Trust me I'm a doctor. 3/3.

This documentary is presented by medical journalist, Michael Mosley, who takes an accessible look at the science behind various health claims, with the assistance of various other doctors. This programme looks at brain boosters, painkillers, salt intake and whether electronic cigarettes are safe and whether greasy food affects your skin. Chris Van Tulleken investigates what is meant by moderate intensity exercise as described by the NHS; do household chores count? Four volunteers are monitored in an experiment in a gym. Gabriel Weston investigates the effects of caffeine on the brain; in test conditions the sbujects perform some tests before and after drinking a caffeine drink. Salehya Ahsan looks at whether fatty food causes bad skin. Spots are caused by hormones and high levels of blood insulin, although research on the latter is in early stages. Mosley looks at 'vaping' and the use of electronic cigarettes. Nicotine is present in both and is addictive. Chris Van Tulleken returns to the issue of what to do when you want a pick-me-up. Studies suggest that sugar, sage and chewing gum could all provide an alternative to tea or coffee, Salehya Ahsan provides advice about how to treat hypothermia. Graham MacGregor, Pofessor of Cardiovascular Medicine at the Wolfson Institute of Preventive Medicine, tells Mosley about his research into salt and his campaign to reduce salt intake. His research indicates that high blood pressure is caused by salt consumption. Hugh Tunstall-Pedoe, Professor of Cardiovascular Epidemiology at the University of Dundee, has a different view with 40 years research into blood pressure. Salehya Ahsan looks at the reputed benefits of Omega 3; oily fish is beneficial so Omega 3 in food rather than tablet form. Gabriel Weston visits Papworth Hospital in Cambridgeshire to witness pioneering surgery on a blood clot lodged deep in a patient's lung; the patient's blood is completely drained from his system. His heart is stopped; the surgeons have a short period of time to operate. The patient is cooled. This process has to be done twice more to remove all the clotting material. Chris Van Tulleken looks at pain relief.