Vitamin D2 is produced in plants because they use that. Similarly, D3 is produced in animals because they use that. Supementation of D2 has no effect on how muc

Vitamin D2 is produced in plants because they use that. Similarly, D3 is produced in animals because they use that. Supementation of D2 has no effect on how much D3 animals end up with. From your 3rd link: Total serum 1,25(OH)2D did not change significantly with either treatment (p>0.05, post-treatment vs baseline). From your second link: only 3 of 10 possible studies included in the meta-analysis were randomized, controlled, double-blind, parallel intervention studies, which is the gold-standard design in nutrition research. Therefore, because of the lack of specific information surrounding the randomization and allocation of intervention to participants in all studies, there was an unknown degree of selection, performance, and detection bias. A meta-analysis of RCTs indicated that supplementation with vitamin D3 had a significant and positive effect in the raising of serum 25(OH)D concentrations compared with the effect of vitamin D2 (P = 0.001).