Effects of a High-Protein/Moderate-Carbohydrate Diet on Appetite, Gut Peptides, and Endocannabinoids-A Preview Study

The circulating and central endocannabinoid system in obesity and weight loss

Major advances have been made in obesity treatment, focusing on restoring disturbances along the gut-brain axis. The endocannabinoid system (ECS) is a neuromodulatory signaling system, present along the entire gut-brain axis, that plays a critical role in central and peripheral regulation of food intake and body weight. Evidence on the impact of weight loss on the ECS is, however, more limited. Therefore, we set out to review the existing literature for changes in central and circulating endocannabinoid levels after bariatric surgery and other weight loss strategies in humans. The PubMed, Embase and Web of Science databases were searched for relevant articles. Fifty-six human studies were identified. Most studies measuring circulating 2-arachidonoylglycerol (2-AG) found no difference between normal weight and obesity, or no correlation with BMI. In contrast, studies measuring circulating arachidonoylethanolamine (AEA) found an increase or positive correlation with BMI. Two studies found a negative correlation between BMI and cannabinoid receptor type 1 (CB1) receptor availability in the brain. Only one study investigated the effect of pharmacological weight management on circulating endocannabinoid concentrations and found no effect on AEA concentrations. So far, six studies investigated potential changes in circulating endocannabinoids after bariatric surgery and reported conflicting results. Available evidence does not univocally support that circulating endocannabinoids are upregulated in individuals with obesity, which may be explained by variability across studies in several potential confounding factors (e.g. age and sex) as well as heterogeneity within the obesity population (e.g. BMI only vs. intra-abdominal adiposity). While several studies investigated the effect of lifestyle interventions on the circulating ECS, more studies are warranted that focus on pharmacologically and surgically induced weight loss. In addition, we identified several research needs which should be fulfilled to better understand the role of the ECS in obesity and its treatments.

Dietary carbohydrate quality index (CQI), cardio-metabolic risk factors and insulin resistance among adults with obesity

BACKGROUND

Metabolic syndrome (MetS), as a cluster of cardiometabolic risk factors, is a global public health concern due to its increasing prevalence. Considering the previous evidence of the association between carbohydrate quality and cardiometabolic risk factors, our study was aimed to evaluate any possible association between carbohydrate quality index (CQI) and cardiometabolic risk factors among obese adults.

METHODS

In this cross-sectional study, 336 apparently healthy individuals with obesity were participated. Dietary intake was assessed by a semi-quantitative Food Frequency Questionnaire (FFQ), including 168 food items validated for the Iranian population. CQI was calculated with three components of solid carbohydrates to total carbohydrates ratio, dietary fiber intake, and dietary glycemic index (GI). Body composition was determined by bioelectrical impedance analysis (BIA). Blood pressure was measured by sphygmomanometer and enzymatic methods were used to evaluate serum lipid, glucose, and insulin concentrations.

RESULTS

Subjects in the third quartile of CQI had significantly lower systolic blood pressure (SBP) (P = 0.03) and diastolic blood pressure (DBP) (P = 0.01). Participants in the higher quartiles of CQI had more intake of energy, carbohydrates, fat, saturated fatty acid (SFA), and mono-saturated fatty acid (MUFA) (P < 0.05). Moreover, the homeostasis model assessment of insulin resistance (HOMA-IR) was decreased in the second quartile of CQI [odds ratio (OR) = 0.146, P = 0.01) after adjustment for age, body mass index (BMI), sex, physical activity, socioeconomic status (SES) and energy intake.

CONCLUSION

According to our findings, a higher quality of dietary carbohydrates, determined by CQI, could be associated with a lower risk of hypertension.

Applied Clinical Tandem Mass Spectrometry-Based Quantification Methods for Lipid-Derived Biomarkers, Steroids and Cannabinoids: Fit-for-Purpose Validation Methods

The emergence of metabolomics and quantification approaches is revealing new biomarkers applied to drug discovery. In this context, tandem mass spectrometry is the method of choice, requiring a specific validation process for preclinical and clinical applications. Research on the two classes of lipid mediators, steroids and cannabinoids, has revealed a potential interaction in cannabis addiction and metabolism-related disorders. Here we present the development of GC-MS/MS and LC-MS/MS methods for routine quantification of targeted steroids and cannabinoids, respectively. The methods were developed using an isotopic approach, including validation for linearity, selectivity, LLOQ determination, matrix effect, carryover, between- and within-run accuracy and precision, and stability tests to measure 11 steroids and seven cannabinoids in human plasma. These methods were satisfactory for most validity conditions, although not all met the acceptance criteria for all analytes. A comparison of calibration curves in biological and surrogate matrices and in methanol showed that the latter condition was more applicable for our quantification of endogenous compounds. In conclusion, the validation of our methods met the criteria for GLP-qualified rather than GLP-validated methods, which can be used for routine analytical studies for dedicated preclinical and clinical purposes, by combining appropriate system suitability testing, including quality controls in the biological matrix.

Associations of quantity and quality of carbohydrate sources with subjective appetite sensations during 3-year weight-loss maintenance: Results from the PREVIEW intervention study

BACKGROUND & AIMS

The association of quantity and quality of carbohydrate sources with appetite during long-term weight-loss maintenance (WLM) after intentional weight loss (WL) is unclear. We aimed to investigate longitudinal associations of quantity and quality of carbohydrate sources with changes in subjective appetite sensations during WLM.

METHODS

This secondary analysis evaluated longitudinal data from the 3-year WLM phase of the PREVIEW study, a 2 × 2 factorial (diet-physical activity arms), multi-center, randomized trial. 1279 individuals with overweight or obesity and prediabetes (25-70 years; BMI≥25 kg m^-2) were included. Individuals were merged into 1 group to assess longitudinal associations of yearly changes in appetite sensations. Quantity and quality of carbohydrate sources including total carbohydrate, glycemic index (GI), glycemic load (GL), and total dietary fiber were assessed via 4-day food diaries at 4 timepoints (26, 52, 104, and 156 weeks) during WLM. Visual analog scales were used to assess appetite sensations in the previous week.

RESULTS

During WLM, participants consumed on average 160.6 (25th, 75th percentiles 131.1, 195.8) g·day^-1 of total carbohydrate, with GI 53.8 (48.7, 58.8) and GL 85.3 (67.2, 108.9) g day^-1, and 22.3 (17.6, 27.3) g·day^-1 of dietary fiber. In the available-case analysis, multivariable-adjusted linear mixed models with repeated measures showed that each 30-g increment in total carbohydrate was associated with increases in hunger (1.36 mm year^-1, 95% CI 0.77, 1.95, P < 0.001), desire to eat (1.10 mm year^-1, 0.59, 1.60, P < 0.001), desire to eat something sweet (0.99 mm year^-1, 0.30, 1.68, P = 0.005), and weight regain (0.20%·year^-1, 0.03, 0.36, P = 0.022). Increasing GI was associated with weight regain, but not associated with increases in appetite sensations. Each 20-unit increment in GL was associated with increases in hunger (0.92 mm year^-1, 0.33, 1.51, P = 0.002), desire to eat (1.12 mm year^-1, 0.62, 1.62, P < 0.001), desire to eat something sweet (1.13 mm year^-1, 0.44, 1.81, P < 0.001), and weight regain (0.35%·year^-1, 0.18, 0.52, P < 0.001). Surprisingly, dietary fiber was also associated with increases in desire to eat, after adjustment for carbohydrate or GL.

CONCLUSIONS

In participants with moderate carbohydrate and dietary fiber intake, and low to moderate GI, we found that higher total carbohydrate, GL, and total fiber, but not GI, were associated with increases in subjective desire to eat or hunger over 3 years. This study was registered as ClinicalTrials.gov, NCT01777893.

Reproducibility and associations with obesity and insulin resistance of circadian-rhythm parameters in free-living vs. controlled conditions during the PREVIEW lifestyle study

BACKGROUND

Circadian rhythm is altered in individuals with obesity and insulin resistance, showing a smaller amplitude, less stability, and increased intradaily variation.

OBJECTIVE

We compared reproducibility of circadian-rhythm parameters over time and under free-living vs. controlled conditions in participants with obesity and pre-diabetes after 2- and 3-year weight-loss maintenance during the 3-year PREVIEW (PREVention of diabetes through lifestyle intervention and population studies In Europe and around the World) study. Associations of obesity and insulin resistance with circadian-rhythm parameters were assessed.

SUBJECTS AND METHODS

Circadian-rhythm parameters were determined using continuous wrist-temperature measurements in free-living environments at year 2 (n = 24; age 56.8 ± 10.3 y; body mass index (BMI) = 30 ± 3.9 kg/m²; homeostatic model assessment of insulin resistance (HOMA-IR) 2.4 ± 1.1), at year 3 (n = 97; age 61.7 ± 7.8; BMI = 29.7 ± 3.9; HOMA-IR 2.9 ± 2.1), and at year 3 in a controlled condition (n = 38; age 63.4 ± 6.7; BMI = 28.7 ± 3.9; HOMA-IR 3.8 ± 1.4). Reproducibility was assessed by analyzing repeatability coefficients (CR), differences, and associations, over time as well as between conditions. Associations of BMI and HOMA-IR with circadian-rhythm parameters were assessed at y-3 in both conditions using factor analysis, followed by Pearson's correlations.

RESULTS

Reproducibility of circadian-rhythm parameters over time in the free-living environments was high (CR 0.002-5.26; no significant differences; associated amplitudes r = 0.57; p < 0.01). In contrast, reproducibility between different conditions was low (CR 0.02-11.36; significant differences between most parameters (p < 0.05); yet associated amplitudes r = 0.59; p < 0.01). In the controlled vs. free-living condition circadian-rhythm was more stable; BMI and HOMA-IR were associated with the physiological amplitude-related parameters (r = -0.45; p < 0.01; r = -0.33; p < 0.05). In the free-living environment, BMI and behavioral circadian-rhythm parameters indicating circadian alignment, contributed most to the explained variation (47.1%), and were inversely associated (r = -0.22; p < 0.05), while HOMA-IR was inversely associated with stability-related circadian-rhythm parameters (r = -0.21; p < 0.05).

CONCLUSIONS

Circadian rhythm was highly reproducible over time in the free-living environments, yet different under different conditions, being more stable in the controlled condition. BMI may play a significant role in circadian alignment and vice versa in the free-living environment.

Dietary carbohydrates and weight loss maintenance

PURPOSE OF REVIEW

Aim of the present review is to provide an overview of the effect of manipulating dietary carbohydrates (content, type) after a period of weight loss on weight loss maintenance and its potential underlying mechanisms.

RECENT FINDINGS

Few recent studies directly tested whether lower carbohydrate/glycaemic load or higher fibre diets help to limit weight regain after weight loss and they did not provide evidence supporting a role of a reduction of the carbohydrate or an increase of the fibre content of the diet in the prevention of weight regain after weight loss. Some evidence is emerging that personal characteristics (gut microbiota, glycaemia) may interact with diet composition. but randomized clinical trials are needed to substantiate these claims.

SUMMARY

There is currently no convincing evidence that lowering dietary carbohydrates has a clinically relevant effect on weight regain after weight loss, unless there is an increase in protein intake at the same time. Further randomized trials are needed to investigate potential interactions with personal characteristics while improving strategies for long-term adherence.

Role and Mechanism of Gut Microbiota in Human Disease

The human gut microbiome is a huge microbial community that plays an irreplaceable role in human life. With the further development of research, the influence of intestinal flora on human diseases has been gradually excavated. Gut microbiota (GM) dysbiosis has adverse health effects on the human body that will lead to a variety of chronic diseases. The underlying mechanisms of GM on human diseases are incredibly complicated. This review focuses on the regulation and mechanism of GM on neurodegenerative diseases, cardiovascular diseases, metabolic diseases and gastrointestinal diseases, thus providing a potential target for the prevention and treatment of disease.

Endocannabinoids, endocannabinoid-like molecules and their precursors in human small intestinal lumen and plasma: does diet affect them?

PURPOSE

To determine the small intestinal concentration of endocannabinoids (ECs), N-acylethanolamines (NAEs) and their precursors N-acylphosphatidylethanolamines (NAPEs) in humans. To identify relationships between those concentrations and habitual diet composition as well as individual inflammatory status.

METHODS

An observational study was performed involving 35 participants with an ileostomy (18W/17M, aged 18-70 years, BMI 17-40 kg/m²). Overnight fasting samples of ileal fluid and plasma were collected and ECs, NAEs and NAPEs concentrations were determined by LC-HRMS. Dietary data were estimated from self-reported 4-day food diaries.

RESULTS

Regarding ECs, N-arachidonoylethanolamide (AEA) was not detected in ileal fluids while 2-arachidonoylglycerol (2-AG) was identified in samples from two participants with a maximum concentration of 129.3 µg/mL. In contrast, mean plasma concentration of AEA was 2.1 ± 0.06 ng/mL and 2-AG was 4.9 ± 1.05 ng/mL. NAEs concentrations were in the range 0.72-17.6 µg/mL in ileal fluids and 0.014-0.039 µg/mL in plasma. NAPEs concentrations were in the range 0.3-71.5 µg/mL in ileal fluids and 0.19-1.24 µg/mL in plasma being more abundant in participants with obesity than normal weight and overweight. Significant correlations between the concentrations of AEA, OEA and LEA in biological fluids with habitual energy or fat intakes were identified. Plasma PEA positively correlated with serum C-reactive protein.

CONCLUSION

We quantified ECs, NAEs and NAPEs in the intestinal lumen. Fat and energy intake may influence plasma and intestinal concentrations of these compounds. The luminal concentrations reported would allow modulation of the homeostatic control of food intake via activation of GPR119 receptors located on the gastro-intestinal mucosa.

CLINICAL TRIAL REGISTRY NUMBER AND WEBSITE

NCT04143139; www.clinicaltrials.gov .

Intuitive eating is associated with elevated levels of circulating omega-3-polyunsaturated fatty acid-derived endocannabinoidome mediators

The regulation of food intake and eating behaviours involves interactions between different systems. The endocannabinoidome, comprising several fatty acid-derived mediators, plays a central role in the regulation of food intake. Alterations of this system have been suggested to intervene in the aetiology of eating disorders. This study aimed to examine the associations between non-pathological eating behaviours and circulating endocannabinoidome mediators in a heterogeneous human population. Plasma 2-monoacyl-glycerol and N-acyl-ethanolamine congeners were measured by LC-MS/MS in a sample of 190 men and women. Eating behaviours were assessed using the Three-Factor Eating Questionnaire (TFEQ) and the Intuitive Eating Scale-2 (IES-2). Following adjustment for body mass index and age, plasma levels of omega-3 polyunsaturated fatty acid-derived 2-monoacyl-glycerols, 2-eicosapentaenoyl-glycerol (2-EPG) and 2-docosapentaenoyl-glycerol (2-DPG), were associated with higher intuitive eating scores (0.15 ≤ rho ≤ 0.20; p < 0.05). These associations were independent of the dietary intake of the fatty acid precursors of these 2-monoacyl-glycerols. However, almost no association was found between plasma levels of N-acyl-ethanolamine congeners and the TFEQ or the IES-2 scores. The results of the present study suggest the association of 2-monoacyl-glycerols, especially 2-EPG and 2-DPG, in the regulation of intuitive eating and the potential implication therein of bioactive lipids.

Appetite control: hormones or diet strategies?

PURPOSE OF REVIEW

Appetite control results from metabolic, behavioral, and environmental factors that influence hunger and the desire to eat. We summarize the latest advances in the hormonal and nutritional strategies to control appetite and reduce hunger.

RECENT FINDINGS

The fed-hunger-state is regulated by central and peripheric hormones, which modulate energy balance. Leptin, insulin, ghrelin, peptide YY (PYY), and other gut-derived peptides represent the main appetite controllers. The role of orexins, obestatin, and liver-expressed antimicrobial peptide 2 has been uncovered recently. New insights have demonstrated the role of hippocampal activity as a possible mechanism of action. Glucagon-like peptide 1 (GLP1) receptor agonists are well known agents controlling appetite. Association of GLP1 receptor agonist, PYY, or glucose-dependent insulinotropic polypeptide agonists have been tested as new approaches. Appetite-control hormones have also risen as factors involved in the efficacy of bariatric procedures. High-protein, ketogenic diet, and intermittent fasting have been described as nutritional strategies to reduce appetite, although the physiological mechanism and long-term safety remains unclear.

SUMMARY

Appetite control has been an important target for the treatment of obesity and associated disorders. New studies have demonstrated promising adoption of dietary approaches, hormone-based drugs, and bariatric surgery to control energy intake. Further research will establish a significant association, benefits, and safety of these new therapies.

Effect of consuming a late-night high-protein/moderate-carbohydrate vs. low-protein/high-carbohydrate meal by night workers on their food perceptions later during the day: a randomized crossover study

It is typical of night workers to consume a large dinner meal before their work shift, even though this practice may increase the risk for metabolic disorders. Night workers usually eat at night to socialize with colleagues as well as to stay alert and to avoid upset stomach during the night shift. However, little is known if and how the composition of the nighttime meal by night shift workers influences their food perceptions and eating behavior later during the day. The aim of this study was to analyze the effect of a high-protein/moderate-carbohydrate (HP/MCHO) meal vs. low-protein/high-carbohydrate (LP/HCHO) meal eaten at night by night-shift workers on their food consumption and perceptions later during the day. Fourteen male night shift workers were followed-up for 7 days for their eating and sleep habits. Then, participants underwent two isocaloric dietary events - one event a HP/MCHO meal containing 45% carbohydrate, 35% protein, and 20% fat and the other event a LP/HCHO meal containing 65% carbohydrate, 15% protein, and 20% fat, with a 6-day washout period between them - at 01:00 h during their night shift. Thereafter throughout the day, participants filled a food register of all the food consumed and perceptions, including hunger before meals, enjoyment of meals, and satiety. Generalized estimating equation analyses were used to examine the effect of both conditions on food consumption and food perceptions. Appetite for salty food snacks was greater after the HP/MCHO condition than after the LP/HCHO condition (p = .041). During the day following consumption of the nighttime HP/MCHO vs. LP/HCHO meal, there was higher percentage of carbohydrate consumption during lunch and a lower percentage of fat consumption during dinner (48.14% vs. 36.98% and 27.34% vs. 40.39%, respectively). These findings suggest the composition in terms of carbohydrates, protein, and fats of the meal consumed for the night shift by night workers may affect later during the day both food consumption and perceptions.

Dietary protein and appetite sensations in individuals with overweight and obesity: a systematic review

PURPOSE

This systematic review aimed to synthesize the available evidence on the effects of a high-protein diet on appetite sensations in individuals with overweight and obesity.

METHODS

Two authors independently conducted literature searches, study selection, design of the method, and quality appraisal. The main inclusion criteria were studies involving protocols that present a protein intake greater than 1.2 g/kg/day or 25% of the total daily energy content compared to a normal protein diet, i.e., 0.8-1.2 g/kg/day or 15%-20% of the total energy content. Studies that evaluated test meals or diet within a period of less than 7 days and participants with diabetes, cancer, or other specific conditions were excluded from this review. The literature search was updated until November 2019 using the main databases available.

RESULTS

Of a total of 4191 records, ten articles met the inclusion criteria and included a total of 1079 subjects. In six studies, participants experienced enhanced fullness or satiety in response to a high-dietary protein intake, of which four studies had an intervention period of 10-12 weeks.

CONCLUSION

Our results suggest that among individuals with overweight or obesity, higher dietary protein intake may influence appetite sensations by enhancing fullness or satiety. The low level of evidence, due to the heterogeneity of the protocols and the high risk of bias, highlights the need for further studies to confirm these results.

Role of Endocannabinoids in Energy-Balance Regulation in Participants in the Postobese State-a PREVIEW Study

CONTEXT

Endocannabinoids are suggested to play a role in energy balance regulation.

OBJECTIVE

We aimed to investigate associations of endocannabinoid concentrations during the day with energy balance and adiposity and interactions with 2 diets differing in protein content in participants in the postobese phase with prediabetes.

DESIGN AND PARTICIPANTS

Participants (n = 38) were individually fed in energy balance with a medium protein (MP: 15:55:30% of energy from protein:carbohydrate:fat) or high-protein diet (HP: 25:45:30% energy from P:C:F) for 48 hours in a respiration chamber.

MAIN OUTCOME MEASURES

Associations between energy balance, energy expenditure, respiratory quotient, and endocannabinoid concentrations during the day were assessed.

RESULTS

Plasma-concentrations of anandamide (AEA), oleoylethanolamide (OEA), palmitoyethanolamide (PEA), and pregnenolone (PREG) significantly decreased during the day. This decrease was inversely related to body mass index (AEA) or body fat (%) (PEA; OEA). The lowest RQ value, before lunch, was inversely associated with concentrations of AEA and PEA before lunch. Area under the curve (AUC) of concentrations of AEA, 2-AG, PEA, and OEA were positively related to body fat% (P < .05).The HP and MP groups showed no differences in concentrations of AEA, OEA, PEA, and PREG, but the AUC of 2-arachidonoylglycerol (2-AG) was significantly higher in the HP vs the MP group.

CONCLUSIONS

In energy balance, only the endocannabinoid 2-AG changed in relation to protein level of the diet, whereas the endocannabinoid AEA and endocannabinoid-related compounds OEA and PEA reflected the gradual energy intake matching energy expenditure during the day.

Challenging energy balance - during sensitivity to food reward and modulatory factors implying a risk for overweight - during body weight management including dietary restraint and medium-high protein diets

Energy balance is a key concept in the etiology and prevalence of obesity and its co-morbidities, as well as in the development of possible treatments. If energy intake exceeds energy expenditure, a positive energy balance develops and the risk for overweight, obesity, and its co-morbidities increases. Energy balance is determined by energy homeostasis, and challenged by sensitivity to food reward, and to modulatory factors such as circadian misalignment, high altitude, environmental temperature, and physical activity. Food reward and circadian misalignment increase the risk for overweight and obesity, while high altitude, changes in environmental temperature, or physical activity modulate energy balance in different directions. Modulations by hypobaric hypoxia, lowering environmental temperature, or increasing physical activity have been hypothesized to contribute to body weight loss and management, yet no clear evidence has been shown. Dietary approach as part of a lifestyle approach for body weight management should imply reduction of energy intake including control of food reward, thereby sustaining satiety and fat free body mass, sustaining energy expenditure. Green tea catechins and capsaicin in red pepper in part meet these requirements by sustaining energy expenditure and increasing fat oxidation, while capsaicin also suppresses hunger and food intake. Protein intake of at least 0,8 g/kg body weight meets these requirements in that it, during decreased energy intake, increases food intake control including control of food reward, and counteracts adaptive thermogenesis. Prevention of overweight and obesity is underscored by dietary restraint, implying control of sensitivity to challenges to energy balance such as food reward and circadian misalignment. Treatment of overweight and obesity may be possible using a medium-high protein diet (0,8-1,2 g/kg), together with increased dietary restraint, while controlling challenges to energy balance.

Effects of a High-Protein Diet on Cardiometabolic Health, Vascular Function, and Endocannabinoids-A PREVIEW Study

An unfavorable lipid profile and being overweight are known mediators in the development of cardiovascular disease (CVD) risk. The effect of diet, particularly high in protein, remains under discussion. Therefore, this study examines the effects of a high-protein (HP) diet on cardiometabolic health and vascular function (i.e., endothelial function, arterial stiffness, and retinal microvascular structure), and the possible association with plasma endocannabinoids and endocannabinoid-related compounds in overweight participants. Thirty-eight participants (64.5 ± 5.9 (mean ± SD) years; body mass index (BMI) 28.9 ± 4.0 kg/m²) were measured for 48 h in a respiration chamber after body-weight maintenance for approximately 34 months following weight reduction. Diets with either a HP (n = 20) or moderate protein (MP; n = 18) content (25%/45%/30% vs. 15%/55%/30% protein/carbohydrate/fat) were provided in energy balance. Validated markers for cardiometabolic health (i.e., office blood pressure (BP) and serum lipoprotein concentrations) and vascular function (i.e., brachial artery flow-mediated vasodilation, pulse wave analysis and velocity, and retinal microvascular calibers) were measured before and after those 48 h. Additionally, 24 h ambulatory BP, plasma anandamide (AEA), 2-arachidonoylglycerol (2-AG), oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and pregnenolone (PREG) were analyzed throughout the day. Office and ambulatory BP, serum lipoprotein concentrations, and vascular function markers were not different between the groups. Only heart rate (HR) was higher in the HP group. HR was positively associated with OEA, while OEA and PEA were also positively associated with total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol concentrations. Vascular function markers were not associated with endocannabinoids (or endocannabinoid-related substances). In conclusion, the HP diet did not affect cardiometabolic health and vascular function in overweight participants after completing a weight-loss intervention. Furthermore, our data indicate a possible association between OEA and PEA with TC and LDL cholesterol.