Malnutrition

Malnutrition occurs when the body does not get the right amount of nutrients it needs to function properly. It can refer to undernutrition (not getting enough nutrients) or overnutrition, though in clinical practice it most commonly refers to deficiency states.

Malnutrition can result from a poor diet, digestive conditions that impair nutrient absorption, chronic illness, eating disorders and excessive alcohol use. It is particularly common in older adults and people with long-term health conditions.

Symptoms may include unintentional weight loss, fatigue, muscle weakness, poor wound healing, frequent infections and difficulty concentrating.

Blood tests for micronutrients such as magnesium and zinc can identify specific deficiencies. Addressing the underlying cause and correcting nutrient levels are both important for recovery.

Causes of Malnutrition

Malnutrition can develop when nutrient intake, absorption or utilisation is inadequate.

Common causes include:

Reduced food intake due to loss of appetite, difficulty swallowing, dental problems, depression or social isolation, particularly in older adults
Digestive conditions that impair nutrient absorption, including coeliac disease, Crohn's disease and chronic pancreatitis
Chronic illness such as cancer, COPD and heart failure, which increase metabolic demands while reducing appetite
Excessive alcohol use, which displaces nutritious food from the diet and impairs absorption of several micronutrients including magnesium, zinc and B vitamins
Eating disorders such as anorexia nervosa
Medications that affect appetite or nutrient absorption

Malnutrition is a significant and underrecognised problem in the UK, affecting an estimated 3 million people. Older adults living alone and people recently discharged from hospital are at particular risk.

Tests that can help check this condition

Learn more on the official NHS page .

Medical review

Dr. Shahzaib Ahmad MBBS, BSc, MRCP, FRCA, FFICM

Clinical Supervisor - Vitall|GMC 7495062|Profile

Dr Shahzaib Ahmad is a Consultant in Intensive Care Medicine with subspecialty experience in cardiac critical care and neurocritical care. He has extensive experience managing complex acute and cardiovascular conditions in hospital intensive care settings. Dr Ahmad supports Vitall in reviewing health content for clinical accuracy and alignment with current medical practice.

Reviewed on 22/05/2026

Next review due 22/05/2027

Review focus: Blood biomarkers, laboratory testing methodology, and biochemical interpretation.

This content has been reviewed for medical and scientific accuracy but does not replace advice from a qualified healthcare professional.