Caloric restriction-induced weight loss with a high-fat diet does not fully recover visceral adipose tissue inflammation in previously obese C57BL/6 mice

Caloric restriction (CR) reduces body weight and systemic inflammation, but the effects on adipose tissue under dietary lipid overload are controversial. We evaluated the effects of CR-induced weight loss with a high-fat diet on adipose tissue inflammation of obese mice. Male mice were assigned into low-fat diet (LF) and high-fat diet (HF) groups. After 8 weeks, the mice in the HF group were reassigned for another 7 weeks into the following 3 conditions: (i) kept in the HF condition; (ii) changed to low-fat diet ad libitum (LFAL); and (iii) changed to high-fat calorie-restricted (RHF) diet to reach LFAL body weight. Serum markers, adipocytokines, morphology, and inflammatory infiltrates in retroperitoneal adipose tissue (RAT) were accessed. The body weights of the LFAL and RHF groups were reduced, equaling the body weights of the LF group. The LFAL mice had restored almost all inflammatory markers as the LF mice, except tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and adiponectin. Compared with the HF group, the RHF group had lowered visceral adiposity, retroperitoneal adipocyte sizes, and RAT inflammatory cell infiltration, as well as TNF-α, interleukin-6, and hepatic and serum C-reactive protein, which were higher than that of the LFAL group; adiponectin and MCP-1 did not change. CR with high-fat diet reduced body weight and attenuated visceral adiposity but did not fully recover visceral tissue inflammation. Novelty Caloric restriction in a high-fat diet ameliorated visceral adiposity. Caloric restriction in a high-fat diet did not recover visceral adipose tissue inflammation.

Association between caffeine metabolites in urine and muscle strength in young and older adults: A cross-sectional study from NHANES 2011-2012

BACKGROUND

Elevated levels of reactive oxygen species may contribute to the gradual decline in muscle strength over time. Although caffeine and its metabolites have antioxidant properties that can mitigate oxidative stress, the association of caffeine and its metabolites with muscle strength remains unknown.

AIM

To investigate whether caffeine metabolites in urine are associated with muscle strength in young and older adults.

METHODS

A cross-sectional study was conducted with 1145 individuals aged over 20 years (n = 801 < 60 years and n = 344 ≥ 60 years) from the National Health and Nutrition Examination Survey (NHANES) 2011-2012. Muscle strength was assessed using a handgrip dynamometer, and combined grip strength was determined by summing the highest value from each hand. Caffeine and its metabolites in urine were quantified using ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (1-methyluric acid, 3-methyluric acid, 7-methyluric acid, 1,3-dimethyluric acid, 1,7-dimethyluric acid, 3,7-dimethyluric acid, 1,3,7-trimethyluric acid, 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, 1,3-dimethylxanthine, 1,7-dimethylxanthine, 3,7-dimethylxanthine, 1,3,7-trimethylxanthine, 5-acetylamino-6-amino-3-methyluracil). Linear regression analyses were performed to determine the association of caffeine and its metabolites with muscle strength in young and older adults, adjusting for confounders.

RESULTS

Positive associations between muscle strength and levels of 7-methyluric acid (β = 0.029; p = 0.021), 1,3-dimethyluric acid (β = 0.008; p = 0.004), 3,7-dimethyluric acid (β = 0.645; p = 0.012), 3-methylxanthine (β = 0.020; p = 0.002), 7-methylxanthine (β = 0.020; p = 0.006), 1,3-dimethylxanthine (theophylline) (β = 0.030; p = 0.004) and 3,7-dimethylxanthine (theobromine) (β = 0.035; p = 0.029) were observed in older adults. In contrast, no such associations were noted in young adults.

CONCLUSION

Our study indicates a positive association between certain caffeine metabolites in urine and muscle strength in older adults, but not in younger individuals. These findings indicate that specific caffeine metabolites may contribute to an antioxidant role especially in older adults.