 Differences in digestion and absorption account for the notable differences in bioavailability between vitamers of vitamin B9.Forms of vitamin B9 that occur in minimally processed foods, sometimes referred to as “food folates”, require digestion by enzymatic hydrolysis prior to absorption whereas folic acid does not.Some vitamins have toxic effects when consumed in excess amounts and certain vitamers have a greater potential for toxicity compared to other forms of the same vitamin.