A person’s height may influence the bacterial diversity of their gut microbiome. This could be due to taller people potentially having longer gastrointestinal tracts that can house a broader array of microorganisms. Not everyone is convinced by this, however, with one scientist arguing that a person’s genetics or having a poor diet during childhood could both inhibit their growth and affect their gut microbiome.
Among vertebrates, . While this trend is most evident between animals with large size differentials, for example mice and elephants, at the Institute for Systems Biology in Seattle and her colleagues wanted to see whether it applies to people.
The researchers gathered data from more than 5000 people who previously took part in a gut-related experiment and more than 3000 people from a wellness programme. All provided information on their height, which ranged from 127 to 218 centimetres, as well as faecal samples for gut microbiome sequencing.
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They found that the diversity of bacterial species within the participants’ guts increased in proportion to their heights.
The researchers liken this to the island biogeography idea, which states that larger islands tend to have greater species diversity than smaller ones. Perhaps taller people have longer gastrointestinal tracts, allowing for greater microbial diversity, they say.
To understand what this might mean for health outcomes, the researchers then focused on 130 people who took part in the previous gut experiment, all of whom had a history of infection with the bacterium Clostridium difficile. This usually lives harmlessly in the bowel, but can cause diarrhoea if the balance of bacteria in the gut changes, for example after taking antibiotics.
By comparing these individuals to the remaining participants in the gut experiment, the researchers found that those with a history of C. difficile infection were marginally shorter – with an average height of 168.1 centimetres compared with 171.7 centimetres – and had significantly lower gut diversity scores.
When the researchers looked at other aspects of the participants’ characteristics and lifestyles, aside from just their heights, they found that eating a high-fibre diet seemed to protect against an infection of C. difficile more than any effect of height. “This suggests that the effects of height can be overridden by diet,” says team member at the Institute for Systems Biology. “For example, if you’re shorter, eat more vegetables.”
With future studies, a person’s height could help to guide advice about their lifestyle and even medical treatments. “I think height could be a potential candidate for personalised medicine,” says Sarmiento. “Our research would suggest shorter individuals would benefit from changing their diet to increase their gut microbiome diversity.”
Yet at the University of Washington in Seattle says that a person’s height doesn’t necessarily correlate with the length of their gastrointestinal tract, calling into question comparisons to the island biogeography idea. “While the small intestine does correlate with height to a certain degree, the colon – where most of the gut microbiome lies – correlates better with weight and body mass index,” he says.
Rather than height affecting gut microbial diversity, people may be shorter as a result of their genetics or poor childhood nutrition, with these also potentially influencing their microbiome, says Damman. “A more diverse microbiome is generally associated with healthy eating and perhaps that leads to better or more linear growth as a child, but there certainly needs to be a lot of work to evaluate that more rigorously,” he says.
The researchers intend to analyse the extent to which the gut microbiomes of people of different heights are restored after taking oral antibiotics.
“Perhaps we might see that taller individuals’ microbiomes return to a more diverse state in comparison to their shorter peers, after this major disturbance to their gut microbiota,” says Sarmiento. “Additionally, we could see if our findings with [C. difficile infection] are consistent with other gut infections.”
bioRxiv
