What is Doctor’s Best Probiotic? Doctor’s Best Probiotic supplies six strains of Bifidobacterium and Lactobacillus probiotics and delivers 20 billion CFU of bacterial families with solidly established digestive and whole-body health. Doctor’s Best Probiotic promotes digestion bowel regulatory and healthy immune response. Doctor’s Best Probiotic can help replenish losses of beneficial bacteria that commonly result from stress, poor diet, and other aggravating factors. How does it work? Probiotic lactobacilli are found more commonly in the mouth, stomach and small intestine than in the large intestine. The six strains in Doctor’s Best Probiotic have strong resistance to both the stomach acid and the harsh bile substances in the upper small intestine. They attach to the intestinal lining, residing mainly in the mucus layer that extends out from it. They release substances that help them compete against less beneficial bacteria. Lactobacillus acidophilus La-14 is a well-studied, especially hardy strain that strongly resists the challenging conditions of the intestinal environment. Lactobacillus salivarius Ls-33 may help protect the vulnerable intestinal lining against toxic chemical attack. Lactobacillus paracasei Lpc-37 has also been used in conjunction with other lactobacilli. Probiotic bifidobacteria are most abundant in the large intestine, colonizing it right after birth. The trademarked strain Bifidobacterium lactis HN019 (Bl019) is well documented for its intestinal and immune benefits. Bifidobacterium lactis Bi-07 (Bi07) is genetically well defined with 100 percent of its DNA sequence known, and has proven clinical benefit. Bifidobacterium lactis Bl-04 (Bl04) also is genetically well defined. It is able to attach to the intestinal lining, tolerates exposure to the bile fluids, and is extremely versatile at using non-digestible carbohydrates for energy. Use of Bifidobacteria results superior gastrointestinal comfort and function when compared to a placebo.