Elite athletes really are different from you and me. Or, at least their gut microbes are.
Scientists who analyzed stool samples of 15 runners a week before and after they competed in the 2015 Boston Marathon found unusually high levels of one particular microbe compared to 10 non-athletes. Levels of the microbe in question, Veillonella, spiked after an intense workout and bloomed even more after the marathon.
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“Veillonella acts like a “metabolic sink” for lactate, the scientists suspect, converting into fuel the by-product of hard-working muscles runners blame for their aching legs in the latter part of long-distance races” is misleading by calling lactate a “by-product.” Lactate is made by cells and used as a preferred fuel by the cells, including those in the muscle and brain, through oxidation of lactate in their mitochondria. Athletes upregulate their mitochondrial mass and the number of their lactate transporters so that they can use the extra lactate produced during exercise as fuel. Under strenuous aerobic conditions so much lactate is produced that it cannot be fully oxidized because of the limits of oxygen availability, and therefore accumulates in our tissues. Lactate is also a signaling molecule and a gluconeogenic precursor. Dr. George Brooks, Ph.D., professor at Berkeley, has an excellent review article on lactate (Brooks, 2018, Cell Metabolism, 27: 757-785).
Th article headline and text say that the marathoners had an “unusually high levels of one particular microbe compared to 10 non-athletes”. However that is not what the study being discussed reports.
It instead says that the athletes had a significantly higher level of Veillonella after they ran the marathon compared to before. No significant difference in the microbe levels was found among the 10 non-athletes and 15 athletes (before they ran the marathon).
I quote: “Phylum-level relative abundance partitioned by individual, time (−5 to +5 d in relation to running the marathon), and whether the participant was an athlete (Fig. 1a) showed that, at this high-level taxonomic view, any orthogonal differences were likely to be due to variation at the level of the individual.”
Ignoring the small size of the human-part of the study, the reported difference in Veillonella levels pre- and post-exercise state can be plausibly explained by the increased lactate levels in the latter state. Given that lactate is the primary food of Veillonella, it is not at all surprising hat their population explodes when more of it is available.