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Vitamin D deficiency is a global health issue with consequences for bone health. Complexation of vitamin D3 with specific whey proteins might increase the bioavailability and enhance the effect of dietary supplementation on health outcomes. The current rat study was set up to investigate if complexation of vitamin D3 with whey protein isolate (WPI) or β-lactoglobulin (B-LG) increases bioavailability of the vitamin and how it impacts markers of bone turnover and bone structure. For 8 weeks, growing male Sprague Dawley rats (n = 48) were fed a vitamin D-deficient diet and during the final 4 weeks gavage dosing of vitamin D3 either alone (VitD) or complexed with WPI (VitD + WPI) or β-LG (VitD + B-LG) was administered. A placebo treatment (placebo) was also included. After sacrifice, samples of bone were collected and analyzed using biomechanical testing and μCT scanning. The concentrations of vitamin D3, vitamin D3 metabolites and bone markers (P1NP and CTX) were measured in serum. The results showed that VitD + B-LG appeared to induce lower levels of 25-hydroxy vitamin D3 in serum compared to VitD alone. Markers of bone turnover were generally higher in the VitD group compared to placebo and the VitD + WPI and VitD + B-LG treatments. No effects of treatments on bone strength or bone microstructure were detected. In conclusion, whey protein complexation of vitamin D3 supplements appeared to have no beneficial effects on circulating vitamin D3 metabolites but this did not impose changes in bone strength or trabecular bone microstructure.

OBJECTIVES: Vitamin D insufficiency (blood 25-hydroxyvitamin D METHODS: In this randomized, multiple crossover trial, we enrolled 30 postmenopausal women 60 to 80 y of age with vitamin D insufficiency. We measured changes in serum concentrations of vitamin D3 (D3) postprandially for 24 h in response to the intake of 500 mL of different food matrices with 200 µg D3 added compared with a control (500 mL of water). Foods included apple juice with whey protein isolate (WPI), apple juice, semi-skim milk, and water (with D3). The food matrices were provided in a randomized order with ≥10-d washout period between them. On each intervention day, blood samples were collected at 0, 2, 4, 6, 8, 10, 12 and 24 h.RESULTS: D3 with WPI in juice did not enhance area under the curve (AUC) of serum D3 compared with juice without WPI (370 nmol × 24 h/L; 95% confidence interval [CI], 321-419 versus 357 nmol × 24 h/L; 95% CI, 308-406 nmol × 24 h/L; P = 0.65). However, compared with juice, the AUC was significantly higher in response to the intake of D3 in milk (452 nmol × 24 h/L; 95% CI, 402-502 nmol × 24 h/L) and water with D3 (479 nmol × 24 h/L; 95% CI, 430-527 nmol × 24 h/L; P < 0.05). No difference was observed between milk and water (P = 0.34).CONCLUSIONS: The bioavailability of D3 was superior in milk and water compared with juice, regardless of whether WPI was added.

Vitamin D insufficiency (blood 25-hydroxyvitamin D50 nmol/L) is a global health problem. Vitamin D food fortification might be a solution, but knowledge is sparse on which food matrices yield the highest bioavailability. The aim of this study was to investigate the influence of different food matrices including complex formations with whey proteins on the human bioavailability of vitamin D.In this randomized, multiple crossover trial, we enrolled 30 postmenopausal women 60 to 80 y of age with vitamin D insufficiency. We measured changes in serum concentrations of vitamin DDThe bioavailability of D

This study investigated the effect of complexation with whey and casein protein, respectively, on post prandial absorption of vitamin D3. For this purpose, Sprague-Dawley rats (n = 78) were administered 840 IU vitamin D3 dissolved in ethanol and either (i) complexed with whey protein isolate (protein : vitamin ration 2 : 1), (ii) complexed with caseinate (protein : vitamin ration 2 : 1), or (iii) provided in a water solution. Serum concentrations of vitamin D3, 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 were measured before and 2, 3, 4, 5, 6, 7, 8, and 10 hours after administration of vitamin D3. Significant effects of complexation on serum concentrations of vitamin D3, 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 were demonstrated. Complexation with whey protein isolate resulted in the fastest and highest absorption of vitamin D3 while an effect of complexation with caseinate was evident but more modest and non-significant. In conclusion, the study demonstrates that complexation with milk proteins is an efficient strategy to enhance bioaccessibility of vitamin D3.

Background: Abdominal obesity and exaggerated postprandial lipemia are independent risk factors for cardiovascular disease (CVD) and mortality, and both are affected by dietary behavior. Objective: We investigated whether dietary supplementation with whey protein and medium-chain saturated fatty acids (MC-SFAs) improved postprandial lipid metabolism in humans with abdominal obesity. Design: We conducted a 12-wk, randomized, double-blinded, diet intervention study. Sixty-three adults were randomly allocated to one of 4 diets in a 2 3 2 factorial design. Participants consumed 60 g milk protein (whey or casein) and 63 g milk fat (with high or low MCSFA content) daily. Before and after the intervention, a high-fat meal test was performed. We measured changes from baseline in fasting and postprandial triacylglycerol, apolipoprotein B-48 (apoB-48; reflecting chylomicrons of intestinal origin), free fatty acids (FFAs), insulin, glucose, glucagon, glucagon-like peptide 1 (GLP-1), and gastric inhibitory polypeptide (GIP). Furthermore, changes in the expression of adipose tissue genes involved in lipid metabolism were investigated. Two-factor ANOVA was used to examine the difference between protein types and fatty acid compositions, as well as any interaction between the two. Results: Fifty-two participants completed the study. We found that the postprandial apoB-48 response decreased significantly after whey compared with casein (P = 0.025) independently of fatty acid composition. Furthermore, supplementation with casein resulted in a significant increase in the postprandial GLP-1 response compared with whey (P = 0.003). We found no difference in postprandial triacylglycerol, FFA, insulin, glucose, glucagon, or GIP related to protein type or MC-SFA content. We observed no interaction between milk protein and milk fat on postprandial lipemia. Conclusion: We found that a whey protein supplement decreased the postprandial chylomicron response compared with casein in persons with abdominal obesity, thereby indicating a beneficial impact on CVD risk.