The images of the mice are from one of the elegant MIT studies from Poutahidis et al investigating the effects of Lactobacillus reuteri ATCC PTA 6475. Even if you are not a fan of reading such detailed experimental studies, I urge you to read these, as they are well-written, wonderfully detailed, and written by people who have a real understanding of the full implications of the work they are doing.
Specifically, the above photo shows what happens at 12 months of age in control mice (example on left) compared to mice fed L. reuteri in their water (example on right). Notice that the control mouse is fat, while the treated mouse is slender.
This and related studies demonstrate that:
- While control mice got old—stopped playing, lost interest in mating or grooming each other, and got fat—L. reuteri mice stayed slender, mated more and continued to groom each other. In other words, L. reuteri mice stayed youthful as they aged.
- Testicular size (specifically Leydig cell number) and testosterone production in L. reuteri mice was considerably greater
- Sebum production, hair density, skin thickness, and dermal collagen were dramatically greater
- Skin healing was hugely accelerated
- Inflammatory measures (e.g., IL-10, neutrophil blood count) were lower
- On an obesogenic diet, control mice got fat while L. reuteri mice stayed slender
Most of these effects were found to be mediated through increased oxytocin blood levels, mimicking the findings of studies in parabiosis, in which immunologically compatible mice had their circulatory systems combined, one old and one young: the older mouse reverse-aged and became young again, mediated largely via oxytocin.
Other studies in mice and in humans have demonstrated that L. reuteri or oxytocin are associated with:
- Marked weight loss without change in diet or exercise
- Greater bone density or less bone loss
- Increased muscle mass
- Reduced insulin resistance, reduced visceral fat
- More rapid skin healing
- Increased empathy
To put this all another way, L. reuteri mice stayed young and slender until death (without life extension).
More and more of the findings in mice are being corroborated in humans. Will this youth-preserving effect also translate to humans? Could it mean that at, say, at age 40, you begin to supplement with L. reuteri (as we have been doing by amplifying bacterial counts with prebiotic-infused yogurt making) and you can remain 40 years old for another 40, 50, or 60 years with preservation of healthy, smooth skin, dense bones, high levels of testosterone and estrogen, thick hair, preservation of muscle, prevention of visceral fat accumulation, lower levels of inflammation, more youthful mentality, and slender? Could it mean that you are biking, dancing, and socializing at age 80 just as you are at 40 and not the one driving 20 miles per hour in a 45 mile-per-hour zone or asking the sales clerk to help you lift the gallon jug of milk?
I think that we are heading in that direction. And, because of the anorexigenic effect of L. reuteri/oxytocin, i.e., the loss of interest in food (though it still tastes good; you are simply freed from appetite, not taste) may lead us in the direction of caloric restriction that, at least in several experimental models, has been the most effective strategy to lengthen life.