L-Carnitine Research

February 10, 2012 Written by JP    [Font too small?]

In last week’s interview with Jonny Bowden, the good doctor mentioned L-carnitine as a noteworthy supplement that benefits heart health. A recent review in the journal Current Drug Metabolism concurs and describes several mechanisms that make this so. Among them, the authors cite carnitine’s ability to transport “fatty acids into the mitochondrial matrix, thus allowing the cells to break down fat and get energy from stored fat reserves”. They go on to report that carnitine reduces oxidative stress and may, therefore, be a helpful adjunct in conditions including angina, heart failure and even overweight. But, this “endogenous molecule” has plenty to offer beyond the confines of the cardiovascular system.

Far and away, beef is the richest food source of L-carnitine. However, the benefits of carnitine are not exclusively available to carnivores and omnivores. The body is capable of manufacturing carnitine when adequate amounts of L-lysine, an essential amino acid, are consumed. Thankfully for vegetarians, lysine is present in many plant-based foods such as lentils, peas and soybeans. In addition, carnitine supplements are affordable, widely available and frequently offered in a vegetarian friendly format (i.e. liquids, tablets or vegetarian capsules).

Emerging research indicates that three prevalent conditions and diseases may be aided by the use of therapeutic amounts of L-carnitine. Recent studies reveal that asthmatics often have lower plasma concentrations of free and total carnitine compared to healthy subjects. When researchers treat asthmatic children with carnitine, select measures of asthma control and pulmonary function improve. Supplementing with up to 4 grams/day of L-carnitine has likewise been shown to: a) enhance blood sugar control, lower insulin production and reduce associated hypertension in those with insulin resistance and; b) improve treatment compliance and outcomes, while reducing side effects in patients receiving conventional treatment (interferon-a 2b plus ribavirin) for chronic hepatitis C.

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

To learn more about the studies referenced in today’s column, please click on the following links:

Study 1 – L-Carnitine – Metabolic Functions and Meaning in Humans Life (link)

Study 2 – Serum Total and Free Carnitine Levels in Children with Asthma (link)

Study 3 – The Role of L-Carnitine in Treatment of a Murine Model of Asthma (link)

Study 4 – L-Carnitine Improves the Asthma Control in Children with Moderate (link)

Study 5 – Role of Carnitine in the Regulation of Glucose Homeostasis and … (link)

Study 6 – Oral Acetyl-l-Carnitine Therapy and Insulin Resistance (link)

Study 7 – Caloric Restriction and L-Carnitine Administration Improves Insulin (link)

Study 8 – L-Carnitine Supplementation Improves Hematological Pattern (link)

Study 9 – Plasma Carnitine is Associated with Fatigue in Chronic Hepatitis C (link)

Study 10 – The Supplementation of Acetyl-l-Carnitine Decreases Fatigue and (link)

L-Carnitine Supplementation May Improve Hepatitis C Treatment Response

Source: World J Gastroenterol. 2011 October 21; 17(39): 4414–4420. (link)

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Posted in Children's Health, Diabetes, Nutritional Supplements

6 Comments & Updates to “L-Carnitine Research”

  1. JP Says:

    Update: Carnitine supplementation reduces CAD-related inflammation …


    Nutrition. 2015 Mar;31(3):475-9.

    Antiinflammatory effects of l-carnitine supplementation (1000 mg/d) in coronary artery disease patients.

    OBJECTIVE: Inflammation mediators have been recognized as risk factors for the pathogenesis of coronary artery disease (CAD). The purpose of this study was to investigate the effect of l-carnitine supplementation (LC, 1000 mg/d) on inflammation markers in patients with CAD.

    METHODS: We enrolled 47 patients with CAD in the study. The patients with CAD were identified by cardiac catheterization as having <50% stenosis of one major coronary artery. The patients were randomly assigned to the placebo (n = 24) and LC (n = 23) groups and the intervention was administered for 12 wk. The levels of LC, antioxidant status (malondialdehyde and antioxidant enzymes activities), and inflammation markers (C-reactive protein [CRP], interleukin [IL]-6, and tumor necrosis factor [TNF]-α) were measured.

    RESULTS: Thirty-nine participants completed the study (19 placebo; 20 LC). After LC supplementation, the levels of inflammation markers were significantly reduced compared with the baseline (CRP, P < 0.01; IL-6, P = 0.03; TNF-α, P = 0.07) and those in the placebo group (CRP, P < 0.05; IL-6, P = 0.04; TNF-α, P = 0.03). The levels of inflammation markers were significantly negatively correlated with the levels of LC and antioxidant enzymes activities (P < 0.05). CONCLUSIONS: We suggest that LC supplementation, due to its antioxidant effects, may have potential utility to reduce inflammation in CAD. Be well! JP

  2. JP Says:

    Update 06/13/15:


    Int Surg. 2015 May 7.

    L-carnitine supplementation reduces short-term neutrophil-lymphocyte ratio in patients undergoing coronary artery bypass grafting.

    OBJECTIVE: We aimed to investigate whether L-carnitine supplementation effects the neutrophil/lymphocyte ratio in patients undergoing coronary artery bypass grafting.

    SUMMARY OF BACKGROUND DATA: The neutrophil/lymphocyte ratio is an inflammatory marker that has proven usefulness for predicting postoperative complications in coronary artery bypass surgery. A lot of studies concerning the role of L-carnitine in the immune system have been performed, contradictory results have been reported on its effects on absolute numbers of WBC subtypes.

    METHODS: This study was conducted among patients scheduled for coronary artery bypass grafting. A total of 60 consecutive patients were divided into two groups. The first group received 2 g of L-carnitine in 1000 mL of 0.9% saline solution over 24 hours for each of the three preoperative days (L-carnitine group, n=30), or only 1000 mL of 0.9% saline solution for the same time period (placebo group, n=30).

    RESULTS: The basal values of leukocyte, neutrophil, lymphocyte counts and neutrophil to lymphocyte ratio were similar in the two groups. After L-Carnitine supplementation leukocyte and neutrophil counts of the L-carnitine group were significantly lower than those of the placebo group (7.7±1.5 vs. 9.7±2.6, p<0.001 and 4.6±1.3 vs. 6.5±2.2, p<0.001). On the first postoperative day, lymphocyte counts were significantly higher in the L-carnitine group (1.1±0.6 vs. 0.8±0.9, p<0.001). The increase in neutrophil to lymphocyte ratio was significantly lower in the L-carnitine group at the first postoperative day (20.7±13.8 vs. 10.8±4.1, p<0.001).

    CONCLUSIONS: Preoperative L-carnitine supplementation may reduce neutrophil-lymphocyte ratio during the early postoperative period of coronary artery bypass grafting surgery.

    Be well!


  3. JP Says:

    Update 06/30/15:


    Nutrition Research Published Online: June 15, 2015

    L-Carnitine supplementation improved clinical status without changing oxidative stress and lipid profile in women with knee osteoarthritis

    Considering the pathologic importance of oxidative stress and altered lipid metabolism in osteoarthritis (OA), this study aimed to investigate the effect of L-carnitine supplementation on oxidative stress, lipid profile and clinical status in females with knee OA. We hypothesized that L-carnitine would improve clinical status by modulating serum oxidative stress and lipid profile. In this randomized double-blind placebo-controlled trial, seventy-two overweight or obese females with mild to moderate knee osteoarthritis were randomly allocated into two groups to receive 750 mg/day L-carnitine or placebo for 8 weeks. Dietary intake was evaluated using 24-hour recall for 3 days; Serum malondialdehyde (MDA), total antioxidant capacity (TAC) and lipid profile, visual analog scale for pain intensity and patient global assessment of severity of disease were assessed before and after supplementation. Only 69 patients (33 in L-carnitine and 36 in placebo group) completed the study. L-carnitine supplementation resulted in significant reductions in serum MDA (2.46±1.13 vs 2.16±0.94nmol/ml), total cholesterol (216.09±34.54 vs 206.12±39.74mg/dl), and LDL-C (129.45±28.69 vs 122.05±32.76mg/dl) levels, compared to baseline(P<0.05); whilst these parameters increased in placebo group. Serum triglyceride, HDL-C and TAC levels didn’t change significantly in both groups(P>0.05). No significant differences were observed in dietary intake, serum lipid profile, MDA and TAC levels between groups after adjusting for baseline values and covariates(P>0.05). There were significant intra- and inter-group differences in pain intensity and patient global assessment of disease status after supplementation(P<0.05). Collectively, L-carnitine improved clinical status without changing oxidative stress and lipid profile significantly in women with knee OA.

    Be well!


  4. JP Says:

    Updated 12/17/15:


    Clin Endocrinol (Oxf). 2015 Dec 15.

    Oral carnitine supplementation reduces body weight and insulin resistance in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial.

    OBJECTIVE: Limited data are available evaluating the effects of oral carnitine supplementation on weight loss and metabolic profiles of women with polycystic ovary syndrome (PCOS). This study was designed to determine the effects of oral carnitine supplementation on weight loss, and glycaemic and lipid profiles in women with PCOS.

    DESIGN, PATIENTS AND MEASUREMENTS: In a prospective, randomized, double-blind, placebo-controlled trial, 60 overweight patients diagnosed with PCOS were randomized to receive either 250 mg carnitine supplements (n=30) or placebo (n=30) for 12 weeks. Fasting blood samples were obtained at the beginning and end of the study to quantify parameters of glucose homeostasis and lipid concentrations.

    RESULTS: At the end of the 12 weeks, taking carnitine supplements resulted in a significant reduction in weight (-2.7±1.5 vs. +0.1±1.8 kg, P<0.001), BMI (-1.1±0.6 vs. +0.1±0.7 kg/m2 , P<0.001), waist circumference (WC) (-2.0±1.3 vs. -0.3±2.0 cm, P<0.001) and hip circumference (HC) (-2.5±1.5 vs. -0.3±1.8 cm, P<0.001) compared with placebo. In addition, compared with placebo, carnitine administration in women with PCOS led to a significant reduction in fasting plasma glucose (-0.38±0.36 vs. +0.11±0.97 mmol/L, P=0.01), serum insulin levels (-14.39±25.80 vs. +3.01±37.25 pmol/L, P=0.04), homeostasis model of assessment-insulin resistance (-0.61±1.03 vs. +0.11±1.43, P=0.04) and dehydroepiandrosterone sulfate (-3.64±7.00 vs. -0.59±3.20 μmol/L, P=0.03).

    CONCLUSIONS: Overall, 12 weeks of carnitine administration in PCOS women resulted in reductions in weight, BMI, WC and HC, and beneficial effects on glycaemic control; however, it did not affect lipid profiles or free testosterone.

    Be well!


  5. JP Says:

    Updated 03/07/16:


    J Am Coll Nutr. 2016 Mar 2:1-7.

    Effects of l-Carnitine Supplementation on Serum Inflammatory Factors and Matrix Metalloproteinase Enzymes in Females with Knee Osteoarthritis: A Randomized, Double-Blind, Placebo-Controlled Pilot Study.

    OBJECTIVE: Considering the importance of inflammation in the pathogenesis of osteoarthritis (OA) and induction of pain, this study was aimed to investigate the effect of L-carnitine supplementation on serum inflammatory mediators and OA-associated pain in females with knee OA.

    METHODS: In this clinical trial, 72 females with mild to moderate knee osteoarthritis started the study, divided into 2 groups to receive 750 mg/day L-carnitine (n = 36) or placebo (n = 36) for 8 weeks. Serum levels of Interleukine-1β (IL-1β), high-sensitivity C-reactive protein (hs-CRP), matrix metalloproteinases (MMPs)-1 and -13, and visual analog scale (VAS) for pain were assessed before and after supplementation. Data were analyzed by t test, Wilcoxon signed rank test, Mann-Whitney U test, and analysis of covariance.

    RESULTS: Only 69 patients (33 in the L-carnitine group and 36 in the placebo group) completed the study. L-Carnitine supplementation decreased serum IL-1β and MMP-1 levels significantly (p = 0.001 and p = 0.021, respectively); however, serum hs-CRP and MMP-13 levels did not change significantly (p > 0.05). In the placebo group, serum IL-1β levels increased significantly (p = 0.011), whereas other studied biomarkers did not change significantly. The mean VAS score decreased significantly in the L-carnitine and placebo groups by 52.67% and 21.82%, respectively (p < 0.001). Significant differences were only observed between the 2 groups in serum IL-1β (p < 0.001) and MMP-1 (p = 0.006) levels and mean VAS score (p = 0.002) after adjusting for baseline values and covariates. CONCLUSION: Despite observed beneficial effects of short-term supplementation of L-carnitine in decreasing serum inflammatory mediators and improving pain in knee OA patients, further studies are needed to achieve concise conclusions. Be well! JP

  6. JP Says:

    Updated 08/18/18:


    Hepatol Commun. 2018 Aug 6;2(8):906-918.

    L-Carnitine Suppresses Loss of Skeletal Muscle Mass in Patients With Liver Cirrhosis.

    Liver cirrhosis (LC) is a major cause of secondary sarcopenia. Sarcopenia makes the prognosis worse; thus, novel therapeutic options for sarcopenia in patients with LC are urgently required as they are currently limited. In this retrospective study, 158 patients with LC were screened, and 35 of those patients who were treated with L-carnitine for more than 6 months and for whom skeletal muscle mass changes could be evaluated by computer tomography were enrolled. Of the 158 patients, 79 patients who did not receive L-carnitine supplementation served as controls. Cases and controls were propensity score matched for age, sex, presence of hepatocellular carcinoma, and branched chain amino acid administration, and changes in skeletal muscle mass and clinical data were compared. The 35 patients who received L-carnitine supplementation and 35 propensity score-matched patients who did not receive carnitine supplementation comprised the final enrollment. Compared with control patients, patients who received L-carnitine had significantly worse liver function, which is associated with rapid progress of skeletal muscle depletion. However, loss of skeletal muscle mass was significantly suppressed in patients receiving L-carnitine, and a significant effect was observed in patient subgroups stratified by age, sex, presence of hepatocellular carcinoma, and branched chain amino acid administration. The change ratios of most laboratory data, including vitamin D and insulin-like growth factor 1 levels, were similar in the two groups, but ammonia levels were significantly less in those receiving L-carnitine. However, even in patients receiving L-carnitine but not showing an ammonia decrease, loss of skeletal muscle was significantly suppressed. Conclusion: L-carnitine suppresses loss of skeletal muscle mass and may therefore be a novel therapeutic option for sarcopenia in patients with LC.

    Be well!


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