This study aimed to investigate the effects of daily intake of vitamin D-fortified yogurt drink (doogh) on central obesity indicators in subjects with type 2 diabetes (T2D) and the possible modulation of this effect by vitamin D receptor (VDR) Cdx-2 genotypes. A total of sixty T2D subjects were randomly allocated to two groups to receive either plain doogh (PD; n 29, containing 170 mg Ca and no vitamin D/250 ml) or vitamin D3-fortified doogh (FD; n 31, containing 170 mg Ca and 12·5 μg/250 ml) twice a day for 12 weeks. 25-hydroxyvitamin D (25(OH)D), glycaemic as well as adiposity indicators were evaluated before and after the intervention. VDR-Cdx-2 genotypes in extended number of T2D subjects in the FD group (n 60) were determined as AA, GA and GG. After 12 weeks, in FD compared with PD, serum 25(OH)D increased (+35·4 v. -4·8 nmol/l; P<0·001) and mean changes of waist circumference (WC; -1·3 v. +1·6 cm; P=0·02), body fat mass (FM; -1·9 v. +0·60 %; P=0·008), truncal fat (TF; -1·1 v. 0·13 %; P=0·003) and visceral adipose tissue (-0·80 v. +0·37 AU; P<0·001) decreased significantly. Circulating 25(OH)D was raised only in the AA group (34·8 nmo/l in AA group v. -6·4 nmol/l in AG and -1·6 nmol/l in GG groups; P<0·001), which was accompanied by a significant decrease in changes of WC (P=0·004), FM% (P=0·01) and TF% (P<0·001) in the AA genotype. Daily intake of vitamin D-FD for 12 weeks improved the central obesity indices in T2D subjects, and the improvement was more pronounced in the carriers of the AA genotype of VDR-Cdx-2.
Keywords: 25(OH)D 25-hydroxyvitamin D; Adiposity; FD fortified doogh; FM fat mass; Fat mass; HbA1c glycated Hb; PD plain doogh; QUICKI Quantitative Insulin Check Index; T2D type 2 diabetes; TF trunk fat; Type 2 diabetes; VAT visceral adipose tissue; VDR vitamin D receptor; Visceral fat; Vitamin D; Vitamin D receptor; Vitamin D receptor genotype; WC waist circumference.