Fructose Intake, Hypertension and Cardiometabolic Risk Factors in Children and Adolescents: From Pathophysiology to Clinical Aspects. A Narrative Review

Effect of a high-fat high-fructose diet on the composition of the intestinal microbiota and its association with metabolic and anthropometric parameters in a letrozole-induced mouse model of polycystic ovary syndrome

OBJECTIVE

It has been suggested that dysbiosis of the gut microbiota is associated with the pathogenesis of Polycystic Ovary Syndrome (PCOS), and that improper diet can aggravate these changes. This study thus aimed to investigate the effects of a high-fat/high-fructose (HF/HFr) diet on the gut microbial community and their metabolites in prepubertal female mice with letrozole (LET)-induced PCOS. We also tested the correlations between the relative abundance of microbial taxa and selected PCOS parameters.

RESEARCH METHODS & PROCEDURES

Thirty-two C57BL/6 mice were randomly divided into four groups (n = 8) and implanted with LET or a placebo, with simultaneous administration of a HF/HFr diet or standard diet (StD) for 5 wk. The blood and intestinal contents were collected after the sacrifice.

RESULTS

Placebo + HF/HFr and LET + HF/HFr had significantly higher microbial alpha diversity than either group fed StD. The LET-implanted mice fed StD had a significantly higher abundance of Prevotellaceae_UCG-001 than the placebo mice fed StD. Both groups fed the HF/HFr diet had significantly lower fecal levels of short-chain fatty acids than the placebo mice fed StD, while the LET + HF/HFr animals had significantly higher concentrations of lipopolysaccharides in blood serum than either the placebo or LET mice fed StD. Opposite correlations were observed between Turicibacter and Lactobacillus and the lipid profile, CONCLUSION: HF/HFr diet had a much stronger effect on the composition of the intestinal microbiota of prepubertal mice than LET itself.

Assessing the impact of concurrent high-fructose and high-saturated fat diets on pediatric metabolic syndrome: A review

High-saturated fat (HF) or high-fructose (HFr) consumption in children predispose them to metabolic syndrome (MetS). In rodent models of MetS, diets containing individually HF or HFr lead to a variable degree of MetS. Nevertheless, simultaneous intake of HF plus HFr have synergistic effects, worsening MetS outcomes. In children, the effects of HF or HFr intake usually have been addressed individually. Therefore, we have reviewed the outcomes of HF or HFr diets in children, and we compare them with the effects reported in rodents. In humans, HFr intake causes increased lipogenesis, hypertriglyceridemia, obesity and insulin resistance. On the other hand, HF diets promote low grade-inflammation, obesity, insulin resistance. Despite the deleterious effects of simultaneous HF plus HFr intake on MetS development in rodents, there is little information about the combined effects of HF plus HFr intake in children. The aim of this review is to warn about this issue, as individually addressing the effects produced by HF or HFr may underestimate the severity of the outcomes of Western diet intake in the pediatric population. We consider that this is an alarming issue that needs to be assessed, as the simultaneous intake of HF plus HFr is common on fast food menus.

Mechanisms Underlying Memory Impairment Induced by Fructose

Fructose consumption has increased over the years, especially in adolescents living in urban areas. Growing evidence indicates that daily fructose consumption leads to some pathological conditions, including memory impairment. This review summarizes relevant data describing cognitive deficits after fructose intake and analyzes the underlying neurobiological mechanisms. Preclinical experiments show sex-related deficits in spatial memory; that is, while males exhibit significant imbalances in spatial processing, females seem unaffected by dietary supplementation with fructose. Recognition memory has also been evaluated; however, only female rodents show a significant decline in the novel object recognition test performance. According to mechanistic evidence, fructose intake induces neuroinflammation, mitochondrial dysfunction, and oxidative stress in the short term. Subsequently, these mechanisms can trigger other long-term effects, such as inhibition of neurogenesis, downregulation of trophic factors and receptors, weakening of synaptic plasticity, and long-term potentiation decay. Integrating all these neurobiological mechanisms will help us understand the cellular and molecular processes that trigger the memory impairment induced by fructose.

Effects of dietary sugar restriction on hepatic fat in youth with obesity

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in children. Like adults, children can develop the progressive form of NAFLD, nonalcoholic steatohepatitis (NASH), which is characterized by hepatic inflammation, often in the presence of fibrosis. Children with NAFLD are at higher risk of liver-related complications, metabolic dysfunction, and cardiovascular disease in adulthood. Many factors contribute to the escalating prevalence of NAFLD in the pediatric population, among which are an array of dietary patterns such as overnutrition, poor diet quality, and heavy consumption of fat and sugar, including fructose. Findings from an increasing number of epidemiological studies support a connection between high habitual sugar consumption and NAFLD, especially within the context of obesity, but these studies are not able to demonstrate whether sugar is a contributing factor or instead an indicator of an overall poor diet (or lifestyle) quality. To date, only four randomized controlled dietary interventions assessing the effects of sucrose/fructose restriction on hepatic fat fraction in youth with obesity have been published. The objectives of this review are to summarize the key findings from these dietary interventions to achieve a better understanding of the strength of the relationship between dietary sugar restriction and liver fat reduction, despite their inherent limitations, and to discuss the potential impact of weight loss and fat mass reduction on improvement in hepatic steatosis.

The Impact of Excessive Fructose Intake on Adipose Tissue and the Development of Childhood Obesity

Worldwide, childhood obesity cases continue to rise, and its prevalence is known to increase the risk of non-communicable diseases typically found in adults, such as cardiovascular disease and type 2 diabetes mellitus. Thus, comprehending its multiple causes to build healthier approaches and revert this scenario is urgent. Obesity development is strongly associated with high fructose intake since the excessive consumption of this highly lipogenic sugar leads to white fat accumulation and causes white adipose tissue (WAT) inflammation, oxidative stress, and dysregulated adipokine release. Unfortunately, the global consumption of fructose has increased dramatically in recent years, which is associated with the fact that fructose is not always evident to consumers, as it is commonly added as a sweetener in food and sugar-sweetened beverages (SSB). Therefore, here, we discuss the impact of excessive fructose intake on adipose tissue biology, its contribution to childhood obesity, and current strategies for reducing high fructose and/or free sugar intake. To achieve such reductions, we conclude that it is important that the population has access to reliable information about food ingredients via food labels. Consumers also need scientific education to understand potential health risks to themselves and their children.

Food Intolerances, Food Allergies and IBS: Lights and Shadows

This narrative review delves into the intricate relationship between irritable bowel syndrome (IBS) and food intolerances. IBS, a chronic functional gastrointestinal disorder, is characterized by symptoms like abdominal pain and altered bowel habits. The prevalence of IBS has increased globally, especially among young adults. Food and dietary habits play a crucial role in IBS management. About 85-90% of IBS patients report symptom exacerbation linked to specific food consumption, highlighting the strong connection between food intolerances and IBS. Food intolerances often exhibit a dose-dependent pattern, posing a challenge in identifying trigger foods. This issue is further complicated by the complex nature of gastrointestinal physiology and varying food compositions. This review discusses various dietary patterns and their impact on IBS, including the low-FODMAP diet, gluten-free diet, and Mediterranean diet. It highlights the importance of a personalized approach in dietary management, considering individual symptom variability and dietary history. In conclusion, this review emphasizes the need for accurate diagnosis and holistic management of IBS, considering the complex interplay between dietary factors and gastrointestinal pathophysiology. It underlines the importance of patient education and adherence to treatment plans, acknowledging the challenges posed by the variability in dietary triggers and the psychological impact of dietary restrictions.

Acute Intake of Fructose Increases Arterial Pressure in Humans: A Meta-Analysis and Systematic Review

Hypertension is a major cardiac risk factor. Higher blood pressures are becoming more prevalent due to changing dietary habits. Here, we evaluated the impact on blood pressure in human subjects after acutely ingesting fructose using meta-analysis. A total of 89 studies were collected from four different electronic databases from 1 January 2008 to 1 August 2023. Of these studies, 10 were selected that fulfilled all the criteria for this meta-analysis. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), and blood glucose level were analyzed using the Cohen's d analysis or standardized mean difference at a confidence interval (CI) of 95%. The SBP, DBP, and MAP showed medium effect size; HR and glucose level displayed small effect size. The standardized mean difference of normal diet groups and fructose diet groups showed a significant increase in SBP (p = 0.04, REM = 2.30), and DBP (p = 0.03, REM = 1.48) with heterogeneity of 57% and 62%, respectively. Acute fructose ingestion contributes to an increase in arterial pressure in humans. The different parameters of arterial pressure in humans correlated with each other. These findings support further rigorous investigation, retrospective of necessity, into the effect of chronic dietary of fructose in humans in order to better understand the impact on long term arterial pressure.

Trichostatin a inhibits expression of the human SLC2A5 gene via SNAI1/SNAI2 transcription factors and sensitizes colon cancer cells to platinum compounds

GLUT5, a key protein encoded by the SLC2A5 gene, is involved in the uptake of fructose from the intestine. Currently, with the increased consumption of this sugar and the associated increased incidence of obesity, diabetes and cancer, GLUT5 may represent an important molecular target in the prevention and treatment of these diseases. Here, we demonstrate that overexpression of the SNAI1 and SNAI2 transcription factors in cells expressing high levels of SLC2A5 mRNA reduced SLC2A5 gene expression. Furthermore, a histone deacetylase inhibitor, trichostatin A, which induces SNAI1 and SNAI2 expression, inhibits SLC2A5/GLUT5 expression and sensitizes colon cancer cells to cisplatin and oxaliplatin. This finding might have potential relevance for the development of therapeutic treatments aimed at modulating fructose transport or genes involved in this process for use with certain cancers.

The Role of a High-Fat, High-Fructose Diet on Letrozole-Induced Polycystic Ovarian Syndrome in Prepubertal Mice

This study aims to investigate the effects of a high-fat, high-fructose (HF/HFr) diet on metabolic/endocrine dysregulations associated with letrozole (LET)-induced Polycystic Ovarian Syndrome (PCOS) in prepubertal female mice. Thirty-two prepubertal C57BL/6 mice were randomly divided into four groups of eight and implanted with LET or a placebo, with simultaneous administration of an HF/HFr/standard diet for five weeks. After sacrifice, the liver and blood were collected for selected biochemical analyses. The ovaries were taken for histopathological examination. The LET+HF/HFr group gained significantly more weight than the LET-treated mice. Both the LET+HF/HFr and the placebo-treated mice on the HF/HFr diet developed polycystic ovaries. Moreover the LET+HF/HFr group had significantly elevated testosterone levels, worsened lipid profile and indices of insulin sensitivity. In turn, the HF/HFr diet alone led to similar changes in the LET-treated group, except for the indices of insulin sensitivity. Hepatic steatosis also occurred in both HF/HFr groups. The LET-treated group did not develop endocrine or metabolic abnormalities, but polycystic ovaries were seen. Since the HF/HFr diet can cause substantial metabolic and reproductive dysregulation in both LET-treated and placebo mice, food items rich in simple sugar-particularly fructose-and saturated fat, which have the potential to lead to PCOS progression, should be eliminated from the diet of young females.