A Pilot Clinical Trial on L-Carnitine Supplementation in Combination with Motivation Training: Effects on Weight Management in Healthy Volunteers

A 4-week low dosage (500 mg/day) L-carnitine supplementation in combination with motivation training was carried out in 24 overweight (BMI 25.8 - 26.6 kg/m2) Japanese males in the course of a double-blind randomized placebo-controlled study. L-carnitine motivated group showed significant body weight loss and a decrement of serum triglyceride level vs. the non-motivated placebo group. Serum adiponectin levels increased in both L-carnitine supplemented groups. The beneficial effects of L-carnitine were amplified by motivation training. For clinical evaluation of supplements, whose efficacy is potentially affected by inter-individual life style variability, supportive motivation training might be advisable for future clinical trials.

L-Carnitine Contents in the Tissues of Rabbits Fed Urea as an Alternative of Dietary Protein

The present study was aimed to observe the effects of urea ingestion, non-protein nitrogen, on the disorder of nitrogen metabolism with the L-carnitine contents using the blood, kidney, liver, and femoral muscle as markers. A total of 8 Japanese white rabbits were used in this experiment. They were fed a basal diet prepared for the control group and the nitrogen volume proportionated to one-third of CP 14%, was replaced with urea in the feed of the experimental group for 7 days. On the final day, the animals were fasted from the previous evening and sacrificed. Blood was collected into a test tube at the same time of the sacrifice and their heart, kidney, liver and femoral muscle were collected. The L-carnitine contents in each sample and the urea in the blood were determined. The results of the growth test showed that there was no significant difference. Furthermore, there was no significant difference in the contents of L-carnitine and urea in each sample. It was concluded that nitrogen replacement of the diet with urea, in the range of 1/3 of dietary protein, had neither effect on the maintenance of body weight nor nitrogen balance, including the de novo synthesis of L-carnitine.

Relationship between Serum L-Carnitine Levels and Sperm Parameters in Boars

This study evaluated the relationship between serum L-carnitine level and sperm parameters in young boars. Serum L-carnitine and semen characteristics were determined for 61 young Duroc boars between the ages of 590 and 630 days. Multiple linear regression analysis was performed to predict total and progressive motility and the total number of spermatozoa based on serum total L-carnitine and free L-carnitine levels. Total number of spermatozoa was not associated with basal serum L-carnitine levels. A regression equation was found in which both total L-carnitine levels and free L-carnitine levels were significant predictors of total and progressive motility (P 0.05). These results suggest that serum L-carnitine level is an important selection parameter for stock boars.

Effects of L-carnitine and Branched-Chain Amino Acids on Energy Metabolism,Body Composition,and Delayed-Onset Muscle Soreness after Exercise in Healthy Subjects

Background Specific nutrients combined with exercise may prevent a loss of lean body mass and consequently prevent sarcopenia.We examined the effects of 2 weeks of supplementation with L-carnitine and a single dose of branched-chain amino acids(BCAAs)on energy metabolism and body composition before and after exercise and on post-exercise muscle soreness in healthy subjects.Methods A total of 12 young,untrained,healthy women were randomly assigned to two groups who received either 2 weeks of supplementation with L-carnitine(1000 mg/day)and a single dose of BCAAs plus 200 kcal energy(LCAR+BCAA group,n=6)or 200 kcal energy alone(control group,n=6)before 60 min of exercise.Energy substrate metabolism and body composition by bio-impedance were examined before and after exercise.Delayed-onset muscle soreness(DOMS)was evaluated by using a visual analogue scale for 3 days after exercise.Results Serum concentrations of free and acyl-L-carnitine in the LCAR+BCAA group were not significantly different from those in the control group.There were no significant differences in body composition before or after exercise between the two groups.Although serum free fatty acid levels 120 min after the oral ingestion of BCAAs were significantly lower in the LCAR+BCAA group than in the control group,there were no significant differences in serum free fatty acid levels immediately after and 60 min after exercise.DOMS for 3 days after exercise was lower in the LCAR+BCAA group than in the control group,but this difference was not significant.Conclusion Continuous supplementation with L-carnitine combined with a dose of BCAAs in young,untrained,healthy subjects caused a blunted response of stimulated lipolysis after exercise.