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“ We don ’ t have a metric for defining health and unhealth of the microbiome , and we are unable to figure out the therapeutics because if you don ’ t know what is wrong with it you don ’ t know how to treat it .” microbiome with all the components that have been decimated [ in the patient ’ s gut ],” explained Dr Chang .
Similar to probiotics , however , doctors have no clue which microbes are more likely to benefit patients , and they simply select healthy donors who haven ’ t been exposed to antibiotics in the past six months to harvest the microbes .
And this lack of knowledge probably explains why in some cases faecal transplants don ’ t work — the donor microbes are rejected by the host because they aren ’ t a good match for their specific microbiome .
The key challenges to reaping the benefits of microbiome medicine The main reason there ’ s still “ more unknown than known ” around microbiome therapies , in Dr Chang ’ s words , is that each person has a specific set of microbes that changes over time due to factors like age and diet , making it hard to identify clear links between their microbial make-up and diseases .
“ We don ’ t have a metric for defining health and unhealth of the microbiome , and we are unable to figure out the therapeutics because if you don ’ t know what is wrong with it you don ’ t know how to treat it ,” he said .
Another challenge is that new microbes added to the gut often fail to engraft , meaning they are rejected by the intestine . This is what happens to probiotics on many occasions , as experiments have shown , making them ineffective . One exception is kefir , a drink made from fermented milk that has shown a stronger ability to colonise the gut .
The problem is that researchers still don ’ t fully understand how to facilitate the engraftment process . If they did , they could improve the efficacy of both probiotics and fecal transplants and match microbes to individual patients as we currently do with blood types , quipped Dr Chang .
Promising microbiome research Medical research on the microbiome is exploding , according to Dr Chang , with several multibillion-dollar companies aiming to develop effective therapies that strengthen gut microbes , potentially benefitting patients across diseases .
Seres Therapeutics , for instance , is testing whether mixes of different microbes can prevent C . diff . recurrence as well as infection or complications after hematopoietic stem cell transplantation . This procedure replaces damaged bone marrow that ’ s not producing healthy blood cells due to cancer or other conditions but causes many patients to develop infections or the donated cells to attack the body . Similarly , Vedanta Biosciences is developing bacterial compositions in the hopes they could help treat inflammatory bowel disease and food allergy or even improve the efficacy of cancer immunotherapy .
Dr Chang says these companies have released preliminary data on the treatment of ulcer and colitis that look promising , so they might be on the verge of identifying some bacterial combinations that boost microbiome health in a way that leads to clinical benefits .
He ’ s not waiting around , however , and has embarked on his own different research approach . “ We are trying to identify the products the microbes produce to impact our biology ,” he said . Called metabolites , these substances are fairly similar across individuals , unlike microbes , making it easier to pinpoint health and disease parameters that are instrumental in developing effective therapies .
This method of working has allowed him to help a patient with bowel disease who couldn ’ t eat most foods as they triggered severe diarrhoea . After diagnosing damages to his microbiome due to prolonged antibiotic use , Dr Chang and his team got his microbes to churn out an increased number of short-chain fatty acids — metabolites produced by bacteria that break down dietary fibres — by concocting a fibre-rich diet the patient could tolerate .
“ Short-chain fatty acids are a set of metabolites most agree are required for a healthy microbiome ,” explained Dr Chang . “ These molecules are well known to be anti-cancer , they help develop the immune system , and are likely to play a role in general health .”
After sticking to the new diet , the patient saw
Medical research on the microbiome is exploding
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