Analyzing vitamin D in foods and supplements: methodologic challenges.

Area of Science:

• Food science
• Analytical chemistry
• Nutritional science

Background:

• Existing chemical methods for vitamin D analysis in foods are time-consuming, require expertise, and have limited validation.
• There is a critical need for standard reference materials with certified vitamin D values to ensure analytical accuracy in food testing.

Purpose of the Study:

• To review current methods for determining vitamin D content in fortified and unfortified foods.
• To address the lack of certified reference materials for vitamin D analysis in food matrices.
• To evaluate and improve the accuracy of existing vitamin D analytical methods.

Main Methods:

• Review of existing chemical methods for vitamin D analysis.
• Establishment of an analytic methods committee by the US Department of Agriculture to compare methods.
• Characterization of five control materials (skim milk, processed cheese, cereal, orange juice, salmon) using established methods.

Main Results:

• Initial relative standard deviations (SDs) for vitamin D analysis ranged from 35% to 50% across five food materials.
• Elimination of systematic biases through method and standard adjustments significantly improved accuracy, yielding relative SDs of 7% to 12%.
• Demonstrated that existing analytical methods can achieve accurate vitamin D quantification in foods.

Conclusions:

• Existing analytical methods, when properly standardized, can provide accurate vitamin D content data for foods.
• The development and availability of certified reference materials are essential for guaranteeing the accuracy of vitamin D analysis in food matrices.
• While current methods can be accurate, simpler and faster analytical techniques are needed to advance the field.