Association Between Basal Metabolic Rate and All-Cause Mortality in a Prospective Cohort of Southern Chinese Adults

Objective: The aim of this study was to assess the relationship between basal metabolic rate (BMR) and all-cause mortality in southern Chinese adults.Methods: We prospectively examined the relationship between BMR and all-cause mortality in 12,608 Southern Chinese adults with age ≥ 35 years who participated in the National Key R&D Program from 2013–2014 to 2019–2020. Cox proportional hazard models were used to examine the association between BMR and all-cause mortality.Results: A total of 809 deaths (including 478 men and 331 women) occurred during a median follow-up period of 5.60 years. All-cause mortality was higher in elderly individuals than in non-elderly individuals (11.48 vs. 2.04%, P < 0.001) and was higher in male subjects than in female subjects (9.84 vs. 4.56%, P < 0.001). There was a significantly inverse relationship between BMR levels and all-cause mortality in elderly male individuals (adjusted-HR per SD increase: 0.80, 95% CI: 0.70–0.91, P < 0.001). Compared with BMR levels ≤ 1,115 kJ/day, there was lower all-cause mortality in third and highest BMR quartiles in the elderly male subjects (adjusted-HR: 0.71, 95% CI: 0.53–0.95, P = 0.022; adjusted-HR: 0.60, 95% CI: 0.43–0.84, P = 0.003, respectively).Conclusion: An elevated BMR was independently inversely associated with all-cause mortality in elderly male subjects in a southern Chinese population.

TSH DAN fT4 DENGAN INDEKS MASSA TUBUH (IMT) PADA PASIEN DEWASA: STUDI CROSS-SECTIONAL DI KLINIK LITBANGKES MAGELANG

Latar Belakang. Disfungsi tiroid terjadi jika fungsi kelenjar tiroid terganggu, ditandai dengan kadar Thyroid Stimulating Hormone (TSH) dan free Thyroxine (fT4) yang lebih tinggi atau lebih rendah dari normal. Perubahan kadar hormon tiroid menyebabkan perubahan basal metabolic rate (BMR) yang menyebabkan perubahan keseimbangan energi dan berat badan. Tujuan. Penelitian bertujuan untuk menganalisis hubungan TSH dan fT4 dengan indeks massa tubuh (IMT) pada pasien dewasa baru di Klinik Litbangkes Magelang. Metode. Penelitian ini dilakukan dengan menggunakan metode cross-sectional dan menggunakan data sekunder dari rekam medis pasien. Sampel penelitian adalah pria dan wanita dewasa (>17 tahun) yang pertama kali mengunjungi Klinik Litbangkes Magelang pada tahun 2019 sebanyak 173 orang. Variabel penelitian adalah TSH, fT4, dan IMT. Pengujian hipotesis dengan uji statistik Korelasi Rank Spearman. Hasil. Rata-rata kadar TSH responden adalah normal yaitu 0,91±2,17 µIU/mL, sedangkan rata-rata kadar fT4 responden di atas normal yaitu 3,20±5,83 ng/dL. Sebagian besar subjek memiliki IMT normal (55,5%) dengan rata-rata 23,74±4,57. Uji Korelasi Rank Spearman menunjukkan bahwa terdapat hubungan yang signifikan antara TSH dan IMT (p=0,003) dengan korelasi positif (r=0,228) dan ada hubungan yang signifikan antara fT4 dan IMT (p=0,000) dengan korelasi negatif (r=-0.323). Kesimpulan. Terdapat hubungan antara kadar TSH dan fT4 dengan nilai IMT pasien. Semakin tinggi kadar TSH maka semakin tinggi pula nilai IMT pasien, begitu juga sebaliknya, serta semakin tinggi kadar fT4 maka nilai IMT pasien semakin rendah, dan sebaliknya.

Incubation temperature and physiological aging in the zebra finch

In birds, incubation temperature has received increased attention as an important source of phenotypic variability in offspring. A lower than optimal incubation temperature may negatively affect aspects of nestling physiology, such as body growth and energy metabolism. However, the long-term effects of sub-optimal incubation temperature on morphology and physiology are not well understood. In a previous study, we showed that zebra finches from eggs incubated at a low temperature (35.9°C) for 2/3 of the total incubation time suffered a lower post-fledging survival compared to individuals that had been incubated at higher temperatures (37.0 and 37.9°C). In the present study, we investigated whether these variations in incubation temperature could cause permanent long-lasting differences in body mass, body size, or basal metabolic rate. Furthermore, we tested whether the observed differences in survival between treatment groups would be reflected in the rate of physiological deterioration, assessed through oxidative damage and decreased metabolic rate with age (i.e. ‘metabolic aging’). Incubation temperature did not significantly affect embryonic or nestling body growth and did not influence final adult body mass or body size. Nor was there any long-term effect on basal metabolic rate. Birds from eggs incubated at the lowest temperature experienced an accumulation of oxidative damage with age, although this was not accompanied by an accelerated rate of metabolic aging. The present results suggest that the low survival in these birds was possibly mediated by increased oxidative stress, but independent of body growth and the basal metabolic rate.

Larger guts and faster growth in mice selected for high basal metabolic rate

Postnatal growth in birds and mammals is the time of highest vulnerability and relatively high energy demands and therefore shapes the organisms' future outcomes. Several different factors might impose limitations on growth in juveniles, one of them being the efficiency of the digestive process and size of the gastrointestinal tract. We tested the gut size–growth rate relationship using a unique experimental model—mice from a selection experiment designed to produce two lines with divergent levels of basal metabolic rate (BMR): the high BMR (H-BMR) and low BMR (L-BMR) line types. These lines differ with respect to not only BMR, but also correlated traits—internal organ size and food intake. Applying a cross-fostering design and a thermoregulatory burden imposed by shaving the mothers, we demonstrated that the mass of intestine strongly affected the growth rate, with the H-BMR pups having larger intestines and growing faster, and with reduced growth rate of pups of both lines nursed by shaved L-BMR mothers. Our study also provides a functional link between high growth rate of neonates and high BMR of adults, partly reflecting metabolic costs of maintenance of their guts.

Significance of variation in basal metabolic rate in laboratory mice for translational experiments

The basal metabolic rate (BMR) accounts for 60–70% of the daily energy expenditure (DEE) in sedentary humans and at least 50% of the DEE in laboratory mice in the thermoneutral zone. Surprisingly, however, the significance of the variation in the BMR is largely overlooked in translational research using such indices as physical activity level (PAL), i.e., the ratio of DEE/BMR. In particular, it is unclear whether emulation of human PAL in mouse models should be carried out within or below the thermoneutral zone. It is also unclear whether physical activity within the thermoneutral zone is limited by the capacity to dissipate heat generated by exercise and obligatory metabolic processes contributing to BMR. We measured PAL and spontaneous physical activity (SPA) in laboratory mice from two lines, divergently selected towards either high or low level of BMR, and acclimated to 30 °C (i.e., the thermoneutral zone), 23 or 4 °C. The mean PAL did not differ between both lines in the mice acclimated to 30 °C but became significantly higher in the low BMR mouse line at the lower ambient temperatures. Acclimation to 30 °C reduced the mean locomotor activity but did not affect the significant difference observed between the selected lines. We conclude that carrying out experiments within the thermoneutral zone can increase the consistency of translational studies aimed at the emulation of human energetics, without affecting the variation in physical activity correlated with BMR.

Hyperthyroidism and gastrointestinal symptoms. Russell Vebrbrycke (Journ. Am. M. A. 1931, 97.8)

Russell Vebrbrycke (Journ. Am. M. A. 1931, 97.8) draws attention to the need to determine the basal metabolic rate, since often, where gl. thyreoidea is not enlarged, it is visible.

Effect of Basal Metabolic Rate on Cancer: A Mendelian Randomization Study

Background: Basal metabolic rate is associated with cancer, but these observations are open to confounding. Limited evidence from Mendelian randomization studies exists, with inconclusive results. Moreover, whether basal metabolic rate has a similar role in cancer for men and women independent of insulin-like growth factor 1 increasing cancer risk has not been investigated.Methods: We conducted a two-sample Mendelian randomization study using summary data from the UK Biobank to estimate the causal effect of basal metabolic rate on cancer. Overall and sex-specific analysis and multiple sensitivity analyses were performed including multivariable Mendelian randomization to control for insulin-like growth factor 1.Results: We obtained 782 genetic variants strongly (p-value < 5 × 10–8) and independently (r2 < 0.01) predicting basal metabolic rate. Genetically predicted higher basal metabolic rate was associated with an increase in cancer risk overall (odds ratio, 1.06; 95% confidence interval, 1.02–1.10) with similar estimates by sex (odds ratio for men, 1.07; 95% confidence interval, 1.002–1.14; odds ratio for women, 1.06; 95% confidence interval, 0.995–1.12). Sensitivity analyses including adjustment for insulin-like growth factor 1 showed directionally consistent results.Conclusion: Higher basal metabolic rate might increase cancer risk. Basal metabolic rate as a potential modifiable target of cancer prevention warrants further study.