It is known that baker’s yeast (Saccharomyces cerevisiae)
is a rich dietary source of native folate, containing around
3 mg folate/100 g dry matter [15, 16]. It has earlier been
shown that the high folate content in kefir is primarily due
to the yeast and not the lactic acid bacteria [14]. When the
yeast content relative to lactic acid bacteria was increased
in kefir grains (from ratio 1:15 to 1:5.6) the total folate
content in fresh kefir was increased from 4.3 to 6.4 μg
folate/100 g. Kefir yeasts might thus potentially contribute
to the total folate in kefir. However, the differences in
folate-producing capabilities among yeast strains from
kefir grains are poorly investigated. Furthermore, the data
634
on the distribution of the different folate forms in yeast
strains from kefir grains are lacking.