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Dietary Composition (dietary + composition)

Distribution by Scientific Domains

Earth and Environmental Science	53%
Medical Sciences	40%

Selected Abstracts

Dietary Composition and Weight Loss: Can We Individualize Dietary Prescriptions According to Insulin Sensitivity or Secretion Status?

NUTRITION REVIEWS, Issue 10 2006
Anastassios G. Pittas MD
There is considerable uncertainty over whether any one dietary pattern broadly facilitates weight loss or maintenance of weight loss, and current dietary guidelines recommend a spectrum of dietary composition for the general population. However, emerging evidence suggests that specific dietary compositions may work better for identifiable groups of overweight/obese individuals based on their individual metabolic status. In particular, characteristics of insulin dynamics, such as insulin sensitivity or insulin secretion status, may interact with diets that vary in macronutrient composition to influence the weight loss achieved with a hypocaloric diet. [source]

Assessing the Potential Impact of Cane Toads on Australian Snakes

CONSERVATION BIOLOGY, Issue 6 2003
BEN L. PHILLIPS
Anecdotal reports suggest that the invasion of toads into an area is followed by dramatic declines in the abundance of terrestrial native frog-eating predators, but quantitative studies have been restricted to nonpredator taxa or aquatic predators and have generally reported minimal impacts. Will toads substantially affect Australian snakes? Based on geographic distributions and dietary composition, we identified 49 snake taxa as potentially at risk from toads. The impact of these feral prey also depends on the snakes' ability to survive after ingesting toad toxins. Based on decrements in locomotor (swimming) performance after ingesting toxin, we estimate the LD50 of toad toxins for 10 of the at-risk snake species. Most species exhibited a similar low ability to tolerate toad toxins. Based on head widths relative to sizes of toads, we calculate that 7 of the 10 taxa could easily ingest a fatal dose of toxin in a single meal. The exceptions were two colubrid taxa (keelbacks [ Tropidonophis mairii] and slatey-grey snakes [ Stegonotus cucullatus]) with much higher resistance to toad toxins (up to 85-fold) and one elapid (swamp snakes [ Hemiaspis signata]) with low resistance but a small relative head size and thus low maximum prey size. Overall, our analysis suggests that cane toads threaten populations of approximately 30% of terrestrial Australian snake species. Resumen: Los sapos (Bufo marinus) son anuros grandes muy tóxicos que fueron introducidos a Australia en 1937. Reportes anecdóticos sugieren que la invasión de sapos a un área es seguida de declinaciones dramáticas en la abundancia de depredadores terrestres nativos que se alimentan de ranas, pero los estudios cuantitativos se han restringido a taxones no depredadores o a depredadores acuáticos y generalmente han indicado impactos mínimos. ¿Los sapos afectarán sustancialmente a las serpientes australianas? Basado en la distribución geográfica y la composición de la dieta, identificamos 49 taxones de serpientes como potencialmente en riesgo por los sapos. El impacto de estas presas también depende de la habilidad de las serpientes para sobrevivir después de ingerir toxinas, estimamos la LD50 de toxinas de sapo para 10 de las especies de serpientes "en riesgo." La mayoría de las especies presentaron la misma poca habilidad para tolerar toxinas de sapo. Tomando en cuenta la anchura del cráneo en relación al tamaño de los sapos, calculamos que 7 de las 10 especies podrían fácilmente ingerir una dosis letal en una sola comida. Las excepciones fueron dos taxones de colúbridos (Tropidonophis mairii y Stegonotus cucullatus) con mucha más resistencia (hasta 85 veces más) a toxinas de sapos y un elápido (Hemiaspis signata) con resistencia baja pero de tamaño cefálico relativamente pequeño (y por lo tanto, tamaño máximo de presa pequeño). En general, nuestro análisis sugiere que los sapos amenazan a 30% de las poblaciones de especies de serpientes terrestres de Australia aproximadamente. [source]

Size-related shifts in dietary composition of Centropomus parallelus (Perciformes: Centropomidae) in an estuarine ecosystem of the southeastern coast of Brazil

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2009
R. Feltrin Contente
Summary Size-related and seasonal evaluation of the dietary composition of fat snook (Centropomus parallelus Poey 1860) in the upper sector of an estuary of the southeastern coast of Brazil were carried out based on stomach analyses of specimens ranging from 40 to 170 mm standard length. Results reveal that C. parallelus is a carnivorous species feeding mainly on benthic crustaceans. Relatively high stomach replenishment suggests that this environment is an important feeding ground for fat snook juveniles. Multivariate analyses indicated that predator size effect is significantly more important than seasonal variation in determining dietary composition. Predator length was associated with increased consumption of palaemonid shrimps (Macrobrachium spp.) and grapsid crabs, and decreased foraging on tanaids (Kalliapseudes schubarti), thus showing a preference shift from smaller to larger prey. Predator length was also positively associated with an increase in the stomach repletion index. Additionally, allometric growth of both gape and head were consistently correlated with this ontogenetic dietary transition, suggesting that such changes might be related to an individual's ability to capture and consume larger, more elusive prey. The digestive tube is short and grows isometrically, which is in accordance with the carnivorous habit of this estuarine fish and its maintenance through ontogeny. [source]

Influence of dietary composition on growth and energy reserves in tench (Tinca tinca)

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2001
N. De Pedro
The effects of different protein, lipid and carbohydrate diets on growth and energy storage in tench, Tinca tinca L., were studied. Over a 2-month period fish were fed four different diets: control, protein-enriched, carbohydrate-enriched and lipid-enriched. The best growth rates were obtained with the control and protein-enriched diets; the carbohydrate diet produced the worst results (lowest specific growth rate, weight gain, nutritional index and hepatosomatic index). These results suggest that it is not advisable to reduce dietary fish protein below 35%, and that it is not possible to obtain a protein-sparing effect of either lipids or carbohydrates, at least in our experimental conditions. The high-protein diet resulted in the storage of energy excess as muscle proteins and hepatic glycogen. Tench fed the high-carbohydrate diet stored carbohydrates as muscle glycogen and reduced plasma triglycerides. Finally, both liver and muscle lipid content were in positive correlation to dietary lipid. [source]

The effect of advice to walk 2000 extra steps daily on food intake

JOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 4 2006
A.-A. Koulouri
Abstract Background, It is currently unclear how physical activity and diet interact within the ranges of activity seen in the general population. This study aimed to establish whether a small, acute, increase in physical activity would lead to compensatory change in energy intake and nutrient balance, and to provide power analysis data for future research in this field. Method, Twelve participants were studied over 7 days of habitual activity and 2 weeks after instruction to increase physical activity by 2000 steps per day. Physical activity was assessed using a diary, the ,activPAL' activity monitor and a pedometer. Dietary analyses from prospective food diaries were compared between the first and third weeks. Results, Participants increased step-counts (+2600 steps per day, P = 0.008) and estimated energy expenditure (+300,1000 kJ day,1, P = 0.002) but did not significantly change their energy intake, dietary composition or number of meals per day. From reverse power analysis 38 participants would be needed to exclude a change in energy intake of 400 kJ day,1 with 90% power at P < 0.05; 400 kJ day,1 would compensate for a 2000 steps per day increase in physical activity. Conclusion, These results did not demonstrate any compensatory increase in food consumption when physical activity was increased by walking an average of 2600 additional steps per day. Power analysis indicates that a larger study (n = 38) will be necessary to exclude such an effect with confidence. [source]

Lifestyle intervention for prevention of diabetes: determinants of success for future implementation

NUTRITION REVIEWS, Issue 3 2009
Cheryl Roumen
Lifestyle interventions are reported to reduce the risk of type 2 diabetes in high-risk individuals after mid- and long-term follow-up. Information on determinants of intervention outcome and adherence and the mechanisms underlying diabetes progression are valuable for a more targeted implementation. Weight loss seems a major determinant of diabetes risk reduction, whereas physical activity and dietary composition may contribute independently. Body composition and genetic variation may also affect the response to intervention. Lifestyle interventions are cost-effective and should be optimized to increase adherence and compliance, especially for individuals in the high-risk group with a low socioeconomic status, so that public health policy can introduce targeted implementation programs nationwide. The aims of this review are to summarize the mid- and long-term effects of lifestyle interventions on impaired glucose tolerance and type 2 diabetes mellitus and to provide determinants of intervention outcome and adherence, which can be used for future implementation of lifestyle interventions. [source]

Impact of diet and adiposity on circulating levels of sex hormone-binding globulin and androgens

NUTRITION REVIEWS, Issue 9 2008
Anne-Sophie Morisset
This review summarizes studies on the effect of various diets on circulating androgen levels and sex hormone-binding globulin (SHBG). Reduced caloric intake leading to significant weight loss increases SHBG levels regardless of diet composition, particularly in women. Cross-sectional studies show that dietary composition is generally not associated with SHBG levels independent of obesity level. No clear conclusion can be reached regarding the effect of various eating habits or dietary composition on circulating androgens. The evidence indicates that dietary effects on circulating SHBG, and possibly androgens, can be expected if body weight or fatness and/or insulin homeostasis are modulated. [source]

Dietary Composition and Weight Loss: Can We Individualize Dietary Prescriptions According to Insulin Sensitivity or Secretion Status?

Linear models to predict the digestible lipid content of fish diets

AQUACULTURE NUTRITION, Issue 5 2009
J. SALES
Abstract Values for the digestible contents of nutrients in diets and feed ingredients are of utmost importance in nutritional strategies for fish. Prediction from dietary composition would eliminate lengthy, tedious and demanding digestibility experiments with fish. Apparent digestible lipid (DL) content [range 7.6,353.4 g kg,1 dry matter (DM)] in compound diets can be predicted with high accuracy (n = 610; studies =127; fish species = 34; R2 = 0.9515; RMSE = 16.9504) from dietary crude lipid (CL) content (range 12.0,388.7 g kg,1 DM) by the linear regression equation DL =,2.7303 + 0.9123 CL. Validation of this equation against 65 values from 15 independent studies presented R2 and mean prediction error (MPE) values of 0.9947 and 0.0671, respectively. The corresponding equation for 37 individual feed ingredients evaluated in 24 studies with 18 fish species (n = 180) was found to be DL = ,1.5824 + 0.8654 CL (R2 = 0.9717; RMSE = 8.3765). However, validation of the latter is currently hampered by a lack of independent values. [source]

Growth performance, feed utilization and body composition of Dentex dentex fed on different macronutrient combinations

AQUACULTURE RESEARCH, Issue 1 2009
Amalia Pérez-Jiménez
Abstract Determining an adequate macronutrient balance is essential to guarantee the production success. As protein is the limiting component for fish food, the utilization of lipids or carbohydrates as partial substitutes of this nutrient is a challenge to improve its use. In order to get an approximation of the maximum levels of utilization for carbohydrates and/or lipids and determine the most adequate macronutrient to partly replace protein as the main energy source of diets for dentex (91.7 ± 1.4 g mean weight), four experimental diets with different protein:lipid:carbohydrate percentages (43/16/28, 43/24/4, 38/19/28 and 38/24/13) were tested for 13 weeks. The results indicated the possibility of using 38% of dietary protein without affecting growth performance, under the experimental conditions. There were no differences among the four diets either in most of the nutritive utilization indicators or in the body composition and haematological parameters. The influence of dietary composition was only observed in the feed intake, being higher with more dietary carbohydrates, and the hepatosomatic index and protein efficiency ratio, showing more elevated values in diets with a higher lipid level. The dentex capacity of using both carbohydrates and lipids efficiently to obtain the necessary energy for its correct growth, as well as to compensate the energetic ,vacuum' caused by the dietary protein reduction, under the assayed conditions, was confirmed. [source]

Influence of selected factors on the dietary compositions of three targeted and co-occurring temperate species of reef fishes: implications for food partitioning

JOURNAL OF FISH BIOLOGY, Issue 6 2010
M. E. Platell
The dietary compositions of three medium to large targeted fish species, which co-occur over reefs in temperate waters of south-western Australia, were determined. These data were then used to ascertain statistically the extent to which body size, season and habitat influence the diets of these species and the degree to which food resources were partitioned among and within those species, and thus reduced the potential of interspecific and intraspecific competition. On the west coast, Bodianus frenchii (Labridae) and Epinephelides armatus (Serranidae) spent their whole life over prominent limestone reefs, as did Glaucosoma hebraicum (Glaucosomatidae) in all but juvenile life, when it lived over low-relief, limestone substrata. The dietary composition of each species changed with increasing body size, which, in G. hebraicum, was particularly pronounced at c. 300 mm total length (LT) and therefore at the size when this species shifts habitat. When the three species co-occurred over the same reefs, their dietary compositions were significantly different, with that of B. frenchii being by far the most discrete, reflecting a far greater contribution by sedentary taxa. Thus, the diet of B. frenchii was distinguished from those of the other two species in containing substantial volumes of bivalve and gastropod molluscs and echinoid echinoderms and essentially no teleosts. Although the diets of G. hebraicum and particularly E. armatus were dominated by teleosts, and especially for larger individuals, the former species ingested greater volumes of cephalopods and small crustaceans. The pointed jaws of B. frenchii, with their forwardly directed and interlocking anterior incisors, are ideally adapted for biting and retaining their invertebrate prey, which are attached to or reside within reef crevices. In contrast, the mouths of G. hebraicum and E. armatus are broader and rounder and contain numerous small, slender and inward-pointing teeth. These teeth, in conjunction with prominent backward-curved canines in E. armatus, facilitate the capture and retention of fish prey. Observations in situ indicate that G. hebraicum is a suction feeder, while E. armatus is predominantly a ram feeder. Although reef environments on the west and south coasts differ, the diet of B. frenchii on these coasts differed only slightly. Interspecific differences in diet, combined with size-related changes in dietary compositions and the occupation of different habitats by juvenile and adult G. hebraicum, reduce the potential for competition for food resources among and within B. frenchii, G. hebraicum and E. armatus and thus helps facilitate the coexistence of these species which historically have been abundant over reefs in south-western Australia. [source]

Dietary Composition and Weight Loss: Can We Individualize Dietary Prescriptions According to Insulin Sensitivity or Secretion Status?

Effects of varying dietary compositions using common feed ingredients on growth and feed efficiency of pond-raised channel catfish Ictalurus punctatus (Rafinesque)

AQUACULTURE RESEARCH, Issue 8 2010
Menghe H Li
Abstract Two experiments were conducted to evaluate various ingredient combinations in a 28% or 32% protein diet for optimum performance of channel catfish Ictalurus punctatus. All diets contained soybean meal and corn, but with or without cottonseed meal, wheat middlings or fish meal (FM). Channel catfish fingerlings were stocked into 0.04 ha earthen ponds at 18 530 fish ha,1. Fish were fed one of eight diets once daily to apparent satiation for two growing seasons. Results demonstrated that the dietary ingredient composition used had significant effects on fish performance, but magnitude of differences was relatively small. Overall, diets containing FM resulted in greater weight gain (Experiments 1 and 2) and lower feed conversion ratio (Experiment 1) than fish fed all-plant diets. However, certain combinations of plant ingredients provided the similar fish growth as some diets containing FM. There were no significant differences in weight gain between fish fed soybean meal,corn or soybean meal,corn,wheat middlings-based diets with cottonseed meal or FM. The use of wheat middlings in the diet had no significant effects on fish production characteristics. [source]