The role of saturation of fat depots in the pathogenesis of insulin resistance

Prevalence of risk factors for cardiovascular and kidney disease in Brazilian healthy preschool children

AIM

To investigate the prevalence of nutritional parameters of risk for cardiovascular disease (CVD) and kidney diseases in healthy preschool children.

METHODS

This is an observational cross-sectional study with 60 healthy children, of both genders, aged two to six years old and 56 mothers, in Belo Horizonte, Minas Gerais, Brazil. Preschool children and their families with regular activities at public schools were invited to paticipate in the study. The following characteristics were assessed: Socio-demographic condictions, clinical health, anthropometric, biochemical, lifestyle and data on food consumption. The 56 healthy children were divided into two groups, overweight (C1) and non-overweight (C2), as well as their mothers, respectively, in overweight (M1) and non-overweight (M2). Nutritional status was defined according to results obtained through the Anthro^® Software for nutritional analysis.

RESULTS

Thirty-five children were male, with mean age of 4.44 ± 1.0 years old. Eighty-nine percent of them were eutrophic, 86.7% were sedentary and they had five meals a day. Body mass index (BMI) for age and total cholesterol (TC) was higher on C1 (P = 0.0001) and high density lipoprotein cholesterol (HDL-c) was higher on C2. Mothers were 32.5 ± 7.1 years old, mostly married and employed. Eighty-six percent of them were sedentary and 62.5% were overweight with BMI = 26.38 ± 5.07 kg/m². Eighteen percent of the overweight mothers had isolated total hypercholesterolemia (TC levels elevated) and 12.5% had low HDL-c levels. The present study showed an association between overweight and obesity during the preschool years and the correspondent mothers’ nutritional status of overweight and obesity (OR = 4.96; 95%CI: 0.558-44.17). There was a positive correlation between the food risk associated with CVD by children and mothers when their consumption was 4 times/wk (P = 0.049; r = 0.516) or daily (P = 0.000008; r = 0.892).

CONCLUSION

Analyzed children showed high rates of physical inactivity, high serum cholesterol levels and high consumption of food associated with risk for CVD and renal disease. Changes in habits should be encouraged early in kindergarten.

Adipose tissue characteristics related to weight z-score in childhood

BACKGROUND

Childhood obesity has grown very fast over recent decades and now it represents a serious public health problem. The number of adipocytes is set in childhood and adolescence and then, an effective understanding of the development of adipose tissue during these periods will help in the prevention of this pathology.

OBJECTIVES

The current study aimed to determine which adipose tissue characteristics are related to a high weight Z-score in childhood.

PATIENTS AND METHODS

The current study included 82 children aged 5-130 months who underwent inguinal hernia surgery. Anthropometric variables were measured, and a nutritional and physical activity questionnaire was completed. Subcutaneous adipose tissue samples, taken during the operation, were analyzed for preadipocyte number, adipocyte volume, fatty acid composition (gas chromatography of FAME), and relative gene expression of various genes (real time PCR).

RESULTS

The results showed that children with a higher weight Z-score spend more time in sedentary activities and less time running or involved in active games. SCD-1 activity index, arachidonic/linoleic index, and adipocyte volume were significantly higher in children with a weight Z-score greater than 0. The preadipocyte number and the genetic expression of the studied genes did not differ between the groups. A multiple regression analysis was done to determine which variables were related to the weight Z-score. R2 values indicated that the model which included adipocyte volume, SREBP-1c, SCD-1 expression, and activity index, predicted 59% of the variability in the weight Z-score among the children. The main variables associated with adipocyte volume were PPARγ, Adiponectin, CB1R expressions, as well as the SCD-1 activity and normalized weight.

CONCLUSIONS

It was concluded that in childhood, the weight Z-score is related to adipocyte volume and adipose tissue gene expression.

Children whose diet contained olive oil had a lower likelihood of increasing their body mass index Z-score over 1 year

OBJECTIVE

Changes in eating habits may be influential in the ever-increasing rate of childhood obesity. Our aim was to determine whether those children who consume olive oil have a lower risk of weight gain compared with children who consume other oils.

DESIGN AND METHODS

The study included 18 girls and 74 boys, all aged 13-166 months. A survey was completed for each subject about eating habits and physical activity. A sample of subcutaneous adipose tissue was also obtained for cellular study. Data were recorded on the mean size of the adipocytes, the number of preadipocytes, and the concentration of particular fatty acids. The weight and height of the children were measured 13 months later.

RESULTS

The likelihood that after 1 year the children would have increased their body mass index (BMI) Z-score above the initial score was less in the children who consumed only olive oil (odds ratio (OR)=0.22; 95% confidence interval (CI): 0.08-0.63; P=0.005). These results remained after adjusting for age, physical activity and BMI (OR=0.19; 95% CI: 0.06-0.61; P=0.005) and after adjusting for age, physical activity and adipocyte volume (OR=0.15; 95% CI: 0.04-0.52; P=0.003).

CONCLUSIONS

Diets with mono unsaturated fatty acid (MUFA)-rich olive oil could reduce the risk of obesity in childhood.

Adipocyte hypertrophy, fatty liver and metabolic risk factors in South Asians: the Molecular Study of Health and Risk in Ethnic Groups (mol-SHARE)

Objective

We sought to determine if differences in the distribution and characteristics of adipose tissue between South Asians and white Caucasians account for differences in risk factors for cardiovascular disease.

Research Design and Methods

We recruited 108 healthy South Asians (36.8 years) and white Caucasians (34.2 years) within three BMI strata. Body composition, adipocyte size, abdominal fat area, and hepatic adiposity were assessed and related to fasting glucose, insulin, lipids and adiponectin.

Results

After adjustment for age, sex, and BMI, South Asians compared to white Caucasians had higher ln fasting insulin (mean difference (md): 0.44; 95% CI: 0.20–0.69), lower HDL cholesterol (md: −0.13; 95% CI:−0.26 to −0.01), and lower adiponectin (md: −2.38; 95% CI: −3.59 to −1.17). South Asians also had more body fat (md: 2.69; 95% CI: 0.70 to 4.69), lower lean muscle mass (md: −3.25; 95%CI: −5.35 to −1.14), increased waist to hip ratio (md: 0.03; 95% CI: 0.01–0.05), less superficial subcutaneous abdominal adipose tissue (md: −2.94; 95% CI: −5.56 to−0.32), more deep/visceral to superficial adipose tissue ratio (md 0.34; 95% CI: 0.02 to 0.65), and more liver fat (md: 7.43%; 95% CI: 2.30 to 12.55%). Adipocyte area was increased in South Asians compared to white Caucasians (md: 64.26; 95% CI: 24.3 to 104.1) units². Adjustment for adipocyte area attenuated the ethnic differences in insulin (md: 0.22; 95% CI: −0.07 to 0.51), HDL (md: −0.01; 95% CI: −0.16 to 0.13) and adiponectin (md: −1.11; 95% CI: −2.61 to 0.39). Adjustment for differences in adipocyte area and fat distribution attenuated the ethnic difference in liver fat (md: 5.19; 95% CI: 0.31 to 10.06).

Conclusion

South Asians have an increased adipocyte area compared to white Caucasians. This difference accounts for the ethnic differences in insulin, HDL cholesterol, adiponectin, and ectopic fat deposition in the liver.

Microcirculation in obesity: an unexplored domain

Obesity is traditionally linked to diabetes and cardiovascular diseases. Very recent experimental, clinical and epidemiological, sometimes provocative, data challenge this automaticity by showing that not the amount but the distribution of fat is the important determinant. Moderate abdominal fat accumulation may thus be more harmful than even consequent overweight. In view of the worldwide burden of obesity, factors leading to it in children and young adults must urgently be identified. Since obesity is a very complex cardiometabolic situation, this will require to focus investigations on uncomplicated obese subjects and adequate animal models. The recent discovery of intergenerational transmissions of obesity risk factors and also the key role played by gestational and perinatal events (epigenetic factors) give rise to completely new concepts and research avenues. Considering the potential close relationship between microcirculation and tissue metabolism, demonstrations of structural and/or functional abnormalities in microvascular physiology very early in life of subjects at risk for obesity might provide a solid basis for further investigations of such links. Microcirculation(arterioles, capillaries and venules) is conceivably a key compartment determining over one or several decades the translation of genetic and epigenetic factors into fat accumulation. Available animal models should serve to answer this cardinal question.

Marginal vitamin C status is associated with reduced fat oxidation during submaximal exercise in young adults

BACKGROUND

Vitamin C is a cofactor in the biosynthesis of carnitine, a molecule required for the oxidation of fatty acids. A reduction in the ability to oxidize fat may contribute to the reported inverse relationship between vitamin C status and adiposity. To examine this possibility, we conducted a preliminary trial to evaluate the impact of vitamin C status on fat oxidation during submaximal exercise.

METHODS

Fat energy expenditure was determined in individuals with marginal (n = 15) or adequate (n = 7) vitamin C status during a submaximal, 60-minute treadmill test. Subsequently, eight of the subjects with marginal vitamin C status completed an 8-week double-blind, placebo-controlled, depletion-repletion trial with submaximal exercise testing.

RESULTS

Individuals with marginal vitamin C status oxidized 25% less fat per kg body weight during the treadmill test as compared to individuals with adequate vitamin C status. Fat oxidation during exercise was inversely related to fatigue (r = -0.611, p = 0.009). Vitamin C repletion of vitamin C depleted subjects (500 mg vitamin C/d) raised fat energy expenditure during exercise 4-fold as compared to depleted control subjects (p = 0.011).

CONCLUSION

These preliminary results show that low vitamin C status is associated with reduced fat oxidation during submaximal exercise. Low vitamin C status may partially explain the inverse relationship between vitamin C status and adiposity and why some individuals are unsuccessful in their weight loss attempts.