Many people have researched the benefits from ingesting fresh, fermented foods which are full of Friendly Bacteria.
Claimed benefits include that:

• they manufacture B-vitamins, such as biotin, niacin(B3),pyridoxine(B6) and folic acid by providing the enzyme lactase they enhance, and indeed allow, the digestion of milk based foods, and the vital calcium which they contain, for people who cannot otherwise digest milk.
   
• they predigest the protein of cultured milk (yoghurt, kefir) thus enhancing protein digestion and absorption. 
   
• they can act as watchdogs by keeping an eye on, and effectively controlling, the spread of undesirable micro-organisms (by altering the acidity of the region they inhabit and/or producing specific anti-biotic substances, as well as by depriving rival unfriendly bacteria of their nutrients). The antibiotics some of the friendly bacteria produce are effective against many harmful bacteria, viruses and fungi. Not the least of the potentially harmful yeasts controlled by some lactobacilli is Candida albicans, now implicated in many health problems in people who are malnourished or whose immune systems are depleted. Food poisoning and many bowl and urinary tract infections (diarrhea, cystitis etc.) can be prevented and treated using high bacterial cultures.
   
• they can help considerably to enhance bowel function. Where bowel bacteria are absent, the function of peristalsis is impaired, and the amount of time it takes for food to pass completely through the system is much increased.
   
• they can help to control high cholesterol levels, thereby affording us protection from the cardiovascular damage which excessive levels of this nonetheless important substance can create.
   
• they sometimes act to relieve the symptoms of anxiety.
   
• they have been shown to control facial acne in 80% of adolescents with this problem.
   
• they play a vital role in the development of a healthy digestive tract in babies.
   
• they play a role in protecting against the negative effects of radiation and toxic pollutants, enhancing immune function.