Metabolic and physiological effects of ingesting extracts of bitter orange, green tea and guarana at rest and during treadmill walking in overweight males

A review of citrus plants as functional foods and dietary supplements for human health, with an emphasis on meta-analyses, clinical trials, and their chemical composition

Fruits, flowers, leaves, essential oils, hydrosols, and juices of citrus spp. Are utilized to prepare various forms of food products. Along with their nutritional values, in the health industry, different parts of the plants of the citrus genus have been used as supplements or remedies to prevent or control diseases. This review focused on reported meta-analyses and clinical trials on the health benefits of citrus plants as functional foods. Also, chemical compounds of various citrus species were reviewed. The following information sources were used for data collection: Google Scholar, the Web of Science, Scopus, and PubMed. Various keywords, including "citrus AND chemical compounds," "citrus AND phytochemicals," "citrus species," "citrus AND meta-analysis," "nutritional and therapeutical values of citrus spp.," "clinical trials AND citrus," "clinical trials AND Rutaceae," "health benefits of citrus spp.," "citrus edible or non-edible applications," and scientific names of the citrus plants were utilized to collect data for the review. The scientific name and common name of all twenty-eight citrus species, along with any of the above keywords, were also searched in the mentioned databases. Scientific papers and data sources were sought to review and discuss the citrus plant's nutritional and therapeutic importance. Several meta-analyses and clinical trials have reported beneficial effects of citrus spices on a variety of cancer risks, cardiovascular risk factors, neurologic disorders, urinary tract conditions, and gastrointestinal tract conditions. They have shown anxiolytic, antimicrobial, and pain-alleviating effects. Some of them can be helpful in managing obesity and cardiovascular risk factors.

The Safety and Efficacy of Citrus aurantium (Bitter Orange) Extracts and p-Synephrine: A Systematic Review and Meta-Analysis

Synephrine has been used to promote weight loss; however, its safety and efficacy have not been fully established. The goals of our study were to give an overview of the safety and efficacy of p-synephrine, to systematically evaluate its efficacy regarding weight loss and to assess its safety, focusing on its cardiovascular side effects in a meta-analysis. PubMed, the Cochrane Library, Web of Science and Embase were searched for relevant studies. Only placebo-controlled, human clinical trials with synephrine intervention were included in the meta-analysis. The meta-analysis was reported according to the PRISMA guidelines using the PICOS format and taking into account the CONSORT recommendations. Altogether, 18 articles were included in the meta-analysis. Both systolic and diastolic blood pressure (DBP) increased significantly after prolonged use (6.37 mmHg, 95% CI: 1.02–11.72, p = 0.02 and 4.33 mmHg, 95% CI: 0.48–8.18, p = 0.03, respectively). The weight loss in the synephrine group was non-significant after prolonged treatment, and it did not influence body composition parameters. Based on the analyzed clinical studies, synephrine tends to raise blood pressure and heart rate, and there is no evidence that synephrine can facilitate weight loss. Further studies are needed to confirm evidence of its safety and efficacy.

Physicochemical and cytotoxicity analysis of green synthesis carbon dots for cell imaging

Carbon dots (CDs) have outstanding optical properties, biocompatibility, and photostability, making them attractive for imaging applications. A facile and green one-step hydrothermal synthesis method is proposed, which can be safely used in a wide range of applications such as chemical sensing, bioimaging, and optoelectronics. In this study, we report green synthesis of carbon dots from bitter orange juice (Citrus Aurantium) by hydrothermal treatment for the first time. We studied effects of time, temperature, and pH on fluorescence of CDs, characterized them using various spectroscopic and microscopic methods, and evaluated their toxicity to different cell lines. Identifying an optimum reaction condition of 180 ºC for 7 h heating gave CDs that showed pH-dependent fluorescence, with the largest fluorescence at a pH of 7.0. The CDs were 1-2 nm in size with a spherical morphology and negative surface charge. The CDs showed a high quantum yield of 19.9 %, reasonable photostability, excellent water solubility, and long fluorescence lifetime. A one step hydrothermal rout led to various hydrophilic functional groups on the surface of the CDs. Our results showed that the CDs were non-toxic over a large concentration range and effective for imaging of cells, indicating their potential as imaging probes in medical diagnostics and biosensor applications.

Effects of p-Synephrine and Caffeine Ingestion on Substrate Oxidation during Exercise

PURPOSE

Caffeine and p-synephrine are substances usually included in commercially available products for weight loss because of their purported thermogenic effects. However, scientific information is lacking about the effects of combining these substances on substrate oxidation during exercise. The purpose of this investigation was to determine the isolated and combined effects of p-synephrine and caffeine on fat oxidation rate during exercise.

METHODS

In a double-blind randomized experiment, 13 healthy subjects participated in four experimental trials after the ingestion of a capsule containing a placebo, 3 mg·kg of caffeine, 3 mg·kg of p-synephrine, or the combination of these doses of caffeine and p-synephrine. Energy expenditure and substrate oxidation rates were measured by indirect calorimetry during a cycle ergometer ramp test from 30% to 90% of V˙O2max.

RESULTS

In comparison with the placebo, the ingestion of caffeine, p-synephrine, or p-synephrine + caffeine did not alter total energy expenditure or heart rate during the whole exercise test. However, the ingestion of caffeine (0.44 ± 0.15 g·min, P = 0.03), p-synephrine (0.43 ± 0.19 g·min, P < 0.01), and p-synephrine + caffeine (0.45 ± 0.15 g·min, P = 0.02) increased the maximal rate of fat oxidation during exercise when compared with the placebo (0.30 ± 0.12 g·min). The exercise intensity that elicited maximal fat oxidation was similar in all trials (~46.2% ± 10.2% of V˙O2max).

CONCLUSION

Caffeine, p-synephrine, and p-synephrine + caffeine increased the maximal rate of fat oxidation during exercise compared with a placebo, without modifying energy expenditure or heart rate. However, the coingestion of p-synephrine and caffeine did not present an additive effect to further increase fat oxidation during exercise.

Analysis of the cytotoxic, genotoxic, mutagenic, and pro-oxidant effect of synephrine, a component of thermogenic supplements, in human hepatic cells in vitro

Thermogenic supplements containing synephrine (SN) are widely used to weight loss. SN is a proto-alkaloid naturally found in the bark of immature fruits of Citrus aurantium (bitter orange) that has been added to thermogenic supplements due to its chemical and pharmacological similarity with adrenergic amines, such as ephedrine and amphetamines. Although orally ingested SN is mainly metabolized in the liver, it remains unclear whether it affects the redox status and genetic material of human hepatic cells. The present study aims to examine whether SN affects cell viability, cell cycle, redox balance, genomic stability, and expression of the DNA damage response (DDR)-related genes ATM, ATR, CHEK1, CHECK2, TP53, and SIRT1 in HepG2 cells - used as in vitro hepatocyte model. SN induced overproduction of intracellular reactive oxygen species (ROS) after 6 h of treatment with the three concentrations tested (2, 20 and 200 μM). After 24 h of treatment, SN at 200 μM induced intracellular ROS overproduction and exerted cytostatic effects, while SN at 20 and 200 μM increased the levels of GPx and GSH. SN was not cytotoxic (2-5000 μM), genotoxic, and mutagenic and did not alter the expression of DDR-related genes (2-200 μM), indicating that the fast/specific SN metabolization and upregulation of antioxidant defense components to detoxify intracellular ROS were sufficient to prevent intracellular damage in HepG2 cells. In conclusion, SN showed no cytotoxic, genotoxic, and mutagenic potential at relevant concentrations for thermogenic users in human hepatic cells in vitro, although, it plays pro-oxidative action, and cytostatic effects. Taken together, our results suggest that other investigations about the hazard absence of this thermogenic compound should be performed.

Effects of acute ingestion of a pre-workout dietary supplement with and without p-synephrine on resting energy expenditure, cognitive function and exercise performance

BACKGROUND

The purpose of this study was to examine the effects of acute ingestion of a pre-workout dietary supplement (PWS) with and without p-synephrine (S) on perceptions of readiness to perform, cognitive function, exercise performance, and markers of safety.

METHODS

In a randomized, double-blind, and counterbalanced manner; 25 healthy and recreationally active male and female participants ingested a flavored maltodextrin placebo (PLA), a PWS containing beta-alanine (3 g), creatine nitrate as a salt (2 g), arginine alpha-ketoglutarate (2 g), N-Acetyl-L-Tyrosine (300 mg), caffeine (284 mg), Mucuna pruiriens extract standardized for 15% L-Dopa (15 mg), Vitamin C as Ascorbic Acid (500 mg), niacin (60 mg), folate as folic acid (50 mg), and Vitamin B12 as Methylcobalamin (70 mg) with 2 g of maltodextrin and flavoring; or, the PWS with Citrus aurantium (PWS + S) extract standardized for 30% p-synephrine (20 mg). Participants had heart rate (HR), blood pressure, resting energy expenditure (REE), 12-lead electrocardiograms (ECG), perceptions about readiness to perform, cognitive function (Stroop Color-Word test), bench and leg press performance (2 sets of 10 repetitions at 70% of 1RM and 1 set to failure), and Wingate anaerobic capacity (WAC) sprint performance determined as well as donated blood samples prior to and/or following exercise/supplementation. Data were analyzed by MANOVA with repeated measures as well as mean changes from baseline with 95% confidence intervals (CI).

RESULTS

No clinically significant differences were observed among treatments in HR, blood pressure, ECG, or general clinical blood panels. There was evidence that PWS and PWS + S ingestion promoted greater changes in REE responses. Participants reported higher perception of optimism about performance and vigor and energy with PWS and PWS + S ingestion and there was evidence that PWS and PWS + S improved changes in cognitive function scores from baseline to a greater degree than PLA after 1 or 2 h. However, the scores in the PWS + S treatment did not exceed PLA or PWS responses at any data point. No statistically significant differences were observed among treatments in total bench press lifting volume, leg press lifting volume or WAC sprint performance.

CONCLUSIONS

Within the confines of this study, ingestion of PWS and/or PWS + S prior to exercise appears to be well-tolerated when consumed by young, healthy individuals. The primary effects appear to be to increase REE responses and improve perceptions about readiness to perform and cognitive function with limited to no effects on muscular endurance and WAC. The addition of 20 mg of p-synephrine to the PWS provided limited to no additive benefits.

TRIAL REGISTRATION

This trial (NCT02952014) was retrospectively registered on September 13th 2016.

Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8 weeks on training adaptations in resistance-trained males

BACKGROUND

The purpose of this study was to examine whether ingesting a pre-workout dietary supplement (PWS) with and without synephrine (S) during training affects training responses in resistance-trained males.

METHODS

Resistance-trained males (N = 80) were randomly assigned to supplement their diet in a double-blind manner with either a flavored placebo (PLA); a PWS containing beta-alanine (3 g), creatine nitrate as a salt (2 g), arginine alpha-ketoglutarate (2 g), N-Acetyl-L-Tyrosine (300 mg), caffeine (284 mg), Mucuna pruiriens extract standardized for 15% L-Dopa (15 mg), Vitamin C as Ascorbic Acid (500 mg), niacin (60 mg), folate as folic acid (50 mg), and Vitamin B12 as Methylcobalamin (70 mg); or, the PWS supplement with Citrus aurantium extract containing 20 mg of synephrine (PWS + S) once per day for 8-weeks during training. Participants donated a fasting blood sample and had body composition (DXA), resting heart rate and blood pressure, cognitive function (Stroop Test), readiness to perform, bench and leg press 1 RM, and Wingate anaerobic capacity assessments determined a 0, 4, and 8-weeks of standardized training. Data were analyzed by MANOVA with repeated measures. Performance and cognitive function data were analyzed using baseline values as covariates as well as mean changes from baseline with 95% confidence intervals (CI). Blood chemistry data were also analyzed using Chi-square analysis.

RESULTS

Although significant time effects were seen, no statistically significant overall MANOVA Wilks' Lambda interactions were observed among groups for body composition, resting heart and blood pressure, readiness to perform questions, 1RM strength, anaerobic sprint capacity, or blood chemistry panels. MANOVA univariate analysis and analysis of changes from baseline with 95% CI revealed some evidence that cognitive function and 1RM strength were increased to a greater degree in the PWS and/or PWS + S groups after 4- and/or 8-weeks compared to PLA responses. However, there was no evidence that PWS + S promoted greater overall training adaptations compared to the PWS group. Dietary supplementation of PWS and PWS + S did not increase the incidence of reported side effects or significantly affect the number of blood values above clinical norms compared to PLA.

CONCLUSION

Results provide some evidence that 4-weeks of PWS and/or PWS + S supplementation can improve some indices of cognitive function and exercise performance during resistance-training without significant side effects in apparently health males. However, these effects were similar to PLA responses after 8-weeks of supplementation and inclusion of synephrine did not promote additive benefits.

TRIAL REGISTRATION

This trial (NCT02999581) was retrospectively registered on December 16th 2016.

Acute p-synephrine ingestion increases fat oxidation rate during exercise

AIMS

p-Synephrine is a protoalkaloid widely used in dietary supplements for weight management because of its purported thermogenic effects. However, there is a lack of scientific information about its effectiveness to increase fat metabolism during exercise. The purpose of this investigation was to determine the effects of an acute ingestion of p-synephrine on fat oxidation at rest and during exercise.

METHODS

In a double-blind, randomized and counterbalanced experimental design, 18 healthy subjects performed two acute experimental trials after the ingestion of p-synephrine (3 mg kg(-1) ) or after the ingestion of a placebo (cellulose). Energy expenditure and fat oxidation rates were measured by indirect calorimetry at rest and during a cycle ergometer ramp exercise test (increases of 25 W every 3 min) until volitional fatigue.

RESULTS

In comparison with the placebo, the ingestion of p-synephrine did not change energy consumption (1.6 ± 0.3 vs. 1.6 ± 0.3 kcal min(-1) ; P = 0.69) or fat oxidation rate at rest (0.08 ± 0.02 vs. 0.10 ± 0.04 g min(-1) ; P = 0.15). However, the intake of p-synephrine moved the fat oxidation-exercise intensity curve upwards during the incremental exercise (P < 0.05) without affecting energy expenditure. Moreover, p-synephrine increased maximal fat oxidation rate (0.29 ± 0.15 vs. 0.40 ± 0.18 g min(-1) ; P = 0.01) during exercise although it did not affect the intensity at which maximal fat oxidation was achieved (55.8 ± 7.7 vs. 56.7 ± 8.2% VO2peak ; P = 0.51).

CONCLUSIONS

The acute ingestion of p-synephrine increased the fat oxidation rate while it reduced the carbohydrate oxidation rate when exercising at low-to-moderate exercise intensities.

Acute consumption of p-synephrine does not enhance performance in sprint athletes

P-Synephrine is a protoalkaloid widely used as an ergogenic aid in sports. This substance has been included in the World Anti-Doping Agency monitoring program, although scientific information about its effects on performance and athletes’ well-being is scarce. The purpose of this investigation was to determine the effectiveness of p-synephrine to increase performance in sprint athletes. In a randomized and counterbalanced order, 13 experienced sprinters performed 2 acute experimental trials after the ingestion of p-synephrine (3 mg·kg−1) or after the ingestion of a placebo (control trial). Forty-five minutes after the ingestion of the substances, the sprinters performed a squat jump, a countermovement jump, a 15-s repeated jump test, and subsequently performed 60-m and 100-m simulated sprint competitions. Self-reported questionnaires were used to assess side-effect prevalence. In comparison with the control trial, the ingestion of p-synephrine did not change countermovement jump height (37.4 ± 4.2 vs 36.7 ± 3.3 cm, respectively; P = 0.52), squat jump height (34.4 ± 3.6 vs 33.9 ± 3.7 cm; P = 0.34), or average 15-s repeated jumps height (31.8 ± 4.1 vs 32.2 ± 3.6 cm; P = 0.18). P-Synephrine did not modify maximal running speed during the 60-m (9.0 ± 0.5 vs 9.0 ± 0.4 m·s−1, respectively; P = 0.55) and 100-m sprint competitions (8.8 ± 0.5 vs 8.8 ± 0.5 m·s−1, respectively; P = 0.92). The ingestion of p-synephrine did not alter the prevalence of headache, gastrointestinal discomforts, muscle pain, or insomnia during the hours following the tests. Acute consumption of 3 mg·kg−1 of p-synephrine was ineffective to increase performance in competitive sprint athletes. Moreover, p-synephrine did not increase the occurrence of side effects after the competition.

The effect of green tea extract on fat oxidation at rest and during exercise: evidence of efficacy and proposed mechanisms

Green tea is made from the leaves of the Camellia sinensis L plant, which is rich in polyphenol catechins and caffeine. There is increasing interest in the potential role of green tea extract (GTE) in fat metabolism and its influence on health and exercise performance. A number of studies have observed positive effects of GTE on fat metabolism at rest and during exercise, following both shorter and longer term intake. However, overall, the literature is inconclusive. The fact that not all studies observed effects may be related to differences in study designs, GTE bioavailability, and variation of the measurement (fat oxidation). In addition, the precise mechanisms of GTE in the human body that increase fat oxidation are unclear. The often-cited in vitro catechol-O-methyltransferase mechanism is used to explain the changes in substrate metabolism with little in vivo evidence to support it. Also, changes in expression of fat metabolism genes with longer term GTE intake have been implicated at rest and with exercise training, including the upregulation of fat metabolism enzyme gene expression in the skeletal muscle and downregulation of adipogenic genes in the liver. The exact molecular signaling that activates changes to fat metabolism gene expression is unclear but may be driven by PPAR-γ coactivator 1-α and PPARs. However, to date, evidence from human studies to support these adaptations is lacking. Clearly, more studies have to be performed to elucidate the effects of GTE on fat metabolism as well as improve our understanding of the underlying mechanisms.

Metabolic response to green tea extract during rest and moderate-intensity exercise

BACKGROUND

Green tea catechins have been hypothesized to increase energy expenditure and fat oxidation by inhibiting catechol-O-methyltransferase (COMT) and thus promoting more sustained adrenergic stimulation. Metabolomics may help to clarify the mechanisms underlying their putative physiological effects.

OBJECTIVE

The study investigated the effects of 7-day ingestion of green tea extract (GTE) on the plasma metabolite profile at rest and during exercise.

METHODS

In a placebo-controlled, double-blind, randomized, parallel study, 27 healthy physically active males consumed either GTE (n=13, 1200 mg catechins, 240 mg caffeine/day) or placebo (n=14, PLA) drinks for 7 days. After consuming a final drink (day 8), they rested for 2 h and then completed 60 min of moderate-intensity cycling exercise (56% ± 4% VO(2)max). Blood samples were collected before and during exercise. Plasma was analyzed using untargeted four-phase metabolite profiling and targeted profiling of catecholamines.

RESULTS

Using the metabolomic approach, we observed that GTE did not enhance adrenergic stimulation (adrenaline and noradrenaline) during rest or exercise. At rest, GTE led to changes in metabolite concentrations related to fat metabolism (3-β-hydroxybutyrate), lipolysis (glycerol) and tricarboxylic acid cycle (TCA) cycle intermediates (citrate) when compared to PLA. GTE during exercise caused reductions in 3-β-hydroxybutyrate concentrations as well as increases in pyruvate, lactate and alanine concentrations when compared to PLA.

CONCLUSIONS

GTE supplementation resulted in marked metabolic differences during rest and exercise. Yet these metabolic differences were not related to the adrenergic system, which questions the in vivo relevance of the COMT inhibition mechanism of action for GTE.

A review of the human clinical studies involving Citrus aurantium (bitter orange) extract and its primary protoalkaloid p-synephrine

This review summarizes the published as well as unpublished human studies involving Citrus aurantium (bitter orange) extract and its primary protoalkaloid p-synephrine, providing information and an assessment of the safety and efficacy of these widely used products. The results of over 20 studies involving a total of approximately 360 subjects that consumed p-synephrine alone or in combination with other ingredients are reviewed and critiqued. Over 50 % of the subjects involved in these studies were overweight/obese, and approximately two-thirds of these overweight/obese subjects consumed caffeine (132-528 mg/day) in conjunction with p-synephrine (10-53 mg/day). Bitter orange/p-synephrine containing products were consumed for up to 12 weeks. Approximately 44 % of the subjects consumed a bitter orange/p-synephrine only product, while the remainder consumed a complex product that contained multiple ingredients in addition to p-synephrine. In general, bitter orange extract alone (p-synephrine) or in combination with other herbal ingredients did not produce significant adverse events as an increase in heart rate or blood pressure, or alter electrocardiographic data, serum chemistry, blood cell counts or urinalysis. p-Synephrine alone as well as in combination products were shown to increase resting metabolic rate and energy expenditure, and modest increases in weight loss were observed with bitter orange extract/p-synephrine-containing products when given for six to 12 weeks. Longer term studies are needed to further assess the efficacy of these products and affirm their safety under these conditions.

A review of the receptor-binding properties of p-synephrine as related to its pharmacological effects

Bitter orange (Citrus aurantium) extract and its primary protoalkaloid p-synephrine are used widely in weight loss/weight management and sports performance products. Because of structural similarities, the pharmacological effects of p-synephrine are widely assumed to be similar to those of ephedrine, m-synephrine (phenylephrine), and endogenous amine neurotransmitters as norepinephrine and epinephrine. However, small structural changes result in the receptor binding characteristics of these amines that are markedly different, providing a plausible explanation for the paucity of adverse effects associated with the wide-spread consumption of p-synephrine in the form of dietary supplements as well as in various Citrus foods and juices. This paper summarizes the adrenoreceptor binding characteristics of p-synephrine relative to m-synephrine, norepinephrine, and other amines as related to the observed pharmacological effects.

Effects of p-synephrine alone and in combination with selected bioflavonoids on resting metabolism, blood pressure, heart rate and self-reported mood changes

Bitter orange (Citrus aurantium) extract is widely used in dietary supplements for weight management and sports performance. Its primary protoalkaloid is p-synephrine. Most studies involving bitter orange extract and p-synephrine have used products with multiple ingredients. The current study assessed the thermogenic effects of p-synephrine alone and in conjunction with the flavonoids naringin and hesperidin in a double-blinded, randomized, placebo-controlled protocol with 10 subjects per treatment group. Resting metabolic rates (RMR), blood pressure, heart rates and a self-reported rating scale were determined at baseline and 75 min after oral ingestion of the test products in V-8 juice. A decrease of 30 kcal occurred in the placebo control relative to baseline. The group receiving p-synephrine (50 mg) alone exhibited a 65 kcal increase in RMR as compared to the placebo group. The consumption of 600 mg naringin with 50 mg p-synephrine resulted in a 129 kcal increase in RMR relative to the placebo group. In the group receiving 100 mg hesperidin in addition to the 50 mg p-synephrine plus 600 mg naringin, the RMR increased by 183 kcal, an increase that was statistically significant with respect to the placebo control (p<0.02). However, consuming 1000 mg hesperidin with 50 mg p-synephrine plus 600 mg naringin resulted in a RMR that was only 79 kcal greater than the placebo group. None of the treatment groups exhibited changes in heart rate or blood pressure relative to the control group, nor there were no differences in self-reported ratings of 10 symptoms between the treatment groups and the control group. This unusual finding of a thermogenic combination of ingredients that elevated metabolic rates without corresponding elevations in blood pressure and heart-rates warrants longer term studies to assess its value as a weight control agent.

The safety of Citrus aurantium (bitter orange) and its primary protoalkaloid p-synephrine

Citrus aurantium (bitter orange) extract and its principal protoalkaloidal constituent p-synephrine are widely used in weight loss and weight management as well as in sports performance products. However, questions are raised frequently regarding the safety of these ingredients. The potential inherent dangers associated with the use of products containing C. aurantium extract are frequently touted, while conversely, millions of doses of dietary supplements have been consumed by possibly millions of individuals in recent years. Furthermore, millions of people consume on a daily basis various juices and food products from Citrus species that contain p-synephrine. This review summarizes current information regarding the safety of C. aurantium (bitter orange) extract and p-synephrine based on human, animal and in vitro assessments as well as receptor binding and mechanistic studies. The data indicate that based on current knowledge, the use of bitter orange extract and p-synephrine appears to be exceedingly safe with no serious adverse effects being directly attributable to these ingredients.

Effect of acute administration of an herbal preparation on blood pressure and heart rate in humans

Confusion and controversy exist regarding the cardiovascular effects of dietary supplements containing caffeine and Citrus aurantium (bitter orange) extract. The primary protoalkaloidal ingredient in bitter orange extract is p-synephrine which has some structural similarities to ephedrine and nor-epinephrine, but exhibits markedly different pharmacokinetic and receptor binding properties. The goal of this study was to investigate the cardiovascular effects of a product containing caffeine, bitter orange extract (p-synephrine) and green tea extract in mildly overweight individuals. Fourteen female and nine male subjects (age 24.7 ±7.4 yrs, BMI: 26.6 ±3.8) volunteered in this randomized, placebo-controlled, crossover, double-blind designed study. On day one, subjects entered the laboratory following an overnight fast. Heart rate and blood pressure were recorded at 60 min. Expired air was analyzed for the next 10 min of the session. At each of three meals, subjects ingested one capsule that was either a non-caloric placebo or a dietary supplement that contained 13 mg p-synephrine and 176 mg caffeine. On the following day, the subjects returned and repeated the protocol for data collection beginning 60 min after consuming one capsule of the placebo or the dietary supplement. No effects of the dietary supplement on heart rate, systolic and diastolic blood pressure or mean arterial pressure were observed. No between or within group differences were observed when data were analyzed for gender and caffeine usage. A small but significant decrease in resting respiratory exchange ratio was observed for the low caffeine user group in response to the product containing caffeine and p-synephrine. The results of this study indicate that ingestion of a product containing bitter orange extract, caffeine and green tea extract does not lead to increased cardiovascular stress and that fat oxidation may increase in certain populations.

Blood orange juice inhibits fat accumulation in mice

OBJECTIVE

To analyze the effect of the juice obtained from two varieties of sweet orange (Citrus sinensis L. Osbeck), Moro (a blood orange) and Navelina (a blond orange), on fat accumulation in mice fed a standard or a high-fat diet (HFD).

METHODS

Obesity was induced in male C57/Bl6 mice by feeding a HFD. Moro and Navelina juices were provided instead of water. The effect of an anthocyanin-enriched extract from Moro oranges or purified cyanidin-3-glucoside (C3G) was also analyzed. Body weight and food intake were measured regularly over a 12-week period. The adipose pads were weighted and analyzed histologically; total RNA was also isolated for microarray analysis.

RESULTS

Dietary supplementation of Moro juice, but not Navelina juice significantly reduced body weight gain and fat accumulation regardless of the increased energy intake because of sugar content. Furthermore, mice drinking Moro juice were resistant to HFD-induced obesity with no alterations in food intake. Only the anthocyanin extract, but not the purified C3G, slightly affected fat accumulation. High-throughput gene expression analysis of fat tissues confirmed that Moro juice could entirely rescue the high fat-induced transcriptional reprogramming.

CONCLUSION

Moro juice anti-obesity effect on fat accumulation cannot be explained only by its anthocyanin content. Our findings suggest that multiple components present in the Moro orange juice might act synergistically to inhibit fat accumulation.

The relation between green tea consumption and cardiovascular disease as evidenced by epidemiological studies

Although substantial evidence from in vitro and animal studies indicates that green tea preparations inhibit cardiovascular disease processes, the possible protective role of green tea consumption against this disease in humans remains unclear. We conducted a population-based prospective cohort study (the Ohsaki Study) to examine the association between green tea consumption and mortality from cardiovascular disease (CVD), cancer, and all causes with 40,530 persons in Miyagi prefecture, in northern Japan. Previously published work has shown that green tea consumption was inversely associated with mortality from CVD and all causes. The inverse association of mortality from CVD was more pronounced in women (P = 0.08 for interaction with sex). In women, the multivariate hazard ratios (95% confidence intervals) of CVD mortality across increasing green tea consumption categories were 1.00, 0.84 (0.63-1.12), 0.69 (0.52-0.93), 0.69 (0.53-0.90) (P for trend = 0.004). Within CVD mortality, the stronger inverse association was observed for stroke mortality. Because our observational study has found the inverse association, I report here the results of a review of epidemiological evidence from randomized controlled trials (RCT) of the association between green tea or green tea extracts and CVD risk profiles. More than half of the RCT have demonstrated the beneficial effects of green tea on CVD risk profiles. These results from RCT suggest a plausible mechanism for the beneficial effects of green tea and provide substantial support for our observations.