How follic acid deficiency causes megaloblastic anemia?

It just does :): Hello- your body needs Folic Acid to make red blood cells properly. If you do not have enough it compromises the process. The body will not be able to produce red blood cells as well (anemia) and they will be bigger than normal red blood cells (megaloblastic = big). Thankfully some Folic Acid replacement should fix the problem quite easily.

Inhibit DNA: Folic acid is essential for dna synthesis. Folic acid deficiency leads to decreased dna synthesis in blood cells, which in turn results in inhibition of nuclei division in continued growth of red blood cells, eventually leads to magaloblastic anemia. Hope helps, refer to any biochemistry textbook for details.

Necessary vitamin: Both Folic Acid and vitamin B12 can produce megaloblastic anemia, which means large appearing red cells and abnormalities of the granulocytes. B12 can cause neurologic problems. Bowel surgery can be associated with deficiencies. Please discuss your concerns with your doctor.