Metabolically unhealthy non-obese (MUNO) individuals are at higher risk of cardiovascular diseases, while not receiving sufficient attention. This study was conducted to explore the association between BMI-adjusted CC and MUNO in non-obese US adults using the NHANES database. A total of 9,628 non-obese US adults (48.01% female and 51.99% male) were included in this cross-sectional study. The metabolically unhealthy phenotype was defined as ≥ 2 components of metabolic abnormalities. BMI-adjusted CC and BMI-adjusted skeletal muscle mass (SMM) were divided into quartiles. Weighted multiple logistic regression model was used to evaluate the study aims. The relation between BMI-adjusted CC and BMI-adjusted SMM was tested by Spearman correlation. In the multivariate analysis, compared with the lowest quartile of BMI-adjusted CC and BMI-adjusted SMM, OR (95%CI) of the highest quartile was 0.30 (0.25, 0.35) (P < 0.001, P for trend < 0.001) and 0.39 (0.29, 0.53) (P < 0.001, P for trend < 0.001), respectively. BMI-adjusted CC was positively correlated with BMI-adjusted SMM for all participants (r = 0.48). A weak non-linear association was observed in BMI-adjusted CC and MUNO (P = 0.047). Similar results were observed in sex- and BMI-specific subgroup and sensitivity analysis. BMI-adjusted CC was inversely associated with MUNO, suggesting more attention should be paid to monitoring BMI-adjusted CC for the public to ease the disease burden, especially for people without obesity.

Background: Under oxidative stress conditions, the increased levels of reactive oxygen species (ROS) within cells disrupt the intracellular homeostasis. Tartary buckwheat peptides exert their effects by scavenging oxidative free radicals, such as superoxide anion and hydrogen peroxide, thereby reducing oxidative damage within cells. Meanwhile, these peptides safeguard mitochondria by maintaining the mitochondrial membrane potential, decreasing the production of mitochondrial oxygen free radicals, and regulating mitochondrial biogenesis and autophagy to preserve mitochondrial homeostasis. Through these mechanisms, Tartary buckwheat peptides restore the intracellular redox balance, sustain cellular energy metabolism and biosynthesis, and ensure normal cellular physiological functions, which is of great significance for cell survival and adaptation under oxidative stress conditions. Objectives: In this experiment, a classical cellular oxidative stress model was established. Indicators related to antioxidant capacity and mitochondrial membrane potential changes, as well as pathways associated with oxidative stress, were selected for detection. The aim was to elucidate the effects of Tartary buckwheat oligopeptides on the metabolism of cells in response to oxidative stress. Methods: In this study, we established an oxidative damage model of mouse skeletal muscle myoblast (SOL8) cells using hydrogen peroxide (H₂O₂), investigated the pre-protective effects of Tartary buckwheat oligopeptides on H₂O₂-induced oxidative stress damage in SOL8 cells at the cellular level, and explored the possible mechanisms. The CCK-8 method is a colorimetric assay based on WST-8-[2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodiumsalt], which is used to detect cell proliferation and cytotoxicity. Results: The value of CCK-8 showed that, when the cells were exposed to 0.01 mmol/L H₂O₂ for 1 h and 10 mg/mL Tartary buckwheat oligopeptides intervention for 48 h, these were the optimal conditions. Compared with the H₂O₂ group, the intervention group (KB/H₂O₂ group) showed that the production of ROS was significantly reduced (p < 0.001), the malondialdehyde (MDA) content was significantly decreased (p < 0.05), and the activity of catalase (CAT) was significantly increased (p < 0.01); the mitochondrial membrane potential in the KB/H₂O₂ group tended to return to the level of the control group, and they all showed dose-dependent effects. Compared with the H₂O₂ group, the mRNA expression of KEAP1 in the KB/H₂O₂ group decreased, while the mRNA expression of NRF2α, HO-1, nrf1, PGC-1, P62, and PINK increased. Conclusions: Therefore, Tartary buckwheat oligopeptides have a significant pre-protective effect on H₂O₂-induced SOL8 cells, possibly by enhancing the activity of superoxide dismutase, reducing ROS attack, balancing mitochondrial membrane potential, and maintaining intracellular homeostasis.