A 2 x 2 phase II randomised controlled trial to investigate the efficacy of St John's wort versus placebo in smoking cessation and the efficacy of chromium intake in preventing weight gain

INTERVENTION: Patients are randomised to receive one of the following interventions: 1. SJW and chromium 2. Chromium and placebo 3. SJW and placebo 4. Control: placebo and placebo CONDITION: Smoking cessation ; Mental and Behavioural Disorders ; Smoking cessation PRIMARY OUTCOME: For SJW, primary outcome will be quitting at four weeks post quit, the standard for the NHS. For chromium, primary outcome will be weight change as defined by week 4 minus week 0 weight. SECONDARY OUTCOME: Relating to SJW, secondary outcomes include:; 1. Side‐effects of SJW withdrawal symptoms; 2. Changes in State Trait Anxiety Inventory (STAI); 3. Questionnaire of Smoking Urges (QSU) brief; 4. Mood and Physical Symptoms Scale (MPSS) questionnaires; 5. Changes in salivary cortisol profile, plasma prolactin and free tryptophan; ; ; For chromium, secondary outcomes include:; 1. Changes in food frequency questionnaire; 2. Metabolic changes that might follow from changes in carbohydrate and lipid metabolism as a result of chromium. These are free tryptophan, Non‐Esterified Free Fatty Acids (NEFFAs), Large Neutral Amino Acids (LNAAs), triglycerides and change in body fat estimated through bioimpedance. INCLUSION CRITERIA: Smokers 18 or over that want to stop smoking in the next two weeks and that have smoked at least 10 cigarettes per day for the past year and are clinically suitable to take SJW and chromium.