http://www.chiro.org/nutrition/FULL/Eat_Right_and_Take_a_Multivitamin.shtml
The New England Journal of Medicine — April 9, 1998 — Vol. 338, No. 15
This editorial by Godfrey P. Oakley, Jr., M.D. of Centers for Disease Control and Prevention highlights the roles of folate and folic acid supplementation.
Paleo diets have far more folate than standard western diets. The low level in the SWD explains why supplements help the average person. Furthermore, 20% of the population carry mutations (C677T) in folate enzymes that increase their requirements for folate/folic acid.