To the point about scientific consensus: https://doi.org/10.1007%2F978-0-387-77574-6_5 https://doi.org/10.1007%2F978-0-387-77574-6_5 The authors suggest that

To the point about scientific consensus: https://doi.org/10.1007%2F978-0-387-77574-6_5 https://doi.org/10.1007%2F978-0-387-77574-6_5 The authors suggest that 30 ng/mL seems like the sweet spot for most health outcomes. Higher levels (~ 50 ng/mL) might be beneficial for fighting cancer, but the risks associated with the prolonged supplementation is unclear, which is why they do not recommend it. Something to keep in mind is that high levels of vit D are linked with high levels of circulating calcium, which is a problem. Protocols that advocate high Vit D doses, like the Coimbra Protocol for autoimmune diseases (100,000 IU per day), try to keep calcium levels low. The Coimbra Protocol tries to find the Vit D dose that minimises parathyroid hormone levels, and needs a diet practically calcium free to be safe. PTH causes calcium levels in the blood to go up, leading to kidney damage and inappropriate calcification. Outside of an extreme setting like the Coimbra Protocol, while PTH is inversely linked to Vit D levels, beyond a certain point rising Vit D levels cause PTH levels to go up. This suggests that there exists a sweet spot of circulating vit D that minimises PTH levels. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6180659/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6180659/ This study among healthy subjects in Nairobi found that the lowest PTH levels were associated with a vit D level around 30 ng/mL.