Protocol for a randomised controlled trial on the feasibility and effects of 10-hour time-restricted eating on cardiometabolic disease risk among career firefighters doing 24-hour shift work: the Healthy Heroes Study

Efficacy of Time-Restricted Eating and Behavioral Economic Intervention in Reducing Fasting Plasma Glucose, HbA1c, and Cardiometabolic Risk Factors in Patients with Impaired Fasting Glucose: A Randomized Controlled Trial

This randomized controlled trial is aimed at assessing the efficacy of combining time-restricted eating (TRE) with behavioral economic (BE) interventions and comparing it to TRE alone and to the usual care for reducing fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), and other cardiometabolic risk factors among patients with impaired fasting glucose (IFG). Seventy-two IFG patients aged 18-65 years were randomly allocated for TRE with BE interventions (26 patients), TRE alone (24 patients), or usual care (22 patients). Mean FPG, HbA1c, and other cardiometabolic risk factors among the three groups were compared using a mixed-effect linear regression analysis. Mean body weight, FPG, HbA1c, fasting insulin, and lipid profiles did not significantly differ among the three groups. When considering only patients who were able to comply with the TRE protocol, the TRE group showed significantly lower mean FPG, HbA1c, and fasting insulin levels compared to the usual care group. Our results did not show significant differences in body weight, blood sugar, fasting insulin, or lipid profiles between TRE plus BE interventions, TRE alone, and usual care groups. However, TRE might be an effective intervention in lowering blood sugar levels for IFG patients who were able to adhere to the TRE protocol.

Effect of a Nutrition Intervention on Mediterranean Diet Adherence Among Firefighters: A Cluster Randomized Clinical Trial

Importance

US firefighters are a working population at risk of chronic diseases, including obesity, cardiovascular disease, and cancer. This risk may be mitigated by a healthy diet.

Objective

To evaluate the effect of a Mediterranean nutrition intervention using a behavioral/environmental approach (firefighter/fire station/home) at the individual participant level.

Design, Setting, and Participants

This 12-month cluster randomized clinical trial included US career firefighters from fire stations and homes within 2 Indiana fire departments. Participants were randomized by fire station to either Mediterranean diet or control (usual care). The study was conducted from October 2016 to December 2019, and data were analyzed in November 2022.

Intervention

For the first 12 months of the study, firefighters located at fire stations randomized to the intervention group were provided with access to supermarket discounts and free samples of Mediterranean diet foods, online nutrition education platforms, email announcements and reminders, family and peer education and support, and chef demonstrations. Firefighters in fire stations allocated to the control group received no intervention and were instructed to follow their usual diet.

Main Outcomes and Measures

Change in dietary habits at 12 months as measured by a modified Mediterranean diet score (range, 0 to 51 points) at baseline and 6-month and 12-month follow-up. Cardiometabolic parameters were secondary outcomes.

Results

Of 485 included firefighters, 458 (94.4%) were male, and the mean (SD) age was 47 (7.5) years. A total of 241 firefighters (27 fire stations) were randomized to the Mediterranean nutrition intervention, and 244 (25 fire stations) were randomized to usual diet. Outcomes were analyzed using generalized linear mixed models for modified Mediterranean diet score at 6 months (n = 336) and 12 months (n = 260), adjusting for baseline age, sex, race and ethnicity, fire department, physical activity, and waist circumference. In the intervention group compared with the control group, the modified Mediterranean diet score significantly increased by 2.01 points (95% CI, 0.62-3.40; P = .005) at 6 months and by 2.67 points (95% CI, 1.14-4.20; P = .001) at 12 months. Among secondary outcomes, changes in cardiometabolic risk factors were not statistically significant at 1 year. Results from analyses with multilevel multiple imputation for missingness were similar.

Conclusions and Relevance

In this Mediterranean nutrition intervention of multicomponent behavioral/environmental changes, career firefighters had increased adherence to a Mediterranean diet.

Trial Registration

ClinicalTrials.gov Identifier: NCT02941757.

Circadian clock and temporal meal pattern

The central circadian clock in the brain controls the time-of-the-day variations in acute meal responses, with a low glycemic response but a high satiety/thermogenic response to meals consumed at waking compared to other time points. Consistently, studies show that consuming a significant proportion of calories, particularly carbohydrates, in breakfast is beneficial for the chronic management of obesity and its associated metabolic syndrome, compared to consuming identical meals at dinner. Conversely, breakfast skipping or/and late dinner can have unfavorable metabolic outcomes. It remains controversial how meal frequency affects metabolic health. In contrast, irregular meals, especially irregular breakfasts, show consistent adverse metabolic consequences. Time-restricted feeding (TRF), with all calories consumed within less than 12-h per day, can improve metabolism and extend lifespan. A major component of TRF in humans is caloric restriction, which contributes significantly to the beneficial effects of TRF in humans. By comparison, TRF effects in rodents can be independent of caloric restriction and show day/night phase specificity. TRF could alleviate metabolic abnormalities due to circadian disruption, but its effects appear independent of the circadian clock in rodents. Understanding neuroendocrine mechanisms underlying clock-mediated metabolic regulation will shed light on the metabolic effects of temporal meal patterns.

Feasibility of time-restricted eating and impacts on cardiometabolic health in 24-h shift workers: The Healthy Heroes randomized control trial

Over a quarter of the workforce in industrialized countries does shift work, which increases the risk for cardiometabolic disease. Yet shift workers are often excluded from lifestyle intervention studies to reduce this risk. In a randomized control trial with 137 firefighters who work 24-h shifts (23-59 years old, 9% female), 12 weeks of 10-h time-restricted eating (TRE) was feasible, with TRE participants decreasing their eating window (baseline, mean 14.13 h, 95% CI 13.78-14.47 h; intervention, 11.13 h, 95% CI 10.73-11.54 h, p = 3.29E-17) with no adverse effects, and improved quality of life assessed via SF-36 (ClinicalTrials.gov: NCT03533023). Compared to the standard of care (SOC) arm, TRE significantly decreased VLDL particle size. In participants with elevated cardiometabolic risks at baseline, there were significant reductions in TRE compared to SOC in glycated hemoglobin A1C and diastolic blood pressure. For individuals working a 24-h shift schedule, TRE is feasible and can improve cardiometabolic health, especially for individuals with increased risk. VIDEO ABSTRACT.

Efficacy of time-restricted eating and behavioural economic interventions in reducing fasting plasma glucose, HbA1c and cardiometabolic risk factors compared with time-restricted eating alone or usual care in patients with impaired fasting glucose: protocol for an open-label randomised controlled trial

INTRODUCTION

Impaired fasting glucose (IFG) is a significant risk factor for diabetes mellitus. Time-restricted eating (TRE) is one type of diet showing positive effects on metabolic signal pathways. However, effects of TRE on cardiometabolic risk factors in humans are limited. Additionally, compliance with TRE remains problematic despite having intention to follow the diet control. Therefore, this study aims to investigate the efficacy of TRE with behavioural economic interventions or TRE alone relative to usual care, in reducing fasting plasma glucose (FPG), haemoglobin A1c (HbA1c) and other cardiometabolic risk factors in patients with IFG.

METHODS AND ANALYSIS

This parallel-group, open-label randomised controlled trial will be conducted at the outpatient clinic of the Department of Family Medicine, Faculty of Medicine, Ramathibodi Hospital, Bangkok, Thailand. Patients aged 18-65 years with IFG defined as FPG 100-125 mg/dL and body mass index ≥25 kg/m² will be recruited between October 2021 and October 2022. Patients will be randomly allocated to three groups (1:1:1 ratio) as (1) TRE with behavioural economic interventions including financial incentives and text reminders, (2) TRE alone or (3) usual care. The number of participants will be 38 per group (a total of 114). The duration of the intervention will be 12 weeks. Primary outcome is FPG levels measured at 12 weeks after randomisation. Secondary outcomes are HbA1c, body weight, systolic and diastolic blood pressure, fasting insulin, serum triglyceride, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and high-sensitivity C reactive protein. P value of <0.05 of two-sided test will be considered as statistical significance.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Ethics Committee of the Faculty of Medicine, Ramathibodi Hospital, Mahidol University (MURA2021/389). All patients will be informed about the details of the study and sign written informed consent before enrollment in the study. Results from this study will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

TCTR20210520002.

Christmas and New Year “Dietary Titbits” and Perspectives from Chronobiology

A historical Christmas card connecting two pioneers of modern chronobiology (Colin Pittendrigh and Jürgen Aschoff) brings together key evolutionary facets of the field at Christmas time. The importance of the field to physiology and medicine is conveyed by the Nobel Prize award in 2017 for discoveries of how body clocks facilitate the temporal organization of physiology across days and nights. Temporal organization can have relevance for dietary Christmas excesses and dietary New Year resolutions. Herein, we examine how diet around Christmas and New Year has been targeted in human health research and we examine published opinion on dietary practice concerning Christmas and New Year using a systematized literature review approach. Thereafter, via a selective literature synthesis regarding time-restricted eating, we explore the chronobiological notion that “when” we eat and drink may make differences in terms of whether we experience weight gain and adverse health effects during and after the festive days. Overall, current Christmas eating is typically detrimental to health in terms of “how much” we consume of “what”. Regarding New Year’s goal-setting, chronobiology-based advice could be considered insofar as “when” we eat may be a healthier and more sustainable nutritional habit alternative. While we need further studies in humans, individual and public health may benefit during and after Christmas by adhering to plausible principles of chrononutrition. That detrimental nutritional excesses over Christmas may encourage individuals to tackle their eating habits should not be left untapped.

The Relationship Between Dietary Intake and Dietary-Focused Lifestyle Interventions on Risk Factors Associated with Cardiovascular Disease in Firefighters

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is the leading cause of death to on-duty firefighters and is a substantial health concern. Preventative measures, including dietary interventions, may improve CVD in firefighters. The purpose of this review is to examine the literature on the relationship between dietary intake, dietary lifestyle interventions, and risk of CVD in firefighters.

RECENT FINDINGS

Existing evidence, albeit limited, suggests that firefighters do not meet dietary guidelines. Lifestyle modifications featuring dietary interventions are effective in improving risk factors associated with CVD in firefighters. Unfortunately, no consistent nutrition-related trend was identified across the retrieved studies and only a limited number of randomized controlled trials have examined the efficacy of lifestyle intervention studies on CVD in firefighters. Although this review suggests dietary lifestyle interventions may facilitate decreases in risk factors associated with CVD in firefighters, current evidence is limited, and additional research is needed.

A Time to Rest, a Time to Dine: Sleep, Time-Restricted Eating, and Cardiometabolic Health

Cardiovascular disease (CVD) poses a serious health and economic burden worldwide. Modifiable lifestyle factors are a focus of research into reducing the burden of CVD, with diet as one of the most investigated factors. Specifically, the timing and regularity of food intake is an emerging research area, with approaches such as time-restricted eating (TRE) receiving much attention. TRE involves shortening the time available to eat across the day and is associated with improved CVD outcomes compared with longer eating windows. However, studies that have examined TRE have not considered the impact of sleep on CVD outcomes despite recent evidence showing that sleep duration can influence the timing and amount of food eaten. In this article, we argue that as TRE and sleep influence each other, and influence the same cardiometabolic parameters, experiencing inadequate sleep may attenuate any positive impact TRE has on CVD. We examine the relationship between TRE and CVD, with sleep as a potential mediator in this relationship, and propose a research agenda to investigate this relationship. This will provide necessary evidence to inform future interventions aimed at reducing the burden of CVD.