Disease related malnutrition is very common across all health care settings.

The risk for common age-associated problems, such as sarcopenia, osteoporosis, and impaired immune responses is increased when protein intakes are inadequate.

The effect of disease related malnutrition can be detrimental on both physical and clinical health, leading to an increased length of hospital stay, morbidity, mortality, and increased cost. The reason for this is that malnutrition not only leads to disease, but it affects disease outcome negatively in several ways which include a decrease in immune function leading to increased infections and decreased ability of the body to recover, muscle weakness that increases the risk of falls, venous thromboembolism, and pressure ulcers. Causes of malnutrition are multifactorial and differ from metabolic effects of underlying disease to reduced nutritional intake.

DIETARY PROTEIN REQUIREMENTS

Appropriate dietary protein intake for older adults is important for maintaining functionality. The risk for common age-associated problems, such as sarcopenia, osteoporosis, and impaired immune responses is increased when protein intakes are inadequate. Inadequate intake of protein, reduced ability to use available protein, as well as higher protein needs variously influence protein use in older individuals (Figure 1).

Figure 1 - Protein requirements and oral nutritional supplementation

Protein requirements changes with ageing and vary according to different chronic diseases, decreased absorption, and synthesis. An international study group was appointed by The European Union Geriatric Medicine Society (EUGMS) and other scientific organisations to review dietary protein needs with aging (PROT-AGE Study Group).

Their goal was to develop updated, evidence-based recommendations for optimal protein intake by older people.

The PROT-AGE study group has the following recommendation with regard to average daily intake: 1.0-1.2g protein per kilogram of body weight per day for older people (>65 years) to maintain and regain lean body mass and function; higher protein intake (i.e., 1.2g/kg body weight/d) for elderly who are exercising and otherwise active.

Older people who have acute or chronic diseases need even more dietary protein (i.e., 1.2-1.5g/kg body weight/d). Sufficient protein of 1.2-1.5g/kg of dry body weight is necessary to maintain or restore lung and muscle strength, as well as to promote immune function in COPD patients and prevent muscle tissue wastage in tuberculosis patients. Similar guidelines were published a year later by the European Society for Clinical Nutrition and Metabolism (ESPEN) Expert group.

Older people with severe kidney disease (i.e., estimated GFR <30 mL/min/1.73m2), but who are not on dialysis, are an exception to the high protein recommendation of 1.2-1.5g/kg body weight/d,and may need to limit protein intake. In critical illness, protein delivery of 2-2.5 g/kg/day is safe and may be optimal for most critically ill patients except for those with refractory hypotension, overwhelming sepsis, or severe liver disease. Deficiency of protein stores and abnormal protein metabolism occur in HIV and AIDS, but no evidence exists for increased protein intake, but with an opportunistic infection, an additional 10% increase in protein intake is recommended.

Protein requirements changes with ageing and vary according to different chronic diseases, decreased absorption, and synthesis.

Protein requirements changes with ageing and vary according to different chronic diseases, decreased absorption, and synthesis.

ORAL NUTRITIONAL SUPPLEMENTS (ONS)

There are different types of ONS available to suit a wide range of needs. ONS vary in styles (milk, juice, yoghurt, savoury), formats (liquid, powder, pudding, pre-thickened), types (high protein, fibre containing, low volume), energy densities (1-2.4kcal/ ml), and flavours. Most ONS provide ~300kcal, 12g of protein and a full range of micronutrients per serving.

The majority of people requiring ONS include the frail, elderly or people diagnosed with dementia, COPD, or cancer. These patients can be managed using standard ONS (1.5-2.4kcal/ml).

High protein ONS are especially suitable for individuals with wounds, post-operative patients, some types of cancer, and the elderly. A high protein ONS can be defined as a supplement containing more than 20% of its energy form protein.

Sources of protein used in supplements differ from manufacturer to manufacturer, but the most popular protein sources used for ONS are soybean and milk proteins (whey and casein).

There are different types of oral nutritional supplements available to suit a wide range of needs.

There are different types of oral nutritional supplements available to suit a wide range of needs.

Conclusion

Malnutrition is associated with decreased muscle function and impaired functional status. Oral nutritional supplementation is a low-risk, cost-effective strategy to meet the protein requirements in the elderly and malnourished patient to limit muscle mass loss during disuse and to improve protein gain during recovery.

There is consistent, good quality evidence demonstrating the beneficial nutritional, functional and clinical effects of ONS in malnourished patients. The evidence also exists to support routinely prescribed protein containing oral nutritional supplements for gastrointestinal surgery patients in the immediate post-operative stage.

Small volume, energy and nutrient dense ONS can therefore be effective to improve nutritional intake and maintaining or improving muscle mass (gain) during recovery.