Increasing ONS Compliance

June 02, 2021 8 min read

Oral nutritional supplements (ONS) are a clinically and cost-effective way to manage disease-related malnutrition.¹, ², ³ The effectiveness of ONS, however, depends on adequate consumption. It is important to achieve good ONS compliance to improve nutritional outcomes and quality of life, and to reduce healthcare costs.², ¹, ⁵

Patient preference plays an important role in ONS compliance.⁶, ⁷ Dietitians should consider this when prescribing ONS; offering suitable alternatives (e.g. juice-style ONS) to milk-based ONS when consumption is not sufficient to meet nutritional goals.

In this article we will explore the role of sensory experiences, such as taste, in influencing patient preference and ONS compliance. We will also discuss practical strategies for using a juice-style ONS product in clinical practice.


Sensory experiences & ONS compliance

A patient’s sensory experience of ONS should not be overlooked when exploring reasons for non-compliance.

Flavour, palatability and texture of ONS all affect compliance.⁸, ⁹ A prospective analysis exploring potential barriers to ONS compliance following upper gastrointestinal surgery found that 64.1% of patients did not comply with their prescribed ONS regimen.¹⁰ Interestingly, flavour or texture dislike was cited as a common reason for non-compliance.¹⁰

Other studies have reported reasons for poor ONS compliance relating to sensory experiences include:

  • Dislike for/health beliefs against milk-based drinks¹¹
  • Unpleasant sensory properties (including thickness and orosensory mouth feel) of ONS¹², ¹³
  • Dislike of available flavours.¹², ¹³

A recent qualitative study explored dietitians’ experiences of prescribing ONS for patients with disease-related malnutrition. Patient acceptance was described as ‘challenging’ and was highlighted as the primary factor determining ONS compliance. The dietitians interviewed described individuals’ preferences as being ‘very diverse’.¹¹ Patient acceptance and involvement, in combination with dietitian flexibility, were expressed as essential when prescribing ONS.¹¹


Taste & ONS compliance

Taste is an important feature influencing both oral intake and ONS compliance.¹⁵, ¹⁶, ¹⁷ Taste can promote appetite for certain foods and also influences sensory-specific satiety (a decline in satisfaction, or taste fatigue, generated by the consumption of a food relative to exposure to a new flavour/food)¹8 Taste also affects palatability, which stimulates hunger and increases food intake.¹⁹ Therefore, taste can affect the motivation to continue or stop further food or drink consumption.¹⁹


Taste fatigue

Prolonged and repeated consumption of ONS is associated with taste fatigue and low ONS compliance rates.²⁰-²³ A qualitative study interviewed 89 patients who had been prescribed ONS by their GP.²⁴ Almost half of the interviewees (48%) self-reported non-compliance with their ONS prescriptions. The most frequently reported reasons for non-compliance included patient boredom/tiredness of ONS product, and/or a dislike of available flavours.²⁴

Offering a variety of different flavours could be used as a strategy to improve ONS compliance. Supporting this, a systematic review of 50 studies looking at compliance to ONS found that offering patients a variety of ONS products and flavours improves compliance.⁵ Studies that used a variety of ONS flavours resulted in a high mean ONS compliance rate of 81%.⁵


Taste changes during treatment/illness

Taste impairments (dysgeusia) may result in complete taste losses (ageusia), partial reductions in taste (hypogeusia), changes in taste perception (parosmia) or hypersensitivity of the sense of taste (hypergeusia). These impairments can lead to appetite loss, which is a risk factor for malnutrition.¹⁵, ²⁵

Taste changes during treatment/ illness are an important feature when considering ONS compliance. Taste alterations are common, for example, in cancer patients as a result of systemic therapy.²⁶ One study of cancer patients undergoing chemotherapy found that the prevalence of taste alterations were as high as 69.9%. A significant association was found between taste alterations and a change in patient's quality of life, appetite and fatigue.²⁷

There is a lack of evidence for effective treatments for alleviating taste changes. However, a qualitative interview study of seventeen people with lung cancer described the strategies they used to deal with taste changes.²⁸ Almost all participants reported experimenting with different flavours and tastes, making food and drink substitutions and avoiding unpleasant tastes and smells.²⁸

Patients recovering from COVID-19 can also be affected by taste changes. A recent meta-analysis of eighteen studies suggests that nearly half (47%) of patients with COVID-19 experience some alteration to their sense of smell or taste.²⁹ It is recommended that an ONS prescription for a patient recovering from COVID-19 should be tailored to their flavour preferences and should consider the patient’s physical function.³⁰

In summary, offering a variety of forms of ONS, such as juice-style ONS, in different flavours, may help to improve ONS compliance in patients with taste changes and/or taste fatigue.


Juice-style ONS – practical strategies for clinical practice

Choosing a juice-style ONS offers a useful and refreshing alternative to milk-based ONS. Here are some evidence-based strategies which may help to address the issues of taste fatigue and poor ONS compliance:

  • Implement shared decision-making

    Discuss patient preferences relating to ONS. Research has shown that allowing patients to taste an average of four different types of ONS products before prescription, and involving them in the choice of flavours, has been associated with a high compliance rate (adherence rates of over 75%).³¹ It is recommended to test preferences and compliance with a prescribable ‘starter pack’ which offers a range of products/flavours and/or samples.³²

  • Regularly review patients

    Regularly monitor and review patients on ONS to assess compliance and flavour preferences. Dietitians should adjust ONSprescriptions accordingly, as part of a patient-centred approach to care.³³

  • Mix it up

    Offer a variety of flavours and styles of ONS to prevent taste fatigue.5 Rather than a complete switch in ONS, consider small and manageable changes to ONS prescriptions (i.e. switching from standard RTD milk-based ONS three times per day to standard RTD milk-based ONS twice per day and juice-styleONS once per day).

  • Implement innovative serving options

    There are plenty of interesting and innovative ways to serve juice-style ONS. You could experiment with different temperatures (e.g. freezing into ice lollies or making into jellies during summer, or serving it as a warmed drink during winter).³⁴



ONS are an effective way of managing disease-related malnutrition when taken as prescribed.

ONS compliance can be poor due to a number of factors such as patient preference, sensory experiences and taste fatigue.

Strategies to improve ONS compliance include offering a variety of different types of ONS (formats and flavours), as well as putting the patient at the heart of ONS prescribing decisions, which is an important part of patient-centred care. Dietitians should recognise that juice-style ONS are a useful addition to an ONS regimen – especially for patients who do not like milk-based drinks and to prevent/overcome taste fatigue.


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