Basically, they found carotenoid production genes to be more abundant in the people who were healthy. And they then appear to have concluded that production of carotenoids by bacteria in the gut protects from strokes. Completely ridiculous. No evidence whatsoever is presented that such production of carotenoids by gut microbes does anything of the kind. Compare the semi careful wording in the paper
Our finding of enriched levels of phytoene dehydrogenase in the metagenomes of healthy controls and its association with elevated levels of β-carotene in the serum may indicate that the possible production of this anti-oxidant by the gut microbiota may have a positive health benefitTo the drivel in the release
Our results indicate that long-term exposure to carotenoids, through production by the bacteria in the digestive system, has important health benefits. These results should make it possible to develop new probiotics. We think that the bacterial species in the probiotics would establish themselves as a permanent culture in the gut and have a long-term effect
As a bonus, they promote a new company of their Metabogen in the press release. Here's a suggestion. Do not invest in this company and do not believe anything they do (unless they retract the claims in the PR). The people involved in this press release, which also are associated with this company, are overselling their own work, do not seem to understand the difference between correlation and causation, and are making dangerous claims about health benefits.
And thus I am awarding them my coveted "Overselling the microbiome award." Past awards include:
- Overselling the microbiome award of the month: Integrative medical group of Irvine
- Overselling the microbiome award: MedicalDaily on Effects of Sugary Drink
- Overselling the microbiome award: Scientists look to mummies for obesity cure
- Overselling the microbiome award #2: The Marshall Protocol
- Overselling the microbiome award: Stephen Barrie on pre and probiotics at the Huffington Post
Some of the other parts of the press release that are bad:
- The title: "Changes in the gut bacteria protect against stroke." Are you kidding me? Ridiculous claim with no evidence.
- Another line: "Jens Nielsen, Professor of Systems Biology at Chalmers, says that it may be preferable to take probiotics instead – for example dietary supplements containing types of bacteria that produce carotenoids." So now they have jumped from a correlation in what microbes are present to treating people with probiotics. Just what priobiotics are they going to use? And is there any evidence that they help?