Acidophilus (Lactobacillus acidophilus) is a species of the bacterium Lactobacillus that produces lactic acid by fermenting LACTOSE (milk sugar). This organism in the upper intestinal tract forms a symbiotic relationship with its human host. Other acid-producing bacteria, including bifidobacteria, are predominant in the lower intestine. Acidophilus is a member of the normal intestinal microflora, the so-called “friendly bacteria,” which produce nutrients like BIOTIN and VITAMIN K. Acidophilus and other Lactobacillus species help balance the digestive system by maintaining conditions that inhibit the growth of yeasts like candida, as well as potentially dangerous bacterial species. Without beneficial bacteria to control them, such opportunistic microorganisms can multiply rapidly, leading to a full-blown infection.

A variety of conditions can drastically lower or eliminate the intestinal acidophilus population. Treatment with broad-spectrum antibiotics, such as tetracycline, imbalances gut micro-ecology because these antibiotics destroy benign as well as disease-producing bacteria. More generally, an unhealthful life-style and a diet high in SUGAR and PROCESSED FOODS also adversely affect beneficial intestinal bacteria.

Acidophilus is a common food supplement that may help repopulate the gut with beneficial bacteria to prevent hard-to-control yeast infections; to break down milk sugar for those with LACTASE DEFICIENCY; to control travelers” DIARRHEA; to relieve CONSTIPATION; to treat vaginitis (when administered as acidophilus douches); and to decrease the production of potential CARCINOGENS by certain bacteria populating the gut.

Chaitow, Leon and Trenev, Natasha. Pro Biotics. Northampton, England: Thorsons, 1990.