The research on the human microbiome has skyrocketed in the last couple of years, and we now know that microorganisms in and on our bodies play an important role in obesity, cancer, IBS, and many other health disorders. It’s also well established that bacteria are passed on from mother to child during birth, breastfeeding, and other types of contact. Children also pick up bacteria from other family members, pets, and close relatives, and it seems likely that the “adult” microbiome is altered by contact (e.g., kissing, breathing) with other humans.
Dr. Art Ayers, an expert on the human microbiome and inflammation, wrote an excellent article in 2011 titled “Contagious health“. In the short piece he hypothesised that microbes are able to spread from one person to another, thereby affecting their microbiome and health.
From an evolutionary perspective, humans are designed to be attracted by healthy, lean and good-looking members of the opposite sex. This not only “ensures” healthy offspring(s) and “the survival of the fittest”, but regular contact between for example husband and wife will also promote sharing of their respective bacterial populations.
If the human microbiome is able to spread between individuals, this would imply that diseases that have been linked to an altered microbiome and generally aren’t considered contagious, actually are contagious. Although someone with colorectal cancer or acne aren’t able to actually spread their condition, they might be able to spread bacteria that have a detrimental effect on the health of anyone they are in regular close contact with.
The microbiome is first seeded with bacteria from our mother and other family members. For example a mother with irritable bowel syndrome passes on her dysbiotic microbiota, making the child more susceptible to the same condition. This close contact (contagious health) between members of the same household is a key reason why many diseases and health problems are so common in some families, while others stay clear of them.
To which extent micoorganisms are able to spread between humans is still unknown
– Is it necessary to have an intimate relationship with someone in order to influence each others microbiome?
– Are people living in the same household spreading their health between each other? E.g., surfaces, bathrooms, foods…
– Can health spread between the “general” population? A western dietary pattern and the rampant use of antibiotics (+other factors) in westernized societies promote an unhealthy microbiome.
More research is needed before we can adequately answer these questions, but it seems that a healthy diet and lifestyle is important not just for your own health, but also for the health of your children, family, and other people you are in regular close contact with!