Fasting – ABC CARDIOL

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Letter to the Editor

Intermittent Fasting in the Control of Hypertension: Do We Have Enough Evidence?

Adriana Camargo Oliveira et al. Natália de Filippo Mariosa Marcos Pereira Caetano Mikaelle Costa Correia

Dear Editor,

The study published by Demirci et al. brings up an interesting and current discussion by evaluating the effect of intermittent fasting (IF) on blood pressure, the renin-angiotensin system (RAS), and the autonomic nervous system (ANS) in hypertensive patients using 24-hour ambulatory blood pressure monitoring (ABPM), Holter electrocardiogram, serum levels of Ang-I and Ang-II and ACE activity before and after IF. Among the findings was a notable reduction in blood pressure in patients undergoing IF, as well as a decreased expression of Ang-II and ACE in this same group. In addition, the reduction in Ang-II levels was identified as a predictive factor for blood pressure improvement after IF.

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Editorial

Intermittent Fasting and Blood Pressure Reduction: Related Mechanisms

Rui Póvoa

Obesity and an inadequate diet are modifiable risk factors that play an important role in the increase of cardiovascular diseases. They have an estimated 13% attributable risk of cardiovascular mortality. Several dietary interventions can improve this risk, most notably calorie restriction, which is linked to weight loss, improved insulin sensitivity, and reduced blood pressure.^,

Intermittent fasting (IF) is a dietary intervention similar to calorie restriction, as it uses the principle of restricting food intake. The two most comprehensive types are alternate daytime fasting (24 hours followed by a 24-hour eating period) and time-restricted fasting (16-20 hour variations).

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Editorial

Can Intermittent Fasting Associated with a Low-Carb Diet Prevent Cardiovascular Disease in Pre-Diabetics?

Luciana Nicolau Aranha

Pre-diabetes is the term used to describe individuals who have altered glucose metabolism but do not meet the diagnostic criteria for diabetes. People with pre-diabetes have an increased risk of type 2 diabetes mellitus (DM2), cardiovascular disease (CVD), and all-cause mortality.^,

Lifestyle changes, including diet and regular physical activity, are effective in preventing diabetes and CVD. Some nutritional approaches have been used to promote weight loss and glycemic control. Intermittent fasting is a dietary practice restricting calorie consumption during a controlled period, followed by ad libitum caloric consumption. A carbohydrate-restricted diet, known as low-carb, is characterized by carbohydrate intake below the lower limit of an acceptable macronutrient distribution range for healthy adults (i.e., < 45% of energy intake).

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Original Article

Improvement in Blood Pressure After Intermittent Fasting in Hipertension: Could Renin-Angiotensin System and Autonomic Nervous System Have a Role?

Erkan Demirci et al. Bekir Çalapkorur Oguzhan Celik Derya Koçer … Selami Demirelli Ziya Şimsek

Abstract

Background

Although it has been reported that the intermittent fasting (IF) diet has positive effects on heart health and improvement in blood pressure, it has not been sufficiently clarified how it could have these positive effects yet.

Objective

We aimed to evaluate the effects of IF on the autonomic nervous system (ANS) and renin-angiotensin system (RAS), which are closely related to blood pressure.

Methods

Seventy-two hypertensive patients were included in the study, and the data of 58 patients were used. All the participants fasted for about 15-16 hours for 30 days. Participants were evaluated with 24-hour ambulatory blood pressure monitoring and Holter electrocardiography before and after IF; also, 5 ml venous blood samples were taken for assessment of Serum angiotensin I (Ang-I) and angiotensin II (Ang-II) levels and angiotensin-converting enzyme (ACE) activity. For data analysis, the p-value <0.05 was accepted as significant.

Results

Compared to pre-IF, a significant decrease was observed in the patients’ blood pressures in post-IF. An increase in high-frequency (HF) power and the mean root square of the sum of squares of differences between adjacent NN intervals (RMSSD) were observed after the IF protocol (p=0.039, p=0.043). Ang-II and ACE activity were lower in patients after IF (p=0.034, p=0.004), and decreasing Ang-II levels were determined as predictive factors for improvement of the blood pressure, like the increase in HF power and RMSSD.

Conclusion

The present findings of our study demonstrated an improvement in blood pressure and the relationship of blood pressure with positive outcomes, including HRV, ACE activity, and Ang-II levels after the IF protocol.

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Original Article

The Value of Intermittent Fasting and Low Carbohydrate Diet in Prediabetic Patients for the Prevention of Cardiovascular Diseases

Mohamed Khalfallah et al. Basma Elnagar Shaimaa S. Soliman Ahmad Eissa Amany Allaithy

Abstract

Background:

Prediabetic patients are at increased risk for cardiovascular diseases and the development of microvascular and macrovascular complications. Intermittent fasting (IF) and low-carbohydrate diet (LCD) are promising dietary plans.

Objectives:

Our aims to analyze the benefits of IF combined with LCD on microvascular and macrovascular outcomes in prediabetic patients.

Methods:

The study included 485 prediabetic patients with no history of cardiovascular diseases divided into group I: (n = 240 patients) who underwent IF (16 h IF 3-4 days per week) combined with LCD (<130 g of carbohydrate per day), and group II: (n = 245 patients) with ad libitum calorie intake. The two groups were followed-up for two years for assessment of micro and macrovascular complications. A p-value < 0.05 was considered statistically significant.

Result:

There was a significant reduction in body weight, body mass index, waist circumference, body fat percentage and glycated hemoglobin in group I. The incidence of progression from prediabetes to diabetes was significantly lower in group I (2.1% vs. 6.9% in group II, p = 0.010). In addition, a significant increase in the incidence of microvascular and macrovascular complications was observed in group II, including retinopathy, neuropathy and unstable angina. Multivariate regression analysis revealed that increased body weight, fasting glucose, glycated hemoglobin and low-density lipoprotein were independent risk factors impacting microvascular and macrovascular outcomes.

Conclusions:

In prediabetic patients, IF, combined with LCD, was associated with lower progression to diabetes mellitus and lower incidence of microvascular and macrovascular complications.

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Counterpoint

Counterpoint: Flexibilization of Fasting for Laboratory Determination of the Lipid Profile in Brazil: Science or Convenience?

Maria Cristina de Oliveira Izar

National and international guidelines for the management of dyslipidemias classically recommend measuring lipid profiles after fasting for at least 8 h.^– Lipid targets for assessing cardiovascular risk traditionally rely on plasma total-cholesterol and low-density lipoprotein-cholesterol (LDL-c) levels, with the latter being calculated by the Friedewald equation.

Some imprecision due to low or high triglycerides in calculating LDL-cholesterol may affect cardiovascular risk assessment, the definition of a therapeutic target, and the need to intensify the treatment.^, Accurate results require triglyceride levels below 400 mg/dL, but above 100 mg/dL the calculated LDL-c starts to be underestimated, when compared to ultracentrifugation measurements. Another limitation to the use of the formula is that samples must not contain beta-VLDL, as in the case of type III hyperlipoproteinemia. When one of these conditions are not satisfied, the equation cannot be used due to imprecision.^–

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Viewpoint

Flexibilization of Fasting for Laboratory Determination of the Lipid Profile in Brazil: Science or Convenience?

Caio Maurício Mendes de Cordova et al. Caroline Galgowski

A statement endorsed by medical specialty associations has been published in our country recommending the flexibilization of fasting before blood drawing for the laboratory determination of the lipid profile encompassing total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), triglycerides (TG) content and the corresponding calculation of non-HDL-cholesterol (TC – HDL-c). It was considered that non-fasting results do not clinically differ from fasting ones, and prospective studies and meta-analyses have consistently demonstrated that non-HDL-C at a non-fasting state would be at least as good as LDL-c in the prediction of CVD. It was also recommended that when TG > 4.52 mmol/L the formula proposed by Martin et al. should be used for LDL-c estimation.

The statement was based on the European Consensus on the matter published by Nordestgaard et al. However, the automatic application of this approach in Brazil deserves deeper consideration, considering the impact that it may cause on patient care. Furthermore, it is far from a consensus among clinical laboratory scientists and professionals in the country, as it became evident during the 44^th Brazilian Congress of Clinical Analysis held last June 11-14^th, 2017, and the 51^st Brazilian Congress of Clinical Pathology and Laboratory Medicine, held last September 26-29^th, 2017.

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Original Article

Hypertriglyceridemic Waist Phenotype and Changes in the Fasting Glycemia and Blood Pressure in Children and Adolescents Over One-Year Follow-Up Period

Priscila Ribas de Farias Costa et al. Ana Marlúcia Oliveira Assis Carla de Magalhães Cunha Emile Miranda Pereira … Gabriela dos Santos de Jesus Lais Eloy Machado da Silva Wilanne Pinheiro de Oliveira Alves

Abstract

Background:

The hypertriglyceridemic waist (HTW) phenotype is defined as the simultaneous presence of increased waist circumference (WC) and serum triglycerides (TG) levels and it has been associated with cardiometabolic risk in children and adolescents.

Objective:

The objective was to evaluate the influence of HTW phenotype in the fasting glycemia and blood pressure in children and adolescents over one-year follow-up period.

Methods:

It is a cohort study involving 492 children and adolescents from 7 to 15 years old, both genders, who were submitted to anthropometric, biochemical and clinical evaluation at the baseline, and also after 6 and 12 months of follow-up. Generalized Estimating Equation (GEE) models were calculated to evaluate the longitudinal influence of the HTW phenotype in the glycemia and blood pressure over one-year.

Results:

It was observed a prevalence of 10.6% (n = 52) of HTW phenotype in the students. The GEE models identified that students with HTW phenotype had an increase of 3.87 mg/dl in the fasting glycemia mean (CI: 1.68-6.05) and of 3.67mmHg in the systolic blood pressure (SBP) mean (CI: 1.55-6.08) over one-year follow-up, after adjusting for confounding variables.

Conclusions:

The results of this study suggest that HTW phenotype is a risk factor for longitudinal changes in glycemia and SBP in children and adolescents over one-year follow-up period.

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