Sex-specific effects of vegetarian diet on adiponectin levels and insulin sensitivity in healthy non-obese individuals

The mysterious association between adiponectin and endometriosis

Adiponectin is a pleiotropic cytokine predominantly derived from adipose tissue. In addition to its role in regulating energy metabolism, adiponectin may also be related to estrogen-dependent diseases, and many studies have confirmed its involvement in mediating diverse biological processes, including apoptosis, autophagy, inflammation, angiogenesis, and fibrosis, all of which are related to the pathogenesis of endometriosis. Although many researchers have reported low levels of adiponectin in patients with endometriosis and suggested that it may serve as a protective factor against the development of the disease. Therefore, the purpose of this review was to provide an up-to-date summary of the roles of adiponectin and its downstream cytokines and signaling pathways in the aforementioned biological processes. Further systematic studies on the molecular and cellular mechanisms of action of adiponectin may provide novel insights into the pathophysiology of endometriosis as well as potential therapeutic targets.

Sexual dimorphism in the context of nutrition and health

Diets and dietary constituents that we consume have a considerable impact on disease risk. Intriguingly these effects may be modulated to some extent by sex. Lack of female representation in nutritional studies as well as a lack of stratification by sex has and continues to limit our understanding of these sex × diet interactions. Here we provide an overview of the current and available literature describing how exposure to certain dietary patterns (Western-style diet, Mediterranean diet, vegetarian/vegan, ketogenic diet) and dietary constituents (dietary fibre, PUFA and plant bioactive) influences disease risk in a sex-specific manner. Interestingly, these sex differences appear to be highly disease-specific. The identification of such sex differences in response to diet stresses the importance of sex stratification in nutritional research.

Reevaluating Adiponectin's impact on obesity hypertension: a Chinese case-control study

BACKGROUND

Obesity and hypertension are major risk factors for cardiovascular diseases that affect millions of people worldwide. Both conditions are associated with chronic low-grade inflammation, which is mediated by adipokines such as adiponectin. Adiponectin is the most abundant adipokine that has a beneficial impact on metabolic and vascular biology, while high serum concentrations are associated with some syndromes. This "adiponectin paradox" still needs to be clarified in obesity-associated hypertension. The aim of this study was to investigate how adiponectin affects blood pressure, inflammation, and metabolic function in obesity hypertension using a Chinese adult case-control study.

METHODS

A case-control study that had finished recruiting 153 subjects divided as four characteristic groups. Adiponectin serum levels were tested by ELISA in these subjects among these four characteristic Chinese adult physical examination groups. Waist circumference (WC), body mass index (BMI), systolic blood pressure (SB), diastolic blood pressure (DB), and other clinical laboratory data were collected. Analyzation of correlations between the research index and differences between groups was done by SPSS.

RESULTS

Serum adiponectin levels in the| normal healthy group (NH group) were significantly higher than those in the newly diagnosed untreated just-obesity group (JO group), and negatively correlated with the visceral adiposity index. With multiple linear egression analysis, it was found that, for serum adiponectin, gender, serum albumin (ALB), alanine aminotransferase (ALT) and high-density lipoprotein cholesterol (HDLC) were the significant independent correlates, and for SB, age and HDLC were the significant independent correlates, and for DB, alkaline phosphatase (ALP) was the significant independent correlate. The other variables did not reach significance in the model.

CONCLUSIONS

Our study reveals that adiponectin's role in obesity-hypertension is multifaceted and is influenced by the systemic metabolic homeostasis signaling axis. In obesity-related hypertension, compensatory effects, adiponectin resistance, and reduced adiponectin clearance from impaired kidneys and liver all contribute to the "adiponectin paradox".

Metabolic and nutritional biomarkers in adults consuming lacto-ovo vegetarian, vegan and omnivorous diets in Spain. A cross-sectional study

Knowledge on the characteristics of consumers who choose plant-based diets and the relationship with nutritional status and disease risk is needed. In the present study, 207 Spanish adults participated in a cross-sectional study, and were classified in three groups: lacto-ovo vegetarian (LOV), vegan (VEG), and omnivore (OMN). Dietary intake, anthropometry, body composition, haematology, and metabolic markers were evaluated. Body composition and body weight did not vary among groups. The majority of these adults performed moderate-vigorous physical activity, and LOV performed more moderate activity than OMN. Total energy intake (En) was similar in the three groups. However, cholesterol and fat intakes (%En) were higher in the order OMN, LOV, VEG, fibre and carbohydrate intakes showed the opposite trend, and protein intake (%En) was higher in OMN than both LOV and VEG (all p < 0.001). Systolic blood pressure (p = 0.04), erythrocytes (p < 0.001), and haematocrit (p < 0.001) were lower in LOV and VEG than OMN, and lymphocyte count was lower in LOV than OMN (p < 0.01). There were marked differences between groups in serum total-cholesterol and LDL-cholesterol that were lower in LOV and VEG than OMN (both p < 0.001). However, glucose, insulin and insulin resistance did not show group differences. Leptin and adiponectin were related with gender and body fat but not with diet. The inflammation marker interleukin-1β was lower in LOV than OMN but TNF-α did not show differences. All levels were within normal ranges. Conclusion: consumption of plant-based diets compared to omnivorous diets in combination with moderate-high physical activity appears to protect similarly from cardiometabolic diseases in Spanish adults.

Plasma Leptin and Adiponectin after a 4-Week Vegan Diet: A Randomized-Controlled Pilot Trial in Healthy Participants

Adiponectin and leptin are important mediators of metabolic homeostasis. The actions of these adipokines extend beyond adipocytes and include systemic modulation of lipid and glucose metabolism, nutrient flux, and the immune response to changes in nutrition. Herein, we hypothesized that short-term intervention with a vegan diet might result in an improvement of plasma concentrations of adiponectin and leptin and the leptin/adiponectin ratio. We investigated the response of plasma adiponectin and leptin to a 4-week intervention with a vegan or meat-rich diet and its associations with sex, BMI and nutritional intake. Fifty-three healthy, omnivore participants (62% female, average age 31 years and BMI 23.1 kg/m²) were randomly assigned to a vegan or meat-rich diet for 4 weeks. Plasma adiponectin and leptin were lower in men compared to women both at the beginning and end of the trial. The concentration of adiponectin in women was significantly higher both when comparing their transition from omnivorous to vegan diet (p = 0.023) and also for vegan versus meat-rich diet at the end of the trial (p = 0.001), whereas plasma leptin did not vary significantly. No changes in adiponectin were identified in men, yet an increase in leptin occurred upon their transition from an omnivorous to a meat-rich diet (p = 0.019). Examination of plasma adiponectin/leptin ratio, a proposed marker of cardiovascular risk, did not differ after 4-weeks of dietary intervention. Our study revealed that adiponectin and leptin concentrations are sensitive to short-term dietary intervention in a sex-dependent manner. This dietary modification of leptin and adiponectin not only occurs quickly as demonstrated in our study, but it remains such as published in studies with individuals who are established (long-term) vegetarians compared to omnivorous.

The Association Between Plant-Based Diet Indices and Obesity and Metabolic Diseases in Chinese Adults: Longitudinal Analyses From the China Health and Nutrition Survey

Background

A wide range of health benefits are associated with consuming a diet high in plant-based foods. Diet quality can be accurately assessed using plant-based diet indices, however there is inadequate evidence that plant-based diet indices are linked to obesity, hypertension, and type 2 diabetes (T2D), especially in Chinese cultures who have traditionally consumed plant-rich foods.

Methods

The data came from the China Nutrition and Health Survey. Overall, 11,580 adult participants were enrolled between 2004 and 2006 and followed up until 2009 or 2015 (follow-up rate: 73.4%). Dietary intake was assessed across three 24-h recalls, and two plant-based dietary indices [overall plant-based diet indice (PDI) and healthy plant-based diet indice (hPDI)] were calculated using China Food Composition Code and categorized into quintiles. The study's endpoints were overweight/obesity, hypertension, and T2D. The Hazard ratio (HR) and dose-response relationship were assessed using the Cox proportional risk model and restricted cubic splines. The areas under the curve of the receiver operating characteristic curve analyses were used to evaluate the predictive performance of the PDI and hPDI.

Results

During the median follow-up period of more than 10 years, 1,270 (33.4%), 1,509 (31.6%), and 720 (11.5%) participants developed overweight / obesity, hypertension, and T2D, respectively. The higher PDI score was linked with a reduced risk of overweight/obesity [HR: 0.71 (95% CI: 0.55–0.93), P-trend <0.001], hypertension [HR: 0.63 (95% CI: 0.51–0.79), P-trend <0.001], and T2D [HR: 0.79 (95% CI: 0.72–0.87), P-trend <0.001]. The hPDI score was inversely associated with overweight/obesity [HR: 0.79 (95% CI: 0.62–0.98), P-trend = 0.02] and T2D [HR: 0.84 (95% CI: 0.75–0.93), P-trend = 0.001]. In the aged <55-year-old group, subgroup analysis indicated a significant negative association between PDI/hPDI and overweight/obesity, hypertension, and T2D. There was no significant difference in the areas under the curve of the fully adjusted obesity, hypertension, and diabetes prediction models between PDI and hPDI.

Conclusion

The PDI and hPDI scores were very similar in application in Chinese populations, and our findings highlight that adherence to overall plant-based diet index helps to reduce the risk of T2D, obesity, and hypertension in Chinese adults who habitually consume plant-based foods, especially for those aged <55 year. Further understanding of how plant-based diet quality is associated with chronic disease will be needed in the future, which will help develop dietary strategies to prevent diabetes, hypertension, and related chronic diseases.

Association between sleep duration and incidence of type 2 diabetes in China: the REACTION study

Backgrounds:

Inadequate sleep duration is associated with a higher risk of type 2 diabetes and the relationship is nonlinear. We aim to assess the curve relationship between night sleep duration and the incidence of type 2 diabetes in China.

Methods:

A cohort of 11,539 participants from the REACTION study without diabetes at baseline (2011) were followed until 2014 for the development of type 2 diabetes. The average number of hours of sleep per night was grouped. Incidence rates and odds ratios (ORs) were calculated for the development of diabetes in each sleep duration category.

Results:

Compared to people who sleep for 7 to 8 h/night, people with longer sleep duration (≥9 h/night) had a greater risk of type 2 diabetes (OR: 1.27; 95% CI: 1.01–1.61), while shorter sleep (<6 h/night) had no significant difference in risk of type 2 diabetes. When the dataset was stratified based on selected covariates, the association between type 2 diabetes and long sleep duration became more evident among individuals <65 years of age, male, body mass index <24 kg/m² or with hypertension or hyperlipidemia, no interaction effects were observed. Furthermore, compared to people persistently sleeping 7 to 9 h/night, those who persistently slept ≥9 h/night had a higher risk of type 2 diabetes. The optimal sleep duration was 6.3 to 7.5 h/night.

Conclusions:

Short or long sleep duration was associated with a higher risk of type 2 diabetes. Persistently long sleep duration increased the risk.

Non-Pharmacological Treatments for Insulin Resistance: Effective Intervention of Plant-Based Diets—A Critical Review

Plant-based diets are becoming increasingly popular. Vegetarian diets are better for the environment and exhibit health benefits. A correctly balanced plant-based diet is appropriate at every stage of life. Compared to omnivores, vegetarians consume more fruits and vegetables, more fibre, vitamins C and E, magnesium and less saturated fats. In general, they have better nutrition knowledge, and they are slimmer, healthier and live longer than omnivores. It also seems that following a plant-based diet prevents the onset of chronic diseases such as cardiovascular diseases, hypertension, type 2 diabetes, obesity and some cancers. Food intake has a key influence on insulin resistance. Consumption of calorie-rich and highly processed foods, meats and sweetened beverages is a characteristic element of Western diets. They promote and elevate insulin resistance and type 2 diabetes. In contrast, intake of pulses and exclusion of meats as well as animal products bring significant benefits to vegetarian diets. According to studies, vegetarians and vegans have better blood parameters, including better glucose, insulin, total cholesterol, and LDL cholesterol levels. Their homeostatic model assessment for insulin resistance (HOMA-IR) test results are also better. More plant-based foods and fewer animal foods in a diet result in lower insulin resistance and a lower risk of prediabetes and type 2 diabetes. The aim of the study was to investigate the effect of plant-based diets on insulin resistance. In this review, we focused on presenting the positive effects of vegetarian and vegan diets on insulin resistance while showing possible clinical applications of plant-based diets in the treatment and prevention of modern-age diseases. Current and reliable publications meeting the requirements of Evidence-Based Medicine (EBM) were taken into account in this review.

Gender differences in cardiometabolic health and disease in a cross-sectional observational obesity study

Background

Beyond the degree of adiposity, the pattern of fat distribution has a profound influence on cardiometabolic risk. It is unclear if sex differences in body fat distribution can potentially explain any sex differences in the prevalence of the metabolic syndrome (MetS) and in individual cardiometabolic risk factors among obese men and women.

Methods

In this cross-sectional analysis, 432 persons from the ongoing Obesity Weight Reduction Study (n = 356 obese, ØBMI 41 ± 8 kg/m², and 76 non-obese, ØBMI 25 ± 3 kg/m²), were included. The relations of sex to MetS prevalence and selected cardiometabolic risk factors were assessed using univariate and multivariate adjusted regression models.

Results

In crude analyses, %fat mass and the fat mass/lean mass ratio were significantly higher in women than in men, regardless of increasing obesity categories, from normal weight to grade-3-obesity. In contrast, markers of abdominal obesity, such as waist circumference and waist-to-hip ratio were higher in men than in women, despite similar BMI. The prevalence of the MetS was higher in obese men than in women (67.6 vs. 45.0%, p < 0.0001), particularly in younger individuals < 40 years (72.5 vs. 36.8%, p < 0.0001), but “metabolically healthy obesity” (BMI ≥ 30, no other NCEP ATPIII MetS component) was more common in women than in men (15.6 vs. 4.1%, p < 0.0001). After adjusting for age, %body fat and height, sex differences were observed for HDL-cholesterol (p < 0.001), triglycerides (p < 0.001), fasting glucose (p = 0.002), insulin and HOMA-IR levels (p < 0.001), ALAT (p < 0.001), adiponectin (p < 0.001), and sE-selectin (p = 0.005). In contrast, crude sex differences in other variables, such as leptin levels (68 ± 4 in obese women vs. 33 ± 2 µg/L in men, p < 0.0001), disappeared after accounting for differences in %body fat (least-squares means of leptin: 52 ± 4 vs. 55 ± 6 µg /L, p = 0.740). A logistic regression model adjusting for age and lifestyle factors revealed a lower risk of having MetS for women as compared to men (OR = 0.38[0.22–0.60]). That risk estimate did not materially alter after adding BMI to the model. In contrast, no statistically significant association between sex and MetS prevalence was observed after adding waist circumference and adiponectin to the model (OR = 1.41[0.59–3.36]).

Conclusions

Different body fat distribution patterns, particularly abdominal adiposity, adiponectin, and related biomarkers, may contribute to sex differences in cardiometabolic risk factors and to the prevalence of the MetS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00416-4.

Inflammatory, oxidative and DNA damage status in vegetarians: is the future of human diet green?

The health benefit of a vegetarian diet is still under debate as it may result in a higher intake of some beneficial micronutrients, while others may be reduced, thus influencing various metabolic pathways and health-related biomarkers. This scoping review discusses inflammatory, oxidative and DNA damage status in vegetarians and vegans compared to omnivores. Most of the reviewed studies indicated favorable effects of a vegetarian diet on oxidative status compared to omnivores but did not clearly associate particular dietary habits to genome damage. The evidence on the effect of vegetarian diet on the inflammatory and immunological biomarkers is poor, which could at least partly be explained by methodological constraints such as small sample size, short duration of vegetarianism and inconsistent definitions of the omnivorous diet. The only inflammatory biomarker that seems to be associated with the vegetarian diet was inflammatory mediator C-reactive protein, which in several studies showed lower values in vegetarians as compared to omnivores. There were very few studies on immunological markers and the results on the difference between vegetarians and omnivores were inconclusive. Although several biomarkers involved in oxidative stress and inflammation showed a beneficial association with the vegetarian diet, further research in well-defined and sufficiently sized cohorts is needed to provide more evidence.

The Influence of Nutrition on Adiponectin-A Narrative Review

The adipose tissue is an active endocrine organ which synthesizes and secretes a variety of adipokines, including adiponectin with its anti-inflammatory properties. Its expression is influenced by numerous factors such as age, sex, body weight and adipose tissue content. However, dietary factors, i.e., diet structure and the percentage of individual nutrients and products, are very important modulators. Beneficial dietary habits are the Mediterranean diet, DASH diet, diet based on plant products and diet with reduced energy value. Moreover, the share of individual products and nutrients which increase the concentration of adiponectin is worth noting. This group may include monounsaturated fatty acids, polyunsaturated omega-3 fatty acids, dietary fiber, polyphenols, alcohol and milk products. Conversely, dietary ingredients which have a negative effect on the concentration of adiponectin are typical components of the Western diet: saturated fatty acids, trans fatty acids, monosaccharides and disaccharides, and red meat. Furthermore, a diet characterized by a high glycemic index such as a high-carbohydrate low-fat diet also seems to be unfavorable. Due to the fact that available knowledge should be systematized, this study aimed to summarize the most recent research on the influence of dietary factors on the concentration of adiponectin.