Milk Kefir has shown some anticandidal activity in vitro. The antagonistic LAB culture present in Kefir produce antifungal by-products such as Lactic Acid. However, it is my opinion, people suffering an active intestinal candidiasis shouldn't drink Kefir during the first months of treatment. Kefir has a considerable amount of galactose and lactose present.
Galactose is an immediate fuel for candida and lactose will be metabolized into glucose and galactose. Also, some candida sufferers are allergic to yeast reacting to the species present in kefir. The casein present may produce an allergic reaction to those people affected by leaky gut.