This study examined the impact of different food matrixes, including complex formations containing whey proteins, on human vitamin D bioavailability.

The prevalence of vitamin D insufficiency varies worldwide, affecting between 24 and 49 percent of the population. Even though the skin synthesizes the majority of vitamin D in the body after exposure to ultraviolet B light, most individuals require some dietary vitamin D to maintain a replete vitamin D status.

Although cholecalciferol (vitamin D3) is the most common dietary source of vitamin D, it is only found in a few foods, making it difficult to get the recommended dose of 10 to 20 µg/d day. Therefore, supplements or fortified foods are the best way to maintain an adequate vitamin D level.

A vital component of the Vitamin D Fortification with Enhanced Bioavailability (DFORT) program is the development of interdisciplinary strategies that will enhance vitamin D fortification efficiency. In previous studies, DFORT demonstrated that vitamin D3 could be stabilized by forming complexes with whey protein α-lactalbumin in vitro, which improved its bioavailability in rats.

Methodology and Results

During this randomized, multiple crossover trial, 30 postmenopausal women 60 to 80 years old with vitamin D deficiency were enrolled. Compared to a control (500 mL of water), the experts measured changes in serum levels of vitamin D3 (D3) after the intake of 500 mL of different food matrixes with 200 g D3 added for 24 h postprandially.

There were three types of food: apple juice enriched with whey protein isolate (WPI), semi-skim milk, and water enriched with D3. The food matrixes were randomly assigned with a 10-day washout period between them. Blood samples were gathered at 0, 2, 4, 6, 8, 10, 12, and 24 hours on each intervention day.

Juices containing D3 and WPI did not affect the serum D3 area under the curve (AUC) compared to juices without WPI. However, when D3 was consumed in milk or water with D3, the AUC was significantly higher than when consumed in juice.

Regardless of whether WPI was added, milk and water had better D3 bioavailability than juice.

Vitamin D fortification is most commonly carried out on milk and dairy products. However, milk as a staple for food fortification is problematic since it doesn’t enhance vitamin D levels in those who don’t consume dairy.

Based on the present findings, water is equivalent to milk as a food matrix delivery system, providing an alternative for those with lactose intolerance or low dairy consumption (e.g., the diabetic).

“A limitation of this study was its inability to assess any long-term effects. Long-term effects are defined by changes in 25(OH)D concentrations, not D3 concentrations, and they are expected to occur after several weeks of treatment. Further studies are required to study the long-term effects of the different food matrices,” the authors added.

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