Oral nutritional supplements and the power of taste

Carrie Ruxton PhD, RD, Freelance dietitian, Nutrition Communications

(Article from Dec 2015)

The malnutrition challenge

In a country like the UK, where around 60% of adults are overweight or obese, the issue of undernutrition (often called malnutrition) is surprisingly persistent. While some researchers estimate that 10-45% of patients in the community and up to 60% of inpatients are affected[i] (see references below), others suggest higher estimates due to a lack of systematic monitoring.[ii]

Malnutrition costs the UK around £13 billion annually due to the extra resources needed to support longer hospital stays, slower patient recovery, higher risk of medical complications and increased medication use.[iii] However, a Quality Standard published by NICE[iv] suggested that £71,800 per 100,000 people could be saved through improving screening, assessment, treatment and follow-up of patients at risk of malnutrition.

Oral nutrition support remains the preferred route for addressing malnutrition[v] as it uses the gut, is less invasive than parenteral nutrition or tube feeding and there are lower cost implications. Oral support often features oral nutritional supplements (ONS) which are multi-nutrient liquids, semi-solid or powder products that provide macronutrients and micronutrients with the aim of increasing oral nutritional intake.[vi] The use of ONS has been thoroughly investigated with one systematic review¹ finding a significant benefit for patients in terms of nutritional intake and weight gain/prevention of weight loss. A number of studies also report clinical benefits such as reduced mortality, fewer complications and shorter hospital stay.[vii],[viii],[ix]

Taste and compliance

ONS can only support nutritional status and wellbeing if patients comply with the volume and frequency prescribed. As reviewed by Jin et al.[x] several complex factors influence compliance such as attitudes and beliefs, health literacy, ability to remember, pain, duration of treatment and side effects. For ONS, flavour, taste, texture, and predictability of the supplements all affect compliance¹², with taste being the most important consideration.[xi],[xii]

Estimates of compliance with ONS vary depending on the setting. A systematic review[xiii], which pooled the results of 46 studies involving 4,328 patients, found a mean compliance rate of 78% (range 37-100%), with better figures seen in community settings compared with hospitals. Higher compliance rates are generally reported in studies as opposed to clinical settings, highlighting the positive impact of regular monitoring.

Factors affecting taste

The basic tastes of sweet, sour, salty, bitter and umami (protein) are well known. Chemical stimuli in foods and drinks activate chemoreceptors on the tongue and in the nose which switch on gustatory and olfactory responses. Impulses are then relayed to the brain where they join information about the appearance, texture and temperature of the food.[xiv]. The overall sensory experience is influenced by mood, anxiety and eating environment.t, as well as disease and type of medication.

In later life, the sensitivity of taste buds declines, possibly due to a lower turnover of receptor cells, and olfactory impairment becomes more common. Surveys suggest that 10-24% of elderly people may experience significant loss of taste and smell.[xv]This, in turn, can affect appetite, leading to reducing energy intakes and a greater risk of malnutrition.

Perception of taste linked to age influences ONS preferences. A study comparing younger and older adults found a reduced sensitivity to sweetness in the older age group, although both groups expressed less liking for the sweeter products.[xvi] Other studies have found greater liking for milk-based, rather than for juice-based, products[xvii], while chilling is known to boost acceptability and palatability of ONS.¹⁰

Role of the dietitian

Dietitians have a leading role in supporting good compliance in patients prescribed ONS. A review[xviii] highlighted the benefits of offering individual dietetic counselling and using different flavours of ONS to prevent taste fatigue. Positive healthcare professional (HCP) attitudes also help. A survey of 70 HCPs¹² revealed that, while there was widespread appreciation of the benefits of ONS, most expressed aversion towards the taste and smell of ONS. Such negative attitudes could inadvertently influence patients’ attitudes and compliance.[xix]

Manufacturers have responded to the evidence on taste by refining the sensory characteristics of ONS, developing new products and testing consumer responses. A new CPD resource, supported by an educational grant from Abbott, has also been developed which features a dietitian (Dr Carrie Ruxton), medic (Dr Patricia Macnair), psychologist (Dr Leigh Gibson) and sensory scientist (Dr Tracey Hollowood). The video explores the psychology of taste, the role of sensory science and the clinical application of taste, as well as providing training, and practical insights. The resource, which includes CPD questions, has been endorsed by the British Dietetic Association for Continuing Professional Development and can be found at www.abbottnutrition.co.uk/support-and-tools/power-of-taste-elearning/ 

Conclusion

Malnutrition is an ongoing issue for HCPs and patients. Improved compliance with ONS, where prescribed, can help to improve patients’ nutritional status. Taste, acceptability and HCP attitudes towards treatment can all influence ONS compliance.