Vitamin D bioavailability: state of the art

Area of Science:

• Nutritional Science
• Gastroenterology
• Biochemistry

Background:

• Growing evidence links vitamin D status to reduced risk of cancers, cardiovascular, and neurodegenerative diseases.
• Despite widespread subdeficient vitamin D status, factors influencing dietary vitamin D absorption remain poorly understood.
• Understanding vitamin D absorption is crucial for optimizing dietary intake and public health strategies.

Purpose of the Study:

• To review the current knowledge on the fate of vitamin D in the upper gastrointestinal tract.
• To identify and evaluate factors affecting vitamin D absorption efficiency from dietary sources.
• To highlight gaps in current research regarding vitamin D bioavailability.

Main Methods:

• Comprehensive literature review of existing studies on vitamin D absorption.
• Analysis of factors including vitamin D form, food matrix, fat content, and physiological influences.
• Identification of areas requiring further investigation using advanced methodologies.

Main Results:

• Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) show similar absorption efficiencies.
• 25-hydroxyvitamin D (25OHD) is absorbed more efficiently than non-hydroxylated forms.
• Dietary fat amount and food matrix have minimal impact; however, certain substances like Olestra and orlistat may reduce absorption. Aging does not appear to affect absorption efficiency.

Conclusions:

• Significant data gaps exist regarding the impact of dietary fiber, baseline vitamin D status, and genetic variations on vitamin D absorption.
• Further research, particularly clinical studies using labeled vitamin D, is essential to accurately determine factors influencing bioavailability.
• Improved understanding of vitamin D absorption can inform strategies to combat widespread vitamin D deficiency.