Encouraging effects of a short-term, adapted Nordic diet intervention on skin microvascular function and skin oxygen tension in younger and older adults

No effect of nitrate-rich beetroot juice on microvascular function and blood pressure in younger and older individuals: a randomised, placebo-controlled double-blind pilot study

Background/Objectives

To compare the effects of supplemental inorganic nitrate (NO₃) on microvascular endothelial function and blood pressure in younger vs. older participants.

Subjects/Methods

25 individuals participated in a double-blind, randomised, placebo-controlled crossover pilot study. Participants were stratified by age (18–35 and ≥55 years) and consumed a single dose beetroot juice (providing 6.4 mmol NO₃) or NO₃-depleted beetroot juice. Blood pressure, microvascular function (via Laser Doppler Flowmetry; LDF) and urinary NO₃ were assessed, and the effects of NO₃ supplementation on cardiovascular parameters were compared between participants and conditions using mixed-design ANOVA.

Results

Treatments and methods were well tolerated, and no adverse events were reported. Urinary NO₃ increased 3 h following ingestion in both groups, (P = 0.02). Levels remained elevated at 24 h post consumption in younger participants only (P = 0.02). Beetroot juice had no effect on blood pressure in either group nor on microcirculatory endothelial function.

Conclusions

Beetroot juice had no effect on blood pressure or microvascular endothelial function in young and older individuals. Dosage and timing regimens for supplemental beetroot juice should be avenues for further inquiry.

Assessing the Physiological Effects of Traditional Regional Diets Targeting the Prevention of Cardiovascular Disease: A Systematic Review of Randomized Controlled Trials Implementing Mediterranean, New Nordic, Japanese, Atlantic, Persian and Mexican Dietary Interventions

Traditional regional diets are considered as sustainable dietary patterns, while many have been examined with regard to their health benefits. The aim of the present systematic review was to aggerate all evidence on the physiological effects of regional diets among adults at high risk for cardiovascular disease (CVD). Three databases were searched for randomized controlled trials (RCTs) implementing any regional diet (Mediterranean (MedD), Persian, Southern European Atlantic, Japanese, Chinese, new Nordic, or other) while examining cardiovascular risk factors among adults at increased risk. Primary outcomes included anthropometric indices and secondary outcomes involved blood lipid concentrations, glucose metabolism, inflammation and other markers of CVD progression. Twenty RCTs fulfilled the study's criteria and were included in the qualitative synthesis, with the majority implementing a MedD. Adherence to most of the regional diets induced a reduction in the BW and anthropometric indices of the participants. The majority of RCTs with blood pressure endpoints failed to note a significant reduction in the intervention compared to the comparator arm, with the exception of some new Nordic and MedD ones. Despite the interventions, inflammation markers remained unchanged except for CRP, which was reduced in the intervention groups of one new Nordic, the older Japanese, and the Atlantic diet RCTs. With regard to blood lipids, regional diet interventions either failed to induce significant differences or improved selective blood lipid markers of the participants adhering to the experimental regional diet arms. Finally, in the majority of RCTs glucose metabolism failed to improve. The body of evidence examining the effect of regional dietary patterns on CVD risk among high-risk populations, while employing an RCT design, appears to be limited, with the exception of the MedD. More research is required to advocate for the efficacy of most regional diets with regard to CVD.

Pyridoxamine and Caloric Restriction Improve Metabolic and Microcirculatory Abnormalities in Rats with Non-Alcoholic Fatty Liver Disease

INTRODUCTION

This study aims to examine the effect of a diet intervention and pyridoxamine (PM) supplementation on hepatic microcirculatory and metabolic dysfunction in nonalcoholic fatty liver disease (NAFLD).

METHODS

NAFLD in Wistar rats was induced with a high-fat diet for 20 weeks (NAFLD 20 weeks), and control animals were fed with a standard diet. The NAFLD diet intervention group received the control diet between weeks 12 and 20 (NAFLD 12 weeks), while the NAFLD 12 weeks + PM group also received PM. Fasting blood glucose (FBG) levels, body weight (BW), visceral adipose tissue (VAT), and hepatic microvascular blood flow (HMBF) were evaluated at the end of the protocol.

RESULTS

The NAFLD group exhibited a significant increase in BW and VAT, which was prevented by the diet intervention, irrespective of PM treatment. The FBG was elevated in the NAFLD group, and caloric restriction improved this parameter, although additional improvement was achieved by PM. The NAFLD group displayed a 31% decrease in HMBF, which was partially prevented by caloric restriction and completely prevented when PM was added. HMBF was negatively correlated to BW, FBG, and VAT content.

CONCLUSION

PM supplementation in association with lifestyle modifications could be an effective intervention for metabolic and hepatic vascular complications.

Contrasting Effects of Short-Term Mediterranean and Vegan Diets on Microvascular Function and Cholesterol in Younger Adults: A Comparative Pilot Study

The Mediterranean diet has been shown to improve cardiovascular health. Vegan diets have demonstrated similar benefits, albeit in fewer studies. In a comparative pilot study, we compared the effects of a short-term Mediterranean Diet (MD) and Vegan Diet (VD) on microvascular function and cholesterol levels in a healthy population. Twenty-four young (aged 18 to 35 years) healthy volunteers followed a four-week intervention (MD = 12; VD = 12) ad libitum. Pre and post-intervention anthropometrics, microvascular function (assessed via LDF and expressed as raw CVC and %CVC MAX), dietary-analysis data (Calories, Protein, Carbohydrates, Total Fat, Saturated Fat, Fibre), Mean Arterial Pressure (MAP), Blood Pressure, Total Cholesterol (TC), High Density Lipoprotein (HDL-C) and TC:HDL-C were compared. MD participants reduced Total Fat intake (p = 0.05). Saturated Fat decreased (MD: p = < 0.001; VD: p = 0.004) and Fibre increased (MD: p = 0.02; VD: p = < 0.001) in both groups. Dietary changes reflected improvements in plateau raw CVC in the MD group (p = 0.005), and a reduction in TC (p = 0.045) and weight loss (p = 0.047) in the VD group. The MD led to improvements in microvascular function; the VD led to reduced TC and weight loss. Although both diets might offer CVD risk-reduction benefits, evidence for the MD appeared to be stronger due to changes in vasodilatory ability and NO bioavailability.

Physiological effects of a short-term lifestyle intervention based on the Mediterranean diet: comparison between older and younger healthy, sedentary adults

OBJECTIVE

The aim of this study was to determine whether short-term adherence to the Mediterranean diet (MD) was associated with improved physiological function.

METHODS

This was a single-center, cohort pilot study with 24 healthy, sedentary younger (18-35 y of age) and older (55-75 y of age) adults. Participants were advised to follow the MD for 4 wk. Baseline and post-intervention measurements were taken of weight, height, waist and hip circumference, blood pressure, and heart rate, as well as microvascular physiological assessments using laser Doppler flowmetry (LDF) at rest, as well as transcutaneous oxygen pressure (TcpO2) during a sub-maximal exercise assessment.

RESULTS

We identified statistically-significant improvements in axon-mediated microvascular vasodilation (2.24 ± 0.56 to 3.14 ± 0.84; P = 0.03) and endothelial-mediated nitric oxide synthesis (2.59 ± 0.67 to 3.32 ± 0.87; P = 0.022) in the younger group. Despite the intervention not including an exercise element, the rate of perceived exertion was reduced in both groups (P < 0.001), after following the MD for 1 mo.

CONCLUSIONS

Improvements in physiological function were observed after a short-term dietary intervention based on the MD in a younger population. These were not statistically matched in an older group. Our findings suggest that different durations should be applied when designing dietary interventions in different age groups, with expectations in physiological improvement differing.