Impact of a combined lower carbohydrate and Mediterranean diet on metabolic syndrome severity: protocol for a randomised controlled trial

The Mediterranean diet and a low-carbohydrate diet are two popular dietary approaches recommended for cardiovascular and metabolic health, respectively. This trial will compare the combined effect of these diets to either approach alone for the treatment of metabolic syndrome (MetS). Males and females (<i>n</i> 222), 30-75 years, with at least three MetS risk factors, will be randomised to one of three diets: (i) traditional Mediterranean (∼55 % of energy carbohydrate:15 % protein:30 % fat), (ii) lower carbohydrate (∼35 % carbohydrate:20 % protein:45 % fat) or (iii) lower carbohydrate Mediterranean (∼35 % carbohydrate:20 % protein:45 % fat) diet for 12 weeks. The primary outcome measure is the MetS severity Z score, a composite score of risk factors, sex and ethnicity. MetS severity Z score will be calculated pre- and post-intervention using fasted blood samples for plasma TAG, HDL-cholesterol and glucose, systolic blood pressure, body weight and waist circumference measures. The findings from this trial will offer new insights into the most effective dietary strategy for managing diabetes and reducing cardiovascular risk in individuals with MetS.