Biomedical subjects

Peter M Clifton

Publications and source records attributed to Peter M Clifton.

At least 19 recordsLinked to original sources

PubMed2006

Health benefits of herbs and spices: the past, the present, the future.

UNLABELLED: Herbs and spices have a traditional history of use, with strong roles in cultural heritage, and in the appreciation of food and its links to health. Demonstrating the benefits of foods by scientific means remains a challenge, particularly when compared with standards applied for assessing pharmaceutical agents. Pharmaceuticals are small-molecular-weight compounds consumed in a purified and concentrated form. Food is eaten in combinations, in relatively large, unmeasured quantities under highly socialised conditions. The real challenge lies not in proving whether foods, such as herbs and spices, have health benefits, but in defining what these benefits are and developing the methods to expose them by scientific means. CULTURAL ASPECTS: The place of herbs and spices in the diet needs to be considered in reviewing health benefits. This includes definitions of the food category and the way in which benefits might be viewed, and therefore researched. Research may focus on identifying bioactive substances in herbs and spices, or on their properties as a whole food, and/or be set in the context of a dietary cuisine. THE ROLE OF HERBS AND SPICES IN HEALTH: The antioxidant properties of herbs and spices are of particular interest in view of the impact of oxidative modification of low-density lipoprotein cholesterol in the development of atherosclerosis. There is level III-3 evidence (National Health and Medical Research Council [NHMRC] levels of evidence) that consuming a half to one clove of garlic (or equivalent) daily may have a cholesterol-lowering effect of up to 9%. There is level III-1 evidence that 7.2 g of aged garlic extract has been associated with anticlotting (in-vivo studies), as well as modest reductions in blood pressure (an approximate 5.5% decrease in systolic blood pressure). A range of bioactive compounds in herbs and spices have been studied for anticarcinogenic properties in animals, but the challenge lies in integrating this knowledge to ascertain whether any effects can be observed in humans, and within defined cuisines. Research on the effects of herbs and spices on mental health should distinguish between cognitive decline associated with ageing and the acute effects of psychological and cognitive function. There is level I and II evidence for the effect of some herbal supplements on psychological and cognitive function. There is very limited scientific evidence for the effects of herbs and spices on type 2 diabetes mellitus, with the best evidence being available for the effect of ginseng on glycaemia, albeit based on four studies. More research is required, particularly examining the effects of chronic consumption patterns. With increasing interest in alternatives to non-steroidal anti-inflammatory agents in the management of chronic inflammation, research is emerging on the use of food extracts. There is level II evidence for the use of ginger in ameliorating arthritic knee pain; however, the improvement is modest and the efficacy of ginger treatment is ranked below that of ibuprofen. More definitive research is required. PUBLIC HEALTH AND DIETARY IMPLICATIONS: Recommendations for intakes of food in the Australian guide to healthy eating do not yet include suggested intakes of herbs and spices. Future consideration should be given to including more explicit recommendations about their place in a healthy diet. In addition to delivering antioxidant and other properties, herbs and spices can be used in recipes to partially or wholly replace less desirable ingredients such as salt, sugar and added saturated fat in, for example, marinades and dressings, stir-fry dishes, casseroles, soups, curries and Mediterranean-style cooking. Vegetable dishes and vegetarian options may be more appetising when prepared with herbs and spices. FUTURE DIRECTIONS: As several metabolic diseases and age-related degenerative disorders are closely associated with oxidative processes in the body, the use of herbs and spices as a source of antioxidants to combat oxidation warrants further attention. Immediate studies should focus on validating the antioxidant capacity of herbs and spices after harvest, as well as testing their effects on markers of oxidation. This will work in parallel with clinical trials that are aiming to establish antioxidants as mediators of disease prevention. From a dietary perspective, the functionality of herbs and spices will be exposed through consideration of their properties as foods. As with most foods, the real benefits of including them in the diet are likely to emerge with a better understanding of the attributes of health that are best supported by food, and in methodological developments addressing the evidence base for their effects. These developments are well underway through evidence-based frameworks for substantiating health claims related to foods. At present, recommendations are warranted to support the consumption of foods rich in bioactive components, such as herbs and spices. With time, we can expect to see a greater body of scientific evidence supporting the benefits of herbs and spices in the overall maintenance of health and protection from disease.

Antioxidants↗

PubMed2006

Appetite regulatory hormone responses to various dietary proteins differ by body mass index status despite similar reductions in ad libitum energy intake.

CONTEXT: Although dietary protein produces higher acute satiety relative to carbohydrate, the influence of protein source and body mass index (BMI) has not been clearly described. OBJECTIVE: The objective of the study was to assess postprandial responses to different protein sources, compared with glucose, in males with normal and high BMI. DESIGN: This was a randomized, crossover study of four preloads followed by blood sampling (+15, 30, 45, 60, 90, 120, 180 min) and buffet meal. SETTING: The study was conducted at an outpatient clinic. PARTICIPANTS: The study population included 72 men, with a BMI range 20.6-39.9 kg/m(2). INTERVENTIONS: Interventions consisted of liquid preloads (1.1 MJ, 450 ml) containing 50 g whey, soy, gluten, or glucose. MAIN OUTCOME MEASURES: Fasting and postprandial plasma glucose, insulin, ghrelin, glucagon-like peptide-1 (GLP-1) and cholecystokinin (n = 38), ad libitum energy intake, and appetite ratings were measured. RESULTS: Energy intake was 10% lower after all protein preloads, compared with the glucose treatment (P < 0.05), independent of BMI status and protein type. All protein loads prolonged the postprandial suppression of ghrelin (P < 0.01) and elevation of GLP-1 (P < 0.01) and cholecystokinin (P < 0.05). Fasting GLP-1 concentrations [overweight, 17.5 +/- 1.3; lean, 14.7 +/- 0.1 pg/ml (5.2 +/- 0.4 and 4.4 +/- 0.1 pmol/liter, respectively); P < 0.001] and postprandial responses (P = 0.038) were higher in overweight subjects. CONCLUSIONS: Whey, soy, and gluten similarly tend to reduce ad libitum food intake 3 h later in lean and overweight males relative to glucose. Postprandial ghrelin, GLP-1, insulin, and cholecystokinin may contribute to this higher satiety after protein consumption. GLP-1 concentrations are increased in overweight subjects, which may affect satiety responses in this group.

Adult↗

PubMed2006

Energy intake, ghrelin, and cholecystokinin after different carbohydrate and protein preloads in overweight men.

CONTEXT: Dietary proteins appear to be more satiating than carbohydrate. The mechanism and effect of protein and carbohydrate type are unclear. OBJECTIVE: The objective of the study is to compare the acute effect of different proteins and carbohydrates on indicators of appetite and appetite regulatory hormones. DESIGN: This is a randomized cross-over study of four orally consumed preloads followed by blood sampling (+15, 30, 45, 60, 90, 120, 180 min), then a buffet meal. SETTING: The study was carried out in an outpatient clinic. PATIENTS AND OTHER PARTICIPANTS: Nineteen overweight (body mass index 32.1 +/- 0.9 kg/m(2)) men participated. INTERVENTIONS: Liquid preloads (1 MJ) contained whey (55 g), casein (55 g), lactose (56 g), or glucose (56 g). MAIN OUTCOME MEASURES: Plasma ghrelin, cholecystokinin (CCK), insulin, glucose and amino acids, gastric emptying rate (plasma paracetamol), appetite rating (visual analog scale), and ad libitum energy intake were the main outcome measures. RESULTS: Energy intake was 10 +/- 3% higher after the glucose preload compared with lactose and protein preloads (P < 0.05), which were predicted by ghrelin at 120 min (P < 0.05). CCK was 71 +/- 6% higher 90 min after the protein preloads compared with glucose and lactose (P < 0.05), which predicted appetite at 180 min (P < 0.05). There was a small increase in branched chain amino acids after the whey preload compared with casein (P < 0.01), but this was independent of appetite and energy intake. CONCLUSION: Acute appetite and energy intake are equally reduced after consumption of lactose, casein, or whey compared with glucose, which was consistent with differences in plasma ghrelin. Higher CCK responses after proteins correlated with satiety but did not affect energy intake.

Acetaminophen↗

PubMed2006

Comparison of isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular risk.

BACKGROUND: It is speculated that high saturated fat very low carbohydrate diets (VLCARB) have adverse effects on cardiovascular risk but evidence for this in controlled studies is lacking. The objective of this study was to compare, under isocaloric conditions, the effects of a VLCARB to 2 low saturated fat high carbohydrate diets on body composition and cardiovascular risk. METHODS: Eighty three subjects, 48 +/- 8 y, total cholesterol 5.9 +/- 1.0 mmol/L, BMI 33 +/- 3 kg/m2 were randomly allocated to one of 3 isocaloric weight loss diets (6 MJ) for 8 weeks and on the same diets in energy balance for 4 weeks: Very Low Fat (VLF) (CHO:Fat:Protein; %SF = 70:10:20; 3%), High Unsaturated Fat (HUF) = (50:30:20; 6%), VLCARB (4:61:35; 20%) RESULTS: Percent fat mass loss was not different between diets VLCARB -4.5 +/- 0.5, VLF-4.0 +/- 0.5, HUF -4.4 +/- 0.6 kg). Lean mass loss was 32-31% on VLCARB and VLF compared to HUF (21%) (P < 0.05). LDL-C increased significantly only on VLCARB by 7% (p < 0.001 compared with the other diets) but apoB was unchanged on this diet and HDL-C increased relative to the other 2 diets. Triacylglycerol was lowered by 0.73 +/- 0.12 mmol/L on VLCARB compared to -0.15 +/- 0.07 mmol/L on HUF and -0.06 +/- 0.13 mmol/L on VLF (P < 0.001). Plasma homocysteine increased 6.6% only on VLCARB (P = 0.026). VLCARB lowered fasting insulin 33% compared to a 19% fall on HUF and no change on VLF (P < 0.001). The VLCARB meal also provoked significantly lower post prandial glucose and insulin responses than the VLF and HUF meals. All diets decreased fasting glucose, blood pressure and CRP (P < 0.05). CONCLUSION: Isocaloric VLCARB results in similar fat loss than diets low in saturated fat, but are more effective in improving triacylglycerols, HDL-C, fasting and post prandial glucose and insulin concentrations. VLCARB may be useful in the short-term management of subjects with insulin resistance and hypertriacylglycerolemia.

Journal Article↗

PubMed2006

Weight loss improves heart rate recovery in overweight and obese men with features of the metabolic syndrome.

BACKGROUND: Heart rate recovery (HRR) is an independent risk factor for cardiovascular disease (CVD) and mortality, but whether it is modifiable and can improve with weight loss is unclear. We sought to determine the effects of weight loss on HRR and its association with traditional CVD risk markers. METHODS: Heart rate recovery (defined as the decrease in heart rate from peak heart rate to that measured 1 minute after a standardized graded treadmill test) and a range of established cardiovascular risk factors were measured in 42 overweight and obese men (body mass index 33.8 +/- 0.6 kg/m2, mean age 46.5 +/- 1.3 years) who had no symptoms of CVD but had components of the metabolic syndrome before and after 12 weeks of weight loss. RESULTS: There was a 9% weight reduction (P < .001), with losses of 6.3 +/- 0.6 kg of fat mass (P < .001) and 3.1 +/- 0.6 kg of non-bone fat-free mass (P < .001). There were significant reductions in waist circumference, blood pressure, plasma triglycerides, total cholesterol, low-density lipoprotein cholesterol, triglyceride/high-density lipoprotein ratio, C-reactive protein, plasma insulin, glucose, and insulin resistance (P < .05). Although peak heart rate remained unchanged, HRR at 1 minute improved from 33.1 +/- 1.4 to 36.9 +/- 1.3 beats/min (P < .001) after weight loss. There was no change in cardiorespiratory fitness (P = .30); neither was there any change in physical activity levels (P = .67). The improvement in HRR was significantly correlated with decreases in body weight, body mass index, waist circumference, plasma glucose, serum triglycerides, and triglyceride/high-density lipoprotein ratio; however, it was only independently associated with changes in weight and plasma glucose concentrations. CONCLUSION: In addition to improving a range of well-accepted cardiovascular and metabolic risk factors, weight loss also improves HRR after exercise, a less recognized risk factor.

Adult↗

PubMed2006

Comparison of three bioelectrical impedance methods with DXA in overweight and obese men.

OBJECTIVE: To compare bioelectrical impedance analysis (BIA) of body composition using three different methods against DXA in overweight and obese men. RESEARCH METHODS AND PROCEDURES: Forty-three healthy overweight or obese men (ages 25 to 60 years; BMI, 28 to 43 kg/m(2)) underwent BIA assessment of body composition using the ImpediMed SFB7 (version 6; ImpediMed, Ltd., Eight Mile Plains, Queensland, Australia) in multifrequency mode (Imp-MF) and DF50 single-frequency mode (Imp-SF) and the Tanita UltimateScale (Tanita Corp., Tokyo, Japan). Validity was assessed by comparison against DXA using linear regression and limits of agreement analysis. RESULTS: All three BIA methods showed good relative agreement with DXA [Imp-MF: fat mass (FM), r(2) = 0.81; fat-free mass (FFM), r(2) = 0.81; percentage body fat (BF%), r(2) = 0.69; Imp-SF: FM, r(2) = 0.65; FFM, r(2) = 0.76; BF%, r(2) = 0.40; Tanita: BF%, r(2) = 0.44; all p < 0.001]. Absolute agreement between DXA and Imp-MF was poor, as indicated by a large bias and wide limits of agreement (bias, +/-1.96 standard deviation; FM, -6.6 +/- 7.7 kg; FFM, 8.0 +/- 7.1 kg; BF%, -7.0 +/- 6.6%). Imp-SF and Tanita exhibited a smaller bias but wide limits of agreement (Imp-SF: FM, -1.1 +/- 8.5 kg; FFM, 2.5 +/- 7.9 kg; BF%, -1.7 +/- 7.3%; Tanita: BF%, 1.2 +/- 9.5%). DISCUSSION: Compared with DXA, Imp-MF produced large bias and wide limits of agreement, and its accuracy estimating body composition in overweight or obese men was poor. Imp-SF and Tanita demonstrated little bias and may be useful for group comparisons, but their utility for assessment of body composition in individuals is limited.

Absorptiometry, Photon↗

PubMed2006

Short-term meal replacements followed by dietary macronutrient restriction enhance weight loss in polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS), a common condition in women, improves with weight loss. Meal replacements in short-term weight loss and strategies for weight maintenance have not been investigated in PCOS. OBJECTIVE: We compared in overweight women with PCOS the effects of meal replacements in short-term weight-loss and longer-term carbohydrate- or fat-restriction strategies on weight maintenance and improvements in reproductive and metabolic variables. DESIGN: Overweight women with PCOS (n = 43; x +/- SD age: 32.1 +/- 5.2 y; weight: 96.1 +/- 18.4 kg) followed an 8-wk weight-loss regimen (2 meal replacements/d, 4904.4 +/- 127 kJ; phase 1) and then a 6-mo weight-maintenance carbohydrate- (<120 g/d) or fat- (<50 g/d) restriction regimen (phase 2). RESULTS: Thirty-four women completed phase 1, and 23 women completed phase 2; the proportion of dropouts was similar in the 2 groups. During phase 1, significant (P < 0.05) reductions in weight (5.6 +/- 2.4 kg), waist circumference (6.1 +/- 2.5 cm), body fat (4.1 +/- 2.2 kg), insulin (2.8 +/- 1.1 mU/L), total testosterone (0.3 +/- 0.7 nmol/L), and free androgen index (3.1 +/- 4.6) occurred; these changes were sustained during phase 2. No significant differences between diet groups were seen for any variables. At 6 mo, both approaches resulted in a net weight loss of 4.7 +/- 4.6 kg. Improvements in menstrual cyclicity occurred for 16 (57.1%) of 28 subjects. CONCLUSIONS: Meal replacements are an effective strategy for the short-term management of PCOS. Advice on moderate fat or carbohydrate restriction was equally effective in maintaining weight reduction and improving reproductive and metabolic variables.

Adult↗

PubMed2006

Use of [14C]-sodium bicarbonate/urea to measure total energy expenditure in overweight men and women before and after low calorie diet induced weight loss.

The aim of this study was to evaluate the use of the [14C]-sodium bicarbonate/urea technique to measure the change in total energy expenditure after weight loss and a period of weight maintenance. Eleven healthy subjects (6 men and 5 women aged 50 +/- 3 yrs, BMI 34.1 +/-2.1 kg/ m2, body fat 38.7 +/-3%) underwent 8 weeks of energy restriction using a combination of "Modifast" formula and one small meal per day (approximately 3.3 MJ/day). For an additional 2 weeks, subjects resumed a solid food diet that contained enough energy to stabilize body weight at the newly reduced level. Body composition, total energy expenditure (TEE), resting energy expenditure (REE) and the thermic effect of a 2.7 MJ test meal (TEF) were measured at both weeks 0 and 10. At week 10 as compared to week 0, body weight decreased by 12.2+/-1.6 kg (12.5%)(P<0.001). Total fat and lean mass decreased by 8.4+/-1.0 kg (20.4%) and 3.8+/-0.7 kg (6.7%), respectively (P< 0.001). REE decreased by 500+/-128 kJ/day (5.6+/-1.3%)(P<0.002). Decreases in the TEE (0.18 +/-;3.7%)and TEF(1.4+/-0.9%) were not significant. In conclusion, although [14C]-sodium bicarbonate/urea was well tolerated and did not interfere with normal daily activities, it did not have sufficient sensitivity to accurately measure weight loss induced changes in TEE in the range of 0.1-10%.

Adult↗

PubMed2005

The satiating effect of dietary protein is unrelated to postprandial ghrelin secretion.

CONTEXT: Increasing dietary protein relative to carbohydrate and fat enhances weight loss, at least in part by increasing satiety. The mechanism for this is unclear. OBJECTIVE: The objective of this study was to compare the effects of isocaloric test meals with differing protein to fat ratios on fasting and postprandial ghrelin, insulin, glucose, appetite, and energy expenditure before and after weight loss on the respective dietary patterns. DESIGN: The study design was a randomized parallel design of 12 wk of weight loss (6 MJ/d) and 4 wk of weight maintenance (7.3 MJ/d) with meals administered at wk 0 and 16. SETTING: The study was performed at an out-patient research clinic. PATIENTS AND OTHER PARTICIPANTS: Fifty-seven overweight (body mass index, 33.8 +/- 3.5 kg/m2) hyperinsulinemic men (n = 25) and women (n = 32) were studied. INTERVENTIONS: High-protein/low-fat (34% protein/29% fat) or standard protein/high-fat (18% protein/45% fat) diets/meals were given. MAIN OUTCOME MEASURES: The main outcome measures were weight loss and fasting and postprandial ghrelin, insulin, glucose, appetite, and energy expenditure before and after weight loss. RESULTS: Weight loss (9.2 +/- 0.7 kg) and improvements in fasting and postprandial insulin and glucose occurred independently of diet composition. At wk 0 and 16, subjects wanted less to eat after the high-protein/low-fat than the standard protein/high-fat meal (P = 0.02). Fasting ghrelin increased (157.5 +/- 3.4 pg/ml or 46.6 +/- 1.0 pmol/liter; P < 0.001), and the postprandial ghrelin response improved with weight loss (P = 0.043) independently of diet composition. Postprandial hunger decreased with weight loss (P = 0.018) and was predicted by changes in fasting and postprandial ghrelin (r2 = 0.246; P = 0.004). Lean mass was the best predictor of fasting (r2 = 0.182; P = 0.003) and postprandial ghrelin (r2 = 0.096; P = 0.039) levels. CONCLUSIONS: Exchanging protein for fat produced similar weight loss and improvements in metabolic parameters and ghrelin homeostasis. The reduced appetite observed with increased dietary protein appears not to be mediated by ghrelin homeostasis.

Adult↗

PubMed2005

Flow-mediated dilatation is impaired by a high-saturated fat diet but not by a high-carbohydrate diet.

OBJECTIVE: It is unknown whether a low-fat diet, which may elevate triglycerides and lower high-density lipoprotein (HDL) cholesterol, harms the endothelium. Our aim was to determine whether a low-fat, high-carbohydrate (CARB) diet impaired endothelial vasodilation compared with high saturated fat (SFA), monounsaturated fat (MUFA), or polyunsaturated fat (PUFA) diets. METHODS AND RESULTS: Forty healthy subjects were randomly crossed over to 4, 3-week isocaloric diets high in PUFA, MUFA, or SFA, containing at least 25 g of the relevant fat or a low-fat, CARB, high-glycemic load diet. Flow-mediated dilatation (FMD), fasting blood lipids, high sensitivity C-reactive protein, plasma intercellular, and vascular adhesion molecules plasma E- and P-selectin were measured after each intervention. SFA impaired FMD compared with all other diets (5.41+/-2.45% versus 10.80+/-3.69%; P=0.01). FMD did not change on CARB relative to MUFA or PUFA, despite 23% to 39% rises in triglyceride and 10% to 15% falls in HDL cholesterol. P-selectin was highest after SFA (121+/-52.7 ng/mL) versus MUFA (98+/-44.5 ng/mL; P=0.001) and PUFA (96+/-36.4 ng/mL; P=0.001). CONCLUSIONS: High SFA caused deterioration in FMD compared with high PUFA, MUFA, or CARB diets. Inflammatory responses may also be increased on this diet.

Adult↗

PubMed2005

The use of novel foods enriched with long-chain n-3 fatty acids to increase dietary intake: a comparison of methodologies assessing nutrient intake.

OBJECTIVE: To evaluate the effect of consuming a variety of foods enriched in long-chain n-3 fatty acids in low fish eaters. DESIGN: Evaluation of reported dietary intakes in a 6-month, double-blind, randomized, controlled parallel design trial. SUBJECTS/SETTING: Eighty-five men and women with overweight and mildly elevated triglyceride levels who have a low habitual intake of fish. INTERVENTION: Subjects were randomized to consume foods either enriched in long-chain n-3 fats or control foods (not enriched). Subjects were asked to consume eight portions per day (equivalent to approximately 1 g/day long-chain n-3 fatty acid if randomized to the intervention). MAIN OUTCOME MEASURE: Reported energy, macronutrient, and fatty acid intakes were measured by diet history, 3-day food records, and body weight. STATISTICAL ANALYSES: Repeated measures analysis of variance, Kruskall-Wallis test, Pearson's correlation coefficient, and Bland-Altman plots were conducted. RESULTS: The two groups did not differ in mean dietary intake of long-chain n-3 fatty acid intake at baseline (258 mg and 313 mg for the intervention and control groups, respectively). At 6 months the intervention group members increased their intake of long-chain n-3 fats 4.5-fold compared with baseline and with the control group (P<.001). The data from the diet histories correlated well with the food records for all reported macronutrient and fatty acid values. Food pattern analysis showed that milk (13.8%), cereal (12.1%), and bread (11.3%) contributed the most to the overall long-chain n-3 fatty acid intake in the intervention group. CONCLUSIONS: This long-term study in free-living subjects indicates that population intakes of long-chain n-3 fatty acids could be substantially increased through the availability of a variety of n-3 fatty acid-enriched processed foods.

Adult↗

PubMed2005

Carbohydrate-restricted diets high in either monounsaturated fat or protein are equally effective at promoting fat loss and improving blood lipids.

BACKGROUND: When substituted for carbohydrate in an energy-reduced diet, dietary protein enhances fat loss in women. It is unknown whether the effect is due to increased protein or reduced carbohydrate. OBJECTIVE: We compared the effects of 2 isocaloric diets that differed in protein and fat content on weight loss, lipids, appetite regulation, and energy expenditure after test meals. DESIGN: This was a parallel, randomized study in which subjects received either a low-fat, high-protein (LF-HP) diet (29 +/- 1% fat, 34 +/- 0.8% protein) or a high-fat, standard-protein (HF-SP) diet (45 +/- 0.6% fat, 18 +/- 0.3% protein) during 12 wk of energy restriction (6 +/- 0.1 MJ/d) and 4 wk of energy balance (7.4 +/- 0.3 MJ/d). Fifty-seven overweight and obese [mean body mass index (in kg/m(2)): 33.8 +/- 0.9] volunteers with insulin concentrations >12 mU/L completed the study. RESULTS: Weight loss (LF-HP group, 9.7 +/- 1.1 kg; HF-SP group, 10.2 +/- 1.4 kg; P = 0.78) and fat loss were not significantly different between diet groups even though the subjects desired less to eat after the LF-HP meal (P = 0.02). The decrease in resting energy expenditure was not significantly different between diet groups (LF-HP, -342 +/- 185 kJ/d; HF-SP, -349 +/- 220 kJ/d). The decrease in the thermic effect of feeding with weight loss was smaller in the LF-HP group than in the HF-SP group (-0.3 +/- 1.0% compared with -3.6 +/- 0.7%; P = 0.014). Glucose and insulin responses to test meals improved after weight loss (P < 0.001) with no significant diet effect. Bone turnover, inflammation, and calcium excretion did not change significantly. CONCLUSION: The magnitude of weight loss and the improvements in insulin resistance and cardiovascular disease risk factors did not differ significantly between the 2 diets, and neither diet had any detrimental effects on bone turnover or renal function.

Adult↗

PubMed2005

Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women.

BACKGROUND: Limited evidence suggests that a higher ratio of protein to carbohydrate during weight loss has metabolic advantages. OBJECTIVE: The objective was to evaluate the effects of a diet with a high ratio of protein to carbohydrate during weight loss on body composition, cardiovascular disease risk, nutritional status, and markers of bone turnover and renal function in overweight women. DESIGN: The subjects were randomly assigned to 1 of 2 isocaloric 5600-kJ dietary interventions for 12 wk according to a parallel design: a high-protein (HP) or a high-carbohydrate (HC) diet. RESULTS: One hundred women with a mean (+/-SD) body mass index (in kg/m(2)) of 32 +/- 6 and age of 49 +/- 9 y completed the study. Weight loss was 7.3 +/- 0.3 kg with both diets. Subjects with high serum triacylglycerol (>1.5 mmol/L) lost more fat mass with the HP than with the HC diet (x +/- SEM: 6.4 +/- 0.7 and 3.4 +/- 0.7 kg, respectively; P = 0.035) and had a greater decrease in triacylglycerol concentrations with the HP (-0.59 +/- 0.19 mmol/L) than with the HC (-0.03 +/- 0.04 mmol/L) diet (P = 0.023 for diet x triacylglycerol interaction). Triacylglycerol concentrations decreased more with the HP (0.30 +/- 0.10 mmol/L) than with the HC (0.10 +/- 0.06 mmol/L) diet (P = 0.007). Fasting LDL-cholesterol, HDL-cholesterol, glucose, insulin, free fatty acid, and C-reactive protein concentrations decreased with weight loss. Serum vitamin B-12 increased 9% with the HP diet and decreased 13% with the HC diet (P < 0.0001 between diets). Folate and vitamin B-6 increased with both diets; homocysteine did not change significantly. Bone turnover markers increased 8-12% and calcium excretion decreased by 0.8 mmol/d (P < 0.01). Creatinine clearance decreased from 82 +/- 3.3 to 75 +/- 3.0 mL/min (P = 0.002). CONCLUSION: An energy-restricted, high-protein, low-fat diet provides nutritional and metabolic benefits that are equal to and sometimes greater than those observed with a high-carbohydrate diet.

Adipose Tissue↗

PubMed2004

Chronic maternal feed restriction impairs growth but increases adiposity of the fetal guinea pig.

Small size at birth has been associated with an increased risk of central obesity and reduced lean body mass in adult life. This study investigated the time of onset of prenatally induced obesity, which occurs after maternal feed restriction, in the guinea pig, a species that, like the human, develops substantial adipose tissue stores before birth. We examined the effect of maternal feed restriction [70% ad libitum intake from 4 wk before to midpregnancy, then 90% until day 60 gestation (term approximately 69 days)] on fetal growth and body composition in the guinea pig. Maternal feed restriction reduced fetal (-39%) and placental (-30%) weight at 60 days gestation and reduced liver, biceps muscle, spleen, and thymus weights, relative to fetal weight, while relative weights of brain, lungs, and interscapular and retroperitoneal fat pads were increased. In the interscapular depot, maternal feed restriction decreased the volume density of multilocular fat and increased that of unilocular fat, resulting in an increased relative weight of interscapular unilocular fat. Maternal feed restriction did not alter the relative weight of perirenal fat or the volume density of adipocyte populations within the depot but increased unilocular lipid locule size. Maternal feed restriction in the guinea pig is associated with decreased weight of major organs, including liver and skeletal muscle, but increased adiposity of the fetus, with relative sparing of unilocular adipose tissue. If this early-onset obesity persists, it may contribute to the metabolic and cardiovascular dysfunction that these offspring of feed-restricted mothers develop as adults.

Adipose Tissue↗

PubMed2004

Plant sterol ester-enriched milk and yoghurt effectively reduce serum cholesterol in modestly hypercholesterolemic subjects.

BACKGROUND: The cholesterol-lowering efficacy of plant sterol esters (PSteE) or stanol esters (PStaE) in regular- and low-fat spreads has been consistently demonstrated, while their effectiveness in a low-fat, aqueous food carrier such as milk and yoghurt is less well established. AIM OF THE STUDY: Two studies were carried out to assess the cholesterol-lowering effect of PSteE-enriched low-fat milk and PSteE- and PStaE-enriched low-fat yoghurt in modestly hypercholesterolemic subjects (total cholesterol between 5-7.5 mmol/l). METHODS: Study one was a single blind crossover design with 4 phases of 3-week interventions. Subjects consumed 300 ml/d of placebo or PSteE-milk (2.0 g plant sterols/d) alone or combined with 25 g/d of placebo or PSteE-spread. Study two was a fully randomised, double blind crossover design with 3 phases of 3-week interventions. Subjects consumed 2 portions (150 g tubs each) of placebo, PSteE-yoghurt (1.8 g plant sterols/d) or PStaE-yoghurt (1.7 g plant stanols/d). In study one 39 subjects (21 men and 18 women) and in study two 40 subjects (17 men and 23 women) completed the dietary intervention. RESULTS: In study one, PSteE-milk and PSteE-spread were equally efficacious in lowering total and LDL-cholesterol as compared to placebo by 6-8% and 8-10%, respectively. No significant additional cholesterol-lowering was observed with the combination of PSteE-milk and PSteE-spread (4 g plant sterols/d). PSteE-enriched milk and the combination of PSteE-enriched milk plus spread both lowered lipid-adjusted serum beta-carotene concentrations by 10-14% (P < 0.02),while the PSteE-rich spread alone did not significantly alter serum beta-carotene levels. In study two, the PSteE- and PStaE-enriched yoghurts reduced LDL-cholesterol significantly compared to placebo by 0.27 +/- 0.05 mmol/l (6%) and 0.23 +/- 0.05 mmol/l (5%), respectively. In both studies, there was no effect on HDL-cholesterol and triacylglycerol concentrations. CONCLUSION: Plant sterols in the form of their esters when provided in lowfat milk and yoghurt are effective in lowering total and LDL-cholesterol.

Adult↗

PubMed2004

High dietary intake of phytosterol esters decreases carotenoids and increases plasma plant sterol levels with no additional cholesterol lowering.

The objective of this study was to measure the effects on serum lipids and plasma phytosterols of 6.6 g/day phytosterols from three foods (bread, breakfast cereal, and spread) consumed for 12 weeks compared with a diet that was not enriched with phytosterols. Thirty-five subjects undertook a nonrandomized, single-blind study consisting of a 2 week baseline period, 6 weeks on high-phytosterol intake, 6 weeks on high-phytosterol intake plus increased fruit and vegetable intake, and a final 2 week washout period. Serum total cholesterol decreased by 8.3% from 6.59 to 6.04 mmol/l, and LDL cholesterol decreased by 12.6% from 4.44 to 3.88 mmol/l. Plasma phytosterol levels increased by 45% (sitosterol) and 105% (campesterol). Cholesterol-adjusted plasma alpha- and beta-carotene levels decreased by 19-23%, lutein by 14%, and lycopene by 11%. Levels of alpha-carotene and lutein increased with extra fruit and vegetables. Only lycopene failed to increase during the washout phase. There were no significant changes in biochemical parameters. Serum LDL cholesterol lowering with 6.6 g/day ingested phytosterols was in the range seen with 1.6-3.2 g/day phytosterols. Lowering of plasma carotenoids was greater than that seen with lower phytosterol intake and was partially reversed by increased fruit and vegetable intake.

Body Mass Index↗

PubMed2004

In vitro mononuclear cell production of tumour necrosis factor-alpha and weight loss.

OBJECTIVE: Elevated tumour necrosis factor-alpha (TNF-alpha) production in adipose tissue has been associated with obesity. We investigated whether mononuclear cell production of TNF-alpha decreased with weight loss in an obese population. RESEARCH METHODS AND PROCEDURES: Seventeen obese patients with type 2 diabetes (BMI 32.5+/-0.9 kg/m(2)) and 33 obese, non-diabetic controls (BMI 31.2+/-0.5 kg/m(2)) underwent 12 weeks of 30% total energy restriction (6622+/-84 KJ per day). Every 4 weeks, weight and blood pressure were measured and fasting venous blood was analysed for lipid, glucose and insulin concentrations. At the beginning and end of energy restriction, mononuclear cells were isolated from whole blood and TNF-alpha production measured by ELSIA. RESULTS: TNF-alpha production was not associated with the degree of adiposity but was higher in diabetic subjects (P<0.04). There was a reduction after energy restriction (281+/-43 to 182+/-30 pg/ml, P<0.05) however the presence of type 2 diabetes did not influence the magnitude of this change. Plasma glucose and insulin levels decreased after weight loss in all subjects and weak correlations were found with TNF-alpha concentrations (r=0.3, P<0.05). CONCLUSIONS: We conclude that maximal production of TNF-alpha from mononuclear cells decreases with energy restriction and is weakly associated with plasma glucose and insulin concentrations in obese patients.

Adipose Tissue↗

PubMed2004

A high dairy protein, high-calcium diet minimizes bone turnover in overweight adults during weight loss.

Weight loss induces bone resorption and this can be attenuated by calcium supplementation. Protein-rich diets were recently associated with favorable effects on bone density, although this remains controversial. We hypothesized that a diet high in calcium and protein would minimize bone resorption during weight loss compared with a lower calcium, protein-rich diet. The effects of dietary calcium in high protein diets on calcium excretion and bone metabolism were examined in overweight adults (n = 50, BMI 33.4 +/- 2.1 kg/m(2)) during 12 wk of energy restriction followed by 4 wk of energy balance. Subjects were randomly assigned to isoenergetic diets (5.5 MJ/d, 34% energy from protein, 41% carbohydrate, 24% fat) high in either dairy protein (DP, 2400 mg Ca/d) or mixed protein sources (MP, 500 mg Ca/d). During energy restriction, weight loss was 10% (-9.7 +/- 3.8 kg, P < 0.01), and 24-h urinary calcium excretion decreased independently of diet (-1.09 +/- 0.23 mmol/d, P < 0.01). By wk 16, the MP diet group had a 40% greater increase in deoxypyridinoline (bone resorption marker) than the DP diet group (P = 0.008). Osteocalcin (bone formation marker) increased from wk 0 to 16 in only the MP diet group [+2.16 +/- 0.63 micro g/L (+0.63 +/- 0.11nmol/L), P = 0.001]. In conclusion, weight loss was associated with increased bone resorption, yet the DP diet had a modest advantage over the MP diet by minimizing overall turnover. Combined with reduced urinary calcium excretion, this suggests that a high-protein, calcium-replete diet may protect against bone loss during weight reduction.

Adult↗