Subject(s)
Global Burden of Disease , Red Meat , Diet , Humans , Meat , Red Meat/adverse effects , Risk FactorsABSTRACT
Objective. This study was to evaluate the efficacy and safety of a Chinese herbal medicine formula (RCM-104) for the management of simple obesity. Method. Obese subjects aged between 18 and 60 years were selected for 12-week, double-blind, randomized, placebo-controlled trial. Subjects were randomly assigned to take 4 capsules of either the RCM-104 formula (n = 59) or placebo (n = 58), 3 times daily for 12 weeks. Measures of BW, BMI and WC, HC, WHR and BF composition were assessed at baseline and once every four weeks during the 12 week treatment period. Results. Of the 117 subjects randomised, 92 were included in the ITT analysis. The weight, BMI and BF in RCM-104 group were reduced by 1.5 kg, 0.6 kg/m(2) and 0.9% and those in the placebo group were increased by 0.5 kg, 0.2 kg/m(2) and 0.1% respectively. There were significant differences in BW and BMI (P < 0.05) between the two groups. Eleven items of the WLQOQ were significantly improved in the RCM-104 group while only 2 items were significantly improved in the placebo group. Adverse events were minor in both groups. Conclusion. RCM-104 treatment appears to be well tolerated and beneficial in reducing BW and BMI in obese subjects.
ABSTRACT
BACKGROUND: Many laboratories offer glycemic index (GI) services. OBJECTIVE: We assessed the performance of the method used to measure GI. DESIGN: The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 laboratories (n=311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally. RESULTS: Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P=0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean+/-SD) for cheese-puffs and fruit-leather were 74.3+/-10.5 and 33.2+/-7.2, respectively. The mean laboratory GI was related to refCV (P=0.003) and the type of restrictions on alcohol consumption before the test (P=0.006, r2=0.509 for model). The within-laboratory SD of GI was related to refCV (P<0.001), the glucose analysis method (P=0.010), whether glucose measures were duplicated (P=0.008), and restrictions on dinner the night before (P=0.013, r2=0.810 for model). CONCLUSIONS: The between-laboratory SD of the GI values is approximately 9. Standardized data analysis and low within-subject variation (refCV<30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.
Subject(s)
Clinical Laboratory Techniques/standards , Dietary Carbohydrates/metabolism , Food Analysis/standards , Food/classification , Glycemic Index , Adolescent , Adult , Aged , Area Under Curve , Blood Glucose/metabolism , Cross-Over Studies , Female , Glucose Tolerance Test , Humans , Male , Middle Aged , Reference Values , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
BACKGROUND: Dietary factors have long been implicated in acne pathogenesis. It has recently been hypothesized that low glycemic load diets may influence sebum production based on the beneficial endocrine effects of these diets. OBJECTIVE: To determine the effect of a low glycemic load diet on acne and the fatty acid composition of skin surface triglycerides. METHODS: Thirty-one male acne patients (aged 15-25 years) completed sebum sampling tests as part of a larger 12-week, parallel design dietary intervention trial. The experimental treatment was a low glycemic load diet, comprised of 25% energy from protein and 45% from low glycemic index carbohydrates. In contrast, the control situation emphasized carbohydrate-dense foods without reference to the glycemic index. Acne lesion counts were assessed during monthly visits. At baseline and 12-weeks, the follicular sebum outflow and composition of skin surface triglycerides were assessed using lipid absorbent tapes. RESULTS: At 12 weeks, subjects on the experimental diet demonstrated increases in the ratio of saturated to monounsaturated fatty acids of skin surface triglycerides when compared to controls [5.3+/-2.0% (mean+/-S.E.M.) vs. -2.7+/-1.7%, P=0.007]. The increase in the saturated/monounsaturated ratio correlated with acne lesion counts(r=-0.39, P=0.03). Increased follicular sebum outflow was also associated with an increase in the proportion of monounsaturated fatty acids in sebum (r=0.49, P=0.006). CONCLUSION: This suggests a possible role of desaturase enzymes in sebaceous lipogenesis and the clinical manifestation of acne. However, further work is needed to clarify the underlying role of diet in sebum gland physiology.
Subject(s)
Acne Vulgaris/diet therapy , Diet, Carbohydrate-Restricted , Fatty Acids/analysis , Skin/chemistry , Triglycerides/analysis , Acne Vulgaris/metabolism , Adolescent , Adult , Glycemic Index , Humans , Male , Sebum/chemistryABSTRACT
Anthropological investigations have confirmed many times over, through multiple fields of research the critical role of consumption of animal source foods (ASF) including meat in the evolution of our species. As early as four million years ago, our early bipedal hominin ancestors were scavenging ASFs as evidenced by cut marks on animal bone remains, stable isotope composition of these hominin remains and numerous other lines of evidence from physiological and paleo-anthropological domains. This ASF intake marked a transition from a largely forest dwelling frugivorous lifestyle to a more open rangeland existence and resulted in numerous adaptations, including a rapidly increasing brain size and altered gut structure. Details of the various fields of anthropological evidence are discussed, followed by a summary of the health implications of meat consumption in the modern world, including issues around saturated fat and omega-3 fatty acid intake and discussion of the critical nutrients ASFs supply, with particular emphasis on brain function.
Subject(s)
Biological Evolution , Diet , Meat , Agriculture , Animals , Humans , Life StyleABSTRACT
BACKGROUND: Although the pathogenesis of acne is currently unknown, recent epidemiologic studies of non-Westernized populations suggest that dietary factors, including the glycemic load, may be involved. OBJECTIVE: The objective was to determine whether a low-glycemic-load diet improves acne lesion counts in young males. DESIGN: Forty-three male acne patients aged 15-25 y were recruited for a 12-wk, parallel design, dietary intervention incorporating investigator-blinded dermatology assessments. The experimental treatment was a low-glycemic-load diet composed of 25% energy from protein and 45% from low-glycemic-index carbohydrates. In contrast, the control situation emphasized carbohydrate-dense foods without reference to the glycemic index. Acne lesion counts and severity were assessed during monthly visits, and insulin sensitivity (using the homeostasis model assessment) was measured at baseline and 12 wk. RESULTS: At 12 wk, mean (+/-SEM) total lesion counts had decreased more (P=0.03) in the low-glycemic-load group (-23.5 +/- 3.9) than in the control group (-12.0 +/- 3.5). The experimental diet also resulted in a greater reduction in weight (-2.9 +/- 0.8 compared with 0.5 +/- 0.3 kg; P<0.001) and body mass index (in kg/m(2); -0.92 +/- 0.25 compared with 0.01 +/- 0.11; P=0.001) and a greater improvement in insulin sensitivity (-0.22 +/- 0.12 compared with 0.47 +/- 0.31; P=0.026) than did the control diet. CONCLUSION: The improvement in acne and insulin sensitivity after a low-glycemic-load diet suggests that nutrition-related lifestyle factors may play a role in the pathogenesis of acne. However, further studies are needed to isolate the independent effects of weight loss and dietary intervention and to further elucidate the underlying pathophysiologic mechanisms.
Subject(s)
Acne Vulgaris/diet therapy , Dietary Carbohydrates/administration & dosage , Glycemic Index/physiology , Acne Vulgaris/metabolism , Adolescent , Adult , Blood Glucose/metabolism , Humans , Insulin/blood , Insulin Resistance/physiology , Male , Urea/urineSubject(s)
Anxiety Disorders/epidemiology , Meat/statistics & numerical data , Mood Disorders/epidemiology , Adult , Aged , Aged, 80 and over , Animals , Australia/epidemiology , Cattle , Cross-Sectional Studies , Diet/statistics & numerical data , Female , Humans , Middle Aged , Sheep , Young AdultABSTRACT
BACKGROUND: No previous study has sought to examine the influence of dietary composition on acne vulgaris. OBJECTIVE: We sought to compare the effect of an experimental low glycemic-load diet with a conventional high glycemic-load diet on clinical and endocrine aspects of acne vulgaris. METHODS: A total of 43 male patients with acne completed a 12-week, parallel, dietary intervention study with investigator-masked dermatology assessments. Primary outcomes measures were changes in lesion counts, sex hormone binding globulin, free androgen index, insulin-like growth factor-I, and insulin-like growth factor binding proteins. RESULTS: At 12 weeks, total lesion counts had decreased more in the experimental group (-21.9 [95% confidence interval, -26.8 to -19.0]) compared with the control group (-13.8 [-19.1 to -8.5], P = .01). The experimental diet also reduced weight (P = .001), reduced the free androgen index (P = .04), and increased insulin-like growth factor binding protein-1 (P = .001) when compared with a high glycemic-load diet. LIMITATIONS: We could not preclude the role of weight loss in the overall treatment effect. CONCLUSION: This suggests nutrition-related lifestyle factors play a role in acne pathogenesis. However, these preliminary findings should be confirmed by similar studies.
Subject(s)
Acne Vulgaris/blood , Acne Vulgaris/diet therapy , Blood Glucose/metabolism , Dietary Carbohydrates/administration & dosage , Dietary Proteins/administration & dosage , Acne Vulgaris/pathology , Acne Vulgaris/physiopathology , Adolescent , Adult , Humans , Insulin Resistance , Male , Sex Hormone-Binding Globulin/metabolism , Single-Blind Method , Treatment OutcomeABSTRACT
The aim of this study was to investigate the possibility of a relationship between plasma homocysteine (Hcy) and phospholipid FA (PUFA) in healthy Australian males. One hundred thirty six healthy male subjects aged 20-55 yr were recruited from the Melbourne metropolitan area. Each volunteer completed a semiquantitative food frequency questionnaire and gave a blood sample. Plasma Hcy concentrations were determined by an established HPLC method; the plasma phospholipid FA were determined by standard methods. Plasma Hcy concentration was significantly negatively correlated with plasma phospholipid concentration of the PUFA 20:5n-3 (r = -0.226, P = 0.009), 22:5n-3 (r= -0.182, P= 0.036), 22:6n-3 (r= -0.286, P= 0.001), total n-3 (r = -0.270, P = 0.002) and the ratio n-3/n-6 PUFA (r = -0.265, P = 0.002), and significantly positively correlated with 20:4n-6 (r= 0.180, P= 0.037). In the partial correlation analysis, after controlling for serum vitamin B12 and folate concentration, plasma Hcy was significantly negatively correlated with the plasma phospholipid concentration of 22:6n-3 (r = -0.205, P = 0.019), total n-3 (r = -0.182, P= 0.038) and the ratio n-3/n-6 PUFA (r= -0.174, P= 0.048). Evidence indicates that an increased concentration of n-3 PUFA in tissues has a beneficial effect on cardiovascular health. Our findings provide further evidence that increased consumption of dietary n-3 PUFA increases the concentration of n-3 PUFA in plasma phospholipid, which is associated with a protective effect on cardiovascular diseases and lower plasma Hcy levels. The mechanism that might explain the association between plasma 22:6n-3 and Hcy levels is not clear.
Subject(s)
Docosahexaenoic Acids/blood , Homocysteine/blood , Diet , Humans , Male , Reference ValuesABSTRACT
High-fat diets are implicated in the onset of cardiovascular disease (CVD), cancer, and obesity. Large intakes of saturated and trans FA, together with low levels of PUFA, particularly long-chain (LC) omega-3 (n-3) PUFA, appear to have the greatest impact on the development of CVD. A high n-6:n-3 PUFA ratio is also considered a marker of elevated risk of CVD, though little accurate data on dietary intake is available. A new Australian food composition database that reports FA in foods to two decimal places was used to assess intakes of FA in four habitual dietary groups. Analysis using the database found correlations between the dietary intakes of LC n-3 PUFA and the plasma phospholipid LC n-3 PUFA concentrations of omnivore and vegetarian subjects. High meat-eaters (HME), who consumed large amounts of food generally, had significantly higher LC n-3 PUFA intakes (0.29 g/d) than moderate meat-eaters (MME) (0.14 g/d), whose intakes in turn were significantly higher than those of ovolacto-vegetarians or vegans (both 0.01 g/d). The saturated FA intake of MME subjects (typical of adult male Australians) was not different from ovolacto-vegetarian intakes, whereas n-6:n-3 intake ratios in vegetarians were significantly higher than in omnivores. Thus, accurate dietary and plasma FA analyses suggest that regular moderate consumption of meat and fish maintains a plasma FA profile possibly more conducive to good health.
Subject(s)
Diet, Vegetarian , Diet , Fatty Acids, Unsaturated/analysis , Fatty Acids/blood , Adult , Animals , Australia , Diet/classification , Dietary Fats/analysis , Fatty Acids, Omega-3/analysis , Fishes , Humans , Male , Meat , Middle Aged , Phospholipids/blood , Phospholipids/chemistryABSTRACT
There is growing awareness that the profound changes in the environment (eg, in diet and other lifestyle conditions) that began with the introduction of agriculture and animal husbandry approximately 10000 y ago occurred too recently on an evolutionary time scale for the human genome to adjust. In conjunction with this discordance between our ancient, genetically determined biology and the nutritional, cultural, and activity patterns of contemporary Western populations, many of the so-called diseases of civilization have emerged. In particular, food staples and food-processing procedures introduced during the Neolithic and Industrial Periods have fundamentally altered 7 crucial nutritional characteristics of ancestral hominin diets: 1) glycemic load, 2) fatty acid composition, 3) macronutrient composition, 4) micronutrient density, 5) acid-base balance, 6) sodium-potassium ratio, and 7) fiber content. The evolutionary collision of our ancient genome with the nutritional qualities of recently introduced foods may underlie many of the chronic diseases of Western civilization.
Subject(s)
Agriculture/methods , Biological Evolution , Diet/trends , Acid-Base Equilibrium , Chronic Disease/epidemiology , Dietary Fiber/administration & dosage , Fatty Acids/administration & dosage , Fatty Acids/analysis , Food Analysis , Food Handling/methods , Glycemic Index , Humans , Potassium, Dietary/administration & dosage , Sodium, Dietary/administration & dosage , United StatesABSTRACT
BACKGROUND: Flavonoids may be partly responsible for some health benefits, including antiinflammatory action and a decreased tendency for the blood to clot. An acute dose of flavanols and oligomeric procyanidins from cocoa powder inhibits platelet activation and function over 6 h in humans. OBJECTIVE: This study sought to evaluate whether 28 d of supplementation with cocoa flavanols and related procyanidin oligomers would modulate human platelet reactivity and primary hemostasis and reduce oxidative markers in vivo. DESIGN: Thirty-two healthy subjects were assigned to consume active (234 mg cocoa flavanols and procyanidins/d) or placebo (< or = 6 mg cocoa flavanols and procyanidins/d) tablets in a blinded parallel-designed study. Platelet function was determined by measuring platelet aggregation, ATP release, and expression of activation-dependent platelet antigens by using flow cytometry. Plasma was analyzed for oxidation markers and antioxidant status. RESULTS: Plasma concentrations of epicatechin and catechin in the active group increased by 81% and 28%, respectively, during the intervention period. The active group had significantly lower P selectin expression and significantly lower ADP-induced aggregation and collagen-induced aggregation than did the placebo group. Plasma ascorbic acid concentrations were significantly higher in the active than in the placebo group (P < 0.05), whereas plasma oxidation markers and antioxidant status did not change in either group. CONCLUSIONS: Cocoa flavanol and procyanidin supplementation for 28 d significantly increased plasma epicatechin and catechin concentrations and significantly decreased platelet function. These data support the results of acute studies that used higher doses of cocoa flavanols and procyanidins.
Subject(s)
Biflavonoids , Blood Platelets/drug effects , Cacao/chemistry , Catechin/administration & dosage , Flavonoids/administration & dosage , Platelet Aggregation Inhibitors/administration & dosage , Proanthocyanidins , Adult , Blood Platelets/physiology , Catechin/blood , Diet , Female , Humans , Male , Middle Aged , Time FactorsABSTRACT
The lipid, FA, and sterol composition of the New Zealand green lipped mussel (NZGLM, Perna canaliculus) and of the Tasmanian blue mussel (TBM, Mytilus edulis) were compared using TLC-FID and GC-MS. The respective mussel species were obtained from three different sites in both New Zealand (NZ) and Tasmania. Lipid class distribution of both mussel species was characterized by a high proportion of phospholipid (PL, 57-79%) and TG (10-25%), FFA (7-12%), and sterols (ST, 12-18%). The NZGLM had higher proportions of TG, FFA, and ST (P < 0.01), whereas the TBM had a higher proportion of PL (P < 0.01). There were higher proportions of total PUFA, saturated FA, n-3 FA, and hydroxy and nonmethylene-interrupted FA (P < 0.05) in the TBM compared with the NZGLM. The major FA in the NZGLM were 16:0 (15-17%), 20:5n-3 (14-20%), and 22:6n-3 (11-17%). The same FA dominated lipids in the TBM, although there were significantly higher proportions of 16:0 (P = 0.000) and 22:6 n-3 (P = 0.003) and lower proportions of 20:5n-3 (P = 0.0072) in the TBM. A novel PUFA, 28:8n-3, was detected in both mussels with higher amounts in the TBM, which probably reflects a greater dietary contribution of dinoflagellates for this species. Cholesterol was the dominant sterol in both mussels. Other major sterols included brassicasterol, 22-methylcholesterol, trans-22-dehydrocholesterol, and desmosterol. There were significant differences (P < 0.05) between the NZGLM and TBM for 12 of the 20 sterols measured. Six sterols showed significant site differences for the NZGLM, and 10 for the TBM. The differences in the FA and sterol composition between the two species may be due to the diet of the NZGLM being more diatom-derived and the diet of the TBM having a greater dinoflagellate component.
Subject(s)
Bivalvia/chemistry , Fatty Acids/analysis , Lipids/analysis , Sterols/analysis , Animals , Chromatography, Thin Layer , Gas Chromatography-Mass Spectrometry , Species SpecificityABSTRACT
Both n-6 and n-3 polyunsaturated fatty acids (PUFA) are recognized as essential nutrients in the human diet, yet reliable data on population intakes are limited. The aim of the present study was to ascertain the dietary intakes and food sources of individual n-6 and n-3 PUFA in the Australian population. An existing database with fatty acid composition data on 1690 foods was updated with newly validated data on 150 foods to estimate the fatty acid content of foods recorded as eaten by 10,851 adults in the 1995 Australian National Nutrition Survey. Average daily intakes of linoleic (LA), arachidonic (AA), alpha-linolenic (LNA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids were 10.8, 0.052, 1.17, 0.056, 0.026, and 0.106 g, respectively, with long-chain (LC) n-3 PUFA (addition of EPA, DPA, and DHA) totaling 0.189 g; median intakes were considerably lower (9.0 g LA, 0.024 g AA, 0.95 g LNA, 0.008 g EPA, 0.006 g DPA, 0.015 g DHA, and 0.029 g LC n-3 PUFA). Fats and oils, meat and poultry, cereal-based products and cereals, vegetables, and nuts and seeds were important sources of n-6 PUFA, while cereal-based products, fats and oils, meat and poultry, cereals, milk products, and vegetable products were sources of LNA. As expected, seafood was the main source of LC n-3 PUFA, contributing 71%, while meat and eggs contributed 20 and 6%, respectively. The results indicate that the majority of Australians are failing to meet intake recommendations for LC n-3 PUFA (> 0.2 g per day) and emphasize the need for strategies to increase the availability and consumption of n-3-containing foods.
Subject(s)
Diet/statistics & numerical data , Fatty Acids, Omega-3/administration & dosage , Fatty Acids, Omega-6/administration & dosage , Adolescent , Adult , Aged , Child , Child, Preschool , Databases, Factual , Dietary Fats/analysis , Energy Intake , Fatty Acids, Omega-3/analysis , Fatty Acids, Omega-6/analysis , Female , Humans , Male , Middle Aged , Nutrition SurveysABSTRACT
Fish are a rich source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two long-chain polyunsaturated n-3 fatty acids (LC n-3 PUFA) with cardiovascular benefits. A related but less-investigated LC n-3 PUFA, docosapentaenoic acid (DPA), is more common in seal oil and pasture-fed red meats. This study compared indicators of platelet function and plasma lipids in healthy volunteers given supplements containing these different fatty acids (FA) for 14 days. Subjects, randomised into three groups of ten, consumed capsules of tuna oil (210 mg EPA, 30 mg DPA, 810 mg DHA), seal oil (340 mg EPA, 230 mg DPA, 450 mg DHA) or placebo (sunola) oil. Supplementary LC n-3 PUFA levels were approximately 1 g/day in both fish and seal oil groups. Baseline dietary FA and other nutrient intakes were similar in all groups. Both fish and seal oil elevated platelet DHA levels (P < 0.01). Seal oil also raised platelet DPA and EPA levels (P < 0.01), and decreased p-selectin (P = 0.01), a platelet activation marker negatively associated with DPA (P = 0.03) and EPA (P < 0.01) but not DHA. Plasma triacylglycerol decreased (P = 0.03) and HDL-cholesterol levels increased (P = 0.01) with seal oil only. Hence, seal oil may be more efficient than fish oil at promoting healthy plasma lipid profiles and lowering thrombotic risk, possibly due to its high DPA as well as EPA content.
Subject(s)
Dietary Fats/pharmacology , Fish Oils/pharmacology , Platelet Activation/drug effects , Adult , Animals , C-Reactive Protein/metabolism , Fatty Acids, Omega-3/pharmacology , Fatty Acids, Unsaturated/pharmacology , Female , Humans , Male , Middle Aged , P-Selectin/blood , Seals, Earless , Triglycerides/blood , Tuna , Young AdultABSTRACT
Observational evidence suggests that dietary glycemic load may be one environmental factor contributing to the variation in acne prevalence worldwide. To investigate the effect of a low glycemic load (LGL) diet on endocrine aspects of acne vulgaris, 12 male acne sufferers (17.0 +/- 0.4 years) completed a parallel, controlled feeding trial involving a 7-day admission to a housing facility. Subjects consumed either an LGL diet (n = 7; 25% energy from protein and 45% from carbohydrates) or a high glycemic load (HGL) diet (n = 5; 15% energy from protein, 55% energy from carbohydrate). Study outcomes included changes in the homeostasis model assessment of insulin resistance (HOMA-IR), sex hormone binding globulin (SHBG), free androgen index (FAI), insulin-like growth factor-I (IGF-I), and its binding proteins (IGFBP-I and IGFBP-3). Changes in HOMA-IR were significantly different between groups at day 7 (-0.57 for LGL vs. 0.14 for HGL, p = 0.03). SHBG levels decreased significantly from baseline in the HGL group (p = 0.03), while IGFBP-I and IGFBP-3 significantly increased (p = 0.03 and 0.03, respectively) in the LGL group. These results suggest that increases in dietary glycemic load may augment the biological activity of sex hormones and IGF-I, suggesting that these diets may aggravate potential factors involved in acne development.
Subject(s)
Acne Vulgaris/blood , Diet , Dietary Carbohydrates/administration & dosage , Glycemic Index , Acne Vulgaris/etiology , Acne Vulgaris/prevention & control , Adolescent , Adult , Androgens/blood , Blood Glucose/analysis , Capillaries , Food , Humans , Insulin/blood , Insulin Resistance , Insulin-Like Growth Factor Binding Proteins/blood , Insulin-Like Growth Factor I/analysis , Lipids/blood , Male , Pilot Projects , Sex Hormone-Binding Globulin/analysis , Testosterone/bloodABSTRACT
Considerable debate has taken place over the safety and validity of increased protein intakes for both weight control and muscle synthesis. The advice to consume diets high in protein by some health professionals, media and popular diet books is given despite a lack of scientific data on the safety of increasing protein consumption. The key issues are the rate at which the gastrointestinal tract can absorb amino acids from dietary proteins (1.3 to 10 g/h) and the liver's capacity to deaminate proteins and produce urea for excretion of excess nitrogen. The accepted level of protein requirement of 0.8g x kg(-1) x d(-1) is based on structural requirements and ignores the use of protein for energy metabolism. High protein diets on the other hand advocate excessive levels of protein intake on the order of 200 to 400 g/d, which can equate to levels of approximately 5 g x kg(-1) x d(-1), which may exceed the liver's capacity to convert excess nitrogen to urea. Dangers of excessive protein, defined as when protein constitutes > 35% of total energy intake, include hyperaminoacidemia, hyperammonemia, hyperinsulinemia nausea, diarrhea, and even death (the "rabbit starvation syndrome"). The three different measures of defining protein intake, which should be viewed together are: absolute intake (g/d), intake related to body weight (g x kg(-1) x d(-1)) and intake as a fraction of total energy (percent energy). A suggested maximum protein intake based on bodily needs, weight control evidence, and avoiding protein toxicity would be approximately of 25% of energy requirements at approximately 2 to 2.5 g x kg(-1) x d(-1), corresponding to 176 g protein per day for an 80 kg individual on a 12,000kJ/d diet. This is well below the theoretical maximum safe intake range for an 80 kg person (285 to 365 g/d).
Subject(s)
Amino Acids/metabolism , Dietary Proteins/administration & dosage , Energy Metabolism/physiology , Muscle, Skeletal/metabolism , Nutritional Requirements , Body Weight/drug effects , Dietary Proteins/adverse effects , Energy Metabolism/drug effects , Exercise/physiology , Humans , SafetyABSTRACT
The influence of feeding systems on the levels of functional lipids and other fatty acid concentrations in Australian beef was examined. Rump, strip loin and blade cuts obtained from grass feeding, short-term grain feeding (80 days; STGF) and long-term grain feedlot rations (150-200 days; LTFL) were used in the present study. The typical Australian feedlot ration contains more than 50% barley and/or sorghum and balanced with whole cottonseed and protein meals were used as feed for STGF and LTFL regimens. Meat cuts from 18 cattle for each feeding regimen were trimmed of visible fat and connective tissue and then minced (300 g lean beef); replicate samples of 7 g were used for fatty acid (FA) analysis. There was a significantly higher level of total omega-3 (n-3) and long chain n-3 FA in grass-fed beef (P< 0.0001) than the grain-fed groups regardless of cut types. Cuts from STGF beef had significantly reduced levels of n-3 FA and conjugated linoleic acid (CLA) and similar levels of saturated, monounsaturated and n-6 FA compared with grass feeding (P < 0.001). Cuts from LTFL beef had higher levels of saturated, monounsaturated,n-6 FA and trans 18:1 than similar cuts from the other two groups (P<0.01), indicating that increased length of grain feeding was associated with more fat deposited in the carcass. There was a step-wise increase in trans 18:1 content from grass to STGF to LTGF, suggesting grain feeding elevates trans FA in beef, probably because of increased intake of 18:2n-6. Only grass-fed beef reached the target of more than 30mg of long chain n-3 FA/100 g muscle as recommended by Food Standard Australia and New Zealand for a food to be considered a source of omega-3 fatty acids. The proportions of trans 18:1 and n-6 FA were higher (P<0.001) for both grain-fed beef groups than grass-fed beef. Data from the present study show that grain feeding decreases functional lipid components (long chain n-3 FA and CLA) in Australian beef regardless of meat cuts, while increasing total trans 18:1 and saturated FA levels.