It has been reported that increased visceral adipose tissue (VAT) is associated with a range of metabolic abnormalities, including decreased glucose tolerance and insulin sensitivity, as well as adverse lipid profiles, all of which are risk factors for type 2 diabetes and CVD (WHO, 2008). In the European Union, a sustained reduction in abdominal fat, and in particular visceral fat, is considered a beneficial physiological effect for adults with adverse health effects associated with excess abdominal fat, including impaired glucose tolerance, dyslipidemia, and hypertension (EFSA, 2012).~This clinical trial is a randomized, double-blinded, placebo-controlled, parallel, single-center study involving a total of 60 male and female adults (aged 18 to 60 years, inclusive) who are overweight (BMI between 25.0 to ˂30.0 kg/m2) and have abdominal obesity (waist circumference >102 cm for males, >88 cm for females) (ATP III, 2001). Each subject's duration of participation will be a total of ~14 weeks, including a ~2-week screening visit and a ~12-week randomized placebo-controlled double-blinded supplementation period.~On the first day of the ~2-week screening period (~Day -14), subjects will be screened according to the study inclusion and exclusion criteria. Subjects meeting all of the inclusion criteria and none of the exclusion criteria will be invited to return to the clinic for a second screening visit (~Day -7). During this second screening visit, subjects will be instructed on how to use the Fitbit (accelerometer) and on how to properly complete the food intake diary. Subjects will be instructed not to alter their dietary intakes or their physical activity levels during the subsequent week, and to record the information as accurately as possible. Participants will be asked to record at least 3 days of physical activity and dietary measurements that includes at least 1 weekend day. Subjects will then be instructed to return to the clinic ~1 week later for the collection of baseline measures (Day 0).~Following the collection of baseline measures on Day 0, subjects will be randomized to the placebo or one of the vinegar groups. Each group will consist of 20 subjects. Randomization will be adaptive according to sex and age; subjects will be asked to return to the clinic twice, once ~11 weeks after the baseline visit to obtain food intake diary, accelerometer, and stool collection materials, and again, ~12 weeks after the baseline visit (i.e., 12 weeks after the baseline visit). Each subject will be required to make a total of 4 visits to the clinical research site (i.e., Days -14, -7, 0, and 84). The entire duration of the clinical study is expected to be approximately 52 weeks from subject enrollment to study closeout.
To assess, relative to a placebo, the effects of consuming 400 mL/day or 200 mL/day of a vinegar beverage providing either 1,500 mg/day of acetic acid (in two 200 mL doses daily) or 750 mg/day of acetic acid (in one 200 mL dose daily), respectively, for 12 weeks on VAT (MRI). Thus the 2 active comparator arms 400 mL and 200 mL of vinegar will be independently tested compared to placebo.