Malnutrition is caused by more than just a lack of food. There is another essential resource that plays a critical role in whether children get the nutrition they need: clean water.
When water is unsafe to drink, cook with, or wash with, it can trigger a dangerous cycle that prevents the body from absorbing the nutrients it needs to survive and thrive. Understanding how water, disease, and nutrition are connected is key to our fight against hunger.
When Water Makes People Sick
Water is fundamental to the body’s ability to process food and absorb nutrients. But when water sources are contaminated, drinking it can cause serious illness and undermine the body’s ability to use the nutrients it receives.
Common waterborne diseases include:
- Diarrhea
- Cholera
- Typhoid fever
- Intestinal parasites
- Other gastrointestinal infections
These illnesses are especially common in areas where communities lack proper sanitation systems or safe hygiene practices. About 1 in 4 people globally are living without reliable access to safe water and are at risk of illness as a result.
Action Against Hunger staff prepare water and sanitation kits for distribution.
The Vicious Cycle: Illness and Malnutrition Reinforce Each Other
The relationship between disease and malnutrition works in both directions. While illness can cause malnutrition, malnutrition also weakens the immune system, making children more vulnerable to infections. This creates a dangerous cycle: a child becomes sick, then malnourished, then sick again, and so on. The risk is heightened when a child continues to drink unclean water or live in unsanitary conditions. Each time this cycle repeats, the child’s health can decline further.
For some children, repeated illness can lead to chronic malnutrition, also known as stunting. Stunted children are shorter for their age and may face long-term health and developmental challenges.
A child carries a safe water storage container from Action Against Hunger.
How Illness Leads to Malnutrition
Continued exposure to unsafe drinking water increases the risk of having recurring sickness, weakening the body over time, and increasing risk of malnutrition and other health challenges. For young children, whose bodies and immune systems are still developing, this risk is particularly severe.
For example, diseases such as diarrhea cause the body to rapidly lose fluids, electrolytes, and essential nutrients. Even if a child has eaten enough food, these nutrients may be flushed out before the body can use them. Children under 5 years old are at a critical growth period and have little reserves to withstand nutrient depletion, so diarrhea can quickly turn dangerous. According to the World Health Organization, diarrhea is the leading cause of malnutrition in children under 5 years old, and the third leading cause of death for children globally.
Illness can also reduce appetite. Children who are sick may refuse food or eat very little for several days. This reduction in food intake means the body receives fewer calories and fewer essential vitamins and minerals needed for growth and recovery. If illness is frequently recurring for reasons like unclean water, malnutrition can occur and cause long-lasting harm to the child’s overall health.
A baby recovering from malnutrition is held by his mother along with an RUTF treatment packet.
How Malnutrition Leads to Illness
Nutrition plays a vital role in fighting illness. Vitamins and minerals are essential for the immune system to function, and the body depends on a steady intake of nutrients to defend itself against infection. Nutrients like vitamin A, zinc, iron, and protein all play key roles in maintaining immune responses and supporting recovery when illness occurs. When a person is malnourished and lacks those essential vitamins and minerals, their vulnerability to illness is heightened.
Malnutrition also causes inflammation that weakens the immune system, reducing the body’s ability to produce immune cells and antibodies that fight infection. As a result, illnesses that might otherwise be mild can become more severe and longer-lasting. Children who are malnourished are more likely to experience frequent infections, including respiratory illnesses, diarrhea, and other common diseases.
Recovery from illness requires energy, protein, and micronutrients. Malnourished individuals often lack these reserves, making it harder to regain strength after being sick. Even after the initial illness passes, the body may remain weakened, increasing the likelihood of relapse or new infections — especially when unclean water continues to be consumed. This can lead to complications, prolonged illness, and, in severe cases, life-threatening conditions.
At an Action Against Hunger clinic in Nigeria, a doctor monitors the health of malnourished twins.
Why Children Are Most at Risk
Young children are particularly vulnerable to the effects of unsafe water, disease, and malnutrition.
Children require more nutrients relative to their body size because they are growing quickly. Even short interruptions in nutrient intake or absorption can have lasting consequences. Additionally, a child’s immune system is still maturing, making it harder to fight infections. In many communities, children play on the ground or in areas where sanitation infrastructure is limited. This increases their exposure to harmful bacteria and parasites.
When illness and malnutrition occur during the first 1,000 days (from pregnancy through a child’s second birthday), the impacts can be particularly severe. This time is critical for brain development and physical growth.
Children play with the runoff water from a safe water truck operated by Action Against Hunger in Pakistan.
Clean Water Is a Powerful Tool for Preventing Malnutrition
Malnutrition is a complex challenge with many causes. But one solution is clear: safe water saves lives.
When communities gain reliable access to safe water and sanitation, rates of diarrhea and other infections decline significantly. Improving access to safe water, sanitation, and hygiene (WASH) can dramatically reduce disease and improve nutrition outcomes.
Action Against Hunger works with communities to improve WASH infrastructure and practices and put an end to the illness-malnutrition cycle.
Key solutions include:
- Safe drinking water systems
- Protected wells and boreholes
- Household water treatment and storage
- Sanitation infrastructure such as latrines
- Hygiene education, including handwashing with soap
Through these activities, children are more likely to stay healthy and absorb the nutrients they need.
