Beyond sodium: nutritional status in heart failure

This invited commentary refers to ‘Sex differences in the nutritional status and its association with long-term prognosis in patients with heart failure with reduced ejection fraction - a prospective cohort study’, by M. Kaluzna-Oleksy et al., https://doi.org/10.1093/eurjcn/zvad105. Despite significant advances in the pharmacological management of heart failure (HF), particularly for those with reduced ejection fraction, outcomes remain poor.1 The majority of patients continue to present to the hospital with advanced signs and symptoms of HF,2 and 30-day post-discharge mortality has not significantly improved.2,3 As HF is the likely end stage of any structural and/or functional cardiac disease,1 its prevalence will inevitably rise as the population of older adults living with co-morbidity increases worldwide.4 A multidisciplinary approach to treatment, which goes beyond pharmacology, is therefore needed. Researchers seeking to optimize outcomes are increasingly looking to nutrition, given the pleiotropic effects it is likely to exert.5 Nutrition in general cardiovascular health has focused mostly on secondary prevention and tackling hypertension and diabetes. Strategies to prevent these diseases are fundamental to mitigate the burden of HF, regardless of the phenotype.6,7 Specific to HF, there is evidence that following a healthier dietary pattern is associated with lower risk of HF and preservation of cardiac function.8 Healthy eating patterns, like the dietary approaches to stop hypertension (DASH) diet, show promise in both preventing and managing HF.6,9 Adverse nutritional statuses, like malnutrition, cachexia, and obesity, have been associated with poorer outcomes.10,11 Emerging evidence suggests that, even in these cases, outcomes may be improved through personalized dietary interventions.12,13 Most patients with HF are deficient in micronutrients due to poor dietary intake and diuretic-related losses. The benefits of iron supplementation, particularly when administered intravenously, are well accepted in the literature and have been widely translated into clinical practice.14 Multiple micronutrient supplementation has also been slowly gaining attention, with promising improvements reported in symptoms, physical function, and even ejection fraction.15 Lastly, the gut microbiome is an increasingly ‘hot topic’. Emerging evidence suggests that systemic inflammation, an important pathophysiological driver of HF, can be caused by disruption of the gut microbiota. Nutritional approaches, for example pre- and probiotics, may offer therapeutic benefit, although, to date, few have been tested.16 Despite mounting evidence of the role and potential of nutrition in HF, the field continues to be marred by small studies of varying quality, which are difficult to replicate or implement in clinical practice.7 Unexpected findings, which challenge the established orthodoxy, have additionally stymied progress in enshrining nutrition as a core component of HF care. For example, the protective effect of obesity in advanced HF, a phenomenon known as the ‘obesity paradox’, might have led to reticence towards recommending weight loss.17 A recent publication demonstrating that the paradox disappears with the use of more modern anthropometric measurements, like waist-to-hip ratio, further muddies the water.18 The lack of efficacy of sodium restriction in reducing HF hospitalizations has also caused controversy, especially given its pathophysiological plausibility. Setbacks have resulted from the retraction of a high-profile review, over concerns about conduct, duplicate data in two trials, and confounding.19 The recent SODIUM-HF trial, which sought to end the debate, concluded salt restriction did not reduce mortality or morbidity; however, there was a promising signal suggesting improved quality of life.20 Small trials, controversial findings, and poor application to clinical practice mean concrete recommendations are difficult to derive. A fact reflected in HF guidelines across the world, which present only limited recommendations on management of underlying nutrition disorders.1,21 In this issue of the European Journal of Cardiovascular Nursing, Kaluzna-Oleksy et al.22 report the results of their prospective analysis of nutritional status in heart failure and reduced ejection fraction (HFrEF). The authors assessed the nutritional status of 276 HFrEF patients via three established methods: the Mini Nutritional Assessment,23 Geriatric Nutritional Risk Index,24 and body mass index (BMI). They then explored sex differences in nutritional status and predictors of all-cause mortality by sex. In this cohort, most patients (50.7%) were either at risk of or were overtly malnourished. Regardless of sex, impaired nutritional status, as assessed by any of the three methods, was not significantly associated with a worse prognosis. Kaluzna-Oleksy et al.22 rightly caution readers against reading too much into these exploratory findings and carefully detail the shortcomings of the analysis. However, the research does raise some important points. Firstly, it highlights the role of nutrition in HF, which is typically restricted by time pressures and knowledge limitations, to an assessment of sodium and fluid intake.25 Secondly, it adds further weight to the body of evidence on the prevalence of malnourishment or malnutrition risk in HFrEF. Thirdly, it highlights the lack of consensus within clinical practice around which nutritional screening tools and anthropometric measures should be used. Heart failure has an unpredictable disease trajectory often marked by fluid overload stages. When presenting with an underlying nutrition disorder, assessing and managing malnutrition are even more challenging. Greater appreciation of the role of nutrition in HF outcomes is essential. Publications like this one from Kaluzna-Oleksy et al.22 serve to remind us that we need to move away from the reductionist view that ‘nutrition in HF equals sodium restriction’. None declared. Not applicable. No new data were used in this invited commentary.