A Nutritionally Meaningful Increase in Vitamin D in Retail Mushrooms is Attainable by Exposure to Sunlight Prior to Consumption

Abstract

The vitamin D2 content of white button mushrooms is relatively low. UV exposure produces vitamin D2 by rapid conversion of ergosterol to ergocalciferol. Commercial-scale UV treatment has been used to produce vitamin D-enhanced mushrooms. The reliability of a consumer-friendly protocol to increase vitamin D2 in mushrooms by a nutritionally meaningful amount using exposure to sunlight was evaluated. Sliced white button mushrooms were exposed to sunlight for 15, 30, or 60 minutes in 16 experiments at different times of day, seasons, and cloud cover. Vitamin D2 was measured by HPLC with 3H-vitamin D3 internal standard. Change in vitamin D2 per 70 g serving relative to untreated mushrooms was evaluated. Vitamin D2 in all unexposed mushrooms was 100% (>600 IU) in many cases. Even under conditions of lower UV intensity similar increases can be achieved after 30-60 minutes.