is the cornerstone of prevention for all individuals. For more information on global health issues related to nutrition, the World Health Organization provides extensive resources.

Conclusion

Protein-energy malnutrition remains a significant health burden worldwide, affecting not only those in resource-limited areas but also vulnerable individuals in developed nations. Children, older adults, and those with chronic or critical illnesses face the highest risk due to their specific physiological needs, underlying diseases, and environmental circumstances. By identifying these high-risk groups and addressing the complex factors at play, we can work towards improving nutritional health outcomes for everyone. Targeted interventions and a focus on preventative nutritional strategies are essential for reducing the devastating impact of PEM on individuals and communities alike.

Frequently Asked Questions

Marasmus is caused by a severe deficiency of both protein and energy (calories), leading to emaciation and wasting of body fat and muscle. Kwashiorkor, in contrast, results primarily from a lack of protein, often in the presence of adequate or high carbohydrate intake, which causes fluid retention and swelling (edema).

Yes, PEM can and does affect adults in developed countries. It is often seen in hospital settings, among the elderly, and in individuals with chronic diseases, eating disorders like anorexia nervosa, or those following severely restrictive fad diets.

A wide range of medical conditions can increase PEM risk. These include disorders affecting gastrointestinal function (e.g., celiac disease), wasting disorders (e.g., cancer, HIV/AIDS), liver cirrhosis, kidney disease, and any conditions that increase metabolic demands, such as severe infections or burns.

Older adults face several risk factors, including a natural loss of appetite (geriatric anorexia), chronic illnesses, and physical or cognitive impairments that affect their ability to acquire or prepare food. Social isolation and depression can also significantly contribute to inadequate intake.

Infections can worsen or precipitate PEM in two ways: they increase the body's metabolic demands, requiring more energy and protein for healing, and they can cause a loss of appetite and poor nutrient absorption, creating a vicious cycle of illness and malnutrition.

Poverty is a fundamental driver of PEM, particularly in low- and middle-income countries. It limits access to sufficient and nutritious food, as well as proper sanitation and healthcare, which exacerbates the risk of infections that contribute to malnutrition.

Yes, pregnant and lactating women are at increased risk. Their bodies have higher energy and protein requirements to support fetal growth and milk production. Inadequate nutrition during these periods can lead to PEM for both the mother and the infant.