Archivio per novembre, 2012

Snap 2012-11-18 at 10.53

 

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FAT METABOLISM DURING EXERCISE

Pubblicato: novembre 17, 2012 in health, nutrition, training

Edward F. Coyle, Ph.D.
Professor, Department of Kinesiology and Health Education
The University of Texas at Austin
Austin,Texas
Member, GSSI Sports Medicine Review Board

KEY POINTS
1. People store large amounts of body fat in the form of triglycerides within fat (adipose) tissue as well as within muscle fibers
(intramuscular triglycerides).When compared to carbohydrate stored as muscle glycogen, these fat stores are mobilized and oxidized
at relatively slow rates during exercise.
2. As exercise progresses from low to moderate intensity, e.g., 25-65% VO2max, the rate of fatty acid mobilization from adipose
tissue into blood plasma declines, whereas the rate of total fat oxidation increases due to a relatively large use of intramuscular
triglycerides. Intramuscular triglycerides also account for the characteristic increase in fat oxidation as a result of habitual
endurance-training programs.
3. Dietary carbohydrate intake has a large influence on fat mobilization and oxidation during exercise; when dietary carbohydrate
produces sufficient carbohydrate reserves in the body, carbohydrate becomes the preferred fuel during exercise. This is especially
important during intense exercise because only carbohydrate(not fat) can be mobilized and oxidized rapidly enough to
meet the energy requirements for intense muscular contractions.

Snap 2012-11-17 at 18.22

Eliminating Carbohydrate From theDiet of Endurance-Trained People

Recognizing that even smallamounts of dietary carbohydrate mightinfluence fat metabolism, a study was
performed by Phinney et al. (1983) duringwhich they fed endurance-trained
men a high-fat diet containing almostno carbohydrate, i.e., less than 20 g/d
for 4 wk. This diet reduced the concentrationof muscle glycogen by one-half,
and it markedly increased fat oxidation
during exercise at moderate intensitiesof 62-64% VO2max. However, the dietdid not increase the length of time that
exercise could be maintained, despitethe fact that fat oxidation was increased.Furthermore, these subjects were notcapable of exercising at higher intensities.
Even with this extreme diet, itseems clear that fat oxidation cannot beincreased sufficiently to fully replace
muscle glycogen as a source of energyfor intense exercise. Furthermore, high
fat intake is a risk factor for cardiovascularand other diseases.
Snap 2012-11-17 at 18.22Snap 2012-11-17 at 18.23Snap 2012-11-17 at 18.23

 

SUMMARY

People store large amounts of bodyfat in the form of triglyceride within
adipose tissue as well as within musclefibers. These stores must be mobilized
into FFA and transported to musclemitochondria for oxidation during exercise.
Fatty acids from adipose tissueare mobilized into plasma and carried
by albumin to muscle for oxidation. Asexercise intensity increases from low
(25% VO2max) to moderate (65%VO2max) to high (85% VO2max), plasma
FFA mobilization declines.However, total fat oxidation increases
when intensity increases from 25% to
65% VO2max, due to oxidation of intramusculartriglycerides, which provide
about one-half of the fat for oxidation.Endurance training characteristically
increases fat oxidation during moderateintensity exercise by accelerating the
oxidation of intramuscular triglyceridewithout increasing the mobilization or
oxidation of plasma FFA. Similarly,during low-intensity exercise with little
intramuscular triglyceride oxidation,the increased fat oxidation of trained
people does not appear to be caused byincreased mobilization of FFA into
plasma, but rather by a greater rate ofoxidation of the FFA removed from the
blood during exercise. Therefore, itseems that untrained people have
greater abilities to mobilize FFA thanthey do to oxidize it when they exercise
in the fasted state. Carbohydrate ingestionduring the hours before exercise,even in relatively small amounts,
reduces fat oxidation during exercise
largely through the action of insulin.Fat supplementation and special dietshave limited ability to increase fat oxidation
in people, especially duringsport competitions. Therefore, fat frombody stores and/or dietary supplementation
cannot adequately replace muscleglycogen and blood glucose as fuels for intense exercise.

References
Arner, P., E. Kriegholm, P. Engfeldt, and J. Bolinder (1990). Adrenergic regulation of lipolysis in situ at rest and during exercise. J. Clin. In vest.85:893-898.
Ballor, D.L., J.P. McCarthy and E.J. Wilterdink (1990). Exercise intensity does not affect the composition of diet- and exercise-induced body mass loss. Am J Clin Nutr 5.1:142-146.
Costill, D.F., E.F. Coyle, G. Dalsky, W. Evans, W. Fink, and D. Hoopes. (1977). Effects of elevated plasma FFA and insulin on muscle glycogen usage during exercise. J. Appl. Physiol. 43:
695-699.
Coyle, E.F., A.R. Coggan, M.K. Hemmert, R.C. Lowe, and T.J. Walters (1985). Substrate usage during prolonged exercise following a preexercise meal. J. Appl. Physiol.59:429-433.
Essen, B., L. Hagenfeldt, and L. Kaijser (1977). Utilization of blood-borne and intramuscular substrates during continuous and intermittent exercise in man. J. Physiol.265:489-506.
Hurley, B.F., P.M. Nemeth, W.H. Martin, J.M. Hagberg, G.P. Dalsky, and J.O. Holloszy (1986). Muscle triglyceride utilization during exercise: effect of training. J. Appl. Physiol.60:562-567.
Issekutz, B., and B. Paul (1968). Intramuscular energy sources in exercising normal and pancreatectomized dogs. Am. J . Physiol.215(1):197-204.
Jensen, M.D., M. Caruso, V. Heiling, and J.M Miles (1989). Insulin regulation of lypolysis in nondiabetic and IDDM subjects. Diabetes 38:1595-1601.
Jeukendrup, A.E., W.H.M. Saris, P. Schrauwen, F. Brouns, and A.J.M. Wagenmakers (1995). Metabolic availability of medium-chaim triglycerides coingested with carbohydrate during prolonged
exercise. J. Appl. Physiol.79: 756-762.
Kiens, B., B. Essen-Gustavsson, N.J. Christensen, and B. Saltin (1993). Skeletal muscle substrate utilization during submaximal exercise in man: effect of endurance training. J. Physiol.
(London) 469: 459-478.
Klein, S., E.F. Coyle, and R.R. Wolfe (1994). Fat metabolism during low-intensity exercise in endurance-trained and untrained men. Am. J . Physiol. 267 (Endocrinol. Metab E. 93304)-:E940.
Mackie, B.G., G.A. Dudley, H. Kaciuba-Uscilko, and R.L. Terjung (1980). Uptake of chylomicron triglycerides by contracting skeletal muscle in rats. J. Appl. Physiol.49: 851-855.
Martin, W.H., G.P. Dalsky, B.F. Hurley, D.E. Matthews, D.M. Bier, J.O. Hagberg, and J.O. Holloszy (1993). Effect of endurance training on plasma FFA turnover and oxidation during exercise.
Am. J . Physiol. 265 (Endocrinol. Metab E. 72088)-:E714.
Montain, S.J., M.K. Hopper, A.R. Coggan, and E.F. Coyle (1991). Exercise metabolism at different time intervals after a meal. J. Appl. Physiol.70(2):882-888.
Morgan, T.E., F.A. Short, and L.A. Cobb (1969). Effect of long-term exercise on skeletal muscle lipid composition. Am. J . Physiol.216:82-86.
Oscai, L.B., D.A. Essig, and W.K. Palmer (1990). Lipase regulation of muscle triglyceride hydrolysis. J. Appl. Physiol.69: 1571-1577.
Phinney, S.D., Bistrian, W.J. Evans, E. Gervino, and G.L. Blackburn (1983). The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise
capability with reduced carbohydrate oxidation. Metabolism 32:769-776.
Romijn, J.A., E.F. Coyle, L.S. Sidossis, A. Gastaldelli, J.F. Horowitz, E. Endert, and R.R. Wolfe (1993). Regulation of endogenous fat and carbohydrate metabolism in relation to exercise
intensity and duration. Am. J . Physiol. 265 (Endocrinol. Metab :E.3 2880)-E391.
Simonsen, J.C., W.M. Sherman, D.R. Lamb, A.R. Dernbach, J.A. Doyle, and R. Strauss (1991). Dietary carbohydrate, muscle glycogen, and power during rowing training. J. Appl. Physiol.
70: 1500-1505.
Terjung, R. (1995). Muscle adaptations to aerobic training. Sports Sci. Exc han8g(5e4), Number 1.
Terjung,R.L. B. G. Mackie, G.A. Dudley, and H. Kaciuba-Uscilko (1983). Influence of exercise on chylomicron triacylglycerol metabolism: plasma turnover and muscle uptake. Med. Sci.
Sports Exer 1c.5: 340-347.
Turcotte, L.P., B. Kiens and E.A. Richter (1991). Saturation kinetics of palmitate uptake in perfused skeletal muscle. FEBS Letter s279: 327-329.
Vukovich, M.D., D.L. Costill, M.S. Hickey, S.W. Trappe, K.J. Cole, and W.J. Fink (1993). Effect of fat emulsion infusion and fat feeding on muscle glycogen utilization during cycle exercise.
J. Appl. Physiol. 75: 1513-1518.
Wolfe, R.R., S. Klein, F. Carraro, and J.-M. Weber (1990). Role of triglyceride-fatty acid cycle in controlling fat metbolism in humans during and after exercise. Am. J . Physiol. 258
(Endocrinol. Metab . 2:E1)382-E389.
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SportFlowing

Pubblicato: novembre 16, 2012 in general, training

Directly from Csíkszentmihályi’swords

57024 389x292

 

Flow is the mental state of operation in which a person performing an activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity.

images

 

In your daily activities follow the flow….

Some graphics in less or more detail on the concept

imagesCAB09VK8imagesCACRQAA1 imagesCAUTYF79

 

Flow in the Sport

The experience of flow is still one of the least understood phenomena in sport. And yet it is one of the richest, most memorable experiences an athlete will ever know.Some call it a natural “”high.”” Others refer to it as being “”in a zone.”” Whatever it’s called, flow is an elusive and very sought-after psychological state that athletes, coaches, and sport psychologists have tried to understand, harness, and employ to their benefit since Mihaly Csikszentmihalyi first coined the term back in the early 1970s.

Read More buying this book:

51baND7n3CL BO2,204,203,200 PIsitb-sticker-arrow-click,TopRight,35,-76 AA300 SH20 OU01

 

http://www.humankinetics.com/products/all-products/flow-in-sports

Dimensions of the Flow Experience

When a person’s skill matches the challenges of the situation the
quality of experience improves noticeably. Also, an activity that has relatively clear
goals and that provides rather quick and unambiguous feedback is a likely candidate
for flow (Csikszentmihalyi 1988). This allows the person who is involved in the activity
to know what needs to be done, and how they are doing. A game without rules or a
way to assess performance is impossible to play (Csikszentmihalyi 1988).
People who have experienced flow also mention that they are completely
immersed in the activity. All of their attention is so focused on the task at hand, that
they do not have anything left to become distracted with (Csikszentmihalyi 1988).
Also, there is a sense of control over the outcome of the activity, a distortion of time, a
loss of the awareness of self and everyday problems, and a feeling of transcendence, or
oneness with the activity (Csikszentmihalyi 1988).
When goals are clear, above-average challenges are matched to skills, and when
there is accurate feedback, a person becomes involved in the activity. When this occurs,
all attention is focused on what needs to be done. There is no room for anything else to
enter the conscious, or for the self to become self-conscious – the worry of how we look
to others. This is the negentropic experience that is called flow. Because it is so
rewarding, people will strive to replicate it as much as possible. From this tendency to
want to repeat a flow experience, emerges the teleonomy of the self. Also, this leads to
a selective process by the consciousness to seek out those experiences that provide
flow. This state of optimal experience is one that humans have developed “in order to
recognize patterns of action that are worth preserving and transmitting over time”
(Csikszentmihalyi 1988, p. 34).
The last stage of the flow experience involves the transforming the entirety of
one’s life into a single flow activity, with unified goals that provide a constant purpose
(Csikszentmihalyi 1991). Living one’s life from flow experience to flow experience may
be enjoyable during the actual flow experience, but one will probably still not be
assured of optimal experience. If enjoyment is not linked to an overall meaning or
purpose in life, one is still subject to psychic entropy, or chaos (Csikszentmihalyi 1991).
If a person invests all of her psychic energy to reach this goal, all the parts of
consciousness, as well as all actions and feelings, will be in harmony with each other.
These isolated flow experiences will mesh into activities that “make sense” in the
present, as well as the in view of the past and future. By doing this, it is possible to give
meaning to one’s entire life, and therefore achieve, as close is as humanly possible,
optimal experience (Csikszentmihalyi 1991).

Applications of Flow

Csikszentmihalyi began his research on flow out of sheer curiosity; in this sense
it was “pure” research (Csikszentmihalyi 1988). However, because so much time is
spent in the school and the work environment, these are the places of the most urgent
applications of flow (Csikszentmihalyi 1975). Often times, people are either bored or in
a high state of anxiety in these situations. One the first areas flow was practically
applied was education. In an unpublished doctoral dissertation out of the University of
Chicago, Mayers (1978), it was shown that the amount of enjoyment a student received
form a class was a better indicator of their final grade than scholastic achievement or
the student’s aptitude (Csikszentmihalyi 1988). From the teacher’s side of things, it was
shown by Phlihal (1982), another unpublished doctoral dissertation, that the more
attentive the students are in class, the greater the enjoyment a teacher receives from
teaching them (Csikszentmihalyi 1988).
Through personal communication with I. Vitanyi and M. Sagi, Csikszentmihalyi
(1988) learned that studies of industrial factory workers in Hungary found that bored
workers had a tendency to take unreasonable risks, and those who felt anxious
complained of imaginary illnesses. Also, those workers who enjoyed their jobs were
more personally satisfied and contributed more to the goals of the factory.
One of the largest areas flow theory has been utilized is in the context of play
and leisure (Csikszentmihalyi 1988). However, it has also permeated the field of
leadership and management training seminars (Csikszentmihalyi 1988) and in
determining consumer behavior (Bloch 1986). Csikszentmihalyi (1988) also describes
how flow has been applied in psychotherapy, in anti-drug campaigns, ways to deal with
juvenile delinquency, crime, vandalism, and social deviance. Other applications include
advertising research, the redesign of museums, and Davis (1988) wrote a book on how
to help audiences become involved in the theater. Csikszentmihalyi concludes that
anywhere the quality of human experience is an issue, flow becomes relevant.

Critique and Evaluation of Flow

Some critics argue that the flow theory is too much
of a Western concept, and that it applies more to men than women. By this, they imply
that it is too active and goal directed to represent a panhuman trait (Csikszentmihalyi
1988). Another early criticism is that it was too ethereal, bordering on mystical, for it to
be considered something worthy to be studied in the social sciences (Csikszentmihalyi
1988). Also, the flow theory as discussed in Csikszentmihalyi’s book, Flow – The
Psychology of Optimal Experience, only gives indicators of the flow experience, but does
not explicitly explain how to achieve this state.
Applying Littlejohn’s five criteria of scope, appropriateness, heuristic value,
validity, and parsimony, I will evaluate this theory, as well as expand on these criticisms
of the theory.

read more……

http://myweb.stedwards.edu/michaelo/2349/paper1/ConceptOfFlow.pdf

http://www.waltercarl.neu.edu/PDFs/flowpaper.pdf

http://academic.udayton.edu/jackbauer/CsikFlow.pdf

imagesCA81GR39

Riding on my City Bike around CapoPescara’s hydro-springs….. it’s often useful to clarify mind….

bivtubes20002

Research_Update 12thNov2012

Pubblicato: novembre 16, 2012 in general

Effects of 12 weeks of block periodization on performance and performance indices in well-trained cyclists.
Rønnestad BR, Ellefsen S, Nygaard H, Zacharoff EE, Vikmoen O, Hansen J, Hallén J.
Source
Section for Sport Science, Lillehammer University College, Lillehammer, Norway.
Abstract
The purpose of this study was to compare the effects of two different methods of organizing endurance training in trained cyclists during a 12-week preparation period. One group of cyclists performed block periodization (BP; n?=?8), wherein every fourth week constituted five sessions of high-intensity aerobic training (HIT), followed by 3 weeks of one HIT session. Another group performed a more traditional organization (TRAD; n?=?7), with 12 weeks of two weekly HIT sessions. The HIT was interspersed with low-intensity training (LIT) so that similar total volumes of both HIT and LIT were performed in the two groups. BP achieved a larger relative improvement in VO(2max) than TRAD (8.8?±?5.9% vs 3.7?±?2.9%, respectively, P?<?0.05) and a tendency toward larger increase in power output at 2?mmol/L [la(-) ] (22?±?14% vs 10?±?7%, respectively, P?=?0.054). Mean effect size (ES) of the relative improvement in VO(2max) , power output at 2?mmol/L [la(-) ], hemoglobin mass, and mean power output during 40-min all-out trial revealed moderate superior effects of BP compared with TRAD training (ES range was 0.62-1.12). The present study suggests that BP of endurance training has superior effects on several endurance and performance indices compared with TRAD.
© 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis.
Cermak NM, Res PT, de Groot LC, Saris WH, van Loon LJ.
Source
Departments of Human Movement Sciences and Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands, and the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands.
Abstract
BACKGROUND:
Protein ingestion after a single bout of resistance-type exercise stimulates net muscle protein accretion during acute postexercise recovery. Consequently, it is generally accepted that protein supplementation is required to maximize the adaptive response of the skeletal muscle to prolonged resistance-type exercise training. However, there is much discrepancy in the literature regarding the proposed benefits of protein supplementation during prolonged resistance-type exercise training in younger and older populations.
OBJECTIVE:
The objective of the study was to define the efficacy of protein supplementation to augment the adaptive response of the skeletal muscle to prolonged resistance-type exercise training in younger and older populations.
DESIGN:
A systematic review of interventional evidence was performed through the use of a random-effects meta-analysis model. Data from the outcome variables fat-free mass (FFM), fat mass, type I and II muscle fiber cross-sectional area, and 1 repetition maximum (1-RM) leg press strength were collected from randomized controlled trials (RCTs) investigating the effect of dietary protein supplementation during prolonged (>6 wk) resistance-type exercise training.
RESULTS:
Data were included from 22 RCTs that included 680 subjects. Protein supplementation showed a positive effect for FFM (weighted mean difference: 0.69 kg; 95% CI: 0.47, 0.91 kg; P < 0.00001) and 1-RM leg press strength (weighted mean difference: 13.5 kg; 95% CI: 6.4, 20.7 kg; P < 0.005) compared with a placebo after prolonged resistance-type exercise training in younger and older subjects.
CONCLUSION:

Protein supplementation increases muscle mass and strength gains during prolonged resistance-type exercise training in both younger and older subjects.
Blood flow restricted exercise and vascular function.
Horiuchi M, Okita K.
Source
Department of Physiology, Yamanashi Institute of Environmental Sciences, Kami-yoshida 5597, Fuji-yoshida, Yamanashi 4030005, Japan ; Northern Regions, Life long Sports Research Center, Hokusho University, Bunkyoudai 23, Ebetsu, Hokkaido 0698511, Japan.
Abstract
It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

Brain Reorganization following Weight Loss.
Rosenbaum M, Leibel RL.
Source
Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
Abstract
The long-term stability of bodyweight despite wide variation in energy intake and expenditure suggests that at usual weight energy intake and output are ‘coupled’ to maintain body energy stores. Our model for some of the molecular mechanics of this regulation of energy stores is based on the concept of a neurally encoded ‘threshold’ for minimum body fat, below which compensatory physiology is invoked to restore body fat. The existence of such a centrally encoded threshold is supported by the similarities in response to maintenance of a reduced weight between lean and obese individuals, and the tendency for weight-reduced individuals to regain weight to levels of fat stores similar to those present prior to initial weight loss. Brain responses to food and the observed changes in energy expenditure that occur during maintenance of a reduced weight are largely reversed by the administration of the adipocyte-derived hormone, leptin. Copyright © 2012 Nestec Ltd., Vevey/S. Karger AG, Basel.

Dietary intakes of carbohydrates in relation to prostate cancer risk: a prospective study in the Malmo Diet and Cancer cohort.
Drake I, Sonestedt E, Gullberg B, Ahlgren G, Bjartell A, Wallström P, Wirfält E.
Source
Research Group in Nutritional Epidemiology, Department of Clinical Sciences in Malmö, Lund University, Malmö, Sweden, and the Department of Urology, Skåne University Hospital, Malmö, Sweden.
Abstract
BACKGROUND:
Dietary carbohydrates have been implicated in relation to prostate cancer.
OBJECTIVE:
Our objective was to examine the associations between dietary intakes of carbohydrates, fiber, and their food sources and risk of prostate cancer, overall and by case severity, in the Malmö Diet and Cancer cohort.
DESIGN:
The analysis included 8128 men aged 45-73 y without a history of cancer, cardiovascular disease, or diabetes and who were classified as adequate energy reporters. After a median follow-up time of 15 y, prostate cancer was diagnosed in 817 men. We used Cox proportional hazards regression to model associations between energy-adjusted nutrient and food intakes with risk of incident prostate cancer, with competing risk of death from non-prostate cancer causes taken into account.
RESULTS:
After adjustment for age and other known or potential risk factors, we observed no associations between total carbohydrates or dietary fiber and prostate cancer. We observed positive associations between the intake of low-fiber cereals with overall and low-risk prostate cancer and between intakes of cake and biscuits and rice and pasta with low-risk prostate cancer (all P-trend < 0.05). A high intake compared with zero consumption of sugar-sweetened beverages was associated with increased risk of symptomatic prostate cancer (HR: 1.38; 95% CI: 1.04, 1.84).
CONCLUSIONS:
Results from this large study with high-validity dietary data suggest that a high intake of refined carbohydrates may be associated with increased risk of prostate cancer. However we observed no significant associations with high-risk prostate cancer, and not all foods that are typically high in refined carbohydrates were associated with prostate cancer.

[Carbohydrate sweeteners and obesity].
[Article in Polish]
Wystrychowski G, Zukowska-Szczechowska E, Obuchowicz E, Grzeszczak W, Wystrychowski A.
Source
Katedra i Klinika Chorób Wewnetrznych, Diabetologii i Nefrologii SaIskiego Uniwersytetu Medycznego w Katowicach.
wystrych@gmail.com
Abstract
The U.S. prevalence of obesity increases since the mid-70s of the 20th century. Around that time high-fructose corn syrup (HFCS)–mixture of fructose and glucose was introduced as a sweetener replacing sucrose in the food production. HFCS containing 55% fructose and 42-45% glucose (HFCS55) has dominated the American soft drink industry and HFCS has recently become commonly used in Poland. The coincidence of HFCS introduction and obesity epidemic raised widely publicized suspicions of a causal relationship between the two. As a possible mechanism, a higher content of fructose in the HFCS55, as compared with sucrose was suggested -fructose is known to increase serum uric acid level, induce hepatic lipogenesis and not stimulate postprandial hyperinsulinemia, a main activator of leptin release. Few comparative studies of HFCS and sucrose have largely failed to reveal any different impacts on the metabolic parameters, yet they were mainly short-term. It has been recently shown that obesity is linked with changes in the intenstinal flora. Among the causes of allegedly different effects of sucrose and HFCS on metabolism, their influence on the gut microbiome has not been examined. Some bacterial types do not hydrolyze sucrose which may determine different compositions of gut flora with the use of both sweeteners. Studies involving quantitative analysis of bacterial DNA in the stool, both in animals and in humans, shall shed light on the issue that has recently so much absorbed the U.S. public opinion.
PMID:
23029710
[PubMed – indexed for MEDLINE]

Effects of high-fructose corn syrup and sucrose consumption on circulating glucose, insulin, leptin, and ghrelin and on appetite in normal-weight women.
Melanson KJ, Zukley L, Lowndes J, Nguyen V, Angelopoulos TJ, Rippe JM.
Source
Department of Nutrition and Food Sciences, University of Rhode Island, Kingston, Rhode Island, USA.
Abstract
OBJECTIVE:
Fructose has been implicated in obesity, partly due to lack of insulin-mediated leptin stimulation and ghrelin suppression. Most work has examined effects of pure fructose, rather than high-fructose corn syrup (HFCS), the most commonly consumed form of fructose. This study examined effects of beverages sweetened with HFCS or sucrose (Suc), when consumed with mixed meals, on blood glucose, insulin, leptin, ghrelin, and appetite.
METHODS:
Thirty lean women were studied on two randomized 2-d visits during which HFCS- and Suc-sweetened beverages were consumed as 30% of energy on isocaloric diets during day 1 while blood was sampled. On day 2, food was eaten ad libitum. Subjects rated appetite at designated times throughout visits.
RESULTS:
No significant differences between the two sweeteners were seen in fasting plasma glucose, insulin, leptin, and ghrelin (P > 0.05). The within-day variation in all four items was not different between the two visits (P > 0.05). Net areas under the curve were similar for glucose, insulin, and leptin (P > 0.05). There were no differences in energy or macronutrient intake on day 2. The only appetite variable that differed between sweeteners was desire to eat, which had a higher area under the curve the day after Suc compared with HFCS.
CONCLUSION:
These short-term results suggest that, when fructose is consumed in the form of HFCS, the measured metabolic responses do not differ from Suc in lean women. Further research is required to examine appetite responses and to determine if these findings hold true for obese individuals, males, or longer periods.

The CarboMetabolic Tree

Pubblicato: novembre 16, 2012 in health, nutrition

Carbohydrate classification and their main postprandial effects. SDS: slowly
digestible starch; RDS: rapid digestible starch; RS: resistant starch.

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Classification of dietary carbohydrates

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Classification of naturally occurring starch

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Nutrients 2011, 3, 341-369; doi:10.3390/nu3030341

Health Benefits of Nut Consumption

Pubblicato: novembre 16, 2012 in health, nutrition

Emilio Ros
Lipid Clinic, Endocrinology and Nutrition Service, Institutd’Investigacions Biomèdiques August Pii Sunyer, Hospital Clínic, Barcelona and Ciber Fisiopatología de la Obesidady Nutrición (CIBERobn), Instituto de Salud Carlos III (ISCIII), Spain

Abstract: Nuts (tree nuts and peanuts) are nutrient dense foods with complex matrices rich in unsaturated fatty and other bioactive compounds: high-quality vegetable protein, fiber, minerals, tocopherols, phytosterols, and phenolic compounds. By virtue of their unique composition, nuts are likely to beneficially impact health outcomes. Epidemiologic studies have associated nut consumption with a reduced incidence of coronary heart disease and gallstones in both genders and diabetes in women. Limited evidence also suggests beneficial effects on hypertension, cancer, and inflammation. Interventional studies consistently show that nut intake has a cholesterol-lowering effect, even in the context of healthy diets, and there is emerging evidence of beneficial effects on oxidative stress, inflammation, and vascular reactivity. Blood pressure, visceral adiposity and the metabolic syndrome also appear to be positively influenced by nut consumption. Thus it is clear that nuts have a beneficial impact on many cardiovascular risk factors. Contrary to expectations, epidemiologic studies and clinical trials suggest that regular nut consumption is unlikely to contribute to obesity and may even help in weight loss. Safety concerns are limited to the infrequent occurrence of nut allergy in children. In conclusion, nuts are nutrient rich foods with wide-ranging cardiovascular and metabolic benefits, which can be readily incorporated into healthy diets.

Average nutrient composition of nuts (per 100 g)

 

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Calcium, magnesium, sodium and potassium content of nuts and other foods in mg/100 g of edible portion

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Results of prospective studies of nut consumption and risk of death from coronary heart disease

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Results of prospective studies of nut consumption and risk of diabetes. The two
US studies considered the frequency of consumption of all nuts, including peanuts, while
the Chinese study considered exclusively quintiles of peanut consumption in grams/day

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LDL-cholesterol response to nut feeding by baseline LDL-cholesterol level and
BMI. Data from a pooled study of 25 nut feeding trials

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Conclusion
Nuts are energy dense foods rich in bioactive macronutrients, micronutrients and phytochemicals.
The unique composition of nuts is critical for their health effects. Indeed, there are consistent
evidences from epidemiologic and clinical studies of the beneficial effects of nut consumption on risk
of CHD, including sudden cardiac death, as well as on diabetes in women, and on major and emerging
cardiovascular risk factors, as summarized in the following

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