In one major scientific review evaluating 11 articles on dietary Vitamin A and four articles on blood levels of Vitamin A for a total of 12,136 participants, higher dietary Vitamin A intake and blood levels of Vitamin A were inversely associated with the risk of cervical cancer
Oselusi SO, Dube P, Odugbemi AI, Akinyede KA, Ilori TL, Egieyeh E, Sibuyi NR, Meyer M, Madiehe AM, Wyckoff GJ, Egieyeh SA
you may need 100-200 mg daily to sustain adequate blood levels, and more during times of increased need, like during an infection
Cosmetic IV whitening protocols often use 6001,200mg per session, administered multiple times a week, frequently without proper medical oversight a dramatically higher and more abrupt systemic exposure than 500mg taken orally once a day