Besides allergy to vitamin A, another cause of vitamin A deficiency to include is low stomach acid.

"Upper digestive problems, such as low stomach acid, can fail to dissolve vitamin A out of food sources.

Protein deficiency impairs absorption transport through the intestinal lining while fat malabsorption impairs vitamin A absorption into the lymph.

Finally, the liver cannot mobilize stored vitamin A to maintain adequate blood levels when blood protein and zinc levels are low.

Drugs that are used to reduce cholesterol also alter vitamin A in the body. Drugs that increase blood levels of vitamin A include Lescol, Mevacor, Provachol and Zocor, while those that interfere with vitamin A absorption include Cholestyramine and Colestid.

Contraceptives may increase blood levels of vitamin A.

Neomycin, an antibiotic, may decrease the absorption of vitamin A."