Sulforaphane Supplementation Study

Non-alcoholic fatty liver disease (NAFLD) is increasing in the population, and is associated with heart disease and diabetes. At present there are no licensed drugs for treatment of NAFLD, therefore changes in diet and increased physical activity leading to decreased body fatness is the recommended management/treatment strategy. However, these are difficult to achieve and maintain for many individuals. A potential compound gaining interest in regards the treatment/prevention of NAFLD is sulforaphane, which is found in vegetables such as Broccoli. Animal studies suggest supplementing with sulforaphane can increase fat oxidation. This increased "fat burning" may result in lower levels of fat in the liver and overall in the body. The researchers will ask participants to undertake an intervention phase which will involve consuming two sulforaphane tablets a day for approximately 3 weeks. Participants will be asked to maintain all other aspects of their lifestyle throughout the intervention phase. The researchers will measure and compare participants whole-body and liver fat oxidation in response to a standardised test meal before and after the intervention phase by taking blood and breath samples. The researchers will also measure the amount of fat in participants liver and heart using a non-invasive technique known as magnetic resonance spectroscopy (MRS) before and after the intervention.

Participants satisfying the inclusion criteria will be invited to the Oxford Centre for Clinical Magnetic Resonance Research (OCMR), to measure the amount of fat within their liver and heart using magnetic resonance imaging and spectroscopy (MRI/S). Then on a separate day, within one week of having their liver and heart fat content measured, participants will come into the Clinical Research Unit (CRU) at the Oxford Centre for Diabetes Endocrinology and Metabolism (OCDEM) for a 'postprandial study day' after an overnight fast. Participants will be asked to avoid excessive exercise and alcohol for 24 hours prior to the study. The day prior to and over the course of the 'study day' participants will be asked to drink some 'heavy water' ((2H2O) CK Isotopes Limited). The amount of 'heavy water' a volunteer will have to consume is 3g heavy water per kg body water, which will achieve a plasma water enrichment of 0.3%. Once participants arrive at OCDEM the researchers will make some anthropometric measurements (e.g. weight, height, waist circumference etc.), collect a urine sample, and place a small plastic tube (cannula) into a vein on the forearm, from which they will take blood samples. A second cannula will also be placed into a large vein in the elbow crease of the opposite arm. Sequential blood samples will be collected by the researchers at regular intervals for a period of up to 8 hours from placing the first cannula. After the first blood samples have been taken (Time -30) the researchers will start pumping fat labelled with special atoms (stable isotopes from CK Isotopes Limited) into the other cannula. After approximately 30 minutes of infusion, a second blood sample (time 0) will be taken, after which participants will be fed a standardised test meal which will consist of cereal and semi-skimmed milk and a "fatty" chocolate drink. The fatty chocolate drink is made with a blend of oils and will be labelled with a stable isotope (from CK Isotopes Limited). The use of the stable isotopes in small doses is considered to be completely harmless (it is not radioactive). Once the test meal is consumed, the volunteer is free to rest on a bed or in a chair, as they prefer, until the experiment is finished, up to 8 hours. After giving the stable isotopes, blood and breath samples will be taken initially every 30 minutes for the first two hours and then every 60 minutes up until the end of the study day (6 hours post breakfast). The researchers would take blood samples through the cannula in the vein, and at each time point would take approx. 25ml of blood. The most blood taken in total over the day would be 250ml or approximately 1/2 of a pint. Three hours after consumption of the test breakfast meal the researchers will take two adipose tissue biopsies. The first biopsy will be taken from the fat just under the skin in the abdomen (tummy) and the second biopsy will be taken from the gluteal (buttock) region. There will be numbing of the skin and fat tissue as a local anaesthetic (1% lignocaine) is used prior to all biopsies. The choice as to whether or not to undergo biopsies will be given to participants on the study day. At some point during the day a dual energy X-ray absorptiometry (DEXA) scan will be performed. The DEXA scan will measure the total amount of fat (adipose tissue) along with the amount of adipose tissue in specific depots (e.g. upper body, lower body, visceral etc.). When all of the samples have been taken and the measurements are finished, the researchers would take out the plastic tubes, and give the participant something further to eat and drink before making sure they can get home, usually by providing them with a taxi. Participants will also be provided with the sulforaphane capsules to be ingested over the following 3-week period, and guidelines as to when to take supplements. Participants will be asked to maintain their habitual diets during the intervention phase, which will be assessed via the completion of food diaries where all foods and beverages consumed on 3 days a week (two week and one weekend day) each week of the 3 week intervention phase. A member of the research team will be in regular contact with participants via email throughout the intervention phase in an attempt to maintain compliance. Following the 3-week intervention phase the volunteer's liver and heart fat content will again be measured using MRI/S at OCMR, then on a separate day, within one week of having their liver and heart fat content measured, participants will come into the CRU at OCDEM for a second 'study day' after an overnight fast. The second 'study day' will be identical to the first study day described above.