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PubMed2004

Comparison of high-fat and high-protein diets with a high-carbohydrate diet in insulin-resistant obese women.

AIMS/HYPOTHESIS: A diet low in saturated fatty acids and rich in wholegrains, vegetables and fruit is recommended in order to reduce the risk of obesity, cardiovascular disease and type 2 diabetes mellitus. However there is widespread interest in high-fat ("Atkins Diet") and high-protein ("Zone Diet") alternatives to the conventional high-carbohydrate, high-fibre approach. We report on a randomised trial that compared these two alternative approaches with a conventional diet in overweight insulin-resistant women. METHODS: Ninety-six normoglycaemic, insulin-resistant women (BMI >27 kg/m(2)) were randomised to one of three dietary interventions: a high-carbohydrate, high-fibre (HC) diet, the high-fat (HF) Atkins Diet, or the high-protein (HP) Zone Diet. The experimental approach was designed to mimic what might be achieved in clinical practice: the recommendations involved advice concerning food choices and were not prescriptive in terms of total energy. There were supervised weight loss and weight maintenance phases (8 weeks each), but there was no contact between the research team and the participants during the final 8 weeks of the study. Outcome was assessed in terms of body composition and indicators of cardiovascular and diabetes risk. RESULTS: Body weight, waist circumference, triglycerides and insulin levels decreased with all three diets but, apart from insulin, the reductions were significantly greater in the HF and HP groups than in the HC group. These observations suggest that the popular diets reduced insulin resistance to a greater extent than the standard dietary advice did. When compared with the HC diet, the HF and HP diets were shown to produce significantly (p<0.01) greater reductions in several parameters, including weight loss (HF -2.8 kg, HP -2.7 kg), waist circumference (HF -3.5 cm, HP -2.7 cm) and triglycerides (HF -0.30 mmol/l, HP [corrected] -0.22 mmol/l). LDL cholesterol decreased in individuals on the HC and HP diets, but tended to fluctuate in those on the HF diet to the extent that overall levels were significantly lower in the HP group than in the HF group (-0.28 mmol/l, 95% CI 0.04-0.52, p=0.02). Of those on the HF diet, 25% showed a >10% increase in LDL cholesterol, whereas this occurred in only 13% of subjects on the HC diet and 3% of those on the HP diet. CONCLUSIONS/INTERPRETATION: In routine practice a reduced-carbohydrate, higher protein diet may be the most appropriate overall approach to reducing the risk of cardiovascular disease and type 2 diabetes. To achieve similar benefits on a HC diet, it may be necessary to increase fibre-rich wholegrains, legumes, vegetables and fruits, and to reduce saturated fatty acids to a greater extent than appears to be achieved by implementing current guidelines. The HF approach appears successful for weight loss in the short term, but lipid levels should be monitored. The potential deleterious effects of the diet in the long term remain a concern.

Body Mass Index↗
PubMed2000

Five-year-old girls' ideas about dieting are predicted by their mothers' dieting.

OBJECTIVE: To explore 5-year-old girls' ideas, concepts, and beliefs about dieting. DESIGN: Girls were asked to define dieting, to describe the behaviors dieting comprised, and were queried about links between dieting, weight control, and body shape. Parents completed questionnaires addressing family health history, demographics, and issues related to food, dieting, and weight control. SUBJECTS/SETTING: Participants were 197 girls aged 5 years and their parents. All girls lived with both biological parents, and were without food allergies or chronic medical problems. STATISTICAL ANALYSES PERFORMED: For 5 open-ended questions related to dieting, girls were categorized as either having or not having ideas about dieting. These ideas, concepts, and beliefs were categorized, and logistic regression examined predictors of girls' ideas about dieting. RESULTS: Depending on the question, from 34% to 65% of girls aged 5 years had ideas about dieting. Compared to girls whose mothers did not diet, girls whose mothers reported current or recent dieting were more than twice as likely to have ideas about dieting, suggesting that mothers' dieting behavior is a source of young girls' ideas, concepts, and beliefs about dieting. Among mothers, more than 90% reported recent dieting, and most reported use of both health-promoting and health-compromising dieting behaviors. APPLICATIONS: Women should be informed that weight control attempts may influence their young daughters' emerging ideas, concepts, and beliefs about dieting. Mothers should be encouraged to use health-promoting rather than health-compromising weight control strategies, not only for their own well being, but to reduce the likelihood that daughters will incorporate health-compromising dieting behaviors into their concepts, ideas, and beliefs about dieting.

Adult↗
PubMed2005

Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.

Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.

Absorption↗
PubMed2006

The effects of phytase on growth performance and intestinal transit time of broilers fed nutritionally adequate diets and diets deficient in calcium and phosphorus.

Five experiments (Exp.) were conducted to determine the effects of phytase on growth performance and intestinal transit time in chicks fed nutritionally adequate diets and diets deficient in Ca and nonphytate P (nPP). In Exp. 1 and 2, chicks were fed a nutritionally adequate diet from 0 to 6 d or from 0 to 4 d posthatching; assay periods were 8 or 10 d; average initial BW were 98 or 79 g; and average final BW were 371 or 369 g, respectively. Treatments were replicated with 12 pens of 5 chicks each. Corn-soybean meal (C-SBM) diets were adequate in all nutrients except Ca and nPP where appropriate. The treatments were 1) C-SBM, 1.0% Ca, and 0.45% nPP; 2) C-SBM, 0.80% Ca, and 0.25% nPP; 3) Diet 1 + 600 phytase units/kg of diet; 4) Diet 2 + 600 phytase units/kg of diet. Experiments 3, 4, and 5 were conducted to determine the effects of phytase on intestinal transit time in broilers. Broilers were fed the same nutritionally adequate diet from 0 to 18, 27, or 23 d posthatching, and the assay periods were 7 d. Treatments were replicated with 18 individually penned broilers. Average initial BW were 768, 1,108, or 838 g, and average final BW were 1,299, 1,704, or 1,392 g in Exp. 3 to 5, respectively. Transit time data were collected on d 1 and 7 of the Exp. Diets were 1) C-SBM, 0.9% Ca, and 0.35% nPP; 2) C-SBM, 0.80% Ca, and 0.25% nPP + 600 phytase units/kg of diet. Transit time was calculated as the difference between the time feed was first ingested and the time of first appearance of solid feces. In Exp. 1 and 2, the reduction in dietary Ca and nPP reduced (P < 0.01) average daily gain (ADG), average daily feed intake (ADFI), and gain:feed. Phytase addition increased (P < 0.02) ADG and ADFI in diets deficient in Ca and nPP and in the nutritionally adequate diets. In Exp. 2, the reduction in Ca and nPP reduced (P < 0.01) toe and tibia ash percentage, but phytase addition increased (P < 0.01) toe and tibia ash percentage. The increase in toe ash percentage was greater in chicks fed the Ca and nPP deficient diet than in chicks fed the nutritionally adequate diet (Ca and nPP x phytase, P < 0.01). In Exp. 3, 4, and 5, transit time on d 1 was faster (P < 0.03) in chicks fed phytase. On d 7, transit time tended to be faster in chicks fed phytase, but the effect was not significant (P = 0.15). These data indicate that phytase increases ADG and ADFI in diets deficient in Ca and nPP and in diets formulated to be adequate (or excess) in all nutrients for broiler chicks. The increase in ADG and ADFI in chicks fed the nutritionally adequate diet may be due to a faster transit time of feed through the digestive tract, resulting in a greater feed intake and gain.

6-Phytase↗
PubMed2000

Impacts of an endophyte-infected fescue seed diet on traits of mouse lines divergently selected for response to that same diet.

In previous work, mouse lines were selected for eight generations for resistance (R) or susceptibility (S) to endophyte-infected fescue toxicosis using depression in postweaning gain caused by a toxin-containing diet as the selection criterion. Characterizing biological changes associated with resistance or susceptibility in those mice might suggest genetic or therapeutic approaches to alleviate fescue toxicosis in cattle. The first objective of the current experiment was to determine whether the toxin-containing diet depressed reproduction and mature size more severely in S than in R mice. The second was to investigate line and diet effects on hepatic glutathione-S-epoxytransferase (GST) and uridine diphosphate glucuronosyl-transferase (UDPGT) activities and to relate enzyme activities to reproduction within line by diet groups. Twenty-eight pairs per line (S or R) x diet (toxin-containing [+] or toxin-absent [-]) group cohabitated for 36 wk. The + diet depressed the number of pups born and weaned and litter weight weaned (P < .01) within the first two litters produced. Diet effects were greatest early in the experiment. Percentage changes in reproduction caused by the + diet for R and S pairs, respectively, were -13 and -28 for total pups born, -10 and -25 for total pups weaned, -13 and -14 for total litters produced, and -30 and -42 for total litter weight weaned. The S line mice were heavier than R line mice on both diets, but the + diet had a larger depressing effect on mature size of S line than of R line males (line x diet interaction, P = .09) and females (interaction not significant). Averaged across diets, GST activity was higher in R than in S dams (P = .05) at 44 wk of age but was not affected by diet or line x diet. Activity of GST was correlated with number of pups born (-.50), number of litters produced (-.44), and survival percentage (.40) within the R- group; in the R+ group, GST activity was correlated only with survival percentage (.37). In the S- and S+ groups, GST activity was not correlated with any reproductive trait. Line, diet, and their interaction did not affect UDPGT activity, and UDPGT activity was not correlated with any reproductive trait in any line x diet group. Selected lines differed in response to a toxin-containing diet as measured by its effect on reproduction and mature size. The R and S mice also differed in GST activity, but GST activity was correlated with reproductive traits only in R-line mice.

Acremonium↗
PubMed2006

Partial replacement of dietary fish oil with blends of vegetable oils (rapeseed, linseed and palm oils) in diets for European sea bass (Dicentrarchus labrax L.) over a long term growth study: effects on muscle and liver fatty acid composition and effectiveness of a fish oil finishing diet.

Triplicate groups of European sea bass (Dicentrarchus labrax L.), of initial mass 5 g, were fed one of three practical type diets for 64 weeks. The three diets differed only in the added oil and were 100% fish oil (FO; diet A), 40% FO/60% vegetable oil blend (VO; diet B) where the VO blend was rapeseed oil, linseed oil and palm oil in the ratio 10/35/15 by weight and 40% FO/60% VO blend (diet C) where the ratio was 24/24/12 by weight. After final sample collection the remaining fish were switched to a 100% FO finishing diet for a further 20 weeks. After 64 weeks fish fed 60% VO diet B had significantly lower live mass and liver mass than fish fed diets A and C although SGR, FCR and length were not different between groups. There were no differences in any of the above parameters after either 14 or 20 weeks on the FO finishing diet. Fatty acid compositions of flesh were correlated to dietary fatty acids although there was selective retention of docosahexaenoic acid (22:6n-3; DHA) regardless of dietary input. Inclusion of dietary VO resulted in significantly reduced flesh levels of DHA and eicosapentaenoic acid (20:5n-3; EPA) while 18:1n-9, 18:2n-6 and 18:3n-3 were all significantly increased in fish fed the 60% VO diets. Fatty acid compositions of liver showed broadly similar changes, as a result of dietary fatty acid composition, as was seen in flesh. However, the response of flesh and liver to feeding a FO finishing diet was different. In flesh, DHA and EPA values were not restored after 14 or 20 weeks of feeding a FO finishing diet with the values in fish fed the two 60% VO diets being around 70% of the values seen in fish fed FO throughout. Conversely, and despite liver DHA and EPA levels being reduced to only 40% of the value seen in fish fed 100% FO after 64 weeks, the levels of liver DHA and EPA were not significantly different between treatments after feeding the FO finishing diet for 14 weeks. However, a 200 g portion of sea bass flesh, after feeding the experimental diets for 64 weeks followed by a FO diet for 14 weeks, contained 1.22 and 0.95 g of EPA+DHA for fish fed FO or 60% VO, respectively. Therefore, sea bass grown for most of the production cycle using diets containing 60% VO can still contribute a significant quantity of healthy n-3 HUFA to the human consumer.

Animals↗
PubMed2002

Postprandial thermogenesis is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet in healthy, young women.

OBJECTIVE: The recent literature suggests that high-protein, low-fat diets promote a greater degree of weight loss compared to high-carbohydrate, low-fat diets, but the mechanism of this enhanced weight loss is unclear. This study compared the acute, energy-cost of meal-induced thermogenesis on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet. METHODS: Ten healthy, normal weight, non-smoking female volunteers aged 19-22 years were recruited from a campus population. Using a randomized, cross-over design, subjects consumed the high-protein and the high-carbohydrate diets for one day each, and testing was separated by a 28- or 56-day interval. Control diets were consumed for two days prior to each test day. On test day, the resting energy expenditure, the non-protein respiratory quotient and body temperature were measured following a 10-hour fast and at 2.5-hour post breakfast, lunch and dinner. Fasting blood samples were collected test day and the next morning, and complete 24-hour urine samples were collected the day of testing. RESULTS: Postprandial thermogenesis at 2.5 hours post-meal averaged about twofold higher on the high protein diet versus the high carbohydrate diet, and differences were significant after the breakfast and the dinner meals (p < 0.05). Body temperature was slightly higher on the high protein diet (p = 0.08 after the dinner meal). Changes in the respiratory quotient post-meals did not differ by diet, and there was no difference in 24-hour glomerular filtration rates by diet. Nitrogen balance was significantly greater on the high-protein diet compared to the high-carbohydrate diet (7.6 +/- 0.9 and -0.4 +/- 0.5 gN/day, p < 0.05), and at 24-hour post-intervention, fasting plasma urea nitrogen concentrations were raised on the high protein diet versus the high-carbohydrate diet (13.9 +/- 0.9 and 11.2 +/- 1.0 mg/dL respectively, p < 0.05). CONCLUSIONS: These data indicate an added energy-cost associated with high-protein, low-fat diets and may help explain the efficacy of such diets for weight loss.

Adolescent↗
PubMed2003

Nutrient intake and growth characteristics of male Sprague-Dawley rats fed AIN-93M purified diet or NIH-31 natural-ingredient diet in a chronic two-year study.

BACKGROUND AND AIMS: Daily nutrient intake and growth of male Sprague-Dawley (SD) rats fed compositionally different diets were monitored over 114 weeks to determine whether rats fed ad libitum (AL) or diet restricted (DR) followed normal growth parameters. A second objective was to evaluate the usefulness of the American Institutes of Nutrition's AIN-93M (maintenance formulation) diet for aging and DR studies. METHODS: Rats were fed NIH-31 cereal-based diet AL, or a vitamin-fortified modification of the NIH-31 diet at 10, 25, or 40% DR. Other SD rats were fed AIN-93M diet AL or 31% DR; daily nutrient intake and growth response were reported. RESULTS: At all intervals up to 36 weeks of age, rats fed AL the NIH-31 diet consumed significantly (p<0.001) more than rats fed AL the AIN-93M diet, and required more diet per unit of gain than AIN-93M AL rats. However, body weight (BW) gain in rats AL-fed the AIN-93M diet demonstrated that energy components were more efficiently metabolized than in those fed the NIH-31 diet. Whereas diet restriction decreased BW, the rate of maturation, i.e., the rate of reaching a mature BW, increased as intake level decreased. Growth response showed all growth curves were normal, but intake level effects on mature BW and maturation rate differed significantly (p<0.001). Curves for rats AL- and DR-fed the AIN-93M diets were similar to those of rats AL- and DR-fed NIH-31 diet formulations, suggesting that diets adequately met growth requirements and supported normal growth parameters of male SD rats when fed AL or DR. CONCLUSIONS: A modification in the AIN-93M energy components to reduce total calories and an evaluation of other nutrient profiles could improve its usefulness as a maintenance and aging diet.

Aging↗
PubMed2001

Diet, evolution and aging--the pathophysiologic effects of the post-agricultural inversion of the potassium-to-sodium and base-to-chloride ratios in the human diet.

Theoretically, we humans should be better adapted physiologically to the diet our ancestors were exposed to during millions of years of hominid evolution than to the diet we have been eating since the agricultural revolution a mere 10,000 years ago, and since industrialization only 200 years ago. Among the many health problems resulting from this mismatch between our genetically determined nutritional requirements and our current diet, some might be a consequence in part of the deficiency of potassium alkali salts (K-base), which are amply present in the plant foods that our ancestors ate in abundance, and the exchange of those salts for sodium chloride (NaCl), which has been incorporated copiously into the contemporary diet, which at the same time is meager in K-base-rich plant foods. Deficiency of K-base in the diet increases the net systemic acid load imposed by the diet. We know that clinically-recognized chronic metabolic acidosis has deleterious effects on the body, including growth retardation in children, decreased muscle and bone mass in adults, and kidney stone formation, and that correction of acidosis can ameliorate those conditions. Is it possible that a lifetime of eating diets that deliver evolutionarily superphysiologic loads of acid to the body contribute to the decrease in bone and muscle mass, and growth hormone secretion, which occur normally with age? That is, are contemporary humans suffering from the consequences of chronic, diet-induced low-grade systemic metabolic acidosis? Our group has shown that contemporary net acid-producing diets do indeed characteristically produce a low-grade systemic metabolic acidosis in otherwise healthy adult subjects, and that the degree of acidosis increases with age, in relation to the normally occurring age-related decline in renal functional capacity. We also found that neutralization of the diet net acid load with dietary supplements of potassium bicarbonate (KHCO3) improved calcium and phosphorus balances, reduced bone resorption rates, improved nitrogen balance, and mitigated the normally occurring age-related decline in growth hormone secretion--all without restricting dietary NaCl. Moreover, we found that co-administration of an alkalinizing salt of potassium (potassium citrate) with NaCl prevented NaCl from increasing urinary calcium excretion and bone resorption, as occurred with NaCl administration alone. Earlier studies estimated dietary acid load from the amount of animal protein in the diet, inasmuch as protein metabolism yields sulfuric acid as an end-product. In cross-cultural epidemiologic studies, Abelow found that hip fracture incidence in older women correlated with animal protein intake, and they suggested a causal relation to the acid load from protein. Those studies did not consider the effect of potential sources of base in the diet. We considered that estimating the net acid load of the diet (i. e., acid minus base) would require considering also the intake of plant foods, many of which are rich sources of K-base, or more precisely base precursors, substances like organic anions that the body metabolizes to bicarbonate. In following up the findings of Abelow et al., we found that plant food intake tended to be protective against hip fracture, and that hip fracture incidence among countries correlated inversely with the ratio of plant-to-animal food intake. These findings were confirmed in a more homogeneous population of white elderly women residents of the U.S. These findings support affirmative answers to the questions we asked above. Can we provide dietary guidelines for controlling dietary net acid loads to minimize or eliminate diet-induced and age-amplified chronic low-grade metabolic acidosis and its pathophysiological sequelae. We discuss the use of algorithms to predict the diet net acid and provide nutritionists and clinicians with relatively simple and reliable methods for determining and controlling the net acid load of the diet. A more difficult question is what level of acidosis is acceptable. We argue that any level of acidosis may be unacceptable from an evolutionarily perspective, and indeed, that a low-grade metabolic alkalosis may be the optimal acid-base state for humans.

Acid-Base Equilibrium↗
PubMed1994

Hypocaloric high-protein diet improves glucose oxidation and spares lean body mass: comparison to hypocaloric high-carbohydrate diet.

The aim of the study was to investigate the effects of two hypocaloric (800-kcal) diets on body weight reduction and composition, insulin sensitivity, and proteolysis in 25 normal glucose-tolerant obese women. The two diets had the following composition: 45% protein, 35% carbohydrate (CHO), and 20% fat (HP diet, 10 subjects), and 60% CHO, 20% protein, and 20% fat (HC diet, 15 subjects); both lasted 21 days. A euglycemic hyperinsulinemic (25 mU/kg/h) clamp lasting 150 minutes combined with indirect calorimetry was performed before and after the diet. Both diets induced a similar decrease in body weight and fat mass (FM), whereas fat-free mass (FFM) decreased only after the HC diet. 3-Methylhistidine (3-CH3-HIS) excretion was reduced by 48% after the HP diet and remained unchanged after the HC diet (P < .05). A significant correlation was found between the changes in FFM and in 3-CH3-HIS excretion after the diet (rs = .50, P < .02). Blood glucose remained unchanged, while insulin decreased in both diets. Free fatty acids (FFA) significantly increased only after the HC diet (P < .05). During the clamp period, glucose disposal and glucose oxidation significantly increased after the HP diet and significantly decreased after the HC diet. Opposite results were found when measuring lipid oxidation. In conclusion, our experience suggests that (1) a hypocaloric diet providing a high percentage of natural protein can improve insulin sensitivity; and (2) conversely, a hypocaloric high-polysaccharide-CHO diet decreases insulin sensitivity and is unable to spare muscle tissue.

Adult↗
PubMed1992

Comparison of cereal-based diet with purified diet by short-term feeding studies in rats, mice and hamsters, with emphasis on toxicity characteristics.

Animal diets used in toxicity studies are prepared either from natural ingredients (cereal-based diet) or from more refined products (purified diet). The type of diet may influence both the outcome of the study and the values obtained with the various parameters in test and control animals. To detect the parameters sensitive to changes in diet composition, short-term (4-wk) studies were conducted in rats, mice and hamsters fed either a cereal-based diet or the AIN-76A purified diet supplemented with vitamins and minerals at the highest recommended levels for each of the species used. Although the purified diet was more palatable to rats and showed a higher protein quality, growth rate and food intake were generally slightly higher with the cereal-based diet in each of the species examined. The haematological values of the two diet groups were generally comparable. On the cereal-based diet the production of faeces was considerably higher than on the purified diet and was accompanied by a higher weight of the caecum. These findings were attributed to the relatively high level and mixed composition of the fibre fraction in the cereal-based diet. Blood levels of cholesterol and phospholipids were clearly lower on the cereal-based diet than on the purified diet. Because the differences were probably due to the level and composition of the fibre fraction, they support the suggestion to replace the 5% cellulose of the AIN-76A diet by a higher level of a more composite but well defined source of dietary fibre.

Administration, Oral↗
PubMed2000

Insulin sensitivity after a reduced-fat diet and a monoene-enriched diet in subjects with elevated serum cholesterol and triglyceride concentrations.

BACKGROUND AND AIMS: To investigate the effect of a reduced-fat diet and a monoene-enriched diet (MUFA diet) on serum lipids, glucose and insulin metabolism in subjects with elevated cholesterol and triglyceride concentrations. METHODS AND RESULTS: Eighteen subjects with elevated serum cholesterol and triglyceride concentrations consumed the MUFA diet (39% of energy (E%) as fat and 21 E% monoenes) and the reduced-fat diet (34 E% fat, 16 E% monoenes) for 4 weeks according to a randomized cross-over design. Both periods were preceded by consumption of a standardized baseline diet for 2 weeks. Serum lipid and lipoprotein concentrations were determined at the beginning and end of each diet period. A frequently sampled intravenous glucose tolerance test was performed after the MUFA diet and the reduced-fat diet. Insulin sensitivity index (SI) was 40% higher after the reduced-fat diet than after the MUFA diet (2.42 +/- 0.42 vs 1.73 +/- 0.24 10(-4) min-1 U-1 ml-1, p = 0.018). This change in insulin sensitivity was seen in 13 subjects and was most evident in those who began with the MUFA diet. Compared to the baseline diet (high in saturated fat), both experimental diets lowered serum total and LDL cholesterol concentrations (6.6-6.9%, p < 0.05 and 7.4-8.0%, p < 0.05 respectively). CONCLUSIONS: Both diets were equally effective in lowering serum lipid concentrations, but the reduced-fat diet resulted in better insulin sensitivity.

Blood Glucose↗
PubMed1991

Immune parameters in male atheletes after a lacto-ovo vegetarian diet and a mixed Western diet.

The influence of a lacto-ovo vegetarian diet versus a meat-rich Western diet on in vitro measures of immune function was studied in eight male endurance athletes. Subjects consumed two different diets for 2 x 6 wk, separated by 4 wk on an ad libitum diet, in a cross-over design. Both diets consisted of 57 energy % (E%) carbohydrates, 14 E% protein and 29 E% fat. One diet was a mixed meat-rich diet (M) prepared with 69% animal protein sources, whereas the other diet (V) was a lacto-ovo vegetarian diet prepared with 82% vegetable protein sources. Blood for determination of leukocyte subpopulations and in vitro function was collected at the end of each diet period 36 h after the last training bout. Fiber content and P/S ratio of fatty acids were twice as high on the V diet as on the M diet. Training volume was similar on the two diets, and maximal aerobic capacity did not change during diet periods. The number of CD3+ (pan T-cells), CD8+ (mainly T suppressor cells), CD4+ (mainly T helper cells), CD16+ (natural killer cells), and CD14+ (monocytes) was similar after the two different diets. Similarly, proliferations of mononuclear cells after stimulation with interleukin-2 (IL-2), phytohemagglutinin, and purified derivative of tuberculin (PPD), as well as activity of natural killer cells in the unstimulated state and after stimulation with IL-2, indomethacin, and interferon-alpha (IFN-alpha), were identical after the two diet periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Safety and efficacy of long-term diet and diet plus bile acid-binding resin cholesterol-lowering therapy in 73 children heterozygous for familial hypercholesterolemia.

Our specific aim was to examine the efficacy and safety of long-term cholesterol-lowering diet and bile acid-binding resin therapy in 73 children heterozygous for familial hypercholesterolemia (FH). We prospectively followed accretion of height and weight in 40 FH children for 5.8 years on diet alone and in 33 FH children for 4.3 years on diet and bile acid-binding resins (8 to 20 g/d). In 67 of these 73 children, sequential data on plasma cholesterol lowering was obtained, including 32 children on diet plus bile acid-binding resins and 35 on diet alone. For all 73 children, median age, sex, and race-specific percentiles for height and weight at entry were 50 and 50, respectively, and 5.7 years later, were unchanged at 50 and 50. Initial and final percentiles for height (r = .76, P less than .001) and weight (r = .70, P less than .001) were closely correlated. Percentile distributions for height and weight at entry into the study did not differ from those at the end of follow-up (P greater than .1), in both the 40 FH children on diet alone and the 33 on diet plus bile acid-binding resins. Tracking of height and weight did not differ in the 40 children on diet alone v the 33 on diet plus bile acid-binding resins (P greater than .1). During 6 years of follow-up there were no significant differences in the percentage of serial, postbaseline measurements for height which were either less than or greater than or equal to baseline percentiles, comparing 40 FH children on diet alone, 33 FH children on diet plus resin, and 39 normal children (on ad libitum diet). FH children on diet or plus resin had a smaller percentage of weight measurements equal to or more than baseline percentiles than normals on follow-up (P less than .01), probably reflecting restriction of total fat intake to less than 35% of calories. On diet alone, 32 FH children had total plasma cholesterol of 307 +/- 8 mg/dL (mean +/- SE); bile acid-binding resins were added to diet in these children at an average age of 11.5 years, with this regimen maintained for 4.6 +/- 0.4 years, leading to a mean reduction in total plasma cholesterol of 12.5% +/- 2% beyond the effects of diet alone (P less than .01).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1999

Effects of an omnivorous diet compared with a lactoovovegetarian diet on resistance-training-induced changes in body composition and skeletal muscle in older men.

BACKGROUND: Very limited data suggest that meat consumption by older people may promote skeletal muscle hypertrophy in response to resistance training (RT). OBJECTIVE: The objective of this study was to assess whether the consumption of an omnivorous (meat-containing) diet would influence RT-induced changes in whole-body composition and skeletal muscle size in older men compared with a lactoovovegetarian (LOV) (meat-free) diet. DESIGN: Nineteen men aged 51-69 y participated in the study. During a 12-wk period of RT, 9 men consumed their habitual omnivorous diets, which provided approximately 50% of total dietary protein from meat sources (beef, poultry, pork, and fish) (mixed-diet group). Another 10 men were counseled to self-select an LOV diet (LOV-diet group). RESULTS: Maximal strength of the upper- and lower-body muscle groups that were exercised during RT increased by 10-38% (P < 0.001), independent of diet. The RT-induced changes in whole-body composition and skeletal muscle size differed significantly between the mixed- and LOV-diet groups (time-by-group interactions, P < 0. 05). With RT, whole-body density, fat-free mass, and whole-body muscle mass increased in the mixed diet group but decreased in the LOV- diet group. Type II muscle fiber area of the vastus lateralis muscle increased with RT for all men combined (P < 0.01), and the increase tended to be greater in the mixed-diet group (16.2 +/- 4.4 %) than in the LOV diet group (7.3 +/- 5.1%). Type I fiber area was unchanged with RT in both diet groups. CONCLUSION: Consumption of a meat-containing diet contributed to greater gains in fat-free mass and skeletal muscle mass with RT in older men than did an LOV diet.

Aged↗
PubMed1985

Lipid peroxidation of liver microsome membranes induced by choline-deficient diets and its relationship to the diet-induced promotion of the induction of gamma-glutamyltranspeptidase-positive foci.

The effects of varying the type of dietary fat in the choline-deficient (CD) diet on the development of gamma-glutamyltranspeptidase (GGT)-positive foci in the liver of carcinogen-treated rats were investigated, and the results were correlated with the extent of membrane lipid peroxidation induced by the diets. Male Sprague Dawley rats were initiated with a single dose of diethylnitrosamine. Thereafter, groups of rats were fed choline-supplemented or CD diets in which the amount of saturated fat was varied by using hydrogenated vegetable oil (Primex) and corn oil (CO), either alone or in combination. The number and size of GGT-positive foci induced by the CD diet with CO as the sole source of fat were larger than those induced by the diet containing mixtures of Primex and CO. The CD diet with Primex alone was the least effective in inducing GGT-positive foci. Peroxidation of liver microsomal membrane lipids in rats fed regular CD or CD:CO diets was examined by determining the formation of conjugated dienes. The generation of diene conjugate in rats fed a CD:CO diet was evident after 2 days of the diet feeding, and the levels increased at 1 and 2 weeks. No significant diene conjugate was demonstrated in rats fed a regular CD diet for 2 days. However, after 1 and 2 weeks, there was generation of diene conjugate, the levels of which were lower in rats fed the CD diet than those on a CD:CO diet. Addition of an antioxidant, 0.25% butylated hydroxytoluene, to both CD and CD:CO diets abolished the generation of diene conjugate in rat liver microsomal membranes and markedly inhibited the promotion of GGT-positive foci in the liver of diethylnitrosamine-initiated rats. The results suggest that membrane lipid peroxidation in the liver may be related to the promotion of the induction of GGT-positive foci by a CD diet. The enhanced promotion by the inclusion of a higher level of polyunsaturated fat in the diet may be, in part, due to its greater susceptibility to peroxidation.

Animals↗
PubMed2000

Diet high in monounsaturated fat does not have a different effect on arterial elasticity than a low-fat, high-carbohydrate diet.

OBJECTIVE: To compare the effects of a modified-fat diet high in monounsaturated fat, and a low-fat/high-carbohydrate diet on arterial elasticity. DESIGN: Randomized crossover design; each diet period was 1 month and a 2-week wash out period occurred in between. SUBJECTS/SETTING: Thirty healthy, free-living, nonsmoking men and women were recruited from the Melbourne, Australia, metropolitan region of Australia. Men were aged 35 to 55 years and postmenopausal women were aged 50 to 60 years and were not taking hormone replacement therapy. Twenty-eight subjects completed the study. INTERVENTION: Two diets of equal energy value: a modified-fat diet and a low-fat/high-carbohydrate diet; the modified-fat diet had 3 times more energy from monounsaturated fat. MAIN OUTCOME MEASURES: Arterial elasticity and serum lipoprotein concentrations. STATISTICAL ANALYSIS: The general linear model was used to investigate overall effect and any carryover or order effects. Paired t test and the general linear model were used to compare the results from the 2 diet periods. RESULTS: High-density lipoprotein cholesterol concentration was significantly higher on the modified-fat diet than on the low-fat/low-carbohydrate diet. Arterial elasticity and concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were not significantly different on the 2 diets. APPLICATIONS/CONCLUSIONS: There is no evidence to favor a diet high in monounsaturated fat over a low-fat/high-carbohydrate diet because of an effect on arterial elasticity. Other changes in diet may be needed to cause a beneficial effect on arterial elasticity.

Adult↗