Omar Obeid

Variations in Postprandial Ghrelin Status following Ingestion of High-Carbohydrate, High-Fat, and High-Protein Meals in Males

Aim: The purpose of this study was to investigate the response of postprandial acylated ghrelin to changes in macronutrient composition of meals in healthy adult males. Methods: A randomized crossover study was performed. Ten healthy adult males were recruited. All subjects received, on separate occasions, a high-carbohydrate (HC), a high-fat (HF), and a high-protein (HP) meal. Blood samples were collected before and 15, 30, 60, 120, and 180 min following the ingestion of each meal. Plasma acylated ghrelin as well as serum insulin, glucose, and triglycerides were measured. Results: The levels of acylated ghrelin fell significantly following the three meals. The HC meal induced the most significant decrease in postprandial ghrelin secretion (–15.5 ± 2.53 pg/ml) as compared with HF (–8.4 ± 2.17 pg/ml) and HP (–10.0 ± 1.79 pg/ml) meals (p < 0.05). However, at 180 min, the HP meal maintained significantly lower mean ghrelin levels (29.7 ± 3.56 pg/ml) than both HC (58.4 ± 5.75 pg/ml) and HF (45.7 ± 5.89 pg/ml) meals and lower levels than baseline (43.4 ± 5.34 pg/ml) (p <0.01). The postprandial insulin levels increased to significantly higher levels following the HC meal (+80.6 ± 11.14 µU/ml) than following both HF (37.3 ± 4.82 µU/ml) and HP (51.4 ± 6.00 µU/ml) meals (p < 0.001). However, at 180 min, the mean insulin levels were found to be significantly higher following the HP meal (56.4 ± 10.80 µU/ml) as compared with both HC (30.9 ± 4.31 µU/ml) and HF (33.7 ± 4.42 µU/ml) meals (p < 0.05). Acylated ghrelin was also found to be negatively correlated with circulating insulin levels, across all meals. Conclusions: These results indicate that the nutrient composition of meals affects the extent of suppression of postprandial ghrelin levels and that partial substitution of dietary protein for carbohydrate or fat may promote longer-term postprandial ghrelin suppression and satiety. Our results also support the possible role of insulin in meal-induced ghrelin suppression.

Postprandial acylated ghrelin status following fat and protein manipulation of meals in healthy young women.

The aim of the present study was to investigate the postprandial effect of diet composition on circulating acylated ghrelin levels in healthy women. A randomized cross-over study of three experimental treatments was performed. A total of 11 healthy young women of normal body weight completed the study. All 11 subjects consumed three iso-energetic meals of different macronutrient composition, a balanced meal (50% carbohydrates, 30% fat and 20% protein), a high-fat meal (45% carbohydrates, 45% fat and 10% protein) and a high-protein meal (45% carbohydrates, 20% fat and 35% protein), for breakfast on separate days. The test meals were administered 1 month apart. Blood samples were withdrawn immediately before and at 15, 30, 60, 120 and 180 min after the test meal for measurement of plasma acylated ghrelin, as well as serum glucose, insulin and triacylglycerol (triglyceride) levels. Acylated ghrelin fell significantly after ingestion of both the balanced and high-protein meals. Ghrelin persisted at significantly lower levels than baseline for a longer duration following the high-protein meal (P<0.05 at 15, 30, 60 and 120 min) compared with the balanced meal (P<0.05 at 30 and 60 min). Moreover, acylated ghrelin levels correlated negatively with the postprandial insulin levels. In conclusion, postprandial changes in acylated plasma ghrelin depend on the macronutrient composition of the meal and are possibly influenced by insulin.

Folate deficiency is associated with nutritional anaemia in lebanese women of childbearing age

OBJECTIVE The objective of this study was to identify the determinants of anaemia in Lebanese women of childbearing age attending health centres in Lebanon. DESIGN Cross-sectional study carried out between May and December 2003. Anthropometric measurements as well as sociodemographic, health and dietary intake data were collected using a questionnaire. Haemoglobin (Hb), plasma ferritin, plasma folate and vitamin B12 were assessed using standard laboratory methods. SETTING Governmental health centres in Lebanon. SUBJECTS Four hundred and seventy non-pregnant Lebanese women aged 15-45 years. RESULTS Anaemia (Hb <12 g dl(-1)) and iron deficiency (ferritin <15 microg l(-1)) were prevalent in 16.0 and 27.2% of the study sample, respectively. Of the total sample, 7.7% had iron-deficiency anaemia. The percentage of women with either Hb or ferritin deficiency or both was 35.6%. Plasma folate and vitamin B12 deficiency was reported in 25.1 and 39.4%, respectively, and 12.6% of the women had both folate and vitamin B12 deficiencies. Of the anaemic group, 48.0% of the women had iron deficiency. The intake of iron was lower in iron-deficient than in non-deficient women and a positive relationship was shown between folate intake and its corresponding serum levels. Regression analysis showed that ferritin, plasma folate and family history of anaemia were significant determinants of the anaemia in the sample of women. CONCLUSIONS Anaemia not related to iron deficiency was partly explained by plasma folate deficiency. Measures to control folate and iron deficiency should be considered.

Fish oil and the management of hypertriglyceridemia.

Hypertriglyceridemia, regarded as one of the independent clinical markers of metabolic syndrome, is a frequently observed disorder that has been shown to be common in the Arab region. Epidemiologic and clinical trials demonstrated that omega-3 fatty acids have the potential to reduce the incidence of cardiovascular disease (CVD); one of the mechanisms by which this effect is achieved is through reducing plasma triglyceride levels. There is strong scientific evidence from human trials that omega-3 fatty acids from either fish or fish oil supplements significantly reduce blood triglyceride levels and these benefits appear to be dose-dependent. The active ingredients of fish oils include the long chain fatty acids EPA and DHA. The ideal amount of omega-3 fatty acid that should be incorporated into the diet without provoking detrimental effects on other lipid components such as decreasing HDL-C and/or increasing LDL-C has not yet been elucidated. Presently, a prescription form of omega-3 fatty acid has been approved by the United States Food and Drug Administration (USFDA) as an adjunct to the diet for the treatment of very high triglyceride levels (~ 500 mg/dl) in adults. Patients with hypertriglyceridemia have been shown to respond well to the use of omega-3 fatty acids even when used in conjunction with statins where greater improvements in the lipid profile were found as compared to treatment with statins alone. A determinant of the responsiveness to fish oil could be attributed to the ApoE genotype of individuals.

Meal Pattern of Male Rats Maintained on Histidine‐, Leucine‐, or Tyrosine‐Supplemented Diet

Objective: Food intake is known to be affected by macronutrient composition of the diet, and protein manipulation has been reported to alter food intake, but the effect of individual amino acids on eating behavior has not been fully studied. This study investigated the effect of diet supplementation with three individual amino acids on meal pattern in male rats.

Characteristics of nonalcoholic fatty liver disease induced in wistar rats following four different diets

BACKGROUND/OBJECTIVES The prevalence of nonalcoholic fatty liver disease (NAFLD) has increased worldwide in parallel with overnutrition characterized by high-fat and high-carbohydrate intake. Our objective was to establish, in 16 weeks, a model of NAFLD in Wistar pathogen-free rats following four dietary types. MATERIALS/METHODS Forty (6 weeks old) healthy Wistar male rats, weighing an average of 150 g were randomly divided into four groups of ten and assigned a diet with the same quantity (15 g/rat/day), but with different composition. The moderate-fat (MF) group was fed a moderate-fat diet (31.5% fat and 50% carbohydrates), the high-fat (HF) group was fed a fat-rich diet (51% fat), the high-sucrose (HS) group and the high-fructose (HFr) group were fed a carbohydrate-rich diet (61%). The carbohydrate contents of the HS group was composed of 60.3% sucrose while that of the HFr group was composed of 59.3% fructose. RESULTS At week 16, the HF group had the highest percentage of cells enriched in fat (40%) and the highest weight and liver weight (P < 0.05). The HFr group showed significantly higher levels of serum triglycerides, alanine aminotransferase and adiponectin at week 16 as compared to week 1 (P < 0.05). CONCLUSIONS The 15 g/rat/day diet composed of 51% fat or 61% carbohydrates enriched mainly in fructose may induce characteristics of NAFLD in rats.

Effect of Lysine, Vitamin B6, and Carnitine Supplementation on the Lipid Profile of Male Patients With Hypertriglyceridemia: A 12-Week, Open-Label, Randomized, Placebo-Controlled Trial

BACKGROUND Fat metabolism is known to be altered in hypertriglyceridemia. Fat oxidation requires carnitine, which can be obtained either from the diet (animal or dairy products) or through synthesis in the body using both lysine and vitamin B(6). OBJECTIVE The goal of this study was to investigate the effect of lysine, vitamin B(6), and carnitine supplementation on both glycemia and the lipid profiles, specifically triglyceride (TG) levels, in men with hypertriglyceridemia. METHODS This 12-week, randomized, placebo-controlled clinical trial was conducted at a Lebanese medical center. A total of 85 hypertriglyceridemic (TG> 150 mg/dL) male patients were randomized to 1 of 5 groups and given supplements of lysine (1 g/d), vitamin B(6) (50 mg/d), lysine (1 g/d) + vitamin B(6) (50 mg/d), carnitine (1 g/d), or placebo for 12 weeks. The lipid profile (TG, total cholesterol, LDL-C, and HDL-C) and fasting plasma glucose levels were assessed at baseline and at 6 and 12 weeks. RESULTS Adults (∼50 years) Lebanese males from a low socioeconomic status in Beirut were given the appropriate supplements. Vitamin B(6) supplementation was associated with a significant reduction in total cholesterol and HDL-C of ∼10%. In addition, plasma TG was reduced by 36.6 mg/dL at 6 weeks, whereas levels in the placebo group increased by 18 mg/dL; this difference failed to reach statistical significance. No major changes in the lipid profile were observed in the lysine and carnitine groups or when lysine was added to vitamin B(6). CONCLUSION Vitamin B(6) supplementation in these male patients with hypertriglyceridemia reduced plasma total cholesterol and HDL-C concentrations.

Meal pattern of male rats maintained on amino acid supplemented diets: the effect of tryptophan, lysine, arginine, proline and threonine.

The macronutrient composition of the diet has been shown to affect food intake, with proteins having distinct effects. The present study investigated the effect of diet supplementation with individual amino acids (tryptophan, lysine, arginine, proline and threonine) on meal pattern among male rats. Meal pattern and body weight were monitored for two weeks. Proline and threonine had minimal effects on meal pattern, while the most pronounced changes were observed in the tryptophan group. Both tryptophan and lysine decreased overall food intake, which was translated into a reduction in body weight. The reduced food intake of the tryptophan group was associated with an increase in meal size, intermeal intervals (IMI) and meal time and a decrease in meal number. The decrease in the food intake of the lysine group was associated with a reduction in both IMI and meal number, and this was accompanied by an increase in meal time. Arginine increased meal number, while decreasing IMI. Proline and threonine had a minimal effect on meal pattern. Lysine seems to increase satiety, and arginine seems to decrease it, while tryptophan seems to increase satiety and decrease satiation. Accordingly, changes in meal patterns are associated with the type of amino acid added to the diet.

Stimulation of postprandial in vivo glycogenesis and lipogenesis of rats fed high fructose diet with varied phosphate content

It has been reported that increased fructose intake is associated with the development of the metabolic syndrome. The phosphate (P) sequestering capacity of fructose is likely to affect the phosphorylation capacity of different metabolites, and this, in turn, may be the basis for several metabolic derangements, especially in the P requiring reactions, for example, glycogenesis and lipogenesis. We hypothesized that P enrichment of the diet can balance P status and, consequently, affect glycogenesis and lipogenesis. An animal experiment was executed in which adult male Sprague-Dawley rats were maintained for 4 days on high-fructose diets with different P content (0.15%, 0.165%, 0.30%, and 1.65%). At the end of the feeding period, overnight fasted rats were tube fed a test meal, injected with (3)H(2)O and euthanized 1 hour later. Final plasma glucose, insulin, uric acid, and triacylglycerol concentrations, as well as in vivo rates of glycogen and lipid synthesis and hepatic glycogen content, were measured. Results showed that increased P content of the diet was associated with an increase in postprandial epididymal fat pad (P = .007) and hepatic lipogenesis (P = .029), as well as glycogenesis (P = .024). In conclusion, P content of the diet was found to stimulate both glycogenesis and lipogenesis. These alterations in carbohydrate and fat metabolism point to the potential of P in influencing nutritional status.

Acute Effect of Leptin and Ghrelin Injection on Postprandial Glycogen and Lipid Synthesis in Rats

Aim: The study was designed to investigate the immediate (1 h) effect of leptin and ghrelin injection on in vivo postprandial hepatic glycogen and lipid synthesis. Animals andMethods: Adult Sprague-Dawley male rats were fed a semisynthetic control diet ad libitum. Overnight-fasted rats were gavaged with 4 ml of water containing 1.25 g of the diet and immediately injected intraperitoneally with 4 mCi of 3H2O. After 1 h, rats were either intraperitoneally injected with saline (control), leptin (20 µg/rat) or ghrelin (10 µg/rat) and sacrificed 1 h later. Blood, liver and epididymal fat pads (EFP) were taken for analysis. Results: Plasma triglyceride level was higher in the leptin group compared to control. Leptin injection reduced hepatic glycogen synthesis while glycogen accumulation was not affected and ghrelin injection did not affect hepatic glycogen synthesis. Both hepatic and EFP lipogenesis were not affected by leptin or ghrelin. Conclusion: Leptin and ghrelin administration had no immediate effect on hepatic and adipose tissue lipogenesis. Leptin reduced in vivo postprandial hepatic glycogenesis and increased plasma triglyceride level which may be due to reduced uptake by peripheral tissues. Thus, leptin was found to exert an immediate effect on lipid and carbohydrate metabolism unlike that of ghrelin.