Cats: The Use of Folate (vitamin B9)

Folic acid is one of the B vitamins (B9).  It is absorbed in the jejunum and ileum (the middle and last sections of the small intestine), and transported to the liver which either releases it for circulation or stores it.

Gratuitous photo of Spencer 

A deficiency can cause reduced growth in kittens, anemia, neurological development problems, and changes in the bone marrow. It was the relationship to anemia which led to its discovery and to its importance with cats.  As many know, CRF cats often are anemic.  Many owners and vets will give B12 injections to help solve the anemia.  Sometimes this works and sometimes it does not.  When it doesn't, the cause of the anemia may not be low B12 levels, but instead low folic acid levels.  B12 and folic acid work together and both must be present in sufficient amounts to prevent or correct some forms of anemia.

What this means is if you are using B12 for anemia, use mixed vitamin B for the injections and not just B12.  While the cat may have enough folic acid (and other B's), excess folic acid has not known effects.  It is water soluble and so easily removed from the body.

As it is stored in the liver, cats with liver disease often are deficient for folic acid and would benefit from supplementation.  In one study of cats suffering from GI problems (including liver and pancreas problems), 38.8% had low folate levels. http://www.ncbi.nlm.nih.gov/pubmed/17392004

There also are connections between folate levels in the blood and intestinal absorption, bacterial overgrowth, and exocrine pancreatic insufficiency (EPI).  These connections can help with differentiating various gastrointestinal issues.  http://www.ncbi.nlm.nih.gov/pubmed/21596348 

In brachiocephalic dogs, the supplementation of folic acid in pregnant bitches decreases cleft palates significantly.  I could not find any information on this for cats, like Persians, but as neural tube development in mammals seems to be folate sensitive, I would presume cats are equally likely to have this type of developmental problems when folate levels are low.

What all this means is this: 
-- for anemia, you should use mixed vit B and not only B12

-- for cats with liver issues, you should supplement with folic acid

-- for pregnant cats, you should a well balanced food with sufficient folic acid