Very low-carbohydrate, high-fat, weight reduction diet decreases hepatic gene response to glucose in obese rats

The relationship between hepatic steatosis index and hypertension: NHANES 2011-2018

BACKGROUND

The Hepatic Steatosis Index (HSI) serves as a non-invasive indicator for assessing liver fat accumulation. Its potential association with hypertension has garnered increasing attention, as metabolic dysfunctions, including hepatic steatosis, may contribute to elevated blood pressure via mechanisms such as insulin resistance and chronic inflammation.

METHODS

Utilizing data from the NHANES database (2011-2018), the HSI was calculated on the basis of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and BMI.The association between HSI and hypertension was assessed by univariate analysis, weighted multivariate Logistic regression, and restricted cubic spline (RCS) models. Subgroup analyses were performed to increase the reliability of the data.

RESULTS

This cross-sectional study analysed data from 17,501 adults (NHANES 2011-2018) to assess the association between HSI and hypertension. Of these, 9,890 (56.51%) were diagnosed with hypertension.In the unadjusted model, HSI demonstrated a statistically significant correlation with hypertension, showing an odds ratio (OR) of 1.05 (95% confidence interval: 1.04-1.06).After adjustment for potential confounders, a higher prevalence of hypertension was observed in participants in the upper HSI quartiles (Q3 and Q4), with corresponding ORs of 2.29 (95% CI: 2.29-2.63) and 4.03 (95% CI: 3.42-4.74), respectively. RCS analysis revealed a U-shaped non-linear relationship between HSI and hypertension (P < 0.001), indicating that while hypertension risk primarily escalated with increasing HSI, a modest risk elevation was also detected at lower HSI levels. This suggests that both excessive liver fat accumulation (indicated by a high HSI) and underlying metabolic disorders (such as malnutrition or sarcopenia) may contribute to hypertension risk in individuals with unexpectedly low HSI. Subgroup analyses identified significant interactions in relation to education, cancer, and diabetes mellitus (p for interaction < 0.05), whereas no significant interactions were observed in other stratifications.

CONCLUSION

This study found a U-shaped relationship between the hepatic steatosis index (HSI) and the risk of hypertension. Although the HSI shows potential as a practical screening tool in primary care, further longitudinal studies are needed to establish causality and explore the complex bidirectional pathways involved.

CLINICAL TRIAL NUMBER

Not applicable.

Effects of a high-fat low-carbohydrate diet under different energy conditions on glucose homeostasis and fatty liver development in rats and on gluconeogenesis in the isolated perfused liver

The beneficial effects of high-fat low-carbohydrate (HFLC) diets on glucose metabolism have been questioned and their effects on liver metabolism are not totally clear. The aim of this work was to investigate the effects of an HFLC diet under different energy conditions on glucose homeostasis, fatty liver development, and hepatic gluconeogenesis using the isolated perfused rat liver. HFLC diet (79% fat, 19% protein, and 2% carbohydrates in Kcal%) was administered to rats for 4 weeks under three conditions: ad libitum (hypercaloric), isocaloric, and hypocaloric (energy reduction of 20%). Fasting blood glucose levels and total fat in the liver were higher in all HFLC diet rats. Oral glucose tolerance was impaired in isocaloric and hypercaloric groups, although insulin sensitivity was not altered. HFLC diet also caused marked liver metabolic alterations: higher gluconeogenesis rate from lactate and a reduced capacity to metabolize alanine, the latter effect being more intense in the hypocaloric condition. Thus, even when HFLC diets are used for weight loss, our data imply that they can potentially cause harmful consequences for the liver.

Fibroblast Growth Factor 21 and the Adaptive Response to Nutritional Challenges

The Fibroblast Growth Factor 21 (FGF21) is considered an attractive therapeutic target for obesity and obesity-related disorders due to its beneficial effects in lipid and carbohydrate metabolism. FGF21 response is essential under stressful conditions and its metabolic effects depend on the inducer factor or stress condition. FGF21 seems to be the key signal which communicates and coordinates the metabolic response to reverse different nutritional stresses and restores the metabolic homeostasis. This review is focused on describing individually the FGF21-dependent metabolic response activated by some of the most common nutritional challenges, the signal pathways triggering this response, and the impact of this response on global homeostasis. We consider that this is essential knowledge to identify the potential role of FGF21 in the onset and progression of some of the most prevalent metabolic pathologies and to understand the potential of FGF21 as a target for these diseases. After this review, we conclude that more research is needed to understand the mechanisms underlying the role of FGF21 in macronutrient preference and food intake behavior, but also in β-klotho regulation and the activity of the fibroblast activation protein (FAP) to uncover its therapeutic potential as a way to increase the FGF21 signaling.