The Effect of Curcumin on Liver Fat Content in Obese Subjects

The prevalence of obesity is increasing worldwide. Obesity and its associated complications represent an enormous burden for obese individuals, their families, healthcare systems and societies. Non-alcoholic fatty liver disease (NAFLD) has emerged as a frequent and serious complication of obesity. Steatosis, the benign and potentially reversible form of NAFLD, may progress to a more severe form, non-alcoholic steatohepatitis (NASH), which can result in fibrosis and ultimately liver cirrhosis, and rarely hepatocellular carcinoma. The majority of obese have NAFLD. Currently, no pharmacological agents are licenced for the prevention or treatment of NAFLD, and weight loss, notoriously difficult to obtain (and specially to maintain), remains the only treatment option. Interestingly, curcumin, a phenolic compound extracted from the turmeric root, has from in vitro and animal studies shown promising effects in preventing and treating NAFLD, and the sparse available human data point in the same direction; but solid human data are missing. This study seeks to investigate the effects of curcumin on treating NAFLD in humans by looking at the effects of ingestion of curcumin for 6 weeks in obese subject with NAFLD on lipid, glucose and protein metabolism.

In this randomised, double-blinded, placebo-controlled trial, eligible participants will undergo baseline assessments before being randomised to receive two capsules of placebo twice daily or two capsules of curcumin (corresponding to 200 mg) twice daily for 6 weeks. In the end of the 6-week intervention periods, end-of-trial assessments (similar to baseline assessments) will be performed.

Information meeting:

Prior to any protocol-related procedures, an information meeting at Center for Clinical Metabolic Research, Gentofte Hospital, will be arranged, and subjects will be informed of the possibility of bringing a person of own choice to the visit. During this meeting, a member of the research group will explain the purpose, procedures and possible risks of the study in undisturbed and confidential surroundings. The subject will be informed that if extra time to evaluate participation is needed, a minimum of 24 hours from oral information is given until the consent and sign the informed consent form should be given is acceptable. After obtaining the informed consent, time of screening is planned. The subject will be informed that it is possible to withdraw the written consent at any time prior to or during the study.

Screening visit:

If a person agrees to participate in the study following the information meeting, and oral and written informed consent has been obtained, a screening visit will be planned. The subject will be instructed in a 10 hour overnight fast before screening (including medicine, but water may be consumed until 2 hours before screening). After this fast the subject will meet in the department in the morning. Height and body weight will be measured, medication and medical history will be recorded, blood will be sampled for assessment of plasma/serum concentrations of thyroid-stimulating hormone, creatinine, electrolytes, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), lactate dehydrogenase, alkaline phosphatase, albumin, bilirubin, gamma-glutamyltransferase, viral hepatitis markers, platelet count, ferritin and haemoglobin, and albumin-creatinine ratio in the urine will be measured. A Fibro Scan will be performed. A physical examination will be made including evaluation of blood pressure and pulse rate. Alcohol habits will be evaluated based on The Alcohol Use Disorder Identification Test (AUDIT) questionnaire76,77 and quantification of the weekly amount of alcohol. A magnetic resonance (MR) safety checklist will be completed and a MR information sheet will be given. If all inclusion criteria and none of the exclusion criteria are met, dates for baseline assessments and randomisation visit will be planned within 6 weeks from the screening visit. The subject will be instructed in not to consume curcumin-containing food on a daily basis from screening until end of trial.

Baseline assessments and randomisation visit:

Included subjects will undergo an MRS, which will be scheduled as close as possible to the start of intervention. The subject will meet at the Department of Radiology at Herlev Hospital and be placed in a horizontal position during the scan. During the MRS, a spectroscopy of the liver will be assessed, and an estimation of visceral adipose tissue and subcutaneous adipose tissue will be done. The subject will be placed in a horizontal position during the scan (duration: approximately 30 minutes).

Food and physical activity diary and standardised food intake period: Before start of intervention and during the week before end-of-trial visit, each subject will fill out a three days food and physical activity dairy. The food and physical activity diary will be registered manually by participants, using a questionnaire. The two last days before test days, the participants are requested to have a standardized food intake high in carbohydrates, to get the most valid oral glucose tolerance test (OGTT) response, and the subject will be thoroughly instructed in this.

During the last week before randomisation, the subject is kindly asked to collect a stool sample for the determination of gut bacteria count and subtype. The participant will receive sample kits consisting of cooler bag, freezer packs and stool sample tubes. Stool samples will be collected by the participant at home: Prior to defecation a disposable collector will be placed in the toilet from where stool will be transferred to a tube that immediately is transferred to a transport container and placed at -20°C in the patient's freezer. Prior to transport to Gentofte Hospital, the transport container is transferred to the cooler bag and at arrival at Gentofte Hospital the transport container (with the sample tube) is immediately stored in at -80°C for later analysis. This entails DNA extraction, library preparation, MiSeq 16S rRNA sequencing and microbiota analysis (relative abundance, alpha/beta diversity, link to phenotype of interest).

On the randomisation visit, the subject will meet in the laboratory around 8 a.m. after 10 hours of fast (including medication) and refrainment from tobacco or nicotine supplements use. The subject is allowed to drink water until 8 hours before meeting in department. Furthermore, the subject will be requested to avoid heavy alcohol intake and strenuous exercise two days prior to the visit and instructed to use non-strenuous methods of transportation to the research facility. The following procedures will be conducted:

1. A fasting urine sample will be collected, and the participant is kindly asked to empty the bladder completely. Urine volume will be measured.
2. Measurement of bioimpedance.
3. Fasting blood samples will be collected (genetic markers for NASH, biomarkers of NASH and fibrosis, fibroblast growths factors, triglycerides, cholesterols, liver parameters, haemoglobin A1c, inflammatory markers, adipokines, haemoglobin, creatinine) amounting 22 ml.
4. FibroScan: The subject will be lying in a supine position for approximately 10 minutes during which a probe using shear-waves and ultrasound is applied in the right side of the body below the ribs
5. Measurement of blood pressure, pulse rate, body weight and hip and waist circumference
6. One cannula will be inserted in the cubital vein for collection of blood samples; the forearm from which blood samples are drawn will be wrapped in a heating blanket (42°C) throughout the experiment (for arterialisation of venous blood)
7. Blood samples will be collected according to Table 1 below (total amino acids, gut hormones, glucose, glucagon, insulin, c-peptide, urea, free fatty acids)
8. At time 0 min, the subject will ingest 75 g of water-free glucose dissolved in 300 ml water over a period of 5 minutes
9. At time 0, 30, 60, 90, 120, 150, 180, 210 and 240 min, hunger, satiety, fullness and prospective food consumption will be measured by visual analogue scales (VASs). (see enclosure 5 "VAS").
10. During the last hour (~180min - ~240 min), resting energy expenditure (REE) will be measured in a supine position by indirect calorimetry to determine oxygen consumption (V02) and carbon dioxide production (VC02). A flow-through canopy gas analyser will be used.
11. At time ~240 min the subject will be asked to provide a new urine sample for measurement of urea concentration. The participant is kindly asked to empty the bladder completely. Urine volume will be measured.
12. At time 250 min, the subject will ingest a standardised ad libitum meal consisting of minced meat, pasta, corn, carrots, peppers, cream, salt and pepper (50 energy (E) % carbohydrate, 37 E% fat, 13 E% protein); the subject will be instructed to eat as much as possible until feeling comfortable satiated; the meal should be consumed within a maximum of 30 minutes and by the end of the meal, time spent eating, weight of the meal and the total amount of energy consumed will be noted. Additionally, the participants rated the appearance, smell, taste, off-taste, and overall impression of the ad libitum meal on VAS scores during the ad libitum meal. 10 minutes after termination of the meal consumption, the last questionnaire regarding hunger, satiety, fullness and prospective food consumption will be measured by visual analogue scales.

The interventional period:

The intervention will start soon after randomization visit and first MRS. During the entire intervention period, each subject will fill out a dairy to keep track of any new concomitant medication, compliance and possible adverse events. Each subject will take either two capsules of Meriva® or two placebo capsules each morning and each evening for 42 days (±3 days) with a small glass of water, preferably in relation to a meal. Should the subject forget/miss to take a dose, it can be ingested until 6 hours before the next planned dose. If the subject forgets/misses a dose, and the next planned dose is within the next 6 hours, the dose should be passed, and the subject must note the incident in the diary. The subject is kindly asked to keep the alcohol and smoking habits they might have had before screening and, thus, not to consume more than 21 units of alcohol per week. Furthermore, it is not allowed to consume more than 5 units in one night or to consume curcumin-containing food on a daily basis until end of trial. Mid-way through the intervention period, the subject will receive a phone call from the investigator or other delegated site staff, checking on adverse events, concomitant medication and compliance, and to answer any questions from the subject.

In the last week of intervention, participants are once more requested to fill out questionnaires regarding food intake and physical activity. Starting two days prior to end-of-trial visit, the subject must once more follow two days of standardized food intake.

End-of-trial assessments and visit:

The end-of-trial visit will be scheduled 42±3 days after start of intervention. Within one week prior to the end-of-trial visit, stool sample collection will be scheduled and performed as described above under "Baseline assessments and randomisation visit" and MRS in assessed as close to end-of-trial visit as possible. Procedures during the end-of-trial visit are similar to the ones described above under "Baseline assessments and randomisation visit". Also, during this day, to check for any effect of curcumin intervention, physical examination will be performed by a physician from the research team and additional blood samples (identical with the samples at the screening visit, except viral hepatitis markers) will be collected (which adds another 5 ml blood samples compared to randomisation visit) and albumin-creatinine ratio in the urine will be measured.