Those of you following my DrDavisInfiniteHealth.com blog, as well as its predecessor, the Wheat Belly Blog, know that I am a big fan of the microbe, Lactobacillus reuteri, L. reuteri.
Recall that L. reuteri is ubiquitous in human populations unexposed to antibiotics and other microbiome-disruptive factors unique to modern life. If we were to therefore analyze the intestinal microbiome of native New Guineans who spear or club their next meal, dig in the dirt for roots and tubers, gather berries, birds, eggs, mushrooms, drink from rivers and puddles, have no running water, etc. they all have L. reuteri. If we were to assess the intestinal microbiomes of wolves, squirrels, rabbits, or deer in the forest, who likewise consume food foraged from the wild, they all have L. reuteri. Sequence the intestinal microbiome of a modern American, however, and you are unlikely to find L. reuteri—nearly all of us have lost this microbe. The German microbiologist, Dr. Gerhard Reuter, who first identified this microbe in human breast milk in 1962, found it increasingly difficult to isolate this species from humans over his subsequent 40-year career. This is likely because of the microbe’s susceptibility to common antibiotics such as penicillin, amoxicillin, and others.
A wealth of experimental evidence, as well as a growing number of human clinical trials, suggest that most effects of L. reuteri are due to increased release of oxytocin from the hypothalamus and pituitary glands in the brain, thereby making it a prototypical “psychobiotic.” Restoration of this lost microbe, L. reuteri, has been associated with:
- Restoration or preservation of youthful muscle and strength—Recall that we typically lose about 35% of muscle mass as we age. While it may increase strength in younger people, this observation suggests L. reuteri yields a youth-preserving effect against age-related muscle loss, including sarcopenia in the aged frail.
- Preservation of bone density—Existing evidence suggests that there is half as much bone loss with restoration of L. reuteri compared to placebo. This is also consistent with observations made in experimental studies (e.g., increased osteoblast activity in building the elements of bone).
- Maintenance of sexual behavior—Animals experience this as mating and grooming even as old mice. Humans experience this as maintenance of sexual interest and libido as we age.
- Restoration of youthful immunity—Two studies now document that age-related loss of T-cell immunity due to atrophy of the thymus gland reverses with L. reuteri. This could potentially mean that age-related loss of immunity and immunosurveillance (against appearance of cancer cells) may be addressed or reversed with restoration of this microbe.
- Deeper, more sustained sleep—With (actigraphically-measured) extension of REM (rapid eye-movement) periods. This observation is anecdotal, not yet formally studied. I personally experience it to an extravagant degree, converting me from a chronic insomniac to someone who enjoys deep, uninterrupted sleep every night.
- Acceleration of healing—Skin wounds inflicted on animals and humans heal more rapidly, interpreted to be a gauge of youthful healing responses that extend beyond skin.
- Reduction in endotoxemia—This effect has far-reaching potential implications including reductions in insulin resistance, blood sugar, blood pressure, and other measures. This is likely a consequence of L. reuteri’s upper-GI colonizing ability and its capacity to produce bacteriocins, natural antibiotics effective against many of the species of small intestinal bacterial overgrowth, SIBO, that I believe is epidemic in the U.S.
- Increase in empathy, social connection, and accepting the opinions of others—These are the effects that I find the most interesting. It makes you a better member of a community, better able to understand and connect with other people.
Stronger muscles and bones, heightened immunity, deeper sleep, accelerated healing, reduced inflammation. I hope that you are beginning to appreciate the enormous implications for human health—emotional, physical, and social–of restoring this lost microbe. I don’t think it’s a stretch to say that L. reuteri and its boost in oxytocin make you a better human being. It is not about longevity; it’s about maintaining youthfulness and vigor for as long as possible. But it’s a microbe lost by the majority of people. Restoring it, I believe, is a genuinely huge advantage for the human experience. Restoration of L. reuteri won’t make a 70-year old into a 20-year old, but I believe it turns back the clock on many of the phenomena of aging by 10-20 years. I don’t know of anything else that has this effect yet is so benign, so accessible, and accompanied by so many other beneficial effects.