Oral Carnitine Supplementation Reduces Body Weight and Insulin Resistance in Women With Polycystic Ovary Syndrome

A Randomized, Double-Blind, Placebo-Controlled Trial

Mansooreh Samimi; Mehri Jamilian; Faraneh Afshar Ebrahimi; Maryam Rahimi; Banafsheh Tajbakhsh; Zatollah Asemi


Clin Endocrinol. 2016;84(6):851-857. 

In This Article

Abstract and Introduction


Objective Limited data are available for 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 the end of the study to quantify parameters of glucose homoeostasis 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), homoeostasis model of assessment-insulin resistance (−0·61 ± 1·03 vs +0·11 ± 1·43, P = 0·04) and dehydroepiandrosterone sulphate (−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.


Polycystic ovary syndrome (PCOS) is often characterized by obesity and impaired insulin function and affects about 7–10% of women during reproductive age.[1] Obesity may play a role in the aetiology of PCOS, and weight loss has been found to improve some of the clinical aspects of PCOS including menses regularity and fertility,[2] as well as many cardiovascular (CV) risk markers associated with PCOS such as insulin resistance (IR) and dyslipidaemia.[3] IR affects approximately 65% of women with PCOS[4] and can potentially increase the prevalence of impaired glucose tolerance, type 2 diabetes mellitus (T2DM)[5] and metabolic syndrome (MetS).[6]

Carnitine plays a substantial role in weight loss, glucose tolerance, insulin function and fatty acid metabolism. The potential mechanisms include increasing mitochondrial efflux of excess acyl groups from insulin-responsive tissues and facilitating transportation of the long-chain free fatty acids into the mitochondrial matrix.[7–9] Some studies have reported that circulating levels of free and total l-carnitine were significantly lower in PCOS women.[8,10] In addition, in a study by Ismail et al.,[11] combined l-carnitine and clomiphene citrate significantly improved both ovulation and cumulative pregnancy rates in patients with clomiphene-resistant PCOS. Taking intravenous l-carnitine (4 g/day) among patients with MetS for 7 days resulted in weight loss, improved fasting-induced hunger and cholesterol abnormalities.[12] Carnitine supplementation in human studies and animal models has indicted an improvement in parameters of glucose homoeostasis, particularly during an insulin-resistant state.[13,14] However, carnitine administration did not affect weight loss outcomes in valproate-treated bipolar patients consuming an energy-restricted and low-fat diet.[15]

Although there is some evidence to indicate that carnitine administration may help to reduce body weight and improve markers of insulin metabolism and lipid profiles in individuals diagnosed with PCOS, the beneficial effects of carnitine supplementation on these markers has not yet been studied. This study aimed to determine the effect of carnitine administration on weight loss, parameters of glucose homoeostasis and lipid profiles of overweight and/or obese women diagnosed with PCOS. We hypothesized that carnitine administration might reduce body weight and improve the metabolic status of PCOS patients.