Malnutrition can occur for various reasons. The sections below outline these potential causes in more detail.

A low intake of food

Some people develop malnutrition because there is not enough food available or because they have difficulty eating or absorbing nutrients.

This can happen as a result of:

• cancer
• liver disease
• conditions that cause nausea or make it difficult to eat or swallow
• taking medications that make eating difficult — due to nausea, for example

Mouth problems such as badly fitting dentures may also contribute to malnutrition.

Mental health conditions

Undernutrition or malnutrition can affect people with:

• depression
• dementia
• schizophrenia
• anorexia nervosa

Social and mobility problems

Factors that can affect a person’s eating habits and potentially lead to malnutrition include:

• being unable to leave the house or reach a store to buy food
• finding it physically difficult to prepare meals
• living alone, which can affect a person’s motivation to cook and eat
• having limited cooking skills
• not having enough money to spend on food

Digestive disorders and stomach conditions

If the body does not absorb nutrients efficiently, even a healthful diet may not prevent malnutrition.

Examples of digestive and stomach conditions that may cause this include:

• Crohn’s disease
• ulcerative colitis
• celiac disease
• persistent diarrhea, vomiting, or both

Alcohol use disorder

Consuming a lot of alcohol can lead to gastritis or long-term damage to the pancreas. These issues can make it hard to digest food, absorb vitamins, and produce hormones that regulate metabolism.

Alcohol also contains calories, so a person may not feel hungry after drinking it. They may therefore not eat enough healthful food to supply the body with essential nutrients.