NUTRITION IN DISEASE RECOVERY

Nutrition plays a key role in a patient’s recovery from disease and illness. During the Nestlé Nutrition Institute’s Workshop 98, Dietitian Shane McAuliffe highlighted the key relationship between nutrition and disease recovery. His presentation included a detailed examination of the role played by vitamin A in boosting and maintaining immunity. He clearly outlined how illness and nutrition affect each other, how that impacts recovery and what measures can be taken to improve outcomes.

Nutrition and the immune system

Good nutritional status supports an effective immune response, while poor nutritional status can hinder immunity and delay recovery. Glucose, amino acids, fatty acids, vitamins and minerals all play a crucial role.

The role of micronutrients and macronutrients

The relationship between nutrition and immunity is most clearly demonstrated by the essential functions of macronutrients. A competent immune response requires an adequate supply of calories to power cellular processes and, critically, a sufficient intake of protein to manufacture the machinery of defence – from physical barriers to the production of antibodies and immune cells. Therefore, a deficit in either calories or protein directly translates to a compromised immune capacity.

Micronutrients maintain physical barriers, such as the skin and mucosal linings. They also support the activation of antimicrobial proteins that support immune cell memory, as well as regulate inflammation. While vitamins C and D play a role in boosting immunity, McAuliffe specifically highlights the role played by vitamin A.

The role of vitamin A

Vitamin A is sometimes referred to as “the anti-infection vitamin” due to the vital role it plays in the body’s immune system.  A deficiency in vitamin A leaves individuals susceptible to pathogens and infections. In sub-Saharan Africa and South Asia, where the rate of vitamin A deficiency is high, many children face increased health risks. A lack of vitamin A results in a vulnerability to diseases including measles, malaria and diarrheal diseases. This occurs as a result of the breakdown of mucosal integrity in the eyes, lungs, and gut. Beyond these infections, vitamin A deficiency remains the primary cause of preventable childhood blindness in low to middle-income communities.

Studies found that periodic, high-dose vitamin A supplementation is a low-cost intervention that can help to prevent mortality linked to general diseases, including those associated with diarrhoea.  

Illness and malnutrition

Illness often worsens malnutrition. Acute and chronic diseases suppress appetite, affecting intake, while inflammation raises energy expenditure and accelerates the loss of lean and fat mass. Surgical stress further diverts glucose, fatty acids and amino acids from maintaining muscle to wound healing, immune activity and acute phase protein synthesis, markedly increasing requirements for both energy and protein. This catabolic state is amplified by hormonal shifts (for example, elevated glucocorticoids) and cytokines such as IL-6 and TNF-α, which slow gastric emptying, dampen appetite and accelerate muscle loss. The result is predictable: malnourished medical and surgical inpatients experience more complications, longer stays, more frequent readmissions and substantially higher mortality.

What improves patients’ nutritional status during illness?

High-quality trials show that structured nutrition support saves lives and reduces complications. In the Swiss EFFORT trial, protocol-guided, personalised nutrition care for medical inpatients at nutritional risk, using practical steps such as energy- and protein-dense meals, food fortification, aligning menus with patient preferences, and routine use of oral nutritional supplements (ONS), produced a 4% absolute reduction in adverse clinical events (number needed to treat was 25; to prevent one death, 37).

Patients in the intervention arm consumed, on average, about 290 kcal and 10 g more protein per day than those in the control group. Most used ONS in the hospital, and roughly a quarter continued after discharge.

In surgery, Enhanced Recovery After Surgery (ERAS) programmes blunt stress and speed the return of function, with early nutrition as a core component. Oral intake within hours of an operation is the goal; where this is not feasible, early enteral feeding is preferred.

Both approaches are associated with fewer post-operative complications and shorter hospital stays across multiple procedures, not only colorectal surgery.
COVID-19 made these principles stark. Older adults and people with comorbidities, already at high nutritional risk, fared worse, while prolonged hospitalisations, social isolation and limited food access compounded the problem. Many patients were profoundly hypermetabolic: indirect calorimetry often showed energy needs exceeding predictive equations. In one task force case report, a patient with a prolonged ICU stay lost 19 kg in 52 days, around 24% of initial body weight, owing to the difficulty of meeting requirements amid frequent interruptions to feeding.

The response must be systematic: screen for malnutrition, including remotely where necessary; implement personalised nutrition care plans, including food-based strategies, ONS and timely referral to a dietitian; and ensure continuity of care from hospital to community. UK consensus guidance now recommends including nutrition assessment in all clinical and research follow-up protocols for people recovering from COVID-19. More broadly, treat nutritional status as a modifiable risk factor at every stage of illness to improve recovery and build population resilience for future health challenges.

Nutrition and well-being are paramount to immune competence, surgical recovery, and clinical outcomes across illnesses and diseases. If healthcare professionals can identify those at risk at an early stage, they can offer individualised nutrition support to reduce complications and shorten hospital stays, lower costs, and save lives.