Home gut health test warning after new study finds they provide inaccurate results: ‘Could delay people seeking appropriate medical care’
At-home gut health tests can give inaccurate and misleading results and require greater regulation to ensure they are safe and effective, leading experts have warned.
From inflammatory bowel disease, irritable bowel syndrome and even colorectal cancer, gut microbiome kits claim to test for a wide range of conditions.
Over the last decade, scientists have linked activity in the gut microbiome to obesity, diabetes, mental illness, cancer and other medical conditions.
But a new study, published in the journal Communications Biology, found that the results from these kits, which range from £100 to £400, vary enormously, whether they are produced by the same or different producers.
In response, the authors – led by Dr Scott Jackson, a molecular geneticist at the National Institute of Standards and Technology in the US – said consumers and healthcare professionals alike should be ‘very cautious’ when interpreting or acting on test results.
Professor Jacques Ravel, an expert in microbiology and study co-author, added: ‘I think it’s almost impossible for any of these at home tests to have clinical usefulness, which is a position a lot of scientists are sitting on.
‘Our rigorous assessment has spotlighted the systemic issue of poor comparability that plagues the industry.’
The study compared the results obtained from 21 direct-to-consumer gut microbiome testing kits from seven different companies.
Many scientists are skeptical about how useful at-home gut microbiome kits really are, warning that they can do more harm than good
The same combined fecal sample collected from one individual served as the test sample material for each test.
Collection procedures were followed according to instructions provided by each company – whether that was whole bowel movement or used toilet paper – and samples were sent back for analysis.
As the team noted, there are currently no universally accepted best practices for translating stool samples into a microbiome report – and results can be influenced by sample collection and shipping methods, sequencing technology and analyses.
‘This means bias can be introduced at each step, and even minor changes in methodology can lead to significant differences in results,’ Dr Jackson said.
The researchers compared the reports generated by each company and found the quantity of specific gut bacterial species varied across test results.
The American Gut Project, a large well-established data set, reports the average person will return a clostridium reading of just over 2.5 per cent.
One company involved in the study reported five times this abundance whilst three others failed to detect it in one or more samples.
Clostridium includes several human pathogens including C. diff – a type of bacteria that can cause diarrhoea – but it usually lives harmlessly in the bowel.
One of three identical samples analysed by kits from the same company was also categorised as ‘unhealthy’, while the other two were classed as healthy.
Dr Jackson concluded current regulations do not go far enough to protect consumers.
He said: ‘These questions are significant as the test results may lead consumers to make potentially unwarranted or unsafe lifestyle changes.
‘Many of the results are reported with respect to an average of ‘healthy’ microbiome; however, defining a healthy microbiome remains a challenge due to the heterogeneity of the human population, confounders and the possibility of multiple healthy microbiome definitions.’
Whilst the researchers acknowledged that some of these companies share their workflow online, meaning that consumers can see exactly how their sample is processed, this doesn’t ensure validity.
He added that whist the majority of gut microbiome testing companies recommended healthier eating habits to restore balance, which is unlikely to cause direct harm, a lot of consumers who buy these tests suffer from chronic gut conditions.
‘For these individuals, the variability in test results of the lack of outcomes from the recommendations provided, could not only lead to a loss of consumer fait in the science but also result in the delay of appropriate medical care.’
Some companies also recommend that customers take expensive supplements, like probiotics, sold by the company for which there is ‘very little clinical evidence for efficacy,’ according to the researchers.
