Changes in circulating miRNAs in healthy overweight and obese subjects: Effect of diet composition and weight loss

BACKGROUND

MicroRNAs (miRNAs) are small non-coding RNA molecules that can play an important role in several chronic metabolic conditions, including obesity. However, to date little is known about how they are regulated. Weight loss induced by surgical procedures has been effective at modulating specific circulating miRNAs, but the effect of energy-restricted diets with different macronutrient compositions on circulating miRNAs is not well understood. The objective of the present analysis was to explore the effect of three energy-restricted diets of different macronutrient composition and carbohydrate quality on plasma miRNA levels.

METHODS

The GLYNDIET study is a 6-month, parallel, randomized clinical trial conducted on overweight and obese subjects who were randomized to one of three different dietary intervention groups: i) a moderate-carbohydrate and low glycemic index diet (LGI), ii) a moderate-carbohydrate and high glycemic index diet (HGI), and iii) a low-fat and high glycemic index diet (LF). We assessed the genome-wide circulating miRNA profile in a subsample of eight randomly selected participants. A total of 8 miRNAs (miR-411, miR-432, miR-99b, miR-340, miR-423, miR-361, let-7c) were differently quantified according to diet intervention, and were therefore longitudinally validated in 103 participants before and after the energy-restricted diets.

RESULTS

Circulating miR-361 levels were lower in the LGI group than in the HGI group, even after adjusting for differences in weight loss. The intra-group analyses demonstrated a significant down-regulation of all miRNAs screened in our study subjects after the LGI intervention. Similarly, miR-139 and miR-340 were down-regulated after the HGI intervention, while miR-139, miR-432 and miR-423 were down-regulated after the low-fat diet. Changes in circulating miR-139 and let-7c were significantly associated with changes in lipid profile and insulin resistance.

CONCLUSION

An energy-restricted low-glycemic index diet down-regulates circulating miRNA-361 more than an energy-restricted high-glycemic index, regardless of the magnitude of the weight loss.

Extra virgin olive oil consumption reduces the risk of osteoporotic fractures in the PREDIMED trial

BACKGROUND & AIMS

The incidence of osteoporotic fractures is lower in countries in the Mediterranean basin. Virgin olive oil, a key component of the Mediterranean Diet (MDiet), with recognised beneficial effects on metabolism and cardiovascular health, may decrease the risk of osteoporotic fractures. The aim to this study was to explore the effect of chronic consumption of total olive oil and its varieties on the risk of osteoporosis-related fractures in a middle-aged and elderly Mediterranean population.

METHODS

We included all participants (n = 870) recruited in the Reus (Spain) centre of the PREvención con DIeta MEDiterránea (PREDIMED) trial. Individuals, aged 55-80 years at high cardiovascular risk, were randomized to a MedDiet supplemented with extra-virgin olive oil, a MedDiet supplemented with nuts, or a low-fat diet. The present analysis was an observational cohort study nested in the trial. A validated food frequency questionnaire was used to assess dietary habits and olive oil consumption. Information on total osteoporotic fractures was obtained from a systematic review of medical records. The association between yearly repeated measurements of olive oil consumption and fracture risk was assessed by multivariate Cox proportional hazards.

RESULTS

We documented 114 incident cases of osteoporosis-related fractures during a median follow-up of 8.9 years. Treatment allocation had no effect on fracture risk. Participants in the highest tertile of extra-virgin olive oil consumption had a 51% lower risk of fractures (HR:0.49; 95% CI:0.29-0.81. P for trend = 0.004) compared to those in the lowest tertile after adjusting for potential confounders. Total and common olive oil consumption was not associated with fracture risk.

CONCLUSIONS

Higher consumption of extra-virgin olive oil is associated with a lower risk of osteoporosis-related fractures in middle-aged and elderly Mediterranean population at high cardiovascular risk.

A Mediterranean diet supplemented with extra virgin olive oil or nuts improves endothelial markers involved in blood pressure control in hypertensive women

PURPOSE

Serum nitric oxide (NO) reduction and increased endothelin-1 (ET-1) play a pivotal role in endothelial dysfunction and hypertension. Considering that traditional Mediterranean diet (TMD) reduces blood pressure (BP), the aim of this study was to analyze whether TMD induced changes on endothelial physiology elements such as NO, ET-1 and ET-1 receptors which are involved in BP control.

METHODS

Non-smoking women with moderate hypertension were submitted for 1 year to interventions promoting adherence to the TMD, one supplemented with extra virgin olive oil (EVOO) and the other with nuts versus a control low-fat diet (30 participants/group). BP, NO, ET-1 and related gene expression as well as oxidative stress biomarkers were measured.

RESULTS

Serum NO and systolic BP (SBP) or diastolic BP (DBP) were negatively associated at baseline, as well as between NO and ET-1. Our findings also showed a DBP reduction with both interventions. A negative correlation was observed between changes in NO metabolites concentration and SBP or DBP after the intervention with TMD + EVOO (p = 0.033 and p = 0.044, respectively). SBP reduction was related to an impairment of serum ET-1 concentrations after the intervention with TMD + nuts (p = 0.008). We also observed changes in eNOS, caveolin 2 and ET-1 receptors gene expression which are related to NO metabolites levels and BP.

CONCLUSIONS

The changes in NO and ET-1 as well as ET-1 receptors gene expression explain, at least partially, the effect of EVOO or nuts on lowering BP among hypertensive women.

Effect of pistachio consumption on plasma lipoprotein subclasses in pre-diabetic subjects

BACKGROUND AND AIMS

Nuts have been demonstrated to improve several cardiovascular risk factors and the lipid profile in diabetic and pre-diabetic subjects. However, analysis of conventional serum lipid profiles does not completely explain the atherogenic risk associated with pre-diabetes. We therefore investigated whether chronic consumption of pistachio modifies the lipoprotein subclasses to a healthier profile in pre-diabetic subjects.

METHODS AND RESULTS

Randomized cross-over clinical trial in 54 subjects with pre-diabetes. Subjects consumed a pistachio-supplemented diet (PD, 50% carbohydrates, 33% fat, including 57 g/d of pistachios daily) and a control diet (CD, 55% carbohydrates, 30% fat) for 4 months each, separated by a 2-week wash-out. Diets were isocaloric and matched for protein, fiber and saturated fatty acids. Nuclear magnetic resonance (NMR) was performed to determine changes in plasma lipoprotein subclasses. Small low-density lipoprotein particles (sLDL-P) significantly decreased after pistachio consumption compared to the nut-free diet (P = 0.023). The non-high-density lipoprotein particles (non-HDL-P i.e. VLDL-P plus LDL-P) significantly decreased under the PD compared to CD (P = 0.041). The percentage of sHDL-P increased by 2.23% after the PD compared with a reduction of 0.08% after the CD (P = 0.014). Consequently, the overall size of HDL-P significantly decreased in the PD (P = 0.007).

CONCLUSION

Chronic pistachio consumption could modify the lipoprotein particle size and subclass concentrations independently of changes in total plasma lipid profile, which may help to explain the decreased risk of cardiovascular disease and mortality associated with those individuals who frequently consumed nuts.

REGISTRATION NUMBER

This study is registered at www.clinicaltrials.gov as NCT01441921.

Dietary glycemic index/load and peripheral adipokines and inflammatory markers in elderly subjects at high cardiovascular risk

BACKGROUND AND AIMS

Epidemiological and clinical studies suggest that low-glycemic index diets could protect against weight gain. However, the relationship between these diets and adipokines or inflammatory markers is unclear. In the present study we examine how the dietary glycemic index (GI) and dietary glycemic load (GL) are associated with several adipokines and related metabolic risk markers of obesity and diabetes in a cross-sectional and longitudinal manner.

METHODS AND RESULTS

511 elderly community-dwelling men and women at high cardiovascular risk were recruited for the PREDIMED trial. Dietary data were collected at baseline and after 1 year of follow-up. The GI and GL were calculated. Plasma leptin, adiponectin and other metabolic risk markers were measured at baseline and after 1 year. At baseline, subjects in the highest quartiles of GI showed significantly higher levels of TNF and IL-6 than those in the lowest quartiles. Dietary GI index was negatively related to plasma leptin and adiponectin levels. After 1 year of follow-up, subjects with a higher increase in dietary GI or GL showed a greater reduction in leptin and adiponectin plasma levels. There was no association between GI or GL and the other metabolic markers measured.

CONCLUSION

Our results suggest that the consumption of high-GI or high-GL diets may modulate plasma concentrations of leptin and adiponectin, both adipostatic molecules implicated in energy balance and cardiometabolic risk.

Association between red meat consumption and metabolic syndrome in a Mediterranean population at high cardiovascular risk: cross-sectional and 1-year follow-up assessment

BACKGROUND AND AIMS

Little is known about the role that red meat and processed red meat (RM) consumption plays in the development of the metabolic syndrome (MetS). The aim was to assess the relationship between RM consumption and the prevalence or incidence of the MetS and its components in a Mediterranean population at high risk of cardiovascular disease.

METHODS AND RESULTS

Cross-sectional analyses were carried out at baseline and at 1-year follow-up and longitudinal analysis were conducted in a cohort of individuals at high risk of cardiovascular disease from the PREDIMED study. A 137-item validated semi-quantitative food frequency questionnaire, anthropometric measurements, blood pressure, fasting plasma glucose and lipid profile were evaluated both at baseline and after 1-year follow-up. The MetS was defined in accordance with the updated ATP III criteria. Subjects in the upper quartile of RM consumption were more likely to meet the criteria for the MetS at baseline (OR, 2.3; 95% CI, 1.4-3.9; P-trend = 0.001) and after 1-year follow-up (OR, 2.2; 95% CI, 1.3-3.7; P-trend = 0.034) compared with those in the quartile of reference, even after adjusting for potential confounders. The longitudinal analyses showed that individuals in the fourth quartile of RM consumption had an increased risk of MetS (OR, 2.7; 95% CI, 1.1-6.8; P-trend = 0.009) or central obesity incidence (OR, 8.1; 95% CI, 1.4-46.0; P-trend = 0.077) at the end of the follow-up compared to the lowest quartile.

CONCLUSIONS

Higher RM consumption is associated with a significantly higher prevalence and incidence of MetS and central obesity in individuals at high risk of cardiovascular disease.

Bone quantitative ultrasound measurements in relation to the metabolic syndrome and type 2 diabetes mellitus in a cohort of elderly subjects at high risk of cardiovascular disease from the PREDIMED study

OBJECTIVE

The aim of this study is to determine whether metabolic syndrome, its individual components, or the presence of type 2 diabetes mellitus are associated with a better bone status estimated by quantitative ultrasound at the calcaneus.

DESIGN

Cross-sectional study.

SETTING

Outpatient clinics.

PARTICIPANTS

251 elderly subjects at high cardiovascular risk from the PREDIMED study were included.

MEASUREMENTS

MetS was defined according to the ATPIII diagnosis criteria. Calcaneus quantitative ultrasound (QUS) assessment was performed using the Sahara system.

RESULTS

Subjects with MetS showed significantly lower 24-hour urinary deoxypyridinoline/creatinine (u-DPD/creatinine) levels and higher broadband ultrasound attenuation, and a tendency to higher bone mineral density (BMD) and quantitative ultrasound index (QUI) than their counterparts. Individuals with type 2 diabetes mellitus (T2DM) showed a significantly higher bone broadband ultrasound attenuation (BUA) and QUI than their non-diabetic counterparts, despite they shown a higher prevalence of osteoporotic fractures. Multiple linear regression analyses showed that quantitative ultrasound parameters were positively associated with the metabolic syndrome and T2DM. Of the bone biochemical markers, only u-DPD/creatinine was related to MetS, abdominal obesity, hypertriglyceridemia component of the MetS, and the number of features that define the MetS.

CONCLUSION

This is the first study showing a positive association between MetS or T2DM with better bone status and lower bone resorption markers measured by quantitative ultrasound. Our results suggest that metabolic abnormalities have a positive effect on healthy bone in elderly subjects at high risk of cardiovascular disease.

The role of diet in the prevention of type 2 diabetes

Type 2 diabetes mellitus is an important preventable disease and a growing public health problem. Epidemiologic and interventional studies suggest that weight loss is the main driving force to reduce diabetes risk. Landmark clinical trials of lifestyle changes in subjects with prediabetes have shown that diet and exercise leading to weight loss consistently reduce the incidence of diabetes. However, from these studies it cannot be established whether dietary changes alone play a significant role in preventing diabetes. Here we review epidemiologic and clinical trial evidence relating nutrients, foods and dietary patterns to diabetes risk and the possible mechanisms involved. The differential effects of carbohydrate and fat quantity and quality, and those of specific foods and whole diets are discussed. Importantly, most dietary components influencing diabetes risk have similar effects on biomarkers of cardiovascular risk and inflammation. The conclusion is that there is no universal dietary strategy to prevent diabetes or delay its onset. Together with the maintenance of ideal body weight, the promotion of the so-called prudent diet (characterized by a higher intake of food groups that are generally recommended for health promotion, particularly plant-based foods, and a lower intake of red meat, meat products, sweets, high-fat dairy and refined grains) or a Mediterranean dietary pattern rich in olive oil, fruits and vegetables, including whole grains, pulses and nuts, low-fat dairy, and moderate alcohol consumption (mainly red wine) appears as the best strategy to decrease diabetes risk, especially if dietary recommendations take into account individual preferences, thus enabling long-time adherence.

Cross-sectional association of nut intake with adiposity in a Mediterranean population

BACKGROUND AND AIMS

Nut intake has been inversely related to body mass index (BMI) in prospective studies. We examined dietary determinants of adiposity in an elderly Mediterranean population with customarily high nut consumption.

METHODS AND RESULTS

A cross-sectional study was conducted in 847 subjects (56% women, mean age 67 years, BMI 29.7kg/m(2)) at high cardiovascular risk recruited into the PREDIMED study. Food consumption was evaluated by a validated semi-quantitative questionnaire, energy expenditure in physical activity by the Minnesota Leisure Time Activity questionnaire, and anthropometric variables by standard measurements. Nut intake decreased across quintiles of both BMI and waist circumference (P-trend <0.005; both). Alcohol ingestion was inversely related to BMI (P-trend=0.020) and directly to waist (P-trend=0.011), while meat intake was directly associated with waist circumference (P-trend=0.018). In fully adjusted multivariable models, independent dietary associations of BMI were the intake of nuts inversely (P=0.002) and that of meat and meat products directly (P=0.042). For waist circumference, independent dietary associations were intake of nuts (P=0.002) and vegetables (P=0.040), both inversely, and intake of meat and meat products directly (P=0.009). From the regression coefficients, it was predicted that BMI and waist circumference decreased by 0.78kg/m(2) and 2.1cm, respectively, for each serving of 30g of nuts. Results were similar in men and women.

CONCLUSION

Nut consumption was inversely associated with adiposity independently of other lifestyle variables. It remains to be explored whether residual confounding related to a healthier lifestyle of nut eaters might in part explain these results.

Dietary vitamin K intake is associated with bone quantitative ultrasound measurements but not with bone peripheral biochemical markers in elderly men and women

BACKGROUND

Vitamin K may have a protective role against bone loss and osteoporotic fractures associated to aging, although data in humans are inconsistent and the mechanisms involved are still unknown. The main objective of the study was to assess the associations between vitamin K intake, bone density, bone structure quality and biochemical bone metabolism markers in elderly subjects. We also analyzed the relationship between changes in vitamin K intake and the evolution of bone quality markers after two years of follow-up.

METHODS

Cross-sectional analysis was carried out on 365 elderly subjects, 200 of whom were also included in a 2-year longitudinal follow-up study. Usual dietary intakes were assessed using a semi-quantitative 137-item food frequency questionnaire (FFQ). Vitamin K intake was estimated using the USDA database. Bone biochemical markers were measured in a subset of 125 subjects. Quantitative ultrasound assessment (QUS) was performed at the calcaneus to estimate bone mineral density (BMD), speed of sound (SOS), broadband ultrasound attenuation (BUA) and the quantitative ultrasound index (QUI).

RESULTS

Dietary intake of vitamin K was significantly associated with higher BMD and better QUS. No significant associations were found between vitamin K intake and bone biochemical markers. Those subjects who increased their vitamin K intake showed a lower loss of BMD, a lower decrease in SOS and a nonsignificant increase in BUA.

CONCLUSIONS

High dietary vitamin K intake was associated with superior bone properties. Moreover, an increase in dietary vitamin K was significantly related to lower losses of bone mineral density and smaller increases in the porosity and elasticity attributed to aging, which helps to explain the previously described protective effect of vitamin K intake against osteoporotic fractures.

Nuts, hypertension and endothelial function

BACKGROUND AND AIMS

High blood pressure (BP) is considered a major risk factor for cardiovascular disease. Among lifestyle factors, diet plays a key role in the prevention and control of high BP. Therefore, it is important to elucidate which dietary components can exert beneficial effects on BP through modulation of endothelial function (EF) or by other mechanisms. In this paper we review the role of nutrients, foods, particularly nuts, and dietary patterns on BP control.

DATA SYNTHESIS

Because nuts are low in sodium and contain significant amounts of mono- and polyunsaturated fatty acids, fiber, minerals such as magnesium, potassium and calcium, and antioxidants, they have been suggested as potentially protective foods against hypertension. Limited evidence from prospective studies and clinical trials suggests that nut consumption has a beneficial effect on both BP and EF. However, BP changes were a secondary outcome in nut feeding trials and no study used ambulatory BP monitoring as the standard for BP measurements.

CONCLUSIONS

Further clinical trials, ideally using ambulatory BP monitoring, are needed to establish the potential protective effect of nut consumption on hypertension and vascular reactivity.

Effects of one serving of mixed nuts on serum lipids, insulin resistance and inflammatory markers in patients with the metabolic syndrome

BACKGROUND AND AIMS

Knowledge of the effect of nut consumption on metabolic syndrome (MetS) components is limited. We assessed the effects of nut intake on adiposity, serum lipids, insulin resistance, and inflammatory biomarkers in patients with MetS.

METHODS AND RESULTS

In a randomized, parallel-group, 12-week feeding trial, 50 patients with MetS were given recommendations for a healthy diet with or without supplementation with 30 g/day of raw nuts (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts) (Nut and Control diet groups, respectively). Adiposity measures, serum lipids, insulin, Homeostasis Model Assessment (HOMA), interleukin-6 (IL-6) and other inflammatory biomarkers, and 48-h fecal fat were determined basally and at study's completion. Moderate weight loss, decreased adiposity, and lower blood pressure occurred similarly after both diets. The Control, but not the Nut diet, was associated with significant (P<0.05) reduction of LDL-cholesterol, with mean changes of -0.36 versus -0.13 mmol/L, respectively (between-group differences, P=0.154). The Nut diet reduced fasting insulin by 2.60 μU/mL (95% CI, -4.62 to -0.59) and HOMA-insulin resistance by 0.72 (-1.28 to -0.16) (P<0.05 versus Control diet; both). Among inflammatory markers, the Nut diet resulted in changes of median plasma IL-6 of -1.1 ng/L (-2.7 to -0.1; P=0.035 versus Control diet), but adjustment for weight loss attenuated the significance of the association. Stool fat decreased with the Control diet and slightly increased with the Nut diet (P<0.05 for between-group differences).

CONCLUSION

Patients with MetS show decreased lipid responsiveness but improved insulin sensitivity after daily intake of 30 g of mixed nuts.

Dietary fibre: influence on body weight, glycemic control and plasma cholesterol profile

There have been several studies on the effects of dietary fibre on the metabolism. Epidemiologic studies have consistently reported an inverse relationship between dietary fibre and type 2 diabetes mellitus or cardiovascular mortality. This review focuses on observational and experimental studies that examine the effect of different types and sources of dietary fibre on body weight, glucose metabolism and lipid profile. From the available evidence, we conclude that clinical studies consistently show that the intake of viscous dietary fibre decreases the low density lipoprotein cholesterol and postprandial glucose levels, and induces short term satiety. However, few clinical trials have demonstrated that the intake of dietary fibre has a positive effect on the control of diabetes and body weight.

Adherence to the Mediterranean diet and risk of metabolic syndrome and its components

BACKGROUND AND AIMS

The role of diet in the aetiology of metabolic syndrome (MetS) is not well understood. The aim of the present study was to evaluate the relationship between adherence to the Mediterranean diet (MedDiet) and MetS.

METHODS AND RESULTS

A cross-sectional study was conducted with 808 high cardiovascular risk participants of the Reus PREDIMED Centre. MetS was defined by the updated National Cholesterol and Education Program Adult Treatment Panel III criteria. An inverse association between quartiles of adherence to the MedDiet (14-point score) and the prevalence of MetS (P for trend<0.001) was observed. After adjusting for age, sex, total energy intake, smoking status and physical activity, participants with the highest score of adherence to the MedDiet (>/=9 points) had the lowest odds ratio of having MetS (OR [95% CI] of 0.44 [0.27-0.70]) compared to those in the lowest quartile. Participants with the highest MedDiet adherence had 47 and 54% lower odds of having low HDL-c and hypertriglyceridemia MetS criteria, respectively, than those in the lowest quartile. Some components of the MedDiet, such as olive oil, legumes and red wine were associated with lower prevalence of MetS.

CONCLUSION

Higher adherence to a Mediterranean diet is associated with a significantly lower odds ratio of having MetS in a population with a high risk of cardiovascular disease.

Dietary Calcium and Body Mass Index in a Mediterranean Population

This cross-sectional study evaluated the association between daily calcium intake and body mass index (BMI) in 647 subjects from Reus, Spain. 261 men and 313 women, aged 18 to 70 years, were randomly selected from the population census. Food intake was quantified by the 24-hour recall method, for three non-consecutive days including one holiday. Weight and height were measured. The study sample was divided into quartiles of calcium intake adjusted for age, energy, and total fat and fiber intake in both men and women. Average calcium intake was low (557.6 ± 234.0 mg/day). Calcium intake was significantly (p < 0.0001) and positively associated with energy intake (r = 0.50 for men; r = 0.49 for women; p < 0.0001) and dietary fiber consumption (r = 0.27 for men; r = 0.25 for women; p < 0.0001). After adjusting for age, energy intake, fat intake, and dietary fiber, the odds ratio of being in the highest quartile of BMI was significantly reduced in the highest quartile of calcium intake [men: 0.63 (0.30–1.29); women: 0.36 (0.17–0.79)] compared to the lowest quartile in both sexes. We conclude that our study showed a negative relationship between calcium intake and BMI in a Mediterranean community.

Conjugated linoleic acid intake in humans: a systematic review focusing on its effect on body composition, glucose, and lipid metabolism

Studies performed on different species show that the consumption of conjugated linoleic acid (CLA) leads to a loss of fat and total body weight, reduces the plasma concentrations of total and LDL cholesterol, and has an antiinflammatory effect. This article reviews the clinical trials on human beings that evaluate how mixtures of CLA isomers administered as supplements or CLA-enriched products can affect total body weight, body composition, plasma lipid profile, glycemia, insulinemia, insulin sensitivity, lipid oxidation, and inflammation. After analyzing the few studies published to date in reduced samples of healthy humans or patients with overweight, obesity, metabolic syndrome, or diabetes, we deduce that there is not enough evidence to show that conjugated linoleic acid has an effect on weight and body composition in humans. However, some of these studies have observed that the administration of various CLA isomers has adverse effects on lipid profile (it decreases HDL cholesterol concentration and increases Lp(a) circulating levels), glucose metabolism (glycemia, insulinemia or insulin sensitivity), lipid oxidation, inflammation, or endothelial function. Therefore, long-term randomized clinical trials, controlled with placebo, need to be made in large samples of patients to evaluate the efficacy and safety of CLA isomers before its indiscriminate use in human beings can be recommended.

Subcutaneous adipose tissue cytokine production is not responsible for the restoration of systemic inflammation markers during weight loss

CONTEXT

It has been suggested that weight loss can improve systemic inflammation associated with obesity by decreasing the adipose production of pro-inflammatory cytokines. This suggestion, however, remains controversial.

OBJECTIVE

To analyse the effect of weight loss on peripheral inflammatory markers and subcutaneous adipocytokine production.

DESIGN

Patients were studied at baseline, at the end of the weight loss period, and after 2 weeks of weight stabilisation.

SUBJECTS

Nineteen morbid obese non-diabetic patients and 20 lean control subjects.

INTERVENTION

During the weight loss period patients followed a 6-week low-calorie diet.

MEASUREMENTS

Plasma levels of inflammatory markers, maximal in vitro whole-blood cytokine production, subcutaneous adipose tissue expression and content of several cytokines.

RESULTS

Obese subjects had higher circulating levels of C reactive protein (CRP), serum amyloid A (SAA), interleukin IL-6, IL-1 and soluble tumor necrosis factor receptors (sTNFR). Weight loss was associated with a significant decrease in CRP, SAA, leucocytes and plasma IL-6. Maximal in vitro cytokine production of IL-1 and sTNFR1 increased during this period. Weight loss did not induce significant changes in the adipose concentrations of IL-6, IL-1 or sTNF-receptors. However, adipose expression of IL-6, IL-1, TNFalpha, membrane cofactor protein-1 and adiponectin increased at the end of the weight loss period. During weight maintenance, circulating inflammatory parameters increased and in some cases returned to baseline.

CONCLUSIONS

A low-calorie diet is associated with an improvement in the systemic inflammatory status. This seems to be due to energy restriction rather than to adipose mass loss, since inflammatory levels return to baseline soon after weight stabilisation. Furthermore, a negative energy balance and fat mobilisation are associated with increased subcutaneous cytokine adipose expression.

C-reactive protein, adiposity and cardiovascular risk factors in a Mediterranean population

BACKGROUND

Understanding the distribution of high-sensitivity C-reactive protein (CRP) and its relations with classic cardiovascular risk factors in specific populations is important for further diagnostic use.

METHODS

We studied 1,157 adult subjects (652 women and 505 men) participating in the Health Study of Catalonia. CRP concentrations were measured with a high-sensitivity turbidimetric assay.

RESULTS

Median levels of CRP were 1.57 mg/l and 25% of both men and women had CRP values >3 mg/l. No differences were observed between men and women even after adjustment for age and body mass index (BMI). After patients with CRP values above the 97.5th percentile (n = 31) had been excluded, CRP concentrations increased significantly with increasing levels of cardiovascular risk factors in both men and women. Men and women with metabolic syndrome showed significantly higher levels of CRP than their counterparts, even after adjustment for BMI and age. In a multiple regression analysis, BMI, triglycerides and fasting glucose were independent predictors of CRP in women and together explained 42% of its variance. In men, CRP was independently and positively associated to waist circumference, smoking, diastolic blood pressure, uric acid and triglycerides, and negatively associated to HDL-cholesterol. Altogether these variables explained 51% of its variability.

CONCLUSIONS

The present study describes, for the first time, CRP concentrations in a sample that is representative of a Spanish Mediterranean community. CRP distribution and correlates are very similar to those reported previously in spite of the different lifestyle and nutritional habits, and the lower rates of cardiovascular diseases in our population.

[Nutrient content and health effects of nuts]

Nuts are foods with a high energy density, due in part to its small water content. They also present a low saturated fat content (<7%) but a high unsaturated fat contribution (40-60%). They represent one of the richest sources of dietary fiber, which is basically of the insoluble type. The effects of nut intake on health have been widely studied. Several prospective epidemiological studies performed on large cohorts have consistently shown that regular consumption of small amounts of nuts is negatively related to the risk of cardiovascular disease and to the risk of cardiovascular or all-cause mortality. From these studies can be concluded that regular consumption of small amounts of nuts leads to a 30-50% reduction in the risk of cardiovascular disease. Additionally, intervention studies have shown a positive effect of nut intake on lipid profile with significant reductions in total and LDL cholesterol levels and small or null effects on the HDL fraction. More recently, some studies have focused on the effect of nuts on body weight. At present, no evidences support a detrimental effect of nut consumption on body weight. On the contrary some weight loss studies suggest a beneficial effect of nut intake on body weight regulation.

[The teaching of nutrition at medical schools:current situation]

BACKGROUND

Although doctors, students and teachers all coincide in acknowledging the need for an appropriate knowledge of human nutrition in order to practice medicine, the inclusion of this discipline in the undergraduate curriculum has been rather scant. Until a few years ago, there were only two medical schools in Spain with a compulsory course in nutrition as part of the syllabus.

GOAL

An attempt will be made to assess the current status of the teaching of nutrition within the syllabuses for a degree in Medicine and Surgery at Spanish universities.

MATERIALS

The syllabuses of 27 Faculties of Medicine in Spain have been consulted to find out: 1) if there are specific subjects on nutrition, feeding and/or dietetics, 2) if these subjects are compulsory or optional, and 3) if there are specific issues from this area included within other subjects.

RESULTS

The results of the query show that 7 schools (approximately 25% of the total) teach a compulsory subject on nutrition or dietetics whereas 17 have at least one optional subject in this field, particularly during the second or specialization stage, with a mean content worth 4.5 credits. Furthermore, 3 of the schools offer both compulsory and optional courses simultaneously. Within the course material of the core subjects included in the second stage of the degree, the subjects of Endocrinology, Metabolism and Paediatrics seem to be the ones most commonly including clinical nutrition topics, generally with a very small relative weight.

CONCLUSIONS

The results obtained show an increasing interest in the creation of distinctive subjects for nutrition and/or dietetics. Nonetheless, this is still mainly an optional subject and the integration of human nutrition into the syllabus for core subjects seems insufficient for its to be considered a good alternative.

TNFalpha expression of subcutaneous adipose tissue in obese and morbid obese females: relationship to adipocyte LPL activity and leptin synthesis

INTRODUCTION

Tumor necrosis factor (TNFalpha) has been invoked as an adipostat. Accordingly, the adipose tissue expression of TNFalpha has been shown to be proportional to the degree of adiposity. The regulatory role of TNFalpha in obesity may be controlled by several mechanisms. These include the inhibitory effect on LPL activity, the mediation on glucose homeostasis or the effect on leptin. To assess the role of TNFalpha in obesity we measured adipocyte TNFalpha expression in 96 females with a wide range of adiposity and with or without type 2 diabetes. We analysed the relationship between TNFalpha expression, adipocyte LPL activity, insulin resistance and leptin in this population.

RESULTS

The TNFalpha and leptin expression of the adipose tissue in obese and morbid obese patients were significantly higher than in controls. Obese and morbid obese patients had slightly higher levels of LPL activity, but these differences were not significant. We observed a significant relationship between adipose TNFalpha expression and body mass index (r=0.35, P<0.001). TNFalpha expression was negatively related to LPL activity (r=-0.28, P<0.05) and positively related to leptin expression (r=0.35, P<0.001).

CONCLUSION

Our results indicate that obese women, even those with morbid obesity, over-express TNFalpha in subcutaneous adipose tissue in proportion to the magnitude of the fat depot and independently of the presence of type 2 diabetes. The TNFalpha system may be a homeostatic mechanism that prevents further fat deposition by regulating LPL activity and leptin production.

Leptin concentrations do not correlate with fat mass nor with metabolic risk factors in morbidly obese females

AIMS

To investigate the determinants of leptinemia in a cohort of morbid obese females compared to those of normal weight and mild-to-moderate obesity, and the relationships between leptin and metabolic derangements associated with obesity.

METHODS

Recruited females were: moderately obese [n=44; body mass index (BMI) 25-40 kg/m2], morbidly obese (n=34; BMI > or = 40 kg/m2) and normal weight volunteers (n=12; BMI 19-25 kg/m2). Fat mass assessed by bioelectrical impedance and fat distribution by waist-to-hip ratio (WHR) were determined in all subjects. Biochemical determinations included plasma leptin, lipoprotein profile, fasting insulin and cortisol.

RESULTS

Plasma leptin values were significantly increased in morbid obese patients (54.95 +/- 1.8 ng/ml) compared to those moderately obese (30.2 +/- 1.7 ng/ml; p<0.001) and to controls (9.77 +/- 1.4 ng/ml; p<0.001). Fat and age-adjusted leptin values were not different between groups. When subjects with a BMI <40 kg/m2 were considered, plasma leptin was significantly and positively related to anthropometric variables (BMI, percentage body fat and WHR), total cholesterol, LDL-cholesterol, plasma triglycerides, AST, ALT and uric acid; and negatively with HDL-cholesterol. In contrast, when morbidly obese patients were analyzed separately, no relationships were observed between leptin concentrations and BMI, percentage of adiposity or biochemical variables. For obese patients no significant differences were observed in the adjusted leptin values with respect to the presence of diabetes, dyslipidemia or hypertension.

CONCLUSIONS

In morbidly obese women, the plasma leptin concentrations, although increased, do not reflect the amount of adipose stores, and as such, factors other than simply adiposity need to be invoked to explain the variation in leptin values.

Cytokine-driven inflammatory response is associated with the hypermetabolism of AIDS patients with opportunistic infections

BACKGROUND

To assess a possible role of systemic inflammation in the resting metabolic response in AIDS patients with active secondary infections.

METHODS

Fifty-two patients with AIDS-defined criteria and concomitant active infections and 19 healthy subjects were studied. Measurements were as follows: body composition assessed by bioelectrical impedance; resting energy expenditure (REE) by 30-minute indirect calorimetry; cytokine concentrations (IL-6, IFNalpha, TNFalpha, sTNF-R1) by ELISA; C-reactive protein (CRP), erythrocyte sedimentation rate, fibrinogen, and nutritional parameters by standard techniques.

RESULTS

REE adjusted for fat-free mass (REEFFM) was significantly increased in AIDS patients despite 39% of them not being hypermetabolic. The patients were undernourished and were found to have increased levels of acute-phase proteins and increased concentrations of IL-6 and sTNF-R1 relative to controls. REE parameters were positively related to CRP, ESR, ferritin, IL-6, and sTNF-R1 and negatively related to albumin, prealbumin, and transferrin. CRP was an independent predictor of REEFFM in AIDS patients and explained 25% of its variability. Patients with severe inflammation (CRP > or = 37 mg/dL) were significantly hypermetabolic with respect to patients without inflammation (CRP < 6 mg/dL) and had higher levels of IL-6 and sTNF-R1 and lower levels of albumin and prealbumin. Although no significant differences were observed with respect to the infection type, patients with tuberculosis and Pneumocystis carinii infections had higher resting metabolic and inflammatory responses, whereas patients with recurrent bacterial pneumonia were normometabolic and had lower levels of inflammatory markers.

CONCLUSIONS

Resting hypermetabolism observed in AIDS patients with concurrent active infections is related to the presence and severity of systemic cytokine-driven inflammatory response, which could reflect the type of secondary infection.