Effect of low-fat dairy products fortified with 1500IU nano encapsulated vitamin D3 on cardiometabolic indicators in adults with abdominal obesity: a total blinded randomized controlled trial

Background & aims: Vitamin D deficiency is widespread worldwide. In this study, we aimed to evaluate the effect of a nano encapsulated form of vitamin D used for fortifying low-fat dairy products (milk and yogurt) on anthropometric indices, glycemic status, and lipid profile in subjects with abdominal obesity. Methods: In a totally (quadruple) blinded, randomized, and parallel-controlled trial, 306 individuals with abdominal obesity were randomly allocated to one of four groups: fortified low-fat yogurt (FY, 1500 IU nano encapsulated vitamin D ₃ per 150 g/d), non-fortified low-fat yogurt (nFY), fortified low-fat milk (FM, 1500 IU nano encapsulated vitamin D ₃ per 200 g/d), non-fortified low-fat milk (nFM), for 10 weeks (nFM and nFY, were considered as the control groups). Anthropometric and biochemical parameters were measured at baseline and after a ten-week trial in Mashhad, Iran. Results: After the ten-week intervention, we found a significant increase in serum concentration of 25(OH)D in both the FM and FY groups compared to the respective control groups (19.10 ± 5.69 ng/mL and 20.88 ± 5.76 ng/mL respectively, p <.001). We observed a significant reduction in weight to hip ratio (p =.04) and a significant improvement in triglyceride (p <.001) and HDL-C (p =.01) only in FM group compared to nFM group. Also, we found a significant reduction in fasting serum insulin (p <.001), and a significant improvement of HOMA-IR (p <.001) and QUICKI (p <.001) in both intervention groups compared to their placebos. Conclusions: An intake of fortified dairy products containing nano-encapsulated vitamin D ₃ was associated with an improvement in some measures of anthropometric indices, glucose homeostasis, and lipid profiles, particularly in individuals receiving fortified milk. Hence, along with other benefits, fortification of dairy products with vitamin D may be an effective approach to improve some cardiometabolic indicators, such as insulin resistance. Trial registration number: IRCT20101130005280N27.