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Kaneva AM, Bojko ER. Fatty liver index (FLI): more than a marker of hepatic steatosis. J Physiol Biochem 2024; 80:11-26. [PMID: 37875710 DOI: 10.1007/s13105-023-00991-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 10/12/2023] [Indexed: 10/26/2023]
Abstract
Fatty liver index (FLI) was developed as a simple and accurate marker of hepatic steatosis. FLI is derived from an algorithm based on body mass index, waist circumference, and levels of triglycerides and gamma-glutamyltransferase, and it is widely used in clinical and epidemiological studies as a screening tool for discriminating between healthy and nonalcoholic fatty liver disease (NAFLD) subjects. However, a systematic review of the literature regarding FLI revealed that this index has more extensive relationships with biochemical and physiological parameters. FLI is associated with key parameters of lipid, protein and carbohydrate metabolism, hormones, vitamins and markers of inflammation, or oxidative stress. FLI can be a predictor or risk factor for a number of metabolic and nonmetabolic diseases and mortality. FLI is also used as an indicator for determining the effects of health-related prevention interventions, medications, and toxic substances on humans. Although in most cases, the exact mechanisms underlying these associations have not been fully elucidated, they are most often assumed to be mediated by insulin resistance, inflammation, and oxidative stress. Thus, FLI may be a promising marker of metabolic health due to its multiple associations with parameters of physiological and pathological processes. In this context, the present review summarizes the data from currently available literature on the associations between FLI and biochemical variables and physiological functions. We believe that this review will be of interest to researchers working in this area and can provide new perspectives and directions for future studies on FLI.
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Affiliation(s)
- Anastasiya M Kaneva
- Institute of Physiology of Кomi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, 50 Pervomayskaya str., 167982, Syktyvkar, Russia.
| | - Evgeny R Bojko
- Institute of Physiology of Кomi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, 50 Pervomayskaya str., 167982, Syktyvkar, Russia
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Jurado-Fasoli L, Sanchez-Delgado G, Alcantara JMA, Acosta FM, Sanchez-Sanchez R, Labayen I, Ortega FB, Martinez-Tellez B, Ruiz JR. Adults with metabolically healthy overweight or obesity present more brown adipose tissue and higher thermogenesis than their metabolically unhealthy counterparts. EBioMedicine 2024; 100:104948. [PMID: 38184936 PMCID: PMC10808934 DOI: 10.1016/j.ebiom.2023.104948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 01/09/2024] Open
Abstract
BACKGROUND There is a subset of individuals with overweight/obesity characterized by a lower risk of cardiometabolic complications, the so-called metabolically healthy overweight/obesity (MHOO) phenotype. Despite the relatively higher levels of subcutaneous adipose tissue and lower visceral adipose tissue observed in individuals with MHOO than individuals with metabolically unhealthy overweight/obesity (MUOO), little is known about the differences in brown adipose tissue (BAT). METHODS This study included 53 young adults (28 women) with a body mass index (BMI) ≥25 kg/m2 which were classified as MHOO (n = 34) or MUOO (n = 19). BAT was assessed through a static 18F-FDG positron emission tomography/computed tomography scan after a 2-h personalized cooling protocol. Energy expenditure, skin temperature, and thermal perception were assessed during a standardized mixed meal test (3.5 h) and a 1-h personalized cold exposure. Body composition was assessed by dual-energy x-ray absorptiometry, energy intake was determined during an ad libitum meal test and dietary recalls, and physical activity levels were determined by a wrist-worn accelerometer. FINDINGS Participants with MHOO presented higher BAT volume (+124%, P = 0.008), SUVmean (+63%, P = 0.001), and SUVpeak (+133%, P = 0.003) than MUOO, despite having similar BAT mean radiodensity (P = 0.354). In addition, individuals with MHOO exhibited marginally higher meal-induced thermogenesis (P = 0.096) and cold-induced thermogenesis (+158%, P = 0.050). Moreover, MHOO participants showed higher supraclavicular skin temperature than MUOO during the first hour of the postprandial period and during the cold exposure, while no statistically significant differences were observed in other skin temperature parameters. We observed no statistically significant differences between MHOO and MUOO in thermal perception, body composition, outdoor ambient temperature exposure, resting metabolic rate, energy intake, or physical activity levels. INTERPRETATION Adults with MHOO present higher BAT volume and activity than MUOO. The higher meal- and cold-induced thermogenesis and cold-induced supraclavicular skin temperature are compatible with a higher BAT activity. Overall, these results suggest that BAT presence and activity might be linked to a healthier phenotype in young adults with overweight or obesity. FUNDING See acknowledgments section.
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Affiliation(s)
- Lucas Jurado-Fasoli
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; Department of Physiology, Faculty of Medicine, University of Granada, Granada, Andalucía, Spain.
| | - Guillermo Sanchez-Delgado
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; Department of Medicine, Division of Endocrinology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC, Canada; CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Granada, Spain; Instituto de Investigación Biosanitaria, Ibs.Granada, Granada, Spain
| | - Juan M A Alcantara
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Granada, Spain; Department of Health Sciences, "Institute for Sustainability & Food Chain Innovation", Public University of Navarre, Pamplona, Spain; Navarra Institute for Health Research, Pamplona, Spain
| | - Francisco M Acosta
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; Turku PET Centre, University of Turku, Turku, Finland; Turku PET Centre, Turku University Hospital, Turku, Finland; InFLAMES Research Flagship, University of Turku, 20014, Turku, Finland; MediCity/PET Preclinical Laboratory, University of Turku, Turku PET Centre, Turku, Finland
| | - Rocio Sanchez-Sanchez
- Instituto de Investigación Biosanitaria, Ibs.Granada, Granada, Spain; Servicio de Medicina Nuclear, Hospital Universitario Virgen de las Nieves, Granada, Spain
| | - Idoia Labayen
- CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Granada, Spain; Department of Health Sciences, "Institute for Sustainability & Food Chain Innovation", Public University of Navarre, Pamplona, Spain; Navarra Institute for Health Research, Pamplona, Spain
| | - Francisco B Ortega
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Granada, Spain; Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Borja Martinez-Tellez
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Granada, Spain; Department of Education, Faculty of Education Sciences and SPORT Research Group (CTS-1024), CERNEP Research Center, University of Almería, Almería, Spain
| | - Jonatan R Ruiz
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Carretera de Alfacar s/n, 18071, Granada, Spain; CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Granada, Spain; Instituto de Investigación Biosanitaria, Ibs.Granada, Granada, Spain.
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Saito M, Okamatsu-Ogura Y. Thermogenic Brown Fat in Humans: Implications in Energy Homeostasis, Obesity and Metabolic Disorders. World J Mens Health 2023:41.e26. [PMID: 36792089 DOI: 10.5534/wjmh.220224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 11/08/2022] [Indexed: 01/27/2023] Open
Abstract
In mammals including humans, there are two types of adipose tissue, white and brown adipose tissues (BATs). White adipose tissue is the primary site of energy storage, while BAT is a specialized tissue for non-shivering thermogenesis to dissipate energy as heat. Although BAT research has long been limited mostly in small rodents, the rediscovery of metabolically active BAT in adult humans has dramatically promoted the translational studies on BAT in health and diseases. It is now established that BAT, through its thermogenic and energy dissipating activities, plays a role in the regulation of body temperature, whole-body energy expenditure, and body fatness. Moreover, increasing evidence has demonstrated that BAT secretes various paracrine and endocrine factors, which influence other peripheral tissues and control systemic metabolic homeostasis, suggesting BAT as a metabolic regulator, other than for thermogenesis. In fact, clinical studies have revealed an association of BAT not only with metabolic disorders such as insulin resistance, diabetes, dyslipidemia, and fatty liver, but also with cardiovascular diseases including hypertension and atherosclerosis. Thus, BAT is an intriguing tissue combating obesity and related metabolic diseases. In this review, we summarize current knowledge on human BAT, focusing its patho-physiological roles in energy homeostasis, obesity and related metabolic disorders. The effects of aging and sex on BAT are also discussed.
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Affiliation(s)
- Masayuki Saito
- Laboratory of Biochemistry, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
| | - Yuko Okamatsu-Ogura
- Laboratory of Biochemistry, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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