In a recent article published in Npj Metabolic Health and Diseaseresearchers evaluated the effectiveness of the fasting-mimicking diet (FMD) versus the Mediterranean diet (MD) in reducing cardiovascular disease (CVD) risk among obese adults with hypertension.
They conducted a single-center randomized clinical trial (RCT) in Tennessee, United States (USA), at the Hypertension Institute (HTI) between September 2018 and May 2019.
Record
Healthy eating habits may be an effective strategy to protect the vascular endothelium. Abnormalities in the vascular endothelium, such as reduced vasodilatation, may contribute to atherosclerosis and hypertension.
In their previous work, the researchers demonstrated the safety, feasibility, and beneficial effects of a periodic (five-day/month) foot-and-mouth disease on cardiometabolic risk factors in normal and overweight healthy adults. FMD is a low-calorie, low-protein, high-fat plant-based diet.
Similarly, studies have associated MD with multiple benefits, including prevention of cardiovascular disease. The Mediterranean diet is characterized by a high proportion of grains, legumes, fruits/vegetables, moderate amounts of protein from fish and healthy fats from olive oil,
Both FMD and MD diets also provide healthy fats, namely monounsaturated fats [MUFA] {e.g. oleic acid} and polyunsaturated fats [PUFA] {e.g. alpha-linolenic acid (omega-3). docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)}.
However, the fats in FMD are only plant-based (nuts, algae oil), while those in MD tend to come from animal sources.
About the study
In the present RCT, investigators compared the efficacy of four monthly cycles of FMD versus continuous MD in obese hypertensive adults over four months.
They randomly assigned 44 and 40 subjects (both sexes) aged 35 to 75 years to the FMD and MD arms, respectively, and assessed their endothelial function from the beginning to the end of the intervention phase (V3), as indicated by the reactive index hyperemia (RHI) and compliance scores of small and large arteries (AC1/AC2). Second, they assessed changes in cardiometabolic factors.
Participants were included if they had a body mass index (BMI) ≥28 and a confirmed diagnosis of either endothelial dysfunction or low resistance artery compliance (AC2). They excluded all participants with an EndoPAT® score/reactive hyperemia index (RHI) >2.0 and a severe change in blood pressure (BP) >180/105.
According to the study protocol, the team arranged clinical visits of all participants at the following time points, as follows: i) baseline; ii) 5–8 days after the end of the first FMD cycle. iii) 35–38 days after the onset of MD (V1). iv) 5–8 days after the end of the third FMD cycle or 95–98 days after the onset of MD (V2). v) end of nutritional interventions (V3). vi) three months after the end of nutritional interventions (V4).
During each visit, the team asked about waist circumference (WC), body weight (BW), and height of all participants. They forbade the consumption of caffeine, alcohol or tobacco six hours before the BP measurement. Heart rate (HR) data were also collected.
In addition, they quantified tumor necrosis factor-alpha (TNF alpha), insulin-like growth factor 1 (IGF-1), interleukin-6 (IL-6) and leptin levels in blood samples collected after an overnight fast. >12 hours.
They used these data to calculate the homeostasis model assessment of insulin resistance (HOMA-IR) and assess the prevalence of any metabolic syndromes in the participants.
Participants in the FMD group consumed only the contents of the box provided to them. FMD was based on subject’s weight (not sex) and supplemented with glycerin to compensate for caloric deficit due to FMD. It provided total caloric intake ranging from 1000–1100 kcal on day 1 to 700–800 kcal on days 2–5.
During the periods between FMD cycles, the participants followed their normal diet. On the other hand, participants in the MD group received guidelines based on a validated MD but were not required to comply.
The team used several statistical methods to analyze the data, including comparisons of baseline characteristics using a Spearman correlation test, intention-to-treat (ITT) analysis, and linear mixed models to assess the effects of time and treatment, accounting for baseline covariates. and temporal changes.
They used a t-test to calculate p-values for two-group coefficients and to compare treatment effects between MD and FMD.
Results
The FMD group showed a decrease in RHI, which may indicate a possible impairment in endothelial function. However, neither group showed improvements in AC1/AC2 measures or changes in abnormal RHI (< 1.67).
According to Spearman’s correlation test, there was a negligible correlation between RHI and age at baseline.
The FMD group also showed a trend for reduced biological age, heart age, and protein-labile damage signature (PULS) heart test scores that assess five-year stroke risk.
However, considering the lack of AC1/AC2 changes, a reduced RHI likely represented a restorative effect of FMD rather than an impaired endothelial function. Therefore, further work is needed to elucidate these findings.
During the study’s three-month follow-up, the FMD group showed reduced insulin levels and HOMA-IR, while the MD group showed a greater reduction in diabetes prevalence. It was an interesting revelation as the MD group had almost twice as many people with diabetes at the start of the study.
In addition, the FMD group showed a significant decrease in trunk fat mass but not lean muscle mass at the end of the follow-up period, while the MD group showed a loss of lean muscle mass of over two pounds, indicating adherence to this dietary regimen can lead to increased frailty in old age.
MD may have caused reduced protein and, more importantly, some amino acid intake necessary for muscle growth. However, FMD did not interfere with the total protein consumption in the individual’s diet.
Thus, the authors ruled out that the intermittent FMD regimen may maintain lean body mass more effectively than continuous MD intervention.
conclusions
Overall, the study findings suggested that while both FMD and MD interventions were effective in managing weight and improving cardiometabolic disease risk in obese hypertensive subjects, both also had unique effects.
FMD reduced RHI, a change associated with reduced vascular endothelial cell functional integrity or vascular revascularization, PULS cardiac score, calculated heart age, and unchanged arterial compliance. FMD reduced trunk fat mass. MD, in contrast, caused a loss of lean body mass.
In addition, the researchers emphasized the variation of the FMD menu to improve adherence to this diet, especially as many participants did not enjoy its taste but found intermittent feeding regimens more feasible than continuous ones.
