UCL Research Domains


Dietary Adherence in Chronic Conditions

Dr Brian Power, 23 April 2018


People will choose foods that they want to eat. People with chronic conditions such as coeliac disease and kidney disease are not different. Food choices and overall dietary patterns play a key health improving role in these chronic conditions [1,2]. Following a dietary pattern in the context of a chronic condition is, therefore, particularly important. There are several different terms that are used to describe how people with long-term health conditions 'follow' a dietary pattern. These include compliance, concordance and conformance [3]. Adherence, which is the focus of this article, is another. It is the preferred term due to its emphasis on the need for agreement between patient and practitioner. Adherence is defined by the World Health Organisation as 'the extent to which a person's behaviour - following a diet and/or executing lifestyle changes - corresponds with agreed recommendations from a health care provider' [4]. On average, approximately half of people across diverse long-term health conditions stick to dietary advice [4,5,6]. Although the extent of non-adherence reported varies considerably, partially due to diverse definitions and the use of subjective self-reported information. The consequences of non-adherence to dietary advice include reduced clinical benefit, avoidable morbidity and mortality and increased waste in healthcare spending [7].

Understanding what makes dietary adherence difficult and challenging and how to bring about improvements is required. To tackle the problem, it is necessary to understand the varying types and causes of non-adherence. Strategies can then be tailored accordingly. A lot of people talk about sticking to a dietary pattern like it's a muscle that they can somehow control. However, dietary non-adherence can be 'intentional' and 'unintentional' [8]. Unintentional involves practical barriers, such as poor communication between the patient and their healthcare professional - and intentional non-adherence occurs when the patient's perceptions, such as illness and treatment beliefs and motivations, lead to non-adherence. 

Early exploratory work in dietary non-adherence tended to focus on patient-healthcare professional communication [9]. Specifically, the effect of this communication on peoples' understanding, satisfaction and memory as key factors underpinning dietary non-adherence. But this obscures many truths about this crucial behavioural process. The thinking in this area continues to evolve. More recent fruitful work has switched the focus to peoples' motivations, opportunities and capabilities as dynamic components affecting dietary non-adherence. For instance, studies in long-term health conditions indicate confidence and social support may play a key role in adherence to dietary recommendations [10]. Several other unique factors such as social eating occasions, taste and dietetic staffing also play a role in dietary adherence [11]. 

Implications for practice

As life expectancy increases, the number of people managing their long-term health condition is expected to grow. The problem of people not following recommended dietary changes may well become worse in the next few years. The body of evidence described above opens new routes by which dietary adherence among those with a long-term health issue may be appreciably improved. 

Dr Brian Power is a Lecturer at the UCL Institute for Liver and Digestive Health, in the Faculty of Medicine. He is also a member of the Food, Metabolism and Society Domain.


1. Micha R, Peñalvo JL, Cudhea F, Imamura F, Rehm C, Mozaffarian D. Association between dietary factors and mortality from heart disease, stroke, and type 2 diabetes in the United States. JAMA. 2017;317(9):912-24.

2. Romagnolo D, Selmin OI. Mediterranean diet and prevention of chronic diseases. Nutr. Today. 2017;52(5):208-222.

3. Horne R, Weinman J, Barber N, Elliott RA, Morgan M: Concordance, adherence and compliance in medicine taking: a conceptual map and research priorities. 2005, London, National Co-ordinating Centre for NHS Service Delivery and Organisation NCCSDO.

4. Sabaté E. Adherence to long-term therapies. Evidence for action. 2003, Geneva, Switzerland: WHO.

5. Mellen PB, Gao SK, Vitolins MZ, Goff Jr DC. Deteriorating dietary habits among adults with hypertension: DASH dietary accordance, NHANES 1988-1994 and 1999-2004. Arch Intern Med 2008;168:308-314.

6. Luis D, Zlatkis K, Comenge B, et al. Dietary quality and adherence to dietary recommendations in patients undergoing hemodialysis. J Ren Nutr. 2016;26:190- 195.

7. Lovik A, Skodje G, Bratlie J, Brottveit M, Lundin K.E. Diet adherence and gluten exposure in coeliac disease and self-reported non-coeliac gluten sensitivity. Clin Nutr. 2017;36:275-280.

8. Yu ZL, Lee VY, Kang AW, Chan S, Foo M, Chan CM, et al. Rates of intentional and unintentional nonadherence to peritoneal dialysis regimes and associated factors. PLoS One 2016; 11(2):e0149784.

9. Ley P. Communicating with patients: Improving communication, satisfaction and compliance. 1988. New York: Croom Helm.  

10. Michie S, Atkins L, West R. The behaviour Change Wheel: A Guide to Designing Interventions, 1st edn. 2014; London: Silverback.

11. Lambert K, Mullan J, Mansfield, K. An integrative review of the methodology and findings regarding dietary adherence in end stage kidney disease. BMC Nephrol. 2017;18:318.