PubMed Health⌕ Search

Biomedical subjects

Samir Samman

Publications and source records attributed to Samir Samman.

12 recordsLinked to original sources
PubMed2006

Comparison of 4 diets of varying glycemic load on weight loss and cardiovascular risk reduction in overweight and obese young adults: a randomized controlled trial.

BACKGROUND: Despite the popularity of low-glycemic index (GI) and high-protein diets, to our knowledge no randomized, controlled trials have systematically compared their relative effects on weight loss and cardiovascular risk. METHODS: A total of 129 overweight or obese young adults (body mass index, > or =25 [calculated as weight in kilograms divided by the square of height in meters]) were assigned to 1 of 4 reduced-fat, high-fiber diets for 12 weeks. Diets 1 and 2 were high carbohydrate (55% of total energy intake), with high and low GIs, respectively; diets 3 and 4 were high protein (25% of total energy intake), with high and low GIs, respectively. The glycemic load was highest in diet 1 and lowest in diet 4. Changes in weight, body composition, and blood chemistry profile were studied. RESULTS: While all groups lost a similar mean +/- SE percentage of weight (diet 1, -4.2% +/- 0.6%; diet 2, -5.5% +/- 0.5%; diet 3, -6.2% +/- 0.4%; and diet 4, -4.8% +/- 0.7%; P = .09), the proportion of subjects in each group who lost 5% or more of body weight varied significantly by diet (diet 1, 31%; diet 2, 56%; diet 3, 66%; and diet 4, 33%; P = .01). Women on diets 2 and 3 lost approximately 80% more fat mass (-4.5 +/- 0.5 [mean +/- SE] kg and -4.6 +/- 0.5 kg) than those on diet 1 (-2.5 +/- 0.5 kg; P = .007). Mean +/- SE low-density-lipoprotein cholesterol levels declined significantly in the diet 2 group (-6.6 +/- 3.9 mg/dL [-0.17 +/- 0.10 mmol/L]) but increased in the diet 3 group (+10.0 +/- 3.9 mg/dL [+0.26 +/- 0.10 mmol/L]; P = .02). Goals for energy distribution were not achieved exactly: both carbohydrate groups ate less fat, and the diet 2 group ate more fiber. CONCLUSION: Both high-protein and low-GI regimens increase body fat loss, but cardiovascular risk reduction is optimized by a high-carbohydrate, low-GI diet.

Adolescent↗
PubMed2006

The effect of zinc supplementation in humans on plasma lipids, antioxidant status and thrombogenesis.

The potential exists for zinc to influence numerous metabolic functions and to impact a range of diseases. In the present review we examine the reported relationships between zinc and plasma lipids, haemostasis and other factors postulated to play a role in atherogenesis. Ecological studies that investigated zinc intake or status, and incidence of coronary heart disease (CHD) reveal no consistent pattern. The conflicting observations may be explained by differences in the extent of CHD, site of atherosclerosis, or confounding factors. In most studies the diurnal variation in serum zinc concentrations, and the lifestyle factors that affect cholesterol metabolism were not explicitly considered. Results of randomised controlled trials show that low-density lipoprotein (LDL) oxidation and the concentrations of LDL-cholesterol (c), total cholesterol and triglycerides in plasma are unaffected by supplementation with up to 150 mg Zn/d. In contrast, plasma high-density lipoprotein (HDL)-c concentrations decline when zinc supplements provide a dose >50 mg/d. Limited data suggest that sustained hyperzincaemia predisposes individuals to thrombogenesis, whereas acute zinc depletion impairs platelet aggregation and prolongs bleeding time. In addition, Zinc supplements have been shown in some studies to decrease Cu/Zn-superoxide dismutase activity, primarily due to the antagonistic relationship between high zinc intakes and copper absorption. Besides the demonstrated adverse effect of zinc supplementation on plasma HDL-c concentrations in apparently healthy men, there is insufficient evidence to determine the role of zinc supplementation in influencing other risk factors for CHD such as antioxidant status and thrombogenesis.

Antioxidants↗
PubMed2006

Defining core elements and outstanding practice in Nutritional Science through collaborative benchmarking.

Benchmarking has been adopted by educational institutions as a potentially sensitive tool for improving learning and teaching. To date there has been limited application of benchmarking methodology in the Discipline of Nutritional Science. The aim of this survey was to define core elements and outstanding practice in Nutritional Science through collaborative benchmarking. Questionnaires that aimed to establish proposed core elements for Nutritional Science, and inquired about definitions of " good" and " outstanding" practice were posted to named representatives at eight Australian universities. Seven respondents identified core elements that included knowledge of nutrient metabolism and requirement, food production and processing, modern biomedical techniques that could be applied to understanding nutrition, and social and environmental issues as related to Nutritional Science. Four of the eight institutions who agreed to participate in the present survey identified the integration of teaching with research as an indicator of outstanding practice. Nutritional Science is a rapidly evolving discipline. Further and more comprehensive surveys are required to consolidate and update the definition of the discipline, and to identify the optimal way of teaching it. Global ideas and specific regional requirements also need to be considered.

Australia↗
PubMed2005

Antioxidant properties of palm fruit extracts.

Phenolic compounds have been shown to exhibit bioactive properties, and in particular antioxidant effects. A phenolic-rich fraction has been isolated from the aqueous by-product obtained during the milling of oil palm fruits. The objectives of the study were to determine the phenolic content of the crude and ethanolic extracts of oil palm fruits and to evaluate the antioxidant properties of these extracts. The total phenolics content of the crude and ethanol extracts as determined by the Folin-Ciocalteu method were found to be 40.3 +/- 0.5 and 49.6 +/- 0.6 mg GAE/g extract (dry basis), respectively. The radical scavenging activity of the extracts determined using 2,2 diphenyl-1-picrylhydrazyl radical (DPPH.) indicated that both crude and ethanol extracts exhibit hydrogen-donating capacity, and have antiradical power (ARP) comparable to ascorbic acid. The DPPH radical scavenging activity of the extracts were less than that of gallic acid, but the time-course variations of the scavenging curves suggest that the extracts acted by a mechanism similar to that of gallic acid. The electron-donating potentials of the extracts were inferred from the hydrogen peroxide scavenging and reducing power assays. The reducing power of crude and ethanol extracts at 1 mM GAE were found to be comparable to that of 0.3 mM gallic acid. The extracts indicated complete scavenging of hydrogen peroxide at concentrations above 0.4 mM GAE. These findings suggest that the crude and ethanol extracts are able to scavenge free radicals, by either hydrogen or electron donating mechanisms, and can therefore act as primary antioxidants.

Antioxidants↗
PubMed2004

Postprandial lipoprotein(a) is affected differently by specific individual dietary fatty acids in healthy young men.

Lipoprotein(a) [Lp(a)] is considered a risk factor for coronary heart disease. Our aim was to investigate the effect of individual fatty acids on postprandial plasma Lp(a) and its association with lipemia and tissue plasminogen activator (t-PA). Five test fats dominated by (approximately 43% g/kg) stearic (S), palmitic (P), oleic, C18:1 trans (T), or linoleic acid were produced by interesterification. Sixteen young healthy men were served the individual test fats incorporated into meals (1g fat/kg body wt) after a 12-h fast in random order on different days, separated by 3-wk washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after eating. There was a pronounced increase in Lp(a) concentrations after intake of the test meals, and the test fats resulted in a difference in Lp(a) response (P < 0.001; diet x time interaction). However, T fat did not change Lp(a) during the time course studied. T fat resulted in less area under the plasma Lp(a) concentration curve compared to S and P fat (P </= 0.003). Test fat with saturated fatty acids resulted in the highest Lp(a) and lowest plasma triacylglycerol (TAG) response, with the reversed situation for T fat. There was no association between Lp(a) and t-PA. In conclusion, intake of meals high in individual dietary fatty acids increased postprandial plasma Lp(a) differently. There seems to be a complex regulatory role of plasma TAG on nonfasting plasma Lp(a) concentrations.

Adult↗
PubMed2003

Effects of supplementation with purified red clover (Trifolium pratense) isoflavones on plasma lipids and insulin resistance in healthy premenopausal women.

Consumption of isoflavone-rich soyabean protein is reported to reduce total and LDL-cholesterol, but the specific components responsible are undetermined. In a previous crossover trial we showed that purified isoflavones, derived from red clover (Trifolium pratense), raised HDL3-cholesterol in premenopausal women; however, these findings were inconclusive due to period and carryover effects. In an attempt to overcome this problem, we utilised a parallel study designed to re-examine the effects of purified isoflavones on plasma lipoproteins and markers of insulin resistance in premenopausal women. Twenty-five healthy premenopausal women participated in a double-blind, randomised, parallel study. The treatment group (n 12) consumed a placebo for the first menstrual cycle and an isoflavone supplement (86 mg/d, derived from red clover) for three cycles, while the placebo group (n 13) consumed a placebo supplement for four menstrual cycles. Blood samples were collected weekly during cycles 1, 3 and 4. Supplementation with isoflavones resulted in a 15-fold increase in urinary isoflavone excretion (P<0.0001). There were no significant effects on total cholesterol, LDL- and HDL-cholesterol, HDL subfractions, triacylglycerol, lipoprotein(a), glucose or insulin concentrations. Our present results indicate that purified isoflavones derived from red clover have no effect on cholesterol homeostasis or insulin resistance in premenopausal women, a group which is at low risk of CHD.

Adult↗
PubMed2003

Postprandial effects of dietary trans fatty acids on apolipoprotein(a) and cholesteryl ester transfer.

BACKGROUND: The consumption of trans fatty acids adversely affects fasting plasma lipoprotein concentrations. OBJECTIVE: This study aimed to investigate whether postprandial lipoprotein metabolism is affected by the consumption of trans fatty acids. DESIGN: In a randomized crossover study, 19 healthy men consumed fatty meals that were identical except that 10% of energy was provided as trans 18:1 acids in the trans meal and as oleic acid in the cis meal. RESULTS: The meals induced similar responses in plasma lipids. Cholesteryl ester transfer (CET) was activated after consumption of both meals (P < 0.0001); however, it was 28% higher after the trans meal than after the cis meal (280 +/- 129 compared with 219 +/- 116 nmol cholesteryl ester/mL plasma * 6 h; time x diet interaction: P < 0.0001). Plasma apolipoprotein(a) [apo(a)] concentrations remained constant; however, triacylglycerol-rich lipoproteins formed 4 h after ingestion of the trans meal contained a higher concentration of apo(a) than did those formed after ingestion of the cis meal (48.9 +/- 6.6 compared with 39.6 +/- 5.4 U/L; P < 0.02). The change in CET and in the proportion of plasma apo(a) in the triacylglycerol-rich lipoprotein fractions correlated with indexes of alimentary lipemia. CONCLUSIONS: Consumption of meals high in trans fatty acids results in higher CET and postprandial lipoprotein concentrations enriched in apo(a) than does consumption of meals free of trans fatty acids. This study highlights the importance of double-bond configuration in determining postprandial lipoprotein composition.

Adult↗
PubMed2003

A mixed fruit and vegetable concentrate increases plasma antioxidant vitamins and folate and lowers plasma homocysteine in men.

Fruit and vegetable consumption is inversely associated with coronary heart disease (CHD) risk. The aim of the present study was to determine the effect of supplementation with dehydrated juice concentrates from mixed fruit and vegetables on selected plasma vitamins and antioxidant status. We assessed CHD risk by measuring the concentrations of homocysteine, lipids, lipoproteins, glucose and insulin. Men were recruited to participate in a randomized double-blind, crossover trial with 2 periods of 6 wk, separated by a 3-wk wash-out period. Supplementation with the encapsulated mixed extract (Juice Plus) was compared with physically similar placebo capsules. Thirty-two men (13 smokers, 19 nonsmokers) completed the study with a mean compliance of 88%. Compared with placebo, supplementation increased the concentrations of plasma beta-carotene (0.24 +/- 0.15 vs. 1.12 +/- 0.70 micro mol/L; mean +/- SD; P < 0.0001), retinol (1.87 +/- 0.33 vs. 2.00 +/- 0.43 micro mol/L; P < 0.05), alpha-tocopherol (16.8 +/- 7.3 vs. 19.3 +/- 6.8 micro mol/L; P < 0.01), ascorbic acid (72.1 +/- 19.4 vs. 84.1 +/- 13.5 micro mol/L; P < 0.002) and folic acid (24.5 +/- 10.0 vs. 44.9 +/- 16.9 nmol/L; P < 0.0001). Plasma homocysteine was reduced (8.2 +/- 1.5 vs. 7.6 +/- 1.1; P < 0.05) and inversely related (r = -0.40, P < 0.001) with serum folate concentrations. Plasma vitamin C was positively correlated with the resistance of LDL to oxidation (r = 0.26, P < 0.05) and the plasma ferric reducing/antioxidant power (FRAP) tended to be greater after supplementation than after the placebo period (1125.5 +/- 144.1 vs. 1180.3 +/- 158.1 micro mol/L; P < 0.065). Plasma glucose, insulin and lipid concentrations were unaffected. Responses of smokers and nonsmokers did not differ. In the absence of dietary modification, supplementation with a fruit and vegetable concentrate produced responses consistent with a reduction in CHD risk.

Adult↗
PubMed2002

Cross-sectional study of diet and risk factors for metabolic diseases in a Ghanaian population in Sydney, Australia.

Ethnic groups in affluent environments experience higher rates of metabolic diseases than their native counterparts. Our objective was to determine the prevalence of metabolic risk factors in Ghanaians in Sydney, and to investigate the relationship with dietary and lifestyle factors. Cross-sectional design with anthropometry, blood pressure, plasma lipids, glucose and insulin concentrations were measured on two occasions on each subject. Dietary information was obtained by three 24-h dietary recalls. Adults (45 male, 35 female) were recruited from a local association in Sydney, Australia. Overweight was observed in a large proportion of subjects (71% and 66% of men and women, respectively), with 18% of men and 26% of women classified as obese. Abdominal overweight was seen in 63% and 74% of men and women, respectively. Abdominal obesity was seen in 20% of men and 49% of women. Hypertension was detected in 40% of men and 17% of women, 16% of men and 6% of women were diagnosed with definite hypertension. Seventy-one per cent of men and 29% of women were classified as hypercholesterolaemic and 67% of men and 23% of women had elevated low-density lipoprotein cholesterol. In men, low high-density lipoprotein cholesterol and hypertriacylglycerolaemia affected 18% and 13%, respectively. Fasting hyperinsulinaemia was observed in 14% and 9% of men and women, respectively. The majority of subjects (73%) sustained one or more metabolic risk factors. Dietary fat contributed 33% and 35% of total energy intake in men and women, respectively, saturated fat contributing 11% in both sexes. A high prevalence of overweight, diabetes, hypertension and dyslipidaemia exists in this population, particularly in men, highlighting the need for intervention.

Adult↗