Etudes Compléments alimentaires : page 85

Evitez de prendre la glucosamine avec la chondroïtine

19/02/2010 | Etudes Compléments alimentaires et Etudes Anti-âge

 

The human pharmacokinetics of oral ingestion of glucosamine and chondroitin sulfate taken separately or in combination
C.G. Jackson, A.H. Plaas, J.D. Sandy, C. Hua, S. Kim-Rolands     Osteoarthritis and Cartilage Volume 18, Issue 3, Pages 297-302 (March 2010)

Objective
As part of the National Institutes of Health (NIH)-sponsored Glucosamine/Chondroitin sulfate Arthritis Intervention Trial (GAIT) our objective here was to examine (1) the pharmacokinetics (PK) of glucosamine (GlcN) and chondroitin sulfate (CS) when taken separately or in combination as a single dose in normal individuals (n=29) and (2) the PK of GlcN and CS when taken as a single dose after 3 months daily dosing with GlcN, CS or GlcN+CS, in patients with symptomatic knee pain (n=28).

Methods
The concentration of GlcN in the circulation was determined by established fluorophore-assisted carbohydrate electrophoresis (FACE) methods. The hydrodynamic size and disaccharide composition of CS chains in the circulation and dosage samples was determined by Superose 6 chromatography and FACE.

Results
We show that circulating levels of CS in human plasma are about 20μg/ml. Most significantly, the endogenous concentration and CS disaccharide composition were not detectably altered by ingestion of CS, when the CS was taken alone or in combination with GlcN. On the other hand, the Cmax (single-dose study) and AUC values (multiple-dose study) for ingested GlcN were significantly reduced by combination dosing with CS, relative to GlcN dosing alone.

Conclusions
We conclude that pain relief perceived following ingestion of CS probably does not depend on simultaneous or prior intake of GlcN. Further, such effects on joint pain, if present, probably do not result from ingested CS reaching the joint space but may result from changes in cellular activities in the gut lining or in the liver, where concentrations of ingested CS, or its breakdown products, could be substantially elevated following oral ingestion. Moreover, since combined dosing of GlcN with CS was found to reduce the plasma levels seen with GlcN dosing alone, any improved pain relief by combination dosing cannot be explained by higher circulating concentrations of GlcN.

Les sels de citrate contre les calculs rénaux

17/02/2010 | Etudes Compléments alimentaires et Etudes Anti-âge

 

Pour les personnes ayant des prédispositions à avoir des calculs rénaux, les médecins disent ce qu’il ne faut pas faire mais ne disent pas ce qu’il faut faire :
Prendre du citrate !

Impact of long-term potassium citrate therapy on urinary profiles and recurrent stone formation.
J Urol. 2009 Mar;181(3):1145-50. Robinson MR, Leitao VA, Haleblian GE, Scales CD Jr, Chandrashekar A, Pierre SA, Preminger GM.

Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina, USA.

PURPOSE: Potassium citrate therapy has become one of the cornerstones of medical stone management. We elucidated the long-term effects of potassium citrate on urinary metabolic profiles and its impact on stone formation rates. MATERIALS AND METHODS: We performed a retrospective cohort study in patients treated at the Comprehensive Kidney Stone Center at our institution between 2000 and 2006. Patients with pre-therapy and post-therapy 24-hour urinary profiles available who remained on potassium citrate for at least 6 months were included in the analysis. RESULTS: Of the 1,480 patients with 24-hour urinary profiles 503 met study inclusion criteria. Mean therapy duration was 41 months (range 6 to 168). Overall a significant and durable change in urinary metabolic profiles was noted as soon as 6 months after the onset of therapy. These changes included increased urinary pH (5.90 to 6.46, p <0.0001) and increased urinary citrate (470 to 700 mg a day, p <0.0001). The stone formation rate also significantly decreased after the initiation of potassium citrate from 1.89 to 0.46 stones per year (p <0.0001). There was a 68% remission rate and a 93% decrease in the stone formation rate. CONCLUSIONS: Potassium citrate provides a significant alkali and citraturic response during short-term and long-term therapy with the change in urinary metabolic profiles sustained as long as 14 years of treatment. Moreover, long-term potassium citrate significantly decreases the stone formation rate, confirming its usefulness in patients with recurrent nephrolithiasis.

Les anti-oxydants retardent-ils la récupération ?

17/02/2010 | Etudes Compléments alimentaires

 

Antioxidants Do Not Prevent Postexercise Peroxidation and May Delay Muscle Recovery Medicine & Science in Sports & Exercise: September 2009 - Volume 41 - Issue 9 - pp 1752-1760
TEIXEIRA, VITOR H.; VALENTE, HUGO F.; CASAL, SUSANA I.; MARQUES, A. FRANKLIM; MOREIRA, PEDRO A.

Purpose: This study aimed to determine the effects of 4 wk of antioxidants (AOX) supplementation on exercise-induced lipid peroxidation, muscle damage, and inflammation in kayakers. Methods: Subjects (n = 20) were randomly assigned to receive a placebo (PLA) or an AOX capsule (AOX; 272 mg of α-tocopherol, 400 mg of vitamin C, 30 mg of β-carotene, 2 mg of lutein, 400 μg of selenium, 30 mg of zinc, and 600 mg of magnesium). Blood samples were collected at rest and 15 min after a 1000-m kayak race, both before and after the supplementation period, for analysis of α-tocopherol, α-carotene, β-carotene, lycopene, lutein plus zeaxanthin, vitamin C, uric acid, total AOX status (TAS), thiobarbituric reactive acid substances (TBARS) and interleukin-6 (IL-6) levels, and creatine kinase (CK), superoxide dismutase (SOD), glutathione reductase (Gr), and glutathione peroxidase (GPx) activities. Results: With supplementation, plasma α-tocopherol (P = 0.003) and β-carotene (P = 0.007) augmented significantly in the AOX group. IL-6 (exercise, P = 0.039), TBARS (exercise, P < 0.001), and uric acid (exercise, P = 0.032) increased significantly in response to the exercise regardless of treatment group. Cortisol level raised more from pre- to postsupplementation period in the PLA group (time × supplementation, P = 0.002). Although TAS declined after exercise before intervention, it increased above preexercise values after the 4-wk period in the AOX group (supplementation × time × exercise, P = 0.034). CK increased after exercise in both groups (exercise effect, P < 0.001) and decreased from week 0 to week 4 more markedly in the PLA group (supplementation × time, P = 0.049). Conclusions: AOX supplementation does not offer protection against exercise-induced lipid peroxidation and inflammation and may hinder the recovery of muscle damage.

Oméga-3, les nouvelles règles européennes

16/02/2010 | Etudes Compléments alimentaires

 

Pour dire qu’un aliment contient des oméga-3, il doit renfermer 40 mg d’EPA + DHA par 100 g (en fait, une larme).
S’il en contient le double, le produit peut être qualifié de riche en oméga-3, du pigeonnage industriel quoi.
Merci le technocrate !

Créatine et myostatine

05/02/2010 | Etudes Compléments alimentaires

 

Chez des hommes non-entraînés, une cure de 8 semaines de créatine (0,05g par kg après charge) augmente de 50 % l’inhibition de la production de myostatine induite par la musculation. Par contre, la créatine n’a pas d’influence sur le niveau de GASP-1 (un bloqueur naturel de myostatine).

Effects of oral creatine and resistance training on serum myostatin and GASP-1
Molecular and Cellular Endocrinology 317 (2010) 25–30

Myostatin is a catabolic regulator of skeletal muscle mass. The purpose of this study was to determine
the effect of resistance training for 8 weeks in conjunction with creatine supplementation on muscle
strength, lean body mass, and serum levels of myostatin and growth and differentiation factor-associated
serum protein-1 (GASP-1). In a double-blinded design 27 healthy male subjects (23.42±2.2 years) were
assigned to control (CON), resistance training + placebo (RT + PL) and resistance training + creatine supplementation
(RT + CR) groups. The protocol consisted of 3 days per week of training for 8 weeks, each
session including three sets of 8–10 repetitions at 60–70% of 1 RM for whole-body exercise. Blood sampling,
muscular strength testing and body composition analysis (full body DEXA) were performed at 0,
4th and 8th weeks. Myostatin and GASP-1 was measured. Resistance training caused significant decrease
in serum levels of myostatin and increase in that of GASP-1. Creatine supplementation in conjunction
with resistance training lead to greater decreases in serum myostatin, but had not additional
effect on GASP-1. The effects of resistance training on serum levels of myostatin and GASP-1,
may explain the increased muscle mass that is amplified by creatine supplementation.

Le NO, bon pour les muscles

02/02/2010 | Etudes Musculation et Etudes Compléments alimentaires

 

Cette étude montre le rôle essentiel du NO pour la masse musculaire, pour le force et contre la fatigue.

Mais quand est-ce que plus de NO devient trop de NO ?

Journal of Clinical Investigation

Glucosamine et chondroïtine réduisent certains cancers

27/01/2010 | Etudes Compléments alimentaires et Etudes Anti-âge

 

Associations of Herbal and Specialty Supplements with Lung and Colorectal Cancer Risk in the VITamins And Lifestyle Study
Jessie A. Satia,1,2,3,4 Alyson Littman,5,6 Christopher G. Slatore,7 Cancer Epidemiol Biomarkers Prev 2009;18(5):1419-28

Millions of Americans use dietary supplements with little knowledge about their benefits or risks. We examined associations of various herbal/specialty supplements with lung and colorectal cancer risk. Men and women, 50 to 76 years, in the VITamins And Lifestyle cohort completed a 24-page baseline questionnaire that captured duration (years) and frequency (days per week) of use of commonly used herbal/specialty supplements. Dose was not assessed due to the lack of accurate potency information. Supplement exposure was categorized as ‘‘no use’’ or ‘‘any use’’ over the previous 10 years. Hazard ratios (HR) were estimated by multivariate Cox regression models. Incident lung (n = 665) and colorectal cancers (n = 428) were obtained from the Surveillance, Epidemiology, and End Results cancer registry.

Any use of glucosamine and chondroitin, which have anti-inflammatory properties, over the previous 10 years, was associated with significantly lower lung cancer risk: HR 0.74 [95% confidence interval (95% CI), 0.58-0.94] and HR 0.72 (95% CI, 0.54-0.96) and colorectal cancer risk: HR 0.73 (95% CI, 0.54-0.98) and HR 0.65 (95% CI, 0.45-0.93),respectively.

There were also statistically significantly inverse associations of fish oil: HR 0.65 (95% CI, 0.42-0.99), methylsulfonylmethane: HR 0.46 (95% CI,
0.23-0.93), and St. John’s wort: HR 0.35 (95% CI, 0.14-0.85) with colorectal cancer risk. In contrast, garlic pills were associated with a statistically significant
35% elevated colorectal cancer risk. These results suggest that some herbal/specialty supplements may be associated with lung and colorectal cancer risk;
however, these products should be used with caution. Additional studies examining the effects of herbal/specialty supplements on risk for cancer and other
diseases are needed.

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