Allergy medications may be improved by Vitamin D (6X for birch pollen in this case)
Bet v 1 from birch pollen is a hypoallergen with vitamin D3 in the pocket
Allergy https://doi.org/10.1111/all.15052 PDF is behind a $22 paywall
Karin Hufnagl, Livia Kromp, Rodolfo Bianchini, Sheriene Moussa Afify, Markus Wiederstein, Frank A. Redegeld, Iveta Zuvalova, Zdenek Dvorak, Gerlinde Hofstetter, Franziska Roth-Walter
Search Google Scholar for ALLERGY "Vitamin D" 90,000 studies as of Aug 2021
See also VitaminDWiki
By the way: 35 years before this study the founder of VitaminDWiki wrote a booklet on allergy treatments
pages containing ALLERG in title
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