Association of Basal Metabolic Rate and Nutrients Oxidation with Cardiometabolic Risk Factors and Insulin Sensitivity in Sedentary Middle-Aged Adults

Biochemical basis and therapeutic potential of mitochondrial uncoupling in cardiometabolic syndrome

Mild uncoupling of oxidative phosphorylation is an intrinsic property of all mitochondria, allowing for adjustments in cellular energy metabolism to maintain metabolic homeostasis. Small molecule uncouplers have been extensively studied for their potential to increase metabolic rate, and recent research has focused on developing safe and effective mitochondrial uncoupling agents for the treatment of obesity and cardiometabolic syndrome (CMS). Here, we provide a brief overview of CMS and cover the recent mechanisms by which chemical uncouplers regulate CMS-associated risk-factors and comorbidities, including dyslipidemia, insulin resistance, steatotic liver disease, type 2 diabetes, and atherosclerosis. Additionally, we review the current landscape of uncoupling agents, focusing on repurposed FDA-approved drugs and compounds in advanced preclinical or early-stage clinical development. Lastly, we discuss recent molecular insights by which chemical uncouplers enhance cellular energy expenditure, highlighting their potential as a new addition to the current CMS drug landscape, and outline several limitations that need to be addressed before these agents can successfully be introduced into clinical practice.

The Effects of Flaxseed Consumption on Glycemic Control in Native American Postmenopausal Women with Hyperglycemia and Hyperlipidemia

Glucose control in postmenopausal women is influenced by many factors, such as hormones, lifestyle variables, and genetics. Limited data exist on the effect of whole flaxseed on glucose status in postmenopausal Native American women. The aim of this study was to investigate the glucose management effect of a flaxseed dietary intervention on postmenopausal Native American women. In this study, 55 Native American postmenopausal women (aged 47-63 years) with borderline hyperglycemia (>100 and <126 mg/dL) and mild to moderate hypercholestorolemia (≥200 to ≤380 mmol/L), who were not on hormone replacement therapy, were enrolled. Participants were randomly assigned to one of the three dietary regimens (control, flaxseed, and flaxseed + fiber) for three months, receiving interventions in the form of bread, muffins, and flaxseed powder. Despite daily consumption of flaxseed across diverse food formats, no significant changes in glucose (p = 0.3, p = 0.2), insulin levels (p = 0.59, p = 0.9), or HOMA-IR (p = 0.84, p = 0.66) were observed compared to their respective baseline values within the flaxseed and flaxseed + fiber groups, respectively. Conversely, the control group showed a significant rise in final glucose values from baseline (p = 0.01). However, the incorporation of ground flaxseed into low-glycemic foods holds potential for beneficial effects through maintaining glucose status among postmenopausal Native American women. This research provides critical insights into the effects of flaxseed, emphasizing the need for continued exploration to understand its role in supporting glucose management among postmenopausal Native American women. Further exploration is required to investigate the potential long-term impact and the use of flaxseed in managing glucose levels in this demographic.

The association between the basal metabolic rate and cardiovascular disease: A two-sample Mendelian randomization study

BACKGROUND

Mendelian randomization analysis was applied to elucidate the causal relationship between the basal metabolic rate (BMR) and common cardiovascular diseases.

METHOD

We choose BMR as exposure. BMR is the metabolic rate of the body when the basic physiological activities (blood circulation, breathing and constant body temperature) are maintained. The normal BMR is 1507 kcal/day for men and 1276 kcal/day for women. The dataset was drawn from the public GWAS dataset (GWAS ID: ukb-a-268), collected and analysed by UK biobank, containing 331,307 European males and females. SNPs independently and strongly associated with BMR were used as instrumental variables in the inverse variance weighted analysis. MR-Egger, weighted median, MR pleiotropy residual sum, and outlier methods were also performed, and the sensitivity was evaluated using horizontal pleiotropy and heterogeneity analyses to ensure the stability of the results.

RESULTS

An increased BMR is associated with a higher risk of cardiomyopathy (odds ratio [OR] = 2.00, 95% confidence interval [CI], 1.57-2.54, p = 1.87 × 10-8), heart failure (OR = 1.39, 95% CI, 1.27-2.51, p = 8.1 × 10-13), and valvular heart disease (OR = 1.18, 95% CI, 1.10-1.27, p = .00001). However, there was no clear association between BMR and the subtypes of other cardiovascular diseases, such as coronary disease (OR = .96, 95% CI, .85-1.08, p = .48651) and atrial fibrillation (AF) (OR = 1.85, 95% CI, 1.70-2.02, p = 6.28 × 10-44).

CONCLUSION

Our study reveals a possible causal effect of BMR on the risk of cardiomyopathy, heart failure and valvular disease, but not for coronary disease and AF.

Intermittent normobaric hypoxia alters substrate partitioning and muscle oxygenation in individuals with obesity: implications for fat burning

This single-blind, crossover study aimed to measure and evaluate the short-term metabolic responses to continuous and intermittent hypoxic patterns in individuals with obesity. Indirect calorimetry was used to quantify changes in resting metabolic rate (RMR), carbohydrate (CHOox, %CHO), and fat oxidation (FATox, %FAT) in nine individuals with obesity pre and post: 1) breathing normoxic air [normoxic sham control (NS-control)], 2) breathing continuous hypoxia (CH), or 3) breathing intermittent hypoxia (IH). A mean peripheral oxygen saturation ([Formula: see text]) of 80-85% was achieved over a total of 45 min of hypoxia. Throughout each intervention, pulmonary gas exchanges, oxygen consumption (V̇o2) carbon dioxide production (V̇co2), and deoxyhemoglobin concentration (Δ[HHb]) in the vastus lateralis were measured. Both RMR and CHOox measured pre- and postinterventions were unchanged following each treatment: NS-control, CH, or IH (all P > 0.05). Conversely, a significant increase in FATox was evident between pre- and post-IH (+44%, P = 0.048). Although the mean Δ[HHb] values significantly increased during both IH and CH (P < 0.05), the greatest zenith of Δ[HHb] was achieved in IH compared with CH (P = 0.002). Furthermore, there was a positive correlation between Δ[HHb] and the shift in FATox measured pre- and postintervention. It is suggested that during IH, the increased bouts of muscle hypoxia, revealed by elevated Δ[HHb], coupled with cyclic periods of excess posthypoxia oxygen consumption (EPHOC, inherent to the intermittent pattern) played a significant role in driving the increase in FATox post-IH.

Body Composition of Master Swimmers before and after the COVID-19 Pandemic: A Longitudinal Study

The long-term effect of physical activity on body composition in Master athletes is rarely presented in the literature. The aim of this study was to identify possible changes in body composition of Master swimmers over a period of 4 years, including during the COVID-19 pandemic. Additionally, we wanted to discover if sarcopenia symptoms would occur in Master athletes during the analyzed period. The body compositions of one hundred and sixty-seven Master swimmers were assessed with the InBody 270 analyzer in 2018. In 2022, the measurements were repeated in forty-six men and fourteen women. The Muscle Mass Index and the Skeletal Muscle Index were calculated to identify sarcopenia-related changes in body composition. We surveyed participants to gather data on their training patterns and SARS-CoV-2 infection history. No significant changes in body composition parameters were noted in Master swimmers during the analysis period (p > 0.05). Sarcopenia risk was not identified in examined athletes, and sarcopenia indicators did not change markedly over the 4-year period (p > 0.05). Participants with a history of SARS-CoV-2 infection did not differ from non-infected subjects in terms of body composition. Training cessation during the COVID-19 pandemic and SARS-CoV-2 infection did not induce long-term changes in body composition of Master swimmers. Life-long participation in swimming activities appears to delay negative changes in body composition, including sarcopenia symptoms.

Associations of resting and peak fat oxidation with sex hormone profile and blood glucose control in middle-aged women

BACKGROUND AND AIMS

Menopause may reduce fat oxidation. We investigated whether sex hormone profile explains resting fat oxidation (RFO) or peak fat oxidation (PFO) during incremental cycling in middle-aged women. Secondarily, we studied associations of RFO and PFO with glucose regulation.

METHOD AND RESULTS

We measured RFO and PFO of 42 women (age 52-58 years) with indirect calorimetry. Seven participants were pre- or perimenopausal, 26 were postmenopausal, and nine were postmenopausal hormone therapy users. Serum estradiol (E2), follicle-stimulating hormone, progesterone, and testosterone levels were quantified with immunoassays. Insulin sensitivity (Matsuda index) and glucose tolerance (area under the curve) were determined by glucose tolerance testing. Body composition was assessed with dual-energy X-ray absorptiometry; physical activity with self-report and accelerometry; and diet, with food diaries. Menopausal status or sex hormone levels were not associated with the fat oxidation outcomes. RFO determinants were fat mass (β = 0.44, P = 0.006) and preceding energy intake (β = -0.40, P = 0.019). Cardiorespiratory fitness (β = 0.59, P = 0.002), lean mass (β = 0.49, P = 0.002) and physical activity (self-reported β = 0.37, P = 0.020; accelerometer-measured β = 0.35, P = 0.024) explained PFO. RFO and PFO were not related to insulin sensitivity. Higher RFO was associated with poorer glucose tolerance (β = 0.52, P = 0.002).

CONCLUSION

Among studied middle-aged women, sex hormone profile did not explain RFO or PFO, and higher fat oxidation capacity did not indicate better glucose control.