Probiotics and the Microbiome: Clinical Intervention Trial for Anxiety and Depression

Purpose

The human microbiome, also known as microflora, is comprised of the bacterial colonies of the body. Although bacteria are commonly associated with illness, there are good bacteria known as probiotic bacteria that grow naturally in the microbiome of the human gut. Probiotic bacteria are live microorganisms and consist of approximately 400 different bacterial strains that support life in their host organism. The gut microbiome, also known as intestinal flora, plays a role in normal human development, digestion, body weight, nutrition, and immune system regulation, in addition to influencing various neurological functions. It has been found that environmental factors including antibiotics, illness, stress, and diet can alter an individual's microbiome through their effects on probiotic bacteria situated in the gut microflora.

Although probiotic bacteria grow naturally in the human gut, acquisition of the gut microbiome varies in each individual depending on various factors, including birth method and early diet. Research suggests that newborns' first exposure to bacteria and acquisition of the first components of their microbiome takes place during birth. Infants acquire their mothers' bacteria as they pass through the vaginal canal during childbirth. Research indicates that, for this reason, children born through cesarean section have a less diverse microbiome (Dominguez-Bello, Costello, Contreras, Magris, Hidalgo, Fierer, & Knight, 2010). Research also suggests that following birth, infants continue to acquire their gut microbiome in the first two years of life under the influence of dietary nutrition. For example, in a study of six breast-fed and six formula fed infants, those who consumed a specially enriched formula that contained both prebiotics (substances that feed probiotics) and a variety of probiotic bacteria had a much more diverse intestinal flora than those who received breast milk (Harmsen, Wildeboer-Veloo, Raangs, Wagendorp, Klijn, Bindels, & Welling, 2000). Please note that this study does not negate the benefits of breast milk and was intended to assess the effect of heightened prebiotic and probiotic concentrations in a baby formula that was chemically similar to breast milk.

Because probiotic bacteria are acquired naturally from environmental sources in addition to growing normally in the human body, it is safe for humans to consume probiotics. Furthermore, Health Canada has labeled probiotics a natural health product (NHP) safe for human consumption. Common foods we eat each day contain probiotic bacteria that enrich our intestinal flora. For example, yogurt and cheese contain probiotic bacteria. There has been a recent upsurge in interest on probiotics amongst researchers as the positive effects of probiotics on the gut microbiome and recognition of their great therapeutic potential for a wide variety of conditions increases.

The Microbiome and Physical Health