Wellness Database: Carnitine
Carnitine is an amino acid that may improve athletic performance and prevent fatigue.
L-carnitine May Improve Function in Children with Asthma
Summary: L-Carnitine level and the effects of its supplementation in children with moderate persistent asthma (MPA) were investigated in a randomized, double-blind, placebo-controlled trial over 6 consecutive months. Patients were children with MPA (n=50) and a control group of healthy children (n=50.) Subjects received either L-carnitine or placebo and received pulmonary function tests (PFT) and childhood-asthma control test (C-ACT) before and 6 months after carnitine supplementation. Initial L-carnitine levels were significantly lower in the patient group as compared to the control group. PFT and C-ACT showed significant improvements in asthmatic children supplemented with L-carnitine, as compared to placebo. Findings suggest L-carnitine supplementation may lead to improvement of C-ACT and PFT in children with MPA.
Cardiovascular Supplements May Benefit Male Sexual Function
Summary: In this study, the authors found that supplementation with nutraceuticals that exert favorable cardiovascular effects may also exert benefits on male sexual function. Researchers carried out a single-blind, one-arm study to evaluate the effects of 3-month supplementation with propionyl-L-carnitine, L-arginine and niacin in a group of 54 men (35-75 y) with untreated erectile dysfunction (ED), on their sexual performance. Patients had the short-international index of erectile function (IIEF) questionnaire, global assessment questions (GAQs) and routine laboratory testing, at baseline and 3 months afterward. Fifty-one (92%) patients of 54 completed the entire study period. After 3 months of treatment, a small, but statistical significant improvement in total and single items of the IIEF was found (D = 5.7 +/- 4.1 P < 0.01). Analyses on GAQs revealed that treatment improved erections in 40% of cases, with a partial response occurring in up to 77% of enrolled subjects. These preliminary findings indicate that the favorable cardiovascular effects of nutraceuticals might also reflect on male sexual function with possible implications for the treatment and prevention of ED.
Supplementation for a Metabolic Tune Up
An optimum intake of micronutrients and metabolites, which varies with age and genetic constitution, would tune up metabolism and give a marked increase in health, particularly for the poor, young, obese, and elderly, at little cost. (1) DNA damage. Deficiency of vitamins B-12, folic acid, B-6, C or E, or iron or zinc appears to mimic radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions or both. Half of the population may be deficient in at least one of these micronutrients. (2) The Km concept. Approximately 50 different human genetic diseases that are due to a poorer binding affinity (Km) of the mutant enzyme for its coenzyme can be remedied by feeding high-dose B vitamins, which raise levels of the corresponding coenzyme. Many polymorphisms also result in a lowered affinity of enzyme for coenzyme. (3) Mitochondrial oxidative decay. This decay, which is a major contributor to aging, can be ameliorated by feeding old rats the normal mitochondrial metabolites acetyl carnitine and lipoic acid at high levels. Many common micronutrient deficiencies, such as iron or biotin, cause mitochondrial decay with oxidant leakage leading to accelerated aging and neural decay.
Arch Biochem Biophys. 2004 Mar 1;423(1):227-34.
Carnitine Reduces Diabetes Risks
Objective: Aim of the present study is to evaluate the effects of L-carnitine on insulin-mediated glucose uptake and oxidation in type II diabetic patients and compare the results with those in healthy controls.
Design: Fifteen type II diabetic patients and 20 healthy volunteers underwent a short-term (2 hours) euglycemic hyperinsulinemic clamp with simultaneous constant infusion of L-carnitine (0.28 μmole/kg bw/minute) or saline solution. Respiratory gas exchange was measured by an open-circuit ventilated hood system. Plasma glucose, insulin, non-esterified fatty acids (NEFA) and lactate levels were analyzed. Nitrogen urinary excretion was calculated to evaluate protein oxidation.
Results: Whole body glucose uptake was significantly (p<0.001) higher with L-carnitine than with saline solution in the two groups investigated (48.66±4.73 without carnitine and 52.75±5.19 μmoles/kgffm/minute with carnitine in healthy controls, and 35.90±5.00 vs. 38.90±5.16 μmoles/kgffm/minute in diabetic patients). Glucose oxidation significantly increased only in the diabetic group (17.61±3.33 vs. 16.45±2.95 μmoles/kgffm/minute, p<0.001). On the contrary, glucose storage increased in both groups (controls: 26.36±3.25 vs. 22.79±3.46 μmoles/kgffm/minute, p<0.001; diabetics: 21.28±3.18 vs. 19.66±3.04 μmoles/kgffm/minute, p<0.001). In type II diabetic patients, plasma lactate significantly decreased during L-carnitine infusion compared to saline, going from the basal period to the end-clamp period (0.028±0.0191 without carnitine and 0.0759±0.0329 with carnitine, p<0.0003).
Conclusions: L-carnitine constant infusion improves insulin sensitivity in insulin resistant diabetic patients; a significant effect on whole body insulin-mediated glucose uptake is also observed in normal subjects. In diabetics, glucose, taken up by the tissues, appears to be promptly utilized as fuel since glucose oxidation is increased during L-carnitine administration. The significantly reduced plasma levels of lactate suggest that this effect might be exerted through the activation of pyruvate dehydrogenase, whose activity is depressed in the insulin resistant status.
J Am Coll Nutr February 1999 vol. 18 no. 1 77-82
Carnitine Reduces Oxidative Stress
In a study involving 12 healthy subjects, supplementation with liquid L-carnitine (2.0 g) as a single dose was found to be associated with increases in the activities of antioxidant enzymes and total antioxidant capacity (TAC). Specifically, a gradual increase in plasma concentrations of superoxide dismutase, gluatathione peroxidase, catalase, and total antioxidative capacity in the 3.5 hours following L-carnitine administration was found, and plasma concentrations of SOD, GSH-Px, catalase, and T-AOC returned to baseline within 24 hours. A positive association was found between L-carnitine concentration and the antioxidant index of SOD, GSH-Px, catalase, or T-AOC. The authors conclude, "...L-carnitine increases activities of antioxidant enzymes and the total antioxidant capacity in healthy subjects. It may be useful as a supplementary therapy for chronic illnesses involving excessive oxidative stress."
"Single dose administration of L-carnitine improves antioxidant activities in healthy subjects," Cao Y, Qu HJ, et al, Tohoku J Exp Med, 2011; 224(3): 209-13. (Address: Department of Pharmacy, the Affiliated Hospital of Medical College, Qingdao University).
Carnitine Improves Chronic Fatigue
Summary: In a cross-sectional, observational study involving 44 patients with chronic fatigue syndrome (CFS) and 49 age- and gender-matched healthy controls, patients with CFS were found to have significantly altered plasma concentrations of various acylcarnitine concentrations, most significantly, oleyl-L-carnitine and linoleyl-L-carnitine, which were approximately 30-40% lower. The authors discuss how carnitine has been suggested to be involved in chronic fatigue syndrome through its critical role in production of cellular energy in the mitochondria. The authors conclude, "It is proposed that this disturbance in carnitine homeostasis is a result of a reduction in carnitine palmitoyltransferase-I (CPT-I) activity, possibly due to the accumulation of omega-6 fatty acids previously observed in this patient population. It is hypothesised that the administration of omega-3 fatty acids in combination with L-carnitine would increase CPT-I activity and improve chronic fatigue syndrome symptomology.
Reference: "Long-chain acylcarnitine deficiency in chronic fatigue syndrome patients. Potential involvement of altered carnitine palmitoyltransferase-I activity," Reuter SE, Evans AM, J Intern Med, 2010 Dec 22; [Epub ahead of print]. (Address: School of Pharmacy & Medical Sciences Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia).
Carnitine Improves Exercise Performance
Summary: In a randomized, double-blind study involving 14 healthy male volunteers, intravenous L-carnitine infusion following exercise was found to be associated with improvements in exercise metabolism and performance. Subjects performed an exercise test on 3 occasions, 12 weeks apart: one consisting of 30 minutes of cycling at 50% VO2max, the second consisting of 30 mins at 80% VO2max, and a third 30 min work output performance trial. Following the visits, volunteers either ingested 2 g of L-carnitine L-tartrate and 80 g of carbohydrate or 80 g of carbohydrate, twice daily, for a period of 24 weeks. Results found that muscle total carnitine increased from basal by 21% in the carnitine group, and remained unchanged in the control group. Carnitine increaesed work output by 11% as compared to baseline. The authors conclude, "This is the first demonstration that human muscle TC can be increased by dietary means and results in muscle glycogen sparing during low intensity exercise (consistent with an increase in lipid utilisation) and a better matching of glycolytic, PDC and mitochondrial flux during high intensity exercise, thereby reducing muscle anaerobic ATP production. Furthermore, these changes were associated with an improvement in exercise performance."
Carnitine Supplementation Improves Metabolism and Exercise Performance
Research published this year in The Journal of Physiology found that when taking L-carnitine following exercise, there were significant improvements in exercise metabolism and performance.
In a randomized, double-blind study involving 14 healthy male volunteers, intravenous L-carnitine infusion following exercise was found to be associated with improvements in exercise metabolism and performance. Subjects performed an exercise test on 3 occasions, 12 weeks apart: one consisting of 30 minutes of cycling at 50% VO2max, the second consisting of 30 mins at 80% VO2max, and a third 30 min work output performance trial. Following the visits, volunteers either ingested 2 g of L-carnitine L-tartrate and 80 g of carbohydrate or 80 g of carbohydrate, twice daily, for a period of 24 weeks. Results found that muscle total carnitine increased from basal by 21% in the carnitine group, and remained unchanged in the control group. Carnitine increaesed work output by 11% as compared to baseline. The authors conclude, "This is the first demonstration that human muscle TC can be increased by dietary means and results in muscle glycogen sparing during low intensity exercise (consistent with an increase in lipid utilisation) and a better matching of glycolytic, PDC and mitochondrial flux during high intensity exercise, thereby reducing muscle anaerobic ATP production. Furthermore, these changes were associated with an improvement in exercise performance."
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