Folate levels, as determined by the L caseimethod, in whole blood, serum, and liver in rats maintained for 6 weeks on a folate replete diet containing 2 mg/kg folic acid (□), a low folate diet containing no folate (▨), or a very low folate diet consisting of no folate plus 1% succinyl sulfathiazole (▧). There was a significant difference (P ≤ .005) among the three dietary groups for all three tissues, except between low folate and very low folate serum samples (P = .07). SD, standard deviation.