Improving adherence to oral nutritional supplements in clinical practice: a practice pattern for a holistic person-centred approach

Background

Disease-related malnutrition is increasingly recognised as an unwanted consequence of acute and chronic disease.¹ A range of guidelines within different clinical fields and settings recommend the use of oral nutritional supplements (ONS) as part of nutrition therapy for disease-related malnutrition, when food-based strategies alone are insufficient.2,7 Using ONS within nutrition therapy has also proven to be cost-effective.8,10 A common approach in most guidelines is to state that ONS should be initiated without focusing much on how best to do this.^{4 5} There are guidelines that include some descriptions on how to prescribe ONS,^{2 3 7} for example, to take patient preferences into account,² but these guidelines focus on the broader concept of malnutrition treatment and do not comprehensively cover all aspects of ONS adherence. Also, in nutrition intervention studies, fixed doses of ONS are commonly used,¹¹ whereas individualised dosages are more in line with a person-centred care (PCC) approach. Hence, guidance is needed on how ONS should be prescribed to optimise ONS consumption and adherence, to support clinical practice.

Adherence is defined as ‘The extent to which a person’s behaviour—taking medication, following a diet and/or executing lifestyle changes—corresponds with agreed recommendations from a healthcare provider’ (Sabaté, p3).¹² The terms adherence and compliance are often used interchangeably in the literature.¹¹ Adherence can be difficult to achieve, especially in chronic conditions where therapy is needed for longer periods.¹² Optimising adherence to ONS is important, since beneficial effects on nutritional intake and nutritional status are dependent on patients’ consumption of ONS.^{13 14} The WHO recognises the need for a systems approach when addressing adherence to long-term therapies.¹² This system approach looks beyond the individual patient and addresses aspects of the healthcare system, including incentives for healthcare professionals.

In the present practice pattern, guidance is given on how to improve adherence to ONS in order to reach the desired outcomes of nutrition therapy. It is designed for dietitians and other healthcare professionals who are responsible for the nutrition therapy of patients with or at risk of malnutrition, who need ONS. A holistic approach is required, since it is necessary for the entire healthcare system, at all levels, to work on resolving issues related to ONS adherence.

Proposed practice pattern

The practice pattern consists of two parts. Part one includes a step-by-step procedure which focuses on the individual level: the encounter between the patient and the healthcare professional responsible for the ONS prescription (figure 1). Part two focuses on how adherence to ONS can be facilitated on the organisational and system level (figure 2). This practice pattern is in line with descriptions of ‘appropriate prescribing of ONS’^{15 16} and ONS prescribing in ‘managing adult malnutrition in the community’.⁷ These resources cover the whole process of the ONS intervention (assessment, initiation, monitoring, discontinuation), while our practice pattern is designed for use after nutrition assessment has shown that a clinical indication for ONS exists and/or the patient fulfils any local prescribing criteria. The practice pattern does not include guidance on the clinical decision process on whether to include ONS in the nutrition therapy, or when to discontinue the prescription. Yet, it gives a comprehensive description of how to encourage adherence to therapy.

Figure 1. Step-by-step procedure for improving adherence to oral nutritional supplements (ONS) on the individual level. Created in BioRender. Einarsson, S. (2025). https://BioRender.com/izcc0k0. ¹This should be done in parallel to considering patient nutritional requirements, that is, energy and nutrient needs. ²For patients needing long-term use of ONS, regular follow-up is important to consider any adjustments to the ONS prescription that may aid long-term adherence.

Figure 2. Factors on the organisational and system level that facilitate adherence to oral nutritional supplements (ONS) in clinical practice. Created in BioRender. Einarsson, S. (2025) https://BioRender.com/d86q006.

Evidence supporting the practice pattern

This practice pattern was developed by combining insights from scientific evidence and PCC principles. The specific recommendations within the proposed practice pattern are supported by evidence from our recent systematic mixed-studies review, that identified 59 barriers and facilitators to adherence to ONS among patients with disease-related malnutrition or at risk of malnutrition.¹⁷ Additionally, two other systematic reviews on the same topic focusing on older adults¹⁸ and patients living with cancer¹⁹ support parts of the practice pattern. While an extensive amount of quantitative and qualitative research studies contributed to the findings in those reviews, no meta-analysis could be performed.17,19 Therefore, the evidence supporting this present practice pattern is the current best recommendations but will need to be updated as new evidence is identified.

This practice pattern also advocates using a PCC approach when ONS are prescribed. PCC means that ‘patients should be treated as persons, with respect and dignity, and that care should take into account their needs, wants and preferences’ (Nolte et al p22–24).²⁰ This practice pattern endorses using a PCC approach since (1) this was identified as a facilitator to ONS consumption in our review¹⁷ and (2) healthcare decisions should be taken by healthcare professionals together with the person affected by them, regardless of their impact on health or care outcomes, as patient involvement is important by principle.^{20 21}

Evidence supporting part one of the practice pattern: the individual level

When nutrition assessment indicates that the patient fulfils the criteria for ONS prescription, the nutrition intervention phase starts with discussing the need for and expectations of a nutrition intervention, followed by a discussion about goals and preferences (Step 1). During this discussion, awareness of health consequences of malnutrition can be explored since misconceptions can hinder intervention implementation while individualised information can support patient motivation and capability.¹⁷ However, caution should be applied when using the term ‘malnutrition’ since it can easily be misunderstood by patients and healthcare professionals.²² In line with PCC, shared decision-making should be employed when setting goals and when deciding if ONS should be included within the nutrition therapy (Step 2).^{23 24}

When a shared decision has been taken to start with ONS, the prescription should be individually tailored (Step 3),¹⁷ that is, the nutritional care should be responsive to and meet patients’ needs and preferences.²⁵ This should be done in parallel with considering patient nutritional requirements, that is, energy and nutrient needs. Individually tailored ONS prescription includes providing ONS samples, offering a variety of flavours, planning the timing of ONS intake and deciding on the type of ONS product and the amount to be taken daily.17,19 Previous research suggests that liquid format and ready-made ONS¹⁷ in a small volume/with high energy density^{13 17 26} may facilitate adherence, whereas excessive volume may be a barrier.^{17 19} Previous research further supports ‘in between meals’ as the preferred time for taking ONS.²⁶

To further support adherence, the ONS prescriber should discuss and inform patients on the optimal serving style and preferred consumption method for the ONS, for example, to inform patients that ONS can be served chilled, or mixed with other ingredients to alter/enhance flavour, or served in small doses (eg, together with medication administration rounds for inpatients) (Step 4).^{17 18 27} Identifying preferred personal consumption methods may be important for all patients, but perhaps most important for older adults.¹⁸ For example, previous research has found mixed results regarding older adults, with some preferring to drink the ONS from the bottle using a straw,²⁸ while others prefer it served in a glass or beaker.²⁹ The practice pattern further recommends supporting patients with strategies to counteract any ONS-related side effects (Step 5), since this has been described as a central barrier to ONS adherence in previous research.¹⁷ The ONS prescriber should also consider any age-related physiological changes such as olfactory impairments or sensory decline that can alter the perception of ONS in older adults.¹⁸

The last step (Step 6) of the individual-level recommendations highlights the importance of meeting the patient regularly —by phone, face-to-face or during home visits—to follow-up on the ONS prescription (reassessing and revisiting steps 1—5, if needed).¹⁷ The evidence also confirms that adherence to ONS often declines over time, especially among patients with cancer.¹⁷ Consequently, a long treatment duration should be avoided if possible. For patients needing long-term treatment with ONS, regular follow-ups are important to consider any adjustments to the ONS prescription that may aid long-term adherence, for example, to offer alternative flavours, textures or ONS formats.

It is important that healthcare professionals have sufficient knowledge and skills about disease-related malnutrition and its interventions, and adopt a supportive and encouraging attitude during the whole encounter, to support ONS adherence.¹⁷ Healthcare professionals should avoid ambiguity regarding ONS and instead recognise the significance of presenting the ONS in a positive manner to the patient, and refrain from negative comments about the product, to facilitate adherence.^{17 18} Social support from family and friends can also facilitate adherence to ONS, and persons close to the patient should be invited to participate in healthcare encounters and the nutrition intervention, if this is in line with patient wishes.^{17 18}

Evidence supporting part two of the practice pattern: the organisational and system level

Existing evidence supports the notion of adequate nutrition policies within the organisation to aid ONS adherence. One example of successful routines in the inpatient setting is the so-called ‘Nutrition As Medication’ (NAM) programme or ‘Medication Pass Nutritional Supplement Programme’ (MEDPass), which means serving ONS in small amounts during medication rounds.^{17 18 27} Adequate staffing levels and a low number of temporary staff may support ONS consumption,¹⁷ since previous research has shown that limited staff time might lead to a down-prioritisation of nutrition-related tasks.^{30 31} In addition, failure to deliver ONS to patients can also constitute a barrier for ONS adherence.¹⁷ Older adults in nursing homes rely entirely on staff/carers to ensure that ONS is fully accessible to them.¹⁸ Routines on wards may restrict when ONS can be delivered to the patient, for example, if ONS are delivered during mealtimes instead of between meals.³⁰ The practice pattern also highlights the importance of a reliable delivery system for the transporting of ONS products to the patient’s home,¹⁷ which is particularly important for frail patients.³²

Existing evidence further emphasises the importance of institutional routines that support nutrition information transfer when patients are relocated to, for example, another ward at the hospital, from the hospital to a nursing home or from the hospital to the home setting.¹⁷ Previous research further highlights the importance of interprofessional collaboration and nutrition support teams to aid ONS adherence.^{17 19} More specifically, it is vital for different healthcare professionals to align their clinical practice related to disease-related malnutrition and how they communicate their nutritional interventions to each other and to the patient.^{30 33}

On the organisational and system level, cost and product availability are also factors to consider in relation to adherence to ONS prescription.¹⁷ In different types of studies, the patient fee for ONS is considered highly important for patients as it impacts on usage and adherence.3034,36 The economic system within healthcare varies considerably between settings and countries,36,38 which may create different conditions for patients in relation to the prescription as well as ONS usage. In addition, a variety of available ONS products is important to allow for individual tailoring and meeting individual preferences.^{16 39}

Summary and perspective

Adherence to nutrition therapy with ONS involves a multitude of factors related to the individual as well as the organisational and system level. Solely concluding that a patient meets the criteria for ONS prescription is not enough; healthcare professionals need guidance on how to support adherence. The current practice pattern encourages healthcare professionals to have a holistic person-centred care approach when prescribing ONS, to consider patients’ needs and preferences in order to support patient adherence to ONS, which consequently will facilitate desirable outcomes from nutrition therapy.

Data availability statement

All data relevant to the study are included in the article or uploaded as supplementary information.