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Development, validation and implementation of a novel dietary salt monitor in type 2 diabetes in UK

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Babber, Ranjana (2022) Development, validation and implementation of a novel dietary salt monitor in type 2 diabetes in UK. Doctoral thesis, London Metropolitan University.

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Abstract

The risk of cardiovascular morbidity and mortality increases manyfold in Type 2 diabetes, owing to the higher prevalence rates of hypertension. The role of dietary salt intake has been well established in the prevention and management of high blood pressure. However, there is paucity of research interventions and education programme aimed at lowering dietary salt intake in type 2 diabetic population. The aim of this research study is to develop, validate and implement the use of ‘dietary salt monitor’ for reducing dietary salt intake in participants with Type 2 diabetes.

A 24h dietary recall using multiple pass recall method was obtained from the participants with type 2 diabetes and concomitant hypertension (n=50), attending outpatient diabetic foot clinic at NHS hospital in Basildon, Essex. More than a quarter of the participants (28%) consumed salt above the recommended daily limit of <6g. The top ten contributors of salt identified using pivot tables were bread and rolls, processed meats, added salt, ready meals, meat dishes, spreading fats, canned beans, soups, cheese, and sandwiches. An interviewer-administered questionnaire captured the knowledge, attitudes, and practices (KAP) related to dietary salt intake and showed a mean KAP score for the group as 22.6 (SD 6.1) against a maximum achievable score of 40. Poor perception of one’s salt intake; non-practice of reading salt content on nutrition label, frequent addition of salt to food and lack of understanding on daily salt limit and food sources of salt were identified as potential barriers in adherence to the recommended salt intake. The dietary data of these type 2 diabetic participants was further analysed for the development of a novel ‘dietary salt monitor’. It included a short list of 23 food categories that were carefully identified based on its salt density, contribution of salt to the diet, non - achievement of 2017 salt targets, challenges faced by food industry for further salt reduction, foods unrecognised as high in salt by consumers, sustainability, change in cooking practices during COVID-19 and overall nutritional composition of the food category, to fulfil its role as an educational intervention.

The dietary salt monitor was validated against 24h urinary excretions and food records gathered from university students. The Bland and Altman method for agreement between dietary salt monitor and urinary sodium excretion method suggested a bias of 1.5g/ d (upper LOA 7.68 and lower LOA -4.72). The results for cross classification between this tool and urinary biomarker suggested a low level of misclassification (n=1, 11%), but it varied at individual level.

The effectiveness of this dietary salt monitor was pilot tested in an online nutrition education intervention, where type 2 diabetes participants (n=22) were recruited from various online platforms including the Diabetes UK website. This dietary salt monitor was integrated in a web form and supported by a short educational video highlighting the salt content of the food categories and key strategies as ‘4R’s - Reducing portion, Reducing frequent intake, Reduced salt food, Read nutrition label, for lowering salt intake. This short-term intervention study (6 weeks) resulted in a statistically significant reduction in median salt intake for the group, with baseline of 7.9 g/d shifting to 5.2 g/d post the intervention (p=0.001, effect size = 0.6).

This study marked the development of UK’s first dietary salt monitor for use in Type 2 diabetes and is effective for reducing salt intake in this group. The tool is proposed to be further used for monitoring salt intake of these patients in collaboration with their health professionals in NHS, private medical setting and signposted at online platforms as Diabetes UK to reach out to diabetic community, at large.

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