They may also cause a sore tongue, and affect the gut mucosa. Dietary Folate and its absorption Folates are present in most vegetables, especially green leafy ones, and in liver and meat. They are degraded by prolonged boiling. The normal daily requirement is roughly 100 mcg. It takes a few weeks of a folate-free diet to become deficient.
Absorption is largely through the jejunum.
Everything that walks swims or flies contains vitamin B 12 . Nothing that grows out of the ground contains vitamin B 12 . Requirements are about 1-3 mcg per day. Absorption is highly specialised. Vitamin B 12 is protein bound in food, and must be digested free in the stomach by acid and pepsin.