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Home > Anti-aging Research > L-Carnitine


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  • Science Reveals How Red Meat Harms the Heart - WebMD, 12/29/21 - "Researchers found that particular gut bacteria, more abundant in red-meat eaters, are key in turning a dietary nutrient called carnitine into a foe: a chemical known as TMAO, which helps promote blood-clotting and clogged arteries ... The traditional suspect was saturated fat, found almost exclusively in animal products. Saturated fat can boost "bad" LDL cholesterol, which contributes to cardiovascular disease ... But, Hazen said, research has shown that any ill effects of saturated fat are not enough to explain the excess heart disease risks linked to heavy red-meat consumption. There had to be other mechanisms ... Hazen, too, said he is a "big supporter" of using diet to change the gut microbiome, rather than adding certain bugs via probiotic supplements ... "Changing your diet changes the soil" that feeds gut microbes ... The researchers also analyzed stool samples from people who took part in the 2019 diet study. They found that when participants were eating a lot of red meat, their stool harbored more of the culprit E. timonensis microbes; when they switched to non-meat protein sources, those microbial levels dropped ... fermented foods like yogurt and kimchi, which contain certain microbes, can be good choices. But again, she stressed, overall diet is what's key in supporting a healthy gut" - What about prebiotics is your goal is to change the soil?
  • Oral Carnitine Supplementation Reduces Body Weight and Insulin Resistance in Women With Polycystic Ovary Syndrome - Medscape, 8/10/16 - "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" - See L-carnitine at Amazon.com.
  • Nutritional supplement boosts muscle stamina in animal studies - Science Daily, 7/7/15 - "The researchers then introduced a carnitine supplement. Exercise tolerance improved only in animals with normal CrAT activity in muscle. Muoio said these results strongly imply that carnitine and the CrAT enzyme work together to optimize muscle energy metabolism during exercise" - See acetyl l-carnitine products at Amazon.com and l-carnitine at Amazon.com.
  • Serum Carnitine Level in Chronic Viral Hepatitis - Medscape, 7/1/14 - "64 out of 86 patients (74.4%) and 21 out of 86 (24.5%) healthy individuals suffered from carnitine deficiency (p < 0.001). Carnitine dietary intake was significantly lower (p < 0.001). Compared with patients with chronic hepatitis C infection, a more severe form of carnitine deficiency was detected in patients with chronic hepatitis B infection (18.39 ± 15.68 μmol/l vs 42.30 ± 32.92 μmol/l; p = 0.03)"
  • Carnitine Supplement May Improve Survival Rates of Children With Heart Defects - Science Daily, 5/8/13 - "The new study indicates that even without fixing the heart defect, high daily doses of carnitine in the first four weeks of life can prevent endothelial dysfunction. In fact, the laboratory lambs' ability to make nitric oxide is preserved even without the benefit of heart surgery and the responses to the chemical activity that enables blood vessel dilation is normalized"
  • L-carnitine significantly improves patient outcomes following heart attack, study suggests - Science Daily, 4/12/13 - "This systematic review of the 13 controlled trials in 3,629 patients, involving 250 deaths, 220 cases of new heart failure, and 38 recurrent heart attacks, found that L-carnitine was associated with: ... Significant 27% reduction in all-cause mortality (number needed to treat 38) ... Highly significant 65% reduction in ventricular arrhythmias (number needed to treat 4) ... Significant 40% reduction in the development of angina (number needed to treat 3) ... Reduction in infarct size ... These findings may seem to contradict those reported in a study published earlier this month in Nature Medicine by Robert A. Koeth and others (link below), which demonstrated that metabolism by intestinal microbiota of dietary L-carnitine produced trimethylamine N-oxide (TMAO) and accelerated atherosclerosis in mice" - Note:  I read that Koeth study and wasn't buying it with all the previous studies I had read.
  • CoQ10 and L-carnitine for Statin Myalgia? - Medscape, 1/4/13 - "In summary, it has been proposed that CoQ10 can help to treat statin myalgia. While this is not conclusive, there are two randomized controlled trials showing significant improvements in the severity of muscle pain with the use of CoQ10 in patients treated with statins. Thus, it is not unreasonable to supplement a patient who is experiencing muscle pains on a statin with CoQ10. While there are no clinical trials showing improvements in muscle pain with the use of l-carnitine, patients who experience statin myalgia frequently have carnitine abnormalities. It is too soon to recommend l-carnitine for statin myalgia, but future trials should test this supplement to see if it has any place for this adverse effect. Other common alternatives for treating statin myalgias are supplementation with vitamin D or vitamin B12, especially in the setting of suboptimal serum levels"
  • Lonza’s L-carnitine may boost exercise recovery: Study - Nutra USA, 8/12/10 - "Blood samples showed that L-carnitine supplementation significantly improved a range of biochemical markers, including purine metabolism, free radical formation, and muscle tissue disruption ... The l-carnitine l-tartrate supplementation therefore reduced both myoglobin and creatine kinase concentrations, providing additional evidence that LCLT reduces post-exercise muscle disruption ... Such findings support the additional findings that l-carnitine l-tartrate significantly reduced muscle soreness immediately after the exercise workout and at 24 and 48 hours postexercise when compared with the placebo condition" - [Abstract]
  • Carnitine Supplements Reverse Glucose Intolerance In Animals - Science Daily, 8/17/09 - "After just eight weeks of supplementation with carnitine, the obese rats restored their cells' fuel- burning capacity (which was shut down by a lack of natural carnitine) and improved their glucose tolerance, a health outcome that indicates a lower risk of diabetes ... These results offer hope for a new therapeutic option for people with glucose intolerance, older people, people with kidney disease, and those with type 2 diabetes (what used to be called adult-onset diabetes) ... Carnitine is a natural compound known for helping fatty acids enter the mitochondria, the powerhouses of cells, where fatty acids are "burned" to give cells energy for their various tasks. Carnitine also helps move excess fuel from cells into the circulating blood, which then redistributes this energy source to needier organs or to the kidneys for removal"
  • L-carnitine linked to better mental function in the very old - Nutra USA, 12/13/07 - "either the daily L-carnitine supplement (two grams, from Sigma Tau) or placebo for six months ... the supplementation with L-carnitine was associated with significant reductions in fat mass, compared to placebo. Indeed, the active supplement group lost 1.6 kg of fat mass, while the placebo group gained 0.6 kg ... Total muscle mass in the L-carnitine-supplemented group increased by three kilograms more than the placebo group ... Cognitive performance, measured using the 30-point Mini-Mental State Examination (MMSE), showed increases of 4.1 points for the L-carnitine group, compared to only 0.6 points on average for the placebo group" - [Abstract]
  • Four powerhouse nutrients - Functional Foods and Nutraceuticals, 4/05 - "L-carnitine shuttles fuel into cells to be burned as energy; coenzyme Q10 sparks the energy within the cells; ribose is a component of adenosine triphosphate (ATP); and alpha-lipoic acid increases ATP levels"
  • Sperm Swim Better With Carnitine - WebMD, 3/9/05 - "The finding could help men coping with fertility issues -- specifically, those men whose sperm don't move very well"
  • New uses for carnitine - Functional Foods and Nutraceuticals, 11/04 - "Because L-carnitine is central to the formation of energy from fat, the heart is therefore dependent on L-carnitine for most of its energy production ... L-Carnipure carries long-chain fatty acids into the mitochondria where they are oxidised for energy. Its ability to generate energy from fat makes carnitine useful as part of a weight management program ... L-carnitine plus its metabolite, acetyl-L-carnitine, can treat symptoms of male ageing, including sexual dysfunction, depressed mood and fatigue"
  • Carnitine Improves Symptoms of Male Aging - Medscape, 4/14/04 - "Carnitine is more active than testosterone for improving symptoms of male aging such as sexual dysfunction, depressed mood, and fatigue ... In this trial, 120 patients were randomized to receive testosterone undecanoate 160 mg/day, propionyl-L-carnitine 2 g/day plus acetyl-L-carnitine 2 g/day, or placebo for six months" [Abstract] - See GPLC at Amazon.com.
  • Better than testosterone? - Life Extension Foundation, 4/19/04 - "The April 2004 issue of the journal Urology published the findings ... Erectile function, sexual desire, sexual satisfaction and nocturnal penile tumescence increased over the course of the study in the group receiving testosterone as well as the group receiving carnitine. In addition, the group receiving carnitine experienced an increase in orgasm and general sexual well-being. Erectile function and nocturnal penile tumescence were significantly more improved in this group than in those receiving testosterone. While both treatments lowered depression scores, carnitine’s effect was greater"
  • L-Carnitine Effective for Attention Deficit-Hyperactivity Disorder - New Hope Natural Media, 12/19/02 - "According to the parents’ ratings, 54% of the children showed significant improvement in their behavior while taking L-carnitine, whereas only 13% improved during the placebo period. The teachers’ ratings showed a similar, though slightly less pronounced, advantage of L-carnitine over placebo" -  Also see acetyl-l-carnitine.
  • The Benefits of Carnitine and DHEA for Fat Metabolism - Life Extension Magazine, 8/02 - "Carnitine is an amino acid that's critical for converting fatty acids into fuel. Because of this, it has the potential to help people lose weight ... A lack of DHEA may be one of the primary causes of insulin resistance"


  • Dietary supplementation of L-carnitine ameliorates metabolic syndrome independent of trimethylamine N-oxide produced by gut microbes in high-fat diet-induced obese mice - Food Funct 2022 Nov 4 - "Metabolic syndrome (MS) ... L-carnitine (0.5%-4%) reduced HFD-caused body-weight gain, visceral adipose tissue, glucose intolerance, hyperglycemia, HOMA-IR index, hyperlipemia, hypertension, and hyperuricemia. The elevation in the concentrations of IL-6, IL-1β, and TNF-α and decline in IL-10 in both serum and adipose tissue were also attenuated by L-carnitine. Furthermore, dietary L-carnitine increased the serum levels of TMAO produced by gut microbes. High-dose L-carnitine (2% and 4%), but not low-dose L-carnitine (0.2%-1%), notably modulated the composition of gut microbiota and partially attenuated HFD-induced gut microbiota dysbiosis. These results suggest that the ameliorative effect of L-carnitine on MS was independent of TMAO production and only partially related to the regulation of gut microbiota. This study provides crucial evidence for the utilization of L-carnitine as a safe and effective supplement for MS" - See L-carnitine at Amazon.com.
  • Serum L-Carnitine Levels Are Associated With First Stroke in Chinese Adults With Hypertension - Stroke 2022 Jun 30 - "The mean level of serum L-carnitine in the stroke population was 4.7 μg/mL, which was significantly lower than that of the control group (5.7 μg/mL). When L-carnitine was assessed as quintiles, compared with the reference group (quintile 1, <3.3 μg/mL), the odds of stroke were 0.62 (95% CI, 0.39-1.00) in quintile 2, 0.66 (95% CI, 0.40-1.10) in quintile 3, 0.47 (95% CI, 0.28-0.81) in quintile 4, and 0.50 (95% CI, 0.30-0.84) in quintile 5. The trend test was significant (P=0.01). When quintiles 2 to 5 were combined, the adjusted odds ratio of first stroke was 0.58 (95% CI, 0.38-0.87) compared with quintile 1"
  • Association Between Plasma L-Carnitine and Cognitive Impairment in Patients with Acute Ischemic Stroke - J Alzheimers Dis 2022 Jan 14 - "L-carnitine has been shown to exert neuroprotective effects on cerebral ischemia, mainly by improving mitochondrial function and reducing inflammation. L-carnitine supplementation has also been promoted to enhance cognitive function ... The study sample population was drawn from the China Antihypertensive Trial in Acute Ischemic Stroke. Plasma L-carnitine were measured at baseline in 617 patients with ischemic stroke using ultrahigh-performance liquid chromatography-tandem mass spectrometry ... Plasma L-carnitine were inversely associated with cognitive impairment at 3 months after ischemic stroke, and the adjusted odds ratio (95% CI) for the highest versus lowest quartiles of L-carnitine was 0.60 (0.37, 0.98; p for trend = 0.04). Each 1-SD increase in log-transformed L-carnitine concentration was significantly associated with a 15% (95% CI: 1%, 29%) reduction in the risk of cognitive impairment after stroke. The addition of L-carnitine to the model including conventional risk factors significantly improved the risk reclassification for cognitive impairment (net reclassification improvement: 17.9%, integrated discrimination improvement: 0.8% ; both p < 0.05). Furthermore, joint effects of L-carnitine and inflammation markers were observed, and patients with higher L-carnitine and a lower inflammatory status simultaneously had the lowest risk of poststroke cognitive impairment"
  • Serum carnitine as a biomarker of sarcopenia and nutritional status in preoperative gastrointestinal cancer patients - J Cachexia Sarcopenia Muscle 2021 Dec 22 - "Sarcopenia is an important factor in the postoperative outcome of gastrointestinal cancer patients ... One hundred fourteen patients scheduled to undergo gastroenterological surgery between August 2016 and January 2017 were enrolled. Their mean age was 68.4 ± 10.5, and 64.9% were male. Serum carnitine fractions [total carnitine (TC), free l-carnitine (FC), and acylcarnitine (AC)] were measured prior to surgery ... This study suggests that carnitine level is a biomarker of sarcopenia and nutritional status"
  • The Effects of Vitamin E, Silymarin and Carnitine on the Metabolic Abnormalities Associated with Nonalcoholic Liver Disease - J Diet Suppl 2021 Jan 25 - "Studies indicate that antioxidant supplementation may improve abnormal liver chemistries, glucose control, and hyperlipidemia, in patients with nonalcoholic fatty liver disease (NAFLD). The primary objective of the study was to determine the normalization of abnormalities in hepatic function testing in patients with NAFLD when treated with vitamin E 200 IU, Silymarin 750 mg, and l-carnitine 1 gram (VSC) for 18 weeks in comparison to a placebo-controlled group ... VSC caused a significant reduction in serum glucose, insulin, and HOMA levels. While there were downtrends in the other measured values these were not statistically significant. In this 18-week study, the ability of this supplement in reducing markers of liver inflammation, glucose, insulin, and triglycerides indicate that this supplement could play an important role in the treatment of nonalcoholic fatty liver disease, diabetes, and the metabolic syndrome" - See Jarrow FamilE (contains all eight members of the vitamin E family, includes Tocomin) at Amazon.com, silymarin at Amazon.com and L-carnitine at Amazon.com.
  • Effects of L-Carnitine Supplementation in Patients Receiving Hemodialysis or Peritoneal Dialysis - Nutrients 2020 Nov 1 - "L-carnitine is an important factor in fatty acid metabolism, and carnitine deficiency is common in dialysis patients. This study evaluated whether L-carnitine supplementation improved muscle spasm, cardiac function, and renal anemia in dialysis patients. Eighty Japanese outpatients (62 hemodialysis (HD) patients and 18 peritoneal dialysis (PD) patients) received oral L-carnitine (600 mg/day) for 12 months; the HD patients further received intravenous L-carnitine injections (1000 mg three times/week) for 12 months, amounting to 24 months of treatment ... There was no significant improvement in muscle spasms, although decreased muscle cramping after L-carnitine treatment was reported by 31% of patients who had undergone HD for >4 years. Hemoglobin concentrations increased significantly at 12 and 24 months in the HD group. Therefore, L-carnitine may be effective for reducing muscle cramping and improving hemoglobin levels in dialysis patients, especially those who have been undergoing dialysis for >4 years"
  • The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Randomized Clinical Trials - J Am Coll Nutr. 2020 Mar 10:1-12 - "Accumulating evidence of previous experimental studies indicated that L-Carnitine positively ameliorates muscle damage ... Pooled data from seven studies showed that L-Carnitine resulted in significant improvements in muscle soreness (MS) at the five follow-up time points (0, 24, 48, 72 and 96 hours (h)) compared to placebo. Also, pooled data indicated that L-Carnitine significantly reduced creatine kinase (CK), myoglobin (Mb), and lactate dehydrogenase (LDH) levels at one follow-up period (24 h). However, no effects have been observed beyond this period. Our outcomes indicate that L-Carnitine supplementation improves delayed-onset muscle soreness (DOMS) and markers of muscle damage"
  • l-Carnitine Supplementation in Recovery after Exercise - Nutrients. 2018 Mar 13;10(3) - "Given its pivotal role in fatty acid oxidation and energy metabolism, l-carnitine has been investigated as ergogenic aid for enhancing exercise capacity in the healthy athletic population. Early research indicates its beneficial effects on acute physical performance, such as increased maximum oxygen consumption and higher power output. Later studies point to the positive impact of dietary supplementation with l-carnitine on the recovery process after exercise. It is demonstrated that l-carnitine alleviates muscle injury and reduces markers of cellular damage and free radical formation accompanied by attenuation of muscle soreness. The supplementation-based increase in serum and muscle l-carnitine contents is suggested to enhance blood flow and oxygen supply to the muscle tissue via improved endothelial function thereby reducing hypoxia-induced cellular and biochemical disruptions. Studies in older adults further showed that l-carnitine intake can lead to increased muscle mass accompanied by a decrease in body weight and reduced physical and mental fatigue. Based on current animal studies, a role of l-carnitine in the prevention of age-associated muscle protein degradation and regulation of mitochondrial homeostasis is suggested" - [Nutra USA]
  • Enhanced aerobic exercise performance in women by a combination of three mineral Chelates plus two conditionally essential nutrients - J Int Soc Sports Nutr. 2017 Nov 13 - "For 1 mo, aerobically fit, young adult women took either a combination of 3 mineral glycinate complexes (daily dose: 36 mg iron, 15 mg zinc, and 2 mg copper) + 2 CENs (daily dose: 2 g carnitine and 400 mg phosphatidylserine), or the same combination with generic mineral complexes, or placebo (n = 14/group) ... In Trial 1, the mineral glycinates + CENs decreased 3 mile run time (25.6 ± 2.4 vs 26.5 ± 2.3 min, p < 0.05, paired t-test) increased stationary bike distance after 25 min (6.5 ± 0.6 vs 6.0 ± 0.8 miles, p < 0.05, paired t-test), and increased steps in the step test (43.8 ± 4.8 vs 40.3 ± 6.4 steps, p < 0.05, paired t-test). The placebo significantly affected only the biking distance, but it was less than for the glycinates-CENs treatment (0.2 ± 0.4. vs 0.5 ± 0.1 miles, p < 0.05, ANOVA + Tukey). The generic minerals + CENs only significantly affected the step test (44.1 ± 5.2 vs 41.0 ± 5.9 steps, p < 0.05, paired t-test) In Trial 2, 3 mile run time was decreased for the mineral glycinates + CENs (23.9 ± 3.1 vs 24.7 ± 2.5, p < 0.005, paired t-test), but not by the placebo" - [Nutra USA] - See Jarrow Zinc Balance, Bulksupplements Pure L-Carnitine L-Tartrate Powder (500 grams), iron supplements and Extra Strength Phosphatidyl Serine 300 mg Now Foods 50 Softgel at Amazon.com.
  • L-Carnitine supplementation to reverse hyperammonemia in a patient undergoing chronic valproic acid treatment: A case report - J Int Med Res. 2017 Jan 1 - "Carnitine supplementation was useful for reversal of her hyperammonemia, allowing her to continue valproic acid for seizure control" - See L-carnitine at Amazon.com.
  • Efficacy of a novel formulation of L-Carnitine, creatine, and leucine on lean body mass and functional muscle strength in healthy older adults: a randomized, double-blind placebo-controlled study - Nutr Metab (Lond). 2017 Jan 18;14:7 - "Forty-two healthy older adults aged 55-70 years were randomized to receive either a novel L-Carnitine (1500 mg), L-leucine (2000 mg), creatine (3000 mg), Vitamin D3 (10 μg) (L-Carnitine-combination) product (n = 14), L-Carnitine (1500 mg) (n = 14), or a placebo (n = 14) for eight weeks ... Participants supplemented with the L-Carnitine-combination showed a 1.0 kg increase in total lean muscle mass (P = 0.013), leg lean muscle mass (0.35 kg, P = 0.005), and a 1.0 kg increase in lower leg strength (P = 0.029) at week 8. In addition, these increases were significant when compared to the placebo group (P = 0.034, P = 0.026, and P = 0.002, respectively). Total mTOR protein expression was increased in participants in the L-Carnitine-combination group at the end of the study compared to the baseline (P = 0.017). This increase was also significant when compared to the placebo (P = 0.039), suggesting that the increase in muscle mass and strength was due to new protein synthesis and mTOR pathway activation" - [Nutra USA]
  • L-Carnitine/Simvastatin Reduces Lipoprotein (a) Levels Compared with Simvastatin Monotherapy: A Randomized Double-Blind Placebo-Controlled Study - Lipids. 2016 Dec 2 - "Subjects were randomly allocated to receive L-carnitine 2 g/day plus simvastatin 20 mg /day (N = 29) or placebo plus simvastatin 20 mg/day (N = 29) for a total of 12 weeks. Lp(a) was significantly reduced in the L-carnitine/simvastatin group [-19.4%, from 52 (20-171) to 42 (15-102) mg/dL; p = 0.01], but not in the placebo/simvastatin group [-6.7%, from 56 (26-108) to 52 (27-93) mg/dL, p = NS versus baseline and p = 0.016 for the comparison between groups]. Similar significant reductions in total cholesterol, LDL-C, apolipoprotein (apo) B and TAG were observed in both groups" - See L-carnitine at Amazon.com.
  • L-carnitine supplementation for the management of fatigue in patients with hypothyroidism on levothyroxine treatment: a randomized, double-blind, placebo-controlled trial - Endocr J. 2016 Jul 16 - "Hypothyroid patients experience fatigue-related symptoms despite adequate thyroid hormone replacement ... 60 patients (age 50.0 ± 9.2 years, 3 males, 57 females) who still experienced fatigue (fatigue severity scale [FSS] score ≥ 36) were given L-carnitine (n = 30, 990 mg L-carnitine twice daily) or placebo (n = 30) for 12 weeks. After 12 weeks, although neither the FSS score nor the physical fatigue score (PFS) changed significantly, the mental fatigue score (MFS) was significantly decreased by treatment with L-carnitine compared with placebo (from 4.5 ± 1.9 to 3.9 ± 1.5 vs. from 4.2 ± 1.8 to 4.6 ± 1.6, respectively; P < 0.01). In the L-carnitine group, 75.0%, 53.6%, and 50.0% of patients showed improvement in the FSS score, PFS, and MFS, respectively, but only 20.0%, 24.0%, and 24.0%, respectively, did so in the placebo group (all P < 0.05). Both the PFS and MFS were significantly improved in patients younger than 50 years and those with free T3 ≥ 4.0 pg/mL by treatment with L-carnitine compared with placebo"
  • The effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials - Obes Rev. 2016 Jun 22 - "Results from meta-analysis of eligible trials revealed that subjects who received carnitine lost significantly more weight (MD: -1.33 kg; 95% CI: -2.09 to -0.57) and showed a decrease in body mass index (MD: -0.47 kg m-2 ; 95% CI: -0.88 to -0.05) compared with the control group. The results of meta-regression analysis of duration of consumption revealed that the magnitude of weight loss resulted by carnitine supplementation significantly decreased over time (p = 0.002). We conclude that receiving the carnitine resulted in weight loss"
  • Effects of L-carnitine supplementation on lipid profiles in patients with coronary artery disease - Lipids Health Dis. 2016 Jun 17;15(1):107 - "LC supplementation at a dose of 1000 mg/d showed significantly increased in HDL-C and Apo-A1 levels and a slight decrease in TG levels but no other changes in other lipids in CAD patients, and this lipid-lowering effect may be related to its antioxidant ability" - See L-carnitine at Amazon.com.
  • 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 - J Am Coll Nutr. 2016 Mar 2:1-7 - "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 ... The mean VAS score decreased significantly in the L-carnitine and placebo groups by 52.67% and 21.82%, respectively"
  • Oral carnitine supplementation reduces body weight and insulin resistance in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial - Clin Endocrinol (Oxf). 2015 Dec 15 - "60 overweight patients diagnosed with PCOS were randomized to receive either 250 mg carnitine supplements (n=30) or placebo (n=30) for 12 weeks ... 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)"
  • L-Carnitine enhances exercise endurance capacity by promoting muscle oxidative metabolism in mice - Biochem Biophys Res Commun. 2015 Jul 8 - "These results suggest that LC administration promotes fat oxidation and mitochondrial biogenesis while sparing stored glycogen in skeletal muscle during prolonged exercise, resulting in enhanced endurance capacity" - See acetyl l-carnitine products at Amazon.com and l-carnitine at Amazon.com.
  • L-carnitine ameliorated fasting-induced fatigue, hunger, and metabolic abnormalities in patients with metabolic syndrome: a randomized controlled study - Nutr J. 2014 Nov 26;13(1):110 - "In this 7-day, randomized, single-blind, placebo-controlled, pilot study, 15 metabolic syndrome (MetS) patients (11/4 F/M; age 46.9 +/- 9.14 years; body mass index [BMI] 28.2 +/- 1.8 kg/m2) were in the L-carnitine group (LC) and 15 (10/5 F/M; age 46.8 +/- 10.9 years; BMI 27.1 +/- 2.3 kg/m2) were in the control group (CT) ... There were significant differences in weight loss (LC -4.6 +/- 0.9 vs. CT -3.2 +/- 1.1 kg, P = 0.03), and waist circumference (LC -5.0 +/- 2.2 vs. CT -1.7 +/- 1.16 cm, P < 0.001), waist hip ratio (LC -0.023 +/- 0.017 vs. CT 0.012 +/- 0.01, P < 0.001), insulin concentration (LC -9.9 +/- 3.58 vs. CT -6.32 +/- 3.44 muU/mL, P = 0.046), and gamma-glutamyltransferase concentration (LC -7.07 +/- 6.82 vs. CT -2.07 +/- 4.18, P = 0.024). Perceived hunger scores were significantly increased (P < 0.05) in the CT group during starvation, which was alleviated with L-carnitine administration in the LC group. Physical fatigue (LC -3.2 +/- 3.17 vs. CT 1.8 +/- 2.04, P < 0.001) and fatigue severity (LC -11.6 +/- 8.38 vs. CT 8.18 +/- 7.32, P < 0.001) were significantly reduced in the LC group but were aggravated in the CT group"
  • Effects of L-carnitine supplementation on oxidative stress and antioxidant enzymes activities in patients with coronary artery disease: a randomized, placebo-controlled trial - Nutr J. 2014 Aug 4;13(1):79 - "LC supplementation at a dose of 1000 mg/d was associated with a significant reduction in oxidative stress and an increase in antioxidant enzymes activities in CAD patients. CAD patients might benefit from using LC supplements to increase their anti-oxidation capacity"
  • L-Carnitine in the Secondary Prevention of Cardiovascular Disease: Systematic Review and Meta-analysis - Mayo Clin Proc. 2013 Apr 15 - "A systematic review and meta-analysis of 13 controlled trials (N=3629) was conducted to determine the effects of L-carnitine vs placebo or control on mortality, ventricular arrhythmias (VAs), angina, heart failure, and reinfarction ... Compared with placebo or control, L-carnitine is associated with a 27% reduction in all-cause mortality, a 65% reduction in VAs, and a 40% reduction in anginal symptoms in patients experiencing an acute myocardial infarction"
  • Studies on the chemopreventive effect of carnitine on tumorigenesis in vivo, using two experimental murine models of colon cancer - Nutr Cancer. 2012 Nov;64(8):1279-87 - "Carnitine supplementation resulted in significantly increased tissue carnitine and acylcarnitine levels. Carnitine inhibited the development of precancerous lesions and macroscopic colonic tumors in AOM-treated mice"
  • L-Carnitine-supplementation in advanced pancreatic cancer (CARPAN) - a randomized multicentre trial - Nutr J. 2012 Jul 23;11(1):52 - "Cachexia, a >10% loss of body-weight, is one factor determining the poor prognosis of pancreatic cancer. Deficiency of L-Carnitine has been proposed to cause cancer cachexia ... While these data are preliminary and need confirmation they indicate that patients with pancreatic cancer may have a clinically relevant benefit from the inexpensive oral supplementation of L-Carnitine"
  • L-Carnitine prevents the development of ventricular fibrosis and heart failure with preserved ejection fraction in hypertensive heart disease - J Hypertens. 2012 Jul 12 - "Prognosis of heart failure with preserved ejection fraction (HFpEF) remains poor because of unknown pathophysiology and unestablished therapeutic strategy ... L-carnitine supplementation attenuates cardiac fibrosis by increasing prostacyclin production through arachidonic acid pathway, and may be a promising therapeutic option for HFpEF"
  • Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans: the dual role of muscle carnitine in exercise metabolism - J Physiol. 2011 Jan 4 - "total carnitine (TC) ... At 50% VO2max, the Carnitine group utilised 55% less muscle glycogen compared to Control (P<0.05) and 31% less pyruvate dehydrogenase complex activation (PDCa) compared to before supplementation (P<0.05). Conversely, at 80% VO2max, muscle PDCa was 38% higher (P<0.05), acetylcarnitine content showed a trend to be 16% greater (P<0.10), muscle lactate content was 44% lower (P<0.05) and the muscle PCr/ATP ratio was better maintained (P<0.05) in Carnitine compared to Control. The Carnitine group increased work output 11% from baseline in the performance trial, while Control showed no change. 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" - See l-carnitine at Amazon.com.
  • l-Carnitine l-tartrate supplementation favorably affects biochemical markers of recovery from physical exertion in middle-aged men and women - Metabolism. 2010 Aug;59(8):1190-9 - "Two grams of l-carnitine supplementation had positive effects and significantly (P < or = .05) attenuated biochemical markers of purine metabolism (ie, hypoxanthine, xanthine oxidase), free radical formation (malondialdehyde), muscle tissue disruption (myoglobin, creatine kinase), and muscle soreness after physical exertion. However, markers of physical performance (ie, strength, power, get up and go) were not affected by supplementation. These findings support our previous findings of l-carnitine in younger people that such supplementation can reduce chemical damage to tissues after exercise and optimize the processes of muscle tissue repair and remodeling"
  • Glycine Propionyl-L-carnitine Modulates Lipid Peroxidation and Nitric Oxide in Human Subjects - Int J Vitam Nutr Res. 2009 May;79(3):131-141 - "Nitric oxide was increased (p<0.05) from pre- to post-intervention with 3 g GPLC (21.34+/-2.27 vs. 29.46+/-3.61 micromol.L (-1))" - Note:  (29.46 - 21.34) / 21.34 = 38% increase in nitric oxide. See GPLC at Amazon.com.
  • l-Carnitine l-tartrate supplementation favorably affects biochemical markers of recovery from physical exertion in middle-aged men and women - Metabolism. 2009 Dec 30 - "Two grams of l-carnitine supplementation had positive effects and significantly (P </= .05) attenuated biochemical markers of purine metabolism (ie, hypoxanthine, xanthine oxidase), free radical formation (malondialdehyde), muscle tissue disruption (myoglobin, creatine kinase), and muscle soreness after physical exertion. However, markers of physical performance (ie, strength, power, get up and go) were not affected by supplementation. These findings support our previous findings of l-carnitine in younger people that such supplementation can reduce chemical damage to tissues after exercise and optimize the processes of muscle tissue repair and remodeling"
  • L-Carnitine supplementation reduces oxidized LDL cholesterol in patients with diabetes - Am J Clin Nutr. 2008 Dec 3 - "The 2 groups received either 2 g L-carnitine once daily (n = 41) or placebo ... the L-carnitine-treated patients showed significant improvements compared with the placebo group in the following markers: oxidized LDL levels decreased by 15.1 compared with 3.0 U/L (P < 0.001); LDL cholesterol decreased by 0.45 compared with 0.16 mmol/L (P < 0.05); triglycerides decreased by 1.02 compared with 0.09 mmol/L (P < 0.001); apolipoprotein A1 concentrations decreased by 0.12 compared with 0.03 mg/dL (P < 0.05); apolipoprotein B-100 concentrations decreased by 0.13 compared with 0.04 mg/dL (P < 0.05); thiobarbituric acid-reactive substance concentrations decreased by 1.92 compared with 0.05 (P < 0.001), and conjugated diene concentrations decreased by 0.72 compared with 0.11 in the placebo group ... Our study indicates that oral administration of L-carnitine reduces oxidized LDL cholesterol levels in patients with type 2 diabetes" - See l-carnitine at Amazon.com.
  • Effects of carnitine supplementation on flow-mediated dilation and vascular inflammatory responses to a high-fat meal in healthy young adults - Am J Cardiol. 2008 Nov 15;102(10):1413-7 - "flow-mediated dilation (FMD) ... these findings indicate that carnitine supplementation in healthy individuals improves postprandial FMD after a high-fat meal"
  • Renoprotective action of l-carnitine in fructose-induced metabolic syndrome - Diabetes Obes Metab. 2007 Dec 17 - "l-carnitine (CA) administration ... The benefits of CA in this model suggest the therapeutic use of CA to counter the kidney changes associated with metabolic syndrome"
  • L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial - Am J Clin Nutr. 2007 Dec;86(6):1738-44 - "Our study indicates that oral administration of levocarnitine produces a reduction of total fat mass, increases total muscular mass, and facilitates an increased capacity for physical and cognitive activity by reducing fatigue and improving cognitive functions"
  • Effect of L-carnitine and/or L-acetyl-carnitine in nutrition treatment for male infertility: a systematic review - Asia Pac J Clin Nutr. 2007;16 Suppl:383-90 - "the administration of LC and/or LAC may be effective in improving pregnancy rate and sperm kinetic features in patients affected by male infertility"
  • Asymptomatic carnitine depletion on ketogenic diet in patients with pharmacoresistant epilepsies - Klin Padiatr. 2006 Sep-Oct;218(5):260-3 - "Regular controls of carnitine levels should be performed during the treatment with ketogenic diet, both at the beginning and during longterm-therapy"
  • Effect of PLC on functional parameters and oxidative profile in type 2 diabetes-associated PAD - Diabetes Res Clin Pract. 2006 Jan 27 - "These results suggest that adjunct therapy with PLC may be warranted in type 2 diabetes-associated PAD" - See GPLC at Amazon.com.
  • Carnitine Treatment Improved Quality-of-Life Measure in a Sample of Midwestern Hemodialysis Patients - JPEN J Parenter Enteral Nutr. 2006 Jan-Feb;30(1):10-5 - "24 weeks of IV carnitine therapy, SF-36 scores were improved and erythropoietin doses were reduced in hemodialysis patients, relative to the control group"
  • Effect of L-carnitine on plasma glycemic and lipidemic profile in patients with type II diabetes mellitus - Eur J Clin Nutr. 2005 Mar 02 - "fasting plasma glucose (FPG) ... FPG in the L-carnitine group decreased significantly from 143+/-35 to 130+/-33 mg/dl (P=0.03) ... after 12 weeks of treatment"
  • Preliminary observations on the use of propionyl-L-carnitine in combination with sildenafil in patients with erectile dysfunction and diabetes - Curr Med Res Opin. 2004 Sep;20(9):1377-84 - "Salvage therapy with PLC plus sildenafil was more effective than sildenafil in the treatment of ED in patients with diabetes refractory to sildenafil monotherapy" - The way I understand it, propionyl-L-carnitine is the l-carnitine available over-the-counter.  See HealthTouch and "alternative names" at HealthGate.
  • Carnitine versus androgen administration in the treatment of sexual dysfunction, depressed mood, and fatigue associated with male aging - Urology. 2004 Apr;63(4):641-6
  • The role of carnitine in normal and altered fatty acid metabolism - Am J Kidney Dis 2003 Apr;41(4 Suppl 4):S4-S12