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1.  Racial differences between African-American and white women in insulin resistance and visceral adiposity are associated with differences in apoCIII containing apoAI and apoB lipoproteins 
Nutrition & Metabolism  2014;11(1):56.
Background
African-Americans have higher HDL, less visceral adipose tissue (VAT) and lower triglyceride (TG) and apoCIII concentrations than whites, despite being more insulin-resistant. We studied in African-American and white women the influences of insulin resistance and VAT on the apoAI concentrations of two HDL subspecies, one that contains apoCIII that is associated with increased risk of coronary heart disease (CHD) and one that does not have apoCIII that is associated with decreased CHD; and on the apoCIII concentrations of HDL and of the apoB lipoproteins.
Methods
The participants were 32 women (14 African-Americans, 18 white) of similar age (39 ± 12 vs. 42 ± 11y). Mean BMI was 34 kg/m2 in the African-Americans compared to 30 in the whites. A standard diet (33% fat, 52% carbohydrate, 15% protein) was provided for 7 days followed by a test meal (40% fat, 40% carbohydrate, 20% protein) on Day 8. Insulin sensitivity index (SI) was calculated from the minimal model.
Results
After controlling for SI, African-Americans have a higher mean apoAI level in HDL with apoCIII compared with whites (12.9 ± 2.8 and 10.9 ± 2.9 mg/dL, respectively, P = 0.05). SI was associated with higher apoAI in HDL with apoCIII, whereas VAT was not associated with this HDL subspecies. This pattern of results was reversed for apoCIII concentrations in apoB lipoproteins. After adjusting for SI, African-Americans had lower apoCIII in apoB lipoproteins. SI was associated with lower apoCIII in total apoB lipoproteins, whereas VAT was associated with higher apoCIII in all the apoB lipoproteins. Additional adjustment for VAT tended to reduce the difference in apoCIII between the groups.
Conclusions
African-American women have a higher HDL with apoCIII level than whites when controlled for insulin sensitivity. African-Americans have lower insulin sensitivity. Insulin sensitivity is associated with higher levels of HDL with apoCIII. ApoCIII levels in VLDL are lower in African-American women than whites, also affected by insulin sensitivity which is associated with low apoCIII in VLDL. VAT has a strong association with apoCIII in apoB lipoproteins but not with apoAI in HDL with apoCIII.
Trial registration
ClinicalTrials.gov Identifier: NCT00484861
doi:10.1186/1743-7075-11-56
PMCID: PMC4280695  PMID: 25553059
ApoAI; ApoCIII; HDL; ApoB lipoproteins; Visceral adipose tissue; Insulin resistance; African-Americans; Coronary heart disease
2.  Homocysteine downregulates gene expression of heme oxygenase-1 in hepatocytes 
Nutrition & Metabolism  2014;11(1):55.
Background
Hyperhomocysteinemia (HHcy) is an independent risk factor for liver diseases, such as fatty liver and hepatic fibrosis. However, the mechanisms underlying this pro-oxidative effect of homocysteine (Hcy) in hepatocytes remain largely unknown. Thus, we investigated the effect of Hcy on the gene expression of heme oxygenase-1 (HO-1), the primary rate-limiting enzyme in heme catabolism and a key anti-oxidant detoxification enzyme in maintaining cellular redox homeostasis.
Methods
In vivo, twenty male C57BL/6 mice at 8 weeks of age were randomly divided into two groups. One group was fed a chow diet (chow group; n = 10), the other group of mice was fed a methionine-supplemented diet (Met group, 1 mg kg−1 day−1 L-methionine in drinking water; n = 10) for 4 weeks. In vitro, HepG2 cells were stimulated with different doses of homocysteine (Hcy).
Results
Four weeks’ methionine supplementation caused a significant increase of plasma Hcy concentration and a decrease of HO-1 expression in the liver of C57BL/6 mice than mice received chow diet. Besides, SOD enzyme activities were impaired and the level of oxidative stress markers, such as malondialdehyde (MDA) were elevated in the liver from mice supplemented with methionine compared with control mice. In cultured hepatocytes, Hcy treatment reduced both the mRNA and protein levels of HO-1 dose-dependently. However, Hcy had no effect on the gene expression of Nrf2, the major transcriptional regulator of HO-1. Instead, Hcy induced the expression of Bach1, a transcriptional repressor of HO-1. In addition, Hcy stimulated the nuclear localization of Bach1 but prevented that of Nrf2. Furthermore, we found that knockdown of Bach1 attenuated the suppression of the HO-1 expression by Hcy.
Conclusions
Collectively, our results demonstrated that Bach1 plays an important role in Hcy-triggered ROS generations through inhibiting HO-1 expression, likely, resulting from the disturbed interplay between Bach1 and Nrf2.
Electronic supplementary material
The online version of this article (doi:10.1186/1743-7075-11-55) contains supplementary material, which is available to authorized users.
doi:10.1186/1743-7075-11-55
PMCID: PMC4268895  PMID: 25520741
Homocysteine; Reactive oxygen species; Heme Oxygenase-1; Nrf2; Bach1
3.  A high-protein diet for reducing body fat: mechanisms and possible caveats 
Nutrition & Metabolism  2014;11(1):53.
High protein diets are increasingly popularized in lay media as a promising strategy for weight loss by providing the twin benefits of improving satiety and decreasing fat mass. Some of the potential mechanisms that account for weight loss associated with high-protein diets involve increased secretion of satiety hormones (GIP, GLP-1), reduced orexigenic hormone secretion (ghrelin), the increased thermic effect of food and protein-induced alterations in gluconeogenesis to improve glucose homeostasis. There are, however, also possible caveats that have to be considered when choosing to consume a high-protein diet. A high intake of branched-chain amino acids in combination with a western diet might exacerbate the development of metabolic disease. A diet high in protein can also pose a significant acid load to the kidneys. Finally, when energy demand is low, excess protein can be converted to glucose (via gluconeogenesis) or ketone bodies and contribute to a positive energy balance, which is undesirable if weight loss is the goal. In this review, we will therefore explore the mechanisms whereby a high-protein diet may exert beneficial effects on whole body metabolism while we also want to present possible caveats associated with the consumption of a high-protein diet.
doi:10.1186/1743-7075-11-53
PMCID: PMC4258944  PMID: 25489333
High-protein diet; Weight loss; Satiety; Energy expenditure; Thermic effect of food
4.  Pharmacological potential of tocotrienols: a review 
Nutrition & Metabolism  2014;11(1):52.
Tocotrienols, members of the vitamin E family, are natural compounds found in a number of vegetable oils, wheat germ, barley, and certain types of nuts and grains. Like tocopherols, tocotrienols are also of four types viz. alpha, beta, gamma and delta. Unlike tocopherols, tocotrienols are unsaturated and possess an isoprenoid side chain. Tocopherols are lipophilic in nature and are found in association with lipoproteins, fat deposits and cellular membranes and protect the polyunsaturated fatty acids from peroxidation reactions. The unsaturated chain of tocotrienol allows an efficient penetration into tissues that have saturated fatty layers such as the brain and liver. Recent mechanistic studies indicate that other forms of vitamin E, such as γ-tocopherol, δ-tocopherol, and γ-tocotrienol, have unique antioxidant and anti-inflammatory properties that are superior to those of α-tocopherol against chronic diseases. These forms scavenge reactive nitrogen species, inhibit cyclooxygenase- and 5-lipoxygenase-catalyzed eicosanoids and suppress proinflammatory signalling, such as NF-κB and STAT. The animal and human studies show tocotrienols may be useful against inflammation-associated diseases. Many of the functions of tocotrienols are related to its antioxidant properties and its varied effects are due to it behaving as a signalling molecule. Tocotrienols exhibit biological activities that are also exhibited by tocopherols, such as neuroprotective, anti-cancer, anti-inflammatory and cholesterol lowering properties. Hence, effort has been made to compile the different functions and properties of tocotrienols in experimental model systems and humans. This article constitutes an in-depth review of the pharmacology, metabolism, toxicology and biosafety aspects of tocotrienols. Tocotrienols are detectable at appreciable levels in the plasma after supplementations. However, there is inadequate data on the plasma concentrations of tocotrienols that are sufficient to demonstrate significant physiological effect and biodistribution studies show their accumulation in vital organs of the body. Considering the wide range of benefits that tocotrienols possesses against some common human ailments and having a promising potential, the experimental analysis accounts for about a small fraction of all vitamin E research. The current state of knowledge deserves further investigation into this lesser known form of vitamin E.
doi:10.1186/1743-7075-11-52
PMCID: PMC4247006  PMID: 25435896
Dietary tocotrienols; Pharmacology; Antioxidant; Anti-inflammatory; Hypolipidemic; Hypoglycaemic; Anti-cancer; Cardioprotective
5.  Protein energy malnutrition increases arginase activity in monocytes and macrophages 
Nutrition & Metabolism  2014;11(1):51.
Background
Protein energy malnutrition is commonly associated with immune dysfunctions and is a major factor in susceptibility to infectious diseases.
Methods
In this study, we evaluated the impact of protein energy malnutrition on the capacity of monocytes and macrophages to upregulate arginase, an enzyme associated with immunosuppression and increased pathogen replication.
Results
Our results show that monocytes and macrophages are significantly increased in the bone marrow and blood of mice fed on a protein low diet. No alteration in the capacity of bone marrow derived macrophages isolated from malnourished mice to phagocytose particles, to produce the microbicidal molecule nitric oxide and to kill intracellular Leishmania parasites was detected. However, macrophages and monocytes from malnourished mice express significantly more arginase both in vitro and in vivo. Using an experimental model of visceral leishmaniasis, we show that following protein energy malnutrition, the increased parasite burden measured in the spleen of these mice coincided with increased arginase activity and that macrophages provide a more permissive environment for parasite growth.
Conclusions
Taken together, these results identify a novel mechanism in protein energy malnutrition that might contributes to increased susceptibility to infectious diseases by upregulating arginase activity in myeloid cells.
Electronic supplementary material
The online version of this article (doi:10.1186/1743-7075-11-51) contains supplementary material, which is available to authorized users.
doi:10.1186/1743-7075-11-51
PMCID: PMC4228191  PMID: 25392710
Arginase; Macrophages; Monocytes; Nitric oxide; Leishmaniasis
6.  Metabolic programming of adipose tissue structure and function in male rat offspring by prenatal undernutrition 
Nutrition & Metabolism  2014;11(1):50.
Background
A number of different pathways to obesity with different metabolic outcomes are recognised. Prenatal undernutrition in rats leads to increased fat deposition in adulthood. However, the form of obesity is metabolically distinct from obesity induced through other pathways (e.g. diet-induced obesity). Previous rat studies have shown that maternal undernutrition during pregnancy led to insulin hyper-secretion and obesity in offspring, but not to systemic insulin resistance. Increased muscle and liver glycogen stores indicated that glucose is taken up efficiently, reflecting an active physiological function of these energy storage tissues. It is increasingly recognised that adipose tissue plays a central role in the regulation of metabolism and pathophysiology of obesity development. The present study investigated the cell size and endocrine responsiveness of subcutaneous and visceral adipose tissue from prenatally undernourished rats. We aimed to identify whether these adipose tissue depots contribute to the altered energy metabolism observed in these offspring.
Methods
Adipocyte size was measured in both subcutaneous (ScAT) and retroperitoneal adipose tissue (RpAT) in male prenatally ad libitum fed (AD) or prenatally undernourished (UN) rat offspring. Metabolic responses were investigated in adipose tissue explants stimulated by insulin and beta3 receptor agonists ex vivo. Expression of markers of insulin signalling was determined by Western blot analyses. Data were analysed by unpaired t-test or Two Way ANOVA followed by Fisher’s PLSD post-hoc test, where appropriate.
Results
Adipocytes in offspring of undernourished mothers were larger, even at a lower body weight, in both RpAT and ScAT. The insulin response of adipose tissue was reduced in ScAT, and statistically absent in RpAT of UN rats compared with control. This lack of RpAT insulin response was associated with reduced expression of insulin signalling pathway proteins. Adrenergic receptor-driven lipolysis was observed in both adipose depots; however insulin failed to express its anti-lipolytic effect in RpAT in both, AD and UN offspring.
Conclusions
Metabolic dysregulation in offspring of undernourished mothers is mediated by increased adipocyte size and reduced insulin responsiveness in both ScAT and especially in RpAT. These functional and morphological changes in adipocytes were accompanied by impaired activity of the insulin signalling cascade highlighting the important role of different adipose tissue depots in the pathogenesis of metabolic disorders.
doi:10.1186/1743-7075-11-50
PMCID: PMC4210519  PMID: 25352910
Subcutaneous adipose tissue; Retroperitoneal adipose tissue; Insulin response; Beta-adrenergic response; Prenatal undernutrition
7.  Acute lysine supplementation does not improve hepatic or peripheral insulin sensitivity in older, overweight individuals 
Nutrition & Metabolism  2014;11(1):49.
Context
Lysine supplementation may have a positive influence on the regulation of glucose metabolism but it has not been tested in the geriatric population. Objective: We evaluated the impact of acute lysine supplementation using three randomized experimental scenarios: 1) oral glucose alone (control), 2) oral glucose and low-dose lysine (2 grams), and oral glucose and high dose lysine (5 grams) lysine in 7 older (66 ± 1 years/age), overweight/obese (BMI = 28 ± 2 kg/m2) individuals.
Methods
We utilized a dual tracer technique (i.e., [6,6-2H2] glucose primed constant infusion and 1-[13C] glucose oral ingestion) during an oral glucose tolerance test (OGTT) to examine differences in hepatic and peripheral insulin sensitivity under all three scenarios.
Results
Post-absorptive plasma glucose and insulin concentrations were not different between the three trials. Similarly, the response of glucose and insulin concentrations during the oral glucose tolerance tests (OGTT) was similar in the three trials. The results of the Matsuda index (ISI/M) were also not different between the three trials. As an index of hepatic insulin sensitivity, there were no significant differences in the endogenous glucose rate of appearance (glucose Ra) for control, 2 g lysine and 5 g lysine (1.2 ± 0.1, 1.1 ± 0.1, 1.3 ± 0.1 mg•kg-1•min-1), respectively. With respect to peripheral insulin sensitivity, there were no significant differences in the glucose rate of disappearance (glucose Rd) for control, 2 g lysine and 5 g lysine (4.2 ± 0.1, 4.3 ± 0.2, and 4.5 ± 0.4 mg•kg-1•min-1), respectively.
Conclusions
Previous studies in younger participants have suggested that lysine may have a beneficial effect on glucose metabolism. However, acute lysine supplementation in the older population does not facilitate beneficial changes in glucose Ra or glucose Rd.
Electronic supplementary material
The online version of this article (doi:10.1186/1743-7075-11-49) contains supplementary material, which is available to authorized users.
doi:10.1186/1743-7075-11-49
PMCID: PMC4198625  PMID: 25324894
Insulin resistance; Liver; Muscle
8.  Association between smoking and total energy expenditure in a multi-country study 
Nutrition & Metabolism  2014;11(1):48.
Background
The association between smoking and total energy expenditure (TEE) is still controversial. We examined this association in a multi-country study where TEE was measured in a subset of participants by the doubly labeled water (DLW) method, the gold standard for this measurement.
Methods
This study includes 236 participants from five different African origin populations who underwent DLW measurements and had complete data on the main covariates of interest. Self-reported smoking status was categorized as either light (<7 cig/day) or high (≥7 cig/day). Lean body mass was assessed by deuterium dilution and physical activity (PA) by accelerometry.
Results
The prevalence of smoking was 55% in men and 16% in women with a median of 6.5 cigarettes/day. There was a trend toward lower BMI in smokers than non-smokers (not statistically significant). TEE was strongly correlated with fat-free mass (men: 0.70; women: 0.79) and with body weight (0.59 in both sexes). Using linear regression and adjusting for body weight, study site, age, PA, alcohol intake and occupation, TEE was larger in high smokers than in never smokers among men (difference of 298 kcal/day, p = 0.045) but not among women (162 kcal/day, p = 0.170). The association became slightly weaker in men (254 kcal/day, p = 0.058) and disappeared in women (−76 kcal/day, p = 0.380) when adjusting for fat-free mass instead of body weight.
Conclusion
There was an association between smoking and TEE among men. However, the lack of an association among women, which may be partly related to the small number of smoking women, also suggests a role of unaccounted confounding factors.
doi:10.1186/1743-7075-11-48
PMCID: PMC4193288  PMID: 25309614
Smoking; Doubly labeled water; Total energy expenditure; Physical activity; Accelerometer; Body mass index; Body weight
9.  Muscle p70S6K phosphorylation in response to soy and dairy rich meals in middle aged men with metabolic syndrome: a randomised crossover trial 
Nutrition & Metabolism  2014;11(1):46.
Background
The mammalian target of rapamycin (mTOR) pathway is the primary regulator of muscle protein synthesis. Metabolic syndrome (MetS) is characterized by central obesity and insulin resistance; little is known about how MetS affects the sensitivity of the mTOR pathway to feeding.
Methods
The responsiveness of mTOR pathway targets such as p706Sk to a high protein meal containing either dairy or soy foods was investigated in healthy insulin sensitive middle-aged men and those presenting with metabolic syndrome (MetS). Twenty male subjects (10 healthy controls, 10 MetS) participated in a single-blinded randomized cross-over study. In a random sequence, subjects ingested energy-matched breakfasts composed predominately of either dairy-protein or soy-protein foods. Skeletal muscle biopsies were collected in the fasted state and at 2 and 4 h post-meal ingestion for the analysis of mTOR- and insulin-signalling kinase activation.
Results
Phosphorylated Akt and Insulin receptor substrate 1 (IRS1) increased during the postabsorptive period with no difference between groups. mTOR (Ser448) and ribosomal protein S6 phosphorylation increased 2 h following dairy meal consumption only. p70S6K (Thr389) phosphorylation was increased after feeding only in the control subjects and not in the MetS group.
Conclusions
These data demonstrate that the consumption of a dairy-protein rich but not a soy-protein rich breakfast activates the phosphorylation of mTOR and ribosomal protein S6, required for protein synthesis in human skeletal muscle. Unlike healthy controls, subjects with MetS did not increase muscle p70S6K(Thr389) phosphorylation in response to a mixed meal.
Trial registration
This trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR) as ACTRN12610000562077.
doi:10.1186/1743-7075-11-46
PMCID: PMC4190399  PMID: 25302072
10.  Vitamin D deficiency down-regulates Notch pathway contributing to skeletal muscle atrophy in old wistar rats 
Nutrition & Metabolism  2014;11(1):47.
Background
The diminished ability of aged muscle to self-repair is a factor behind sarcopenia and contributes to muscle atrophy. Muscle repair depends on satellite cells whose pool size is diminished with aging. A reduction in Notch pathway activity may explain the age-related decrease in satellite cell proliferation, as this pathway has been implicated in satellite cell self-renewal. Skeletal muscle is a target of vitamin D which modulates muscle cell proliferation and differentiation in vitro and stimulates muscle regeneration in vivo. Vitamin D status is positively correlated to muscle strength/function, and elderly populations develop a vitamin D deficiency. The aim of this study was to evaluate how vitamin D deficiency induces skeletal muscle atrophy in old rats through a reduction in Notch pathway activity and proliferation potential in muscle.
Methods
15-month-old male rats were vitamin D-depleted or not (control) for 9 months (n = 10 per group). Rats were 24-month-old at the end of the experiment. Gene and/or protein expression of markers of proliferation, or modulating proliferation, and of Notch signalling pathway were studied in the tibialis anterior muscle by qPCR and western blot. An unpaired student’s t-test was performed to test the effect of the experimental conditions.
Results
Vitamin D depletion led to a drop in concentrations of plasma 25-hydroxyvitamin D in depleted rats compared to controls (-74%, p < 0.01). Tibialis anterior weight was decreased in D-depleted rats (-25%, p < 0.05). The D-depleted group showed -39%, -31% drops in expression of two markers known to modulate proliferation (Bmp4, Fgf-2 mRNA levels) and -56% drop in one marker of cell proliferation (PCNA protein expression) compared to controls (p < 0.05). Notch pathway activity was blunted in tibialis anterior of D-depleted rats compared to controls, seen as a down-regulation of cleaved Notch (-53%, p < 0.05) and its target Hes1 (-35%, p < 0.05).
Conclusions
A 9-month vitamin D depletion induced vitamin D deficiency in old rats. Vitamin D depletion induces skeletal muscle atrophy in old rats through a reduction in Notch pathway activity and proliferation potential. Vitamin D deficiency could aggravate the age-related decrease in muscle regeneration capacity.
Electronic supplementary material
The online version of this article (doi:10.1186/1743-7075-11-47) contains supplementary material, which is available to authorized users.
doi:10.1186/1743-7075-11-47
PMCID: PMC4195890  PMID: 25317198
Vitamin D deficiency; Aging; Skeletal muscle atrophy; Notch signalling
11.  Mitochondriogenesis and apoptosis: possible cause of vitamin A-mediated adipose loss in WNIN/Ob-obese rats 
Nutrition & Metabolism  2014;11(1):45.
Background
Previously, we reported that vitamin A-enriched diet (129 mg/kg diet) intake reduces the adiposity development in obese rats of WNIN/Ob strain. Here, we hypothesize that dose lesser than 129 mg of vitamin A/kg diet would also be effective in ameliorating the development of obesity in these rats.
Methods
Five-month-old male lean and obese rats designated as A & B were divided into four subgroups (I, II, III and IV) consisting of 8 rats from each phenotype and received diets containing 2.6 mg (control group), 26 mg, 52 mg and 129 mg vitamin A/kg diet as retinyl palmitate for 20 weeks. Body composition and morphological analysis of brown adipose tissue (BAT) was analyzed. Expression of uncoupling protein 1 (UCP1), retinoic acid receptor α (RARα) and retinoid X receptor α (RXRα) in BAT and levels of Bcl2 and Bax in epididymal white adipose tissue (eWAT) were determined by immunoblotting.
Results
Vitamin A supplementation to obese rats at doses of 52 and 129 mg/kg diet showed reduced body weight gain and adiposity compared to control diet-fed obese rats receiving 2.6 mg of vitamin A/kg diet. In BAT of obese rats, vitamin A supplementation at doses of 26 and 52 mg of vitamin A/kg diet resulted in increased UCP1 expression with concomitant decrease in RARα and RXRα levels compared to control diet-fed obese rats. Further, transmission electron microscopy study revealed an increase in number of BAT mitochondria of obese rats supplemented with 26 and 52 mg of vitamin A/kg diet. Also, obese rats fed on 52 mg/kg diet resulted in increased apoptosis by altering the ratio of Bcl2 to Bax protein levels in eWAT. Notably, most of these changes were not observed in lean rats fed vitamin A-enriched diets.
Conclusion
In conclusion, chronic consumption of 52 mg of vitamin A/kg diet seems to be an effective dose in ameliorating obesity possibly through mitochondriogenesis, UCP1-mediated thermogenesis in BAT and apoptosis in eWAT of obese rats. Therefore, the role of dietary vitamin A in correcting human obesity would be of unquestionable relevance and can only be addressed by future studies.
doi:10.1186/1743-7075-11-45
PMCID: PMC4190477  PMID: 25302071
Vitamin A; Dietary supplementation; Uncoupling protein; Thermogenesis; Nuclear receptors; Adipose tissue; Apoptosis
12.  Effects of dietary components on high-density lipoprotein measures in a cohort of 1,566 participants 
Nutrition & Metabolism  2014;11(1):44.
Background
Recent data suggest that an increased level of high-density lipoprotein cholesterol (HDL-C) is not causally protective against heart disease, shifting focus to other sub-phenotypes of HDL. Prior work on the effects of dietary intakes has focused largely on HDL-C. The goal of this study was to identify the dietary intakes that affect HDL-related measures: HDL-C, HDL-2, HDL-3, and apoA1 using data from a carotid artery disease case–control cohort.
Methods
A subset of 1,566 participants with extensive lipid phenotype data completed the Harvard Standardized Food Frequency Questionnaire to determine their daily micronutrient intake over the past year. Stepwise linear regression was used to separately evaluate the effects of dietary covariates on adjusted levels of HDL-C, HDL-2, HDL-3, and apoA1.
Results
Dietary folate intake was positively associated with HDL-C (p = 0.007), HDL-2 (p = 0.0011), HDL-3 (p = 0.0022), and apoA1 (p = 0.001). Alcohol intake and myristic acid (14:0), a saturated fat, were each significantly associated with increased levels of all HDL-related measures studied. Dietary carbohydrate and iron intake were significantly associated with decreased levels of all HDL-related measures. Magnesium intake was positively associated with HDL-C, HDL-2, and HDL-3 levels, but not apoA1 levels, while vitamin C was only associated with apoA1 levels. Dietary fiber and protein intake were both associated with HDL-3 levels alone.
Conclusions
This study is the first to report that dietary folate intake is associated with HDL-C, HDL-2, HDL-3, and apoA1 levels in humans. We further identify numerous dietary intake associations with apoA1, HDL-2, and HDL-3 levels. Given the shifting focus away from HDL-C, these data will prove valuable for future epidemiologic investigation of the role of diet and multiple HDL phenotypes in heart disease.
doi:10.1186/1743-7075-11-44
PMCID: PMC4177053  PMID: 25264450
HDL; HDL-C; HDL-2; HDL-3; Apolipoprotein A1; HDL subfractions; Folate; Alcohol; Fatty acids; Magnesium; Food frequency questionnaire; Cardiovascular disease
13.  Yerba Maté (Illex Paraguariensis) ingestion augments fat oxidation and energy expenditure during exercise at various submaximal intensities 
Background
Ingesting Yerba Maté (YM) has become widely popular for health promotion, obesity prevention and body weight reduction, primarily due its thermogenic effectiveness. However, the YM effects on fat metabolism during exercise, when fat metabolism is already increased several fold, are unknown. The present study investigated whether acute YM ingestion augments fat metabolism parameters of fatty acid oxidation (FAO) and energy expenditure derived from FAO (EEFAO) during exercise with several intensities.
Methods
Fourteen healthy males and females were randomised in a repeated measures crossover experimental design. All participants ingested either 1000 mg of YM or placebo capsules (PLC) 60 min before performing two incremental exercise ergometry tests. Power output was initiated at and increased by 0.5 W.kg-1 of body weight every 3 min stage, until reaching peak oxygen uptake V˙O2Peak. Expired gases and stoichiometric indirect calorimetry were used to analyse FAO and EEFAO. Capillary blood samples were collected and analysed for blood lactate concentration (BLC) at rest and at each submaximal and maximal power output.
Results
YM significantly increased FAO and EEFAO by 24% in all submaximal exercise intensities below 70% of V˙O2peak (p < 0.001, ANOVA main effects) with post hoc tests showing a higher FAO and EEFAO (p < 0.05) at the lower exercise intensities (e.g. 0.26 ± 0.09 vs. 0.35 ± 0.10 and 0.25 ± 0.12 vs. 0.33 ± 0.11 g.min-1 at 40 and 50% of V˙O2peak respectively). These changes were combined with a trend towards a decrease in BLC (P = 0.066), and without a significant difference in V˙O2peak, peak power, peak RER, or peak BLC.
Conclusions
Acute YM ingestion augments the exercise dependent increase in FAO and EEFAO at submaximal exercise intensities without negatively affecting maximal exercise performance, suggesting a potential role for YM ingestion to increase the exercise effectiveness for weight loss and sports performance.
doi:10.1186/1743-7075-11-42
PMCID: PMC4190939  PMID: 25342955
Plant; Ingestion; Metabolism; Weight loss; Thermogenic
14.  Fasting mitigates immediate hypersensitivity: a pivotal role of endogenous D-beta-hydroxybutyrate 
Background
Fasting is a rigorous type of dietary restriction that is associate with a number of health benefits. During fasting, ketone bodies significantly increase in blood and become major body fuels, thereby sparing glucose. In the present study, we investigated effects of fasting on hypersensitivity. In addition, we also investigated the possible role of D-beta-hydroxybutyrate provoked by fasting in the attenuation of immediate hypersensitivity by fasting.
Methods
Effects of fasting on systemic anaphylaxis were examined using rat model of toluene 2, 4-diisocyanate induced nasal allergy. In addition to food restriction, a ketogenic high-fat and low-carbohydrate diet that accelerates fatty acid oxidation and systemic instillation of D-beta-hydroxybutyrate were employed to elevate internal D-beta-hydroxybutyrate concentration. We assessed relationship between degranulation of rat peritoneal mast cells and internal D-beta-hydroxybutyrate concentration in each treatment. Changes in [Ca2+]i responses to compound 48/80 were analyzed in fura 2-loaded rat peritoneal mast cells derived from the ketogenic diet and fasting.
Results
Immediate hypersensitivity reaction was significantly suppressed by fasting. A significant reduction in mast cells degranulation, induced by mast cell activator compound 48/80, was observed in rat peritoneal mast cells delivered from the 24 hours fasting treatment. In addition, mast cells delivered from a ketogenic diet and D-beta-hydroxybutyrate infusion treatment also had reduced mast cell degranulation and systemic D-beta-hydroxybutyrate concentrations were elevated to similar extent as the fasting state. The peak increase in [Ca2+]i was significantly lower in the ketogenic diet and fasting group than that in the control diet group.
Conclusions
The results of the present study demonstrates that fasting suppress hypersensitivity reaction, and indicate that increased level of D-beta-hydroxybutyrate by fasting plays an important role, via the stabilization of mast cells, in suppression of hypersensitivity reaction.
doi:10.1186/1743-7075-11-40
PMCID: PMC4190937  PMID: 25302070
15.  The effect of the macrobiotic Ma-Pi 2 diet vs. the recommended diet in the management of type 2 diabetes: the randomized controlled MADIAB trial 
Background
Diet is an important component of type 2 diabetes therapy. Low adherence to current therapeutic diets points out to the need for alternative dietary approaches. This study evaluated the effect of a different dietary approach, the macrobiotic Ma-Pi 2 diet, and compared it with standard diets recommended for patients with type 2 diabetes.
Methods
A randomized, controlled, open-label, 21-day trial was undertaken in patients with type 2 diabetes comparing the Ma-Pi 2 diet with standard (control) diet recommended by professional societies for treatment of type 2 diabetes. Changes in fasting blood glucose (FBG) and post-prandial blood glucose (PPBG) were primary outcomes. HbA1c, insulin resistance (IR), lipid panel and anthropometrics were secondary outcomes.
Results
After correcting for age, gender, BMI at baseline, and physical activity, there was a significantly greater reduction in the primary outcomes FBG (95% CI: 1.79; 13.46) and PPBG (95% CI: 5.39; 31.44) in those patients receiving the Ma-Pi 2 diet compared with those receiving the control diet. Statistically significantly greater reductions in the secondary outcomes, HbA1c (95% CI: 1.28; 5.46), insulin resistance, total cholesterol, LDL cholesterol and LDL/HDL ratio, BMI, body weight, waist and hip circumference were also found in the Ma-Pi 2 diet group compared with the control diet group. The latter group had a significantly greater reduction of triglycerides compared with the Ma-Pi 2 diet group.
Conclusions
Intervention with a short-term Ma-Pi 2 diet resulted in significantly greater improvements in metabolic control in patients with type 2 diabetes compared with intervention with standard diets recommended for these patients.
Trial registration
Current Controlled Trials ISRCTN10467793.
doi:10.1186/1743-7075-11-39
PMCID: PMC4190933  PMID: 25302069
Fasting blood glucose; Macrobiotic diet; Type 2 diabetes
16.  No protein intake compensation for insufficient indispensable amino acid intake with a low-protein diet for 12 days 
Background
Protein quality evaluation aims to determine the capacity of food sources and diets to meet protein and indispensable amino acid (IAA) requirements. This study determined whether nitrogen balance was affected and whether dietary IAA were adequately obtained from the ad libitum consumption of diets at three levels of protein from different primary sources for 12 days.
Methods
Two 12-day randomized crossover design trials were conducted in healthy subjects [n = 70/67 (M/F); age: 19-70 y; BMI: 18.2-38.7 kg/m2]. The relative dietary protein content was lower than [5% of energy (En%)], similar to (15En%), and higher than (30En%) customary diets. These diets had a limited variety of protein sources, containing wheat protein as a single protein source (5En%-protein diet) or 5En% from wheat protein with 10En% (15En%-protein diets) or 25En% (30En%-protein diets) added from whey with α-lactalbumin, soy or beef protein.
Results
There was a dose-dependent increase in nitrogen excretion with increasing dietary protein content, irrespective of the protein sources (P = 0.001). Nitrogen balance was maintained on the 5En%-protein diet, and was positive on the 15En%- and 30En%-protein diets (P < 0.001) over 12 days. Protein intake from the 5En%-protein diet did not reach the amount necessary to meet the calculated minimal IAA requirements, but IAA were sufficiently obtained from the 15En%- and 30En%-protein diets. In the 15En%- and 30En%-protein conditions, a higher protein intake from the soy-containing diets than from the whey with α-lactalbumin or beef containing diets was needed to meet the minimal IAA requirements.
Conclusion
Protein intake did not compensate for an insufficient indispensable amino acid intake with a low-protein diet for 12 days.
Trial registration
These trials were registered at clinicaltrials.gov as NCT01320189 and NCT01646749.
doi:10.1186/1743-7075-11-38
PMCID: PMC4147096  PMID: 25183991
Protein intake; Nitrogen balance; Indispensable amino acids; DIAAS; Protein source
17.  Embryonic viability, lipase deficiency, hypertriglyceridemia and neonatal lethality in a novel LMF1-deficient mouse model 
Background
Lipase Maturation Factor 1 (LMF1) is an ER-chaperone involved in the post-translational maturation and catalytic activation of vascular lipases including lipoprotein lipase (LPL), hepatic lipase (HL) and endothelial lipase (EL). Mutations in LMF1 are associated with lipase deficiency and severe hypertriglyceridemia indicating the critical role of LMF1 in plasma lipid homeostasis. The currently available mouse model of LMF1 deficiency is based on a naturally occurring truncating mutation, combined lipase deficiency (cld), which may represent a hypomorphic allele. Thus, development of LMF1-null mice is needed to explore the phenotypic consequences of complete LMF1 deficiency.
Findings
In situ hybridization and qPCR analysis in the normal mouse embryo revealed ubiquitous and high-level LMF1 expression. To investigate if LMF1 was required for embryonic viability, a novel mouse model based on a null-allele of LMF1 was generated and characterized. LMF1-/- progeny were born at Mendelian ratios and exhibited combined lipase deficiency, hypertriglyceridemia and neonatal lethality.
Conclusion
Our results raise the possibility of a previously unrecognized role for LMF1 in embryonic development, but indicate that LMF1 is dispensable for the viability of mouse embryo. The novel mouse model developed in this study will be useful to investigate the full phenotypic spectrum of LMF1 deficiency.
doi:10.1186/1743-7075-11-37
PMCID: PMC4190935  PMID: 25302068
Lipase Maturation Factor 1; LMF1; Lipase deficiency; Hyper-triglyceridemia
18.  Different types of soluble fermentable dietary fibre decrease food intake, body weight gain and adiposity in young adult male rats 
Background
Dietary fibre-induced satiety offers a physiological approach to body weight regulation, yet there is lack of scientific evidence. This experiment quantified food intake, body weight and body composition responses to three different soluble fermentable dietary fibres in an animal model and explored underlying mechanisms of satiety signalling and hindgut fermentation.
Methods
Young adult male rats were fed ad libitum purified control diet (CONT) containing 5% w/w cellulose (insoluble fibre), or diet containing 10% w/w cellulose (CELL), fructo-oligosaccharide (FOS), oat beta-glucan (GLUC) or apple pectin (PECT) (4 weeks; n = 10/group). Food intake, body weight, and body composition (MRI) were recorded, final blood samples analysed for gut satiety hormones, hindgut contents for fermentation products (including short-chain fatty acids, SCFA) and intestinal tissues for SCFA receptor gene expression.
Results
GLUC, FOS and PECT groups had, respectively, 10% (P < 0.05), 17% (P < 0.001) and 19% (P < 0.001) lower food intake and 37% (P < 0.01), 37% (P < 0.01) and 45% (P < 0.001) lower body weight gain than CONT during the four-week experiment. At the end they had 26% (P < 0.05), 35% (P < 0.01) and 42% (P < 0.001) less total body fat, respectively, while plasma total glucagon-like peptide-1 (GLP-1) was 2.2-, 3.2- and 2.6-fold higher (P < 0.001) and peptide tyrosine tyrosine (PYY) was 2.3-, 3.1- and 3.0-fold higher (P < 0.001). There were no differences in these parameters between CONT and CELL. Compared with CONT and CELL, caecal concentrations of fermentation products increased 1.4- to 2.2-fold in GLUC, FOS and PECT (P < 0.05) and colonic concentrations increased 1.9- to 2.5-fold in GLUC and FOS (P < 0.05), with no consistent changes in SCFA receptor gene expression detected.
Conclusions
This provides animal model evidence that sustained intake of three different soluble dietary fibres decreases food intake, weight gain and adiposity, increases circulating satiety hormones GLP-1 and PYY, and increases hindgut fermentation. The presence of soluble fermentable fibre appears to be more important than its source. The results suggest that dietary fibre-induced satiety is worthy of further investigation towards natural body weight regulation in humans.
doi:10.1186/1743-7075-11-36
PMCID: PMC4141268  PMID: 25152765
Dietary fibre; Beta-glucan; Fructo-oligosaccharide; Pectin; Cellulose; Fermentation; Satiety; Adiposity; Body weight regulation
19.  Effects and mechanisms of resveratrol on the amelioration of oxidative stress and hepatic steatosis in KKAy mice 
Background
The exact mechanism of the protective role of Resveratrol (Res) in lipid metabolism and oxidative stress is not well elucidated. The present study aimed to investigate the potential benefits and possible mechanisms of Res on the amelioration of oxidative stress and hepatic steatosis in a KKAy mouse model.
Methods
A total of 30 KKAy male mice were randomly divided into three groups: a normal chow group, a low resveratrol group and a high resveratrol group. After a 12-wk study period, serum levels of TG, TC, LDL-C and HDL-C, the liver content of TG and TC, ROS, GSH, GPx, SOD and MDA levels were measured. Ectopic lipid deposition was observed in sectioned frozen liver tissues. The mRNA levels of ATGL and HSL in the liver tissues were determined via real-time PCR. Furthermore, the protein expression of p47phox, gp91phox, ATGL, HSL, Sirt1, AMPK and FOXO1 were analyzed using western blotting.
Results
Following Res supplementation, serum levels of TG and MDA were decreased, while the HDL-C and SOD levels were increased in KKAy mice. Furthermore, Res treatment increased GSH and GPx in liver tissues, while it decreased ROS. In addition, Res significantly reduced hepatic steatosis. After Res treatment, concentrations of p47phox (membrane) and gp91phox proteins were reduced, while p-HSL, HSL and ATGL protein expression levels were increased. Mechanistically, the levels of Sirt1, p-AMPK and p-FOXO1 expression in the liver tissues were up-regulated following supplementation with Res, and FOXO1 protein was released from the nucleus into the cytoplasm.
Conclusions
Res is able to attenuate hepatic steatosis and lipid metabolic disorder and enhance the antioxidant ability in KKAy mice, possibly by up-regulating Sirt1 expression and the phosphorylation of AMPK.
doi:10.1186/1743-7075-11-35
PMCID: PMC4137107  PMID: 25140191
NAFLD; Lipid metabolic disorder; Oxidative stress; Resveratrol; Sirt1; AMPK
20.  The intelligence paradox; will ET get the metabolic syndrome? Lessons from and for Earth 
Mankind is facing an unprecedented health challenge in the current pandemic of obesity and diabetes. We propose that this is the inevitable (and predictable) consequence of the evolution of intelligence, which itself could be an expression of life being an information system driven by entropy. Because of its ability to make life more adaptable and robust, intelligence evolved as an efficient adaptive response to the stresses arising from an ever-changing environment. These adaptive responses are encapsulated by the epiphenomena of “hormesis”, a phenomenon we believe to be central to the evolution of intelligence and essential for the maintenance of optimal physiological function and health. Thus, as intelligence evolved, it would eventually reach a cognitive level with the ability to control its environment through technology and have the ability remove all stressors. In effect, it would act to remove the very hormetic factors that had driven its evolution. Mankind may have reached this point, creating an environmental utopia that has reduced the very stimuli necessary for optimal health and the evolution of intelligence – “the intelligence paradox”. One of the hallmarks of this paradox is of course the rising incidence in obesity, diabetes and the metabolic syndrome. This leads to the conclusion that wherever life evolves, here on earth or in another part of the galaxy, the “intelligence paradox” would be the inevitable side-effect of the evolution of intelligence. ET may not need to just “phone home” but may also need to “phone the local gym”. This suggests another possible reason to explain Fermi’s paradox; Enrico Fermi, the famous physicist, suggested in the 1950s that if extra-terrestrial intelligence was so prevalent, which was a common belief at the time, then where was it? Our suggestion is that if advanced life has got going elsewhere in our galaxy, it can’t afford to explore the galaxy because it has to pay its healthcare costs.
doi:10.1186/1743-7075-11-34
PMCID: PMC4118160  PMID: 25089149
Intelligence; Obesity; Hormesis; Exercise; Metabolic syndrome; Type 2 diabetes; Environment; Aging; Mitochondria; Proton gradients; Evolution; Fermi paradox; Entropy
21.  Three-graded stratification of carbohydrate restriction by level of baseline hemoglobin A1c for type 2 diabetes patients with a moderate low-carbohydrate diet 
Background
A moderate low-carbohydrate diet has been receiving attention in the dietary management of type 2 diabetes (T2DM). A fundamental issue has still to be addressed; how much carbohydrate delta-reduction (Δcarbohydrate) from baseline would be necessary to achieve a certain decrease in hemoglobin A1c (HbA1c) levels.
Objective
We investigated the effects of three-graded stratification of carbohydrate restriction by patient baseline HbA1c levels on glycemic control and effects of Δcarbohydrate on decreases in HbA1c levels (ΔHbA1c) in each group.
Research design and methods
We treated 122 outpatients with T2DM by three-graded carbohydrate restriction according to baseline HbA1c levels (≤ 7.4% for Group 1, 7.5%-8.9% for Group 2 and ≥ 9.0% for Group 3) and assessed their HbA1c levels, doses of anti-diabetic drugs and macronutrient intakes over 6 months.
Results
At baseline, the mean HbA1c level and carbohydrate intake were 6.9 ± 0.4% and 252 ± 59 g/day for Group 1 (n = 55), 8.1 ± 0.4% and 282 ± 85 g/day for Group 2 (n = 41) and 10.6 ± 1.4% and 309 ± 88 g/day for Group 3 (n = 26). Following three-graded carbohydrate restriction for 6 months significantly decreased mean carbohydrate intake (g/day) and HbA1c levels for all patients, from 274 ± 78 to 168 ± 52 g and from 8.1 ± 1.6 to 7.1 ± 0.9% (n = 122, P < 0.001 for both) and anti-diabetic drugs could be tapered. ΔHbA1c and Δcarbohydrate were -0.4 ± 0.4% and -74 ± 69 g/day for Group 1, -0.6 ± 0.9% and -117 ± 78 g/day for Group 2 and -3.1 ± 1.4% and -156 ± 74 g/day for Group 3. Linear regression analysis showed that the greater the carbohydrate intake, the greater the HbA1c levels at baseline (P = 0.001). Also, the greater the reduction in carbohydrate intake (g/day), the greater the decrease in HbA1c levels (P < 0.001), but ΔHbA1c was not significantly influenced by changes in other macronutrient intakes (g/day).
Conclusions
Three-graded stratification of carbohydrate restriction according to baseline HbA1c levels may provide T2DM patients with optimal objectives for carbohydrate restriction and prevent restriction from being unnecessarily strict.
doi:10.1186/1743-7075-11-33
PMCID: PMC4128548  PMID: 25114711
Low-carbohydrate diet; Carbohydrate intake; Macronutrient; Hemoglobin A1c; Stratification; Type 2 diabetes
22.  Sudachitin, a polymethoxylated flavone, improves glucose and lipid metabolism by increasing mitochondrial biogenesis in skeletal muscle 
Background
Obesity is a major risk factor for insulin resistance, type 2 diabetes, and stroke. Flavonoids are effective antioxidants that protect against these chronic diseases. In this study, we evaluated the effects of sudachitin, a polymethoxylated flavonoid found in the skin of the Citrus sudachi fruit, on glucose, lipid, and energy metabolism in mice with high-fat diet-induced obesity and db/db diabetic mice. In our current study, we show that sudachitin improves metabolism and stimulates mitochondrial biogenesis, thereby increasing energy expenditure and reducing weight gain.
Methods
C57BL/6 J mice fed a high-fat diet (40% fat) and db/db mice fed a normal diet were treated orally with 5 mg/kg sudachitin or vehicle for 12 weeks. Following treatment, oxygen expenditure was assessed using indirect calorimetry, while glucose tolerance, insulin sensitivity, and indices of dyslipidemia were assessed by serum biochemistry. Quantitative polymerase chain reaction was used to determine the effect of sudachitin on the transcription of key metabolism-regulating genes in the skeletal muscle, liver, and white and brown adipose tissues. Primary myocytes were also prepared to examine the signaling mechanisms targeted by sudachitin in vitro.
Results
Sudachitin improved dyslipidemia, as evidenced by reduction in triglyceride and free fatty acid levels, and improved glucose tolerance and insulin resistance. It also enhanced energy expenditure and fatty acid β-oxidation by increasing mitochondrial biogenesis and function. The in vitro assay results suggest that sudachitin increased Sirt1 and PGC-1α expression in the skeletal muscle.
Conclusions
Sudachitin may improve dyslipidemia and metabolic syndrome by improving energy metabolism. Furthermore, it also induces mitochondrial biogenesis to protect against metabolic disorders.
doi:10.1186/1743-7075-11-32
PMCID: PMC4128574  PMID: 25114710
Sudachitin; Glucose metabolism; Lipid metabolism; Mitochondria
23.  Promotion of immune and glycaemic functions in streptozotocin-induced diabetic rats treated with un-denatured camel milk whey proteins 
T cell mediated autoimmune diabetes is characterized by immune cell infiltration of pancreatic islets and destruction of insulin-producing β-cells. This study was designed to assess the effect of whey proteins (WP) on the responsiveness of lymphocytes in rats after four months of Streptozotocin (STZ)-induced Type 1 diabetes (T1D). A diabetic group was supplemented with WP daily for five weeks at a dose of 100 mg/kg. Ribonucleic acid (RNA) was extracted from stimulated lymphocytes in order to analyse gene expressions using real time PCR and RT-PCR. PCR results were confirmed with ELISA. The proliferation capacity of lymphocytes and their homing to the spleen were studied. Antigen-activated lymphocytes showed that diabetes impaired the mRNA expression of the protein kinase B (Akt1), Cdc42, and the co-stimulatory molecule, CD28, which are important for cell survival, actin polymerization and T cell activation, respectively. Accordingly, proliferation of lymphocytes was found to be suppressed in diabetic rats, both in vivo and in vitro. WP was found to restore Akt1, Cdc42 and CD28 mRNA expression during diabetes to normal levels. WP, therefore, served to activate the proliferation of B lymphocytes in diabetic rats both in vivo and in vitro. Although WP was found to up-regulate mRNA expression of both interleukin (IL)-2 and interferon gamma (IFN-γ), it suppressed the proliferation activity of almost all T cell subsets. This was confirmed by WP normalizing the structure and function of ß cells. Meanwhile, WP was found to down regulate the mRNA expression of Tumor necrosis factor-alpha (TNF-α) and its programmed cell death-receptor (Fas). Taken together, the results of this study provide evidence for the potential impact of WP in the treatment of immune impairment in T1D, suggesting that it serves to reverse autoimmunity by suppressing autoreactive T cells and down regulating TNF-α and Fas, resulting in improved pancreatic ß cell structure and function.
doi:10.1186/1743-7075-11-31
PMCID: PMC4087124  PMID: 25009576
Lymphocyte proliferation; T and B cells; Pancreatic ß cells; Type 1 diabetes-rat model; Whey protein
24.  Phosphatidic acid enhances mTOR signaling and resistance exercise induced hypertrophy 
Introduction
The lipid messenger phosphatidic acid (PA) plays a critical role in the stimulation of mTOR signaling. However, the mechanism by which PA stimulates mTOR is currently unknown. Therefore, the purpose of this study was to compare the effects of various PA precursors and phospholipids on their ability to stimulate mTOR signaling and its ability to augment resistance training-induced changes in body composition and performance.
Methods
In phase one, C2C12 myoblasts cells were stimulated with different phospholipids and phospholipid precursors derived from soy and egg sources. The ratio of phosphorylated p70 (P-p70-389) to total p70 was then used as readout for mTOR signaling. In phase two, resistance trained subjects (n = 28, 21 ± 3 years, 77 ± 4 kg, 176 ± 9 cm) consumed either 750 mg PA daily or placebo and each took part in an 8 week periodized resistance training program.
Results
In phase one, soy-phosphatidylserine, soy-Lyso-PA, egg-PA, and soy-PA stimulated mTOR signaling, and the effects of soy-PA (+636%) were significantly greater than egg-PA (+221%). In phase two, PA significantly increased lean body mass (+2.4 kg), cross sectional area (+1.0 cm), and leg press strength (+51.9 kg) over placebo.
Conclusion
PA significantly activates mTOR and significantly improved responses in skeletal muscle hypertrophy, lean body mass, and maximal strength to resistance exercise.
doi:10.1186/1743-7075-11-29
PMCID: PMC4066292  PMID: 24959196
Supplementation; Skeletal muscle; Protein synthesis; Phospholipid; Ergogenic aid
25.  Prostate cancer and the influence of dietary factors and supplements: a systematic review 
Background
Prostate cancer is the second most common cause of cancer worldwide after lung cancer. There is increasing evidence that diet and lifestyle plays a crucial role in prostate cancer biology and tumourigenesis. Prostate cancer itself represents a good model of cancer in which to look for chemopreventive agents due to the high disease prevalence, slowly progressive nature, and long latency period. Dietary agents have gained considerable attention, often receiving much publicity in the media.
Aim
To review the key evidence available for potential chemopreventive nutrients.
Methods
The methodology for this review involved a PubMed search from 1990 to 2013 using the key-words “diet and prostate cancer”, “nutrition and prostate cancer”, “dietary factors and prostate cancer”, “prostate cancer epidemiology”, “prostate cancer prevention”, “prostate cancer progression”.
Results
Red meat, dietary fat and milk intake should be minimised as they appear to increase the risk of prostate cancer. Fruit and vegetables and polyphenols may be preventive in prostate cancer, but further studies are needed to draw more solid conclusions and to clarify their role in patients with an established diagnosis of prostate cancer. Selenium and vitamin supplements cannot be advocated for the prevention of prostate cancer and indeed higher doses may be associated with a worse prognosis. There is no specific evidence regarding benefits of probiotics or prebiotics in prostate cancer.
Conclusions
From the wealth of evidence available, many recommendations can be made although more randomised control trials are required. These need to be carefully designed due to the many confounding factors and heterogeneity of the population.
doi:10.1186/1743-7075-11-30
PMCID: PMC4073189  PMID: 24976856
Prostate cancer; Nutrition; Diet; Epidemiology; Tumour prevention

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