The BROAD study. A trial using the whole-foods, plant-based diet in a community programme for people with obesity, or overweight with ischaemic heart disease or diabetes

This randomised controlled trial will determine the benefit of comprehensive lifestyle changes in a sample of New Zealanders with common chronic diseases. Participants will have raised body mass index (BMI) greater than or equal to 30 or BMI greater than or equal to 25 and either ischaemic heart disease (IHD) or type 2 diabetes mellitus (diabetes). Participants who are assigned to the intervention group will participate in a programme of lifestyle change (incorporating a low-fat pure vegetarian diet) for 3 months, and those assigned to the control group will receive their usual-care. A brief, standardised personality assessment will help identify any personality traits associated with adherence. This trial will evaluate the efficacy of a lifestyle intervention incorporating a low-fat, pure vegetarian diet for New Zealanders on a broad range of health determinants and risk factors. As far as we are aware it will be the first trial of such a lifestyle intervention outside of the USA. The intervention involves attendance of twice weekly evening sessions of 2.5 hour duration designed to enable participants to learn about the relation of food and nutrition to a range of diseases and recognized disease risk factors. These will include brief lectures, practical demonstrations, videos, cooking classes, and small group work. Participants will also be provided with educational materials, some food items, and some items of kitchen equipment in order to facilitate the lifestyle changes advocated in the intervention. They may be expected to complete some small assignments, recordings, or ‘homework’ activities between evening sessions. This study intervention will differ significantly from lifestyle interventions previously studied by focusing on the ‘how to’ rather than the ‘why to’. Ongoing adherence will be monitored through the use of food recall diaries monitored monthly for three months in the intervention group, then at months three and six after study initiation. Diet recall will be performed for the control group at study initiation and at six months after study initiation. Evening sessions will run for three months total, with an additional weekend together for an ‘immersion’ in the lifestyle changes and team-building 2 weeks into the programme. The aim of the intervention is to help participant learn and teach one another how to make positive changes in their dietary (and other lifestyle) behaviours so that they can reduce risk of their established diseases progressing (potentially reversing these if related to lifestyle factors) and prevent developing new diseases. The lifestyle intervention will advocate a nutritionally complete dietary plan where participants follow a low-fat (10-15% calories from fat) ‘plant-based’ diet. The diet includes every type of fruit, vegetable and grain. Whole grains are encouraged. Very high-fat plant-foods such as nuts, avocados, and olives are discouraged, as are highly-processed foods. Restricting use of sugar and salt will be encouraged as will minimizing or cessation of caffeine. The diet specifically excludes meat (of any kind, including chicken and fish), dairy (including cheese, yoghurt), and refined oils (such as canola, olive, or sunflower oil). Participants will be encouraged to eat until satiation from the foods included in the diet, without regard for total energy intake (i.e. ‘not counting calories’). A very small amount of B12 supplementation will be provided to all participants following this diet, to ensure adequate intake. Vitamin B12 supplementation will be provided at no cost to those in the intervention group, in the form of drops containing 50mcg per dose, which should be taken daily. In summary, this study will be conducted by doctors providing participants (and when necessary their families) with an intervention in their community in the form of education on the management of chronic disease by dietary and lifestyle changes. Those conducting the study are also the main investigators. Update Nov 2015, post initial study extension: Participants and researchers have agreed to continue approximately 6 further intervention sessions from November 2015 to February 2016, for the participants of both the first randomised group (who are at month 15 of the research) of participants, and the second non-randomised group (who are at month 8 of the research). These sessions will be further meetings of approximately 2 hours length in which we will discuss sustaining the lifestyle changes and providing further support to participants. The participants will each be provided with a cookbook; Prevent and Reverse Heart Disease cookbook, or Happy Herbivore Light and Lean. The Ethics Committee has been informed of these minor additions to the intervention.