Many people have researched the microbiome shift between infancy and adolescence, but very few have researched the changes in the microbiome that occur in the elderly. A new study out of Canada, published in the Journal Microbiome, did just that. Their results show that the frailty associated with old-age may be related to the bacteria in our guts.
The study used groups of mice that were either young, middle aged, or old. They then measured the frailty of these mice which, as one would expect, was tied closely with age. The researchers then studied the microbiome of these mice, as well as the genes expressed by the bacteria, so as to gain an understanding of what the bacteria are actually doing.
The scientists discovered that, when compared to young and middle aged mice, the old mice were abundant in bacteria that could break down simple sugars, but were underrepresented in bacteria that could break down more complex sugars, as well as lactate. This is important because increased lactate in the stool has been associated with ulcerative colitis and other inflammatory bowel diseases in older humans. The old age mice also consisted of less bacteria that could produce vitamins B12 and B7. Both are important vitamins and the lack of B7 has been linked to colon cancer. Finally, the old-age mice had bacteria that would rapidly degade creatine. Creatine is known to build muscle, so constantly breaking it down may cause the decrease in muscle mass observed in the elderly.
Clearly there are changes in the microbiome as we age, and these changes must come with some consequences. As the authors of this paper suggest, perhaps the microbiome holds to key to the difference between aging like a fine wine and aging like moldy cheese.