New Study Shows That Foods and Dietary Changes Can Influence The Cultivation Of Bacteriophages In The Gut According To Needs
Source: Thailand Medical News Jan 25, 2020 4 years, 10 months, 4 weeks, 1 hour, 13 minutes ago
Researchers from San Diego State University in a new study suggests that ancient viruses called
biophages may be just the set of tools needed to cultivate a healthy
microbiome.
Over the last few years, study after study has said that the overall health of the internal
microbiome ecosystem in the gut is critical for overall health and can play a major factor in the development of diseases such as obesity, diabetes and cancer. But research has also shown that simply swallowing pills filled with beneficial bacteria often has no effect on the
microbiome, which is made up of tens of trillions of microorganisms.
Though the 1,000 or so species of bacteria in the gut tend to get all of the attention, there are also a massive number of
biophage viruses swirling around in this complex mix.
Medical researchers led by molecular biologist Dr Lance Boling and microbial ecologist Dr Forest Rohwer found that
foods such as artificial sweeteners, licorice, honey, hot sauce and oregano can stimulate or suppress this omnipresent force. In limited cases, the team found that some
foods could be used to induce
phages to kill harmful bacteria or encourage the growth of those that are beneficial.
As so many bacteria are now resistant to antibiotics, phages have recently been in the spotlight for their hunter killer abilities. San Diego is home to one of the highest-profile examples of
phage power. When other treatments failed, a careful and experimental application of the tiny viruses killed the out-of-control infection that put UC San Diego comparative psychologist Thomas Patterson into a months-long coma.
Patterson's wife, UCSD infectious disease epidemiologist Dr Steffanie Strathdee, and a wide-ranging team of clinicians and researchers from academia and the U.S. Navy, searched for the right
phages, selecting the very few from billions of possibilities that would attack the particular strain of toxin-producing acinetobacter baumannii bacteria that had left Patterson on the verge of death despite months of spare-no-expense intensive care.
It was observed that
Bacteriophages, at least those that attack and destroy bacteria anyway, are extremely specific. They'll gun for one bacteria species and leave every other bug alone.
However that's not the only way these simple viruses work. Some function as "
prophages" living inside their preferred bacterial hosts and often contributing DNA segments that the bacteria can use to help themselves resist antibiotics or even process carbohydrates. Some substances, such as the antibiotic ciprofloxacin, induce
prophages already living inside bacteria to leave suddenly, killing their hosts in the process.
It is a particularly-elegant solution, because there is no need to find the right
phage to fight a specific bacteria as was the case for Patterson. The right virus to do the job is already inside the target and simply has to be induced to change its behavior from help to harm.
Dr Rohwer told
Thailand Medical
trong>News,"What we call
phage induction, it causes these viruses that are already present to activate and effectively blow up the bacteria."
The research team from SDSU team tested 117 different "consumable compounds" on four different bacteria and found that a handful of substances were particularly able to turn
prophages rogue.
It was found that the compound stevia, a commonly used sugar substitute, showed a strong ability to induce
prophages in a strain of Bacteroides thetaiotaomicron bacteria while the best results in another potentially-harmful microbe called enterococcus faecalis were uva ursi, propolis and aspartame. The first is commonly called bearberry, the second is a resin collected by bees and the third an artificial sweetener. Tests also showed that stevia, grapefruit seed extract and toothpaste were the strongest prophage inducers for staphylococcus aureus, a third bacteria tested.
Interestingly, other compounds such as rhubarb, fernet, coffee arabica and oregano reduced the number of viral particles across all types of bacteria tested. Some compounds, including hot sauces, were found to be broadly antimicrobial but did not have the exquisite level of specificity made possible by
prophage induction. Tabasco hot sauce was the broadest bacteria burner of the bunch. The sauce from Louisiana contains capsaicin and vinegar, both compounds known to have antibiotic properties. But there was definitely some Cajun mystery present in Tabasco.
Dr Boiling added, "The Tabasco seemed to have something like a synergistic effect that was more powerful than what you might see just by combining vinegar and capsaicin.”
Although the antibacterial properties of some tested compounds, especially propolis and stevia, have already been observed, the study's results suggest that it is possible to selectively encourage and kill different bacteria in the human
microbiome through the judicious use of foods with inhibitory and promotional properties.
Based on the fact that the health of the gut
microbiome is shown to affect everything from cognitive ability and mood to weight and inflammation, the idea of purposefully tending this particular garden intrigues Dr Steffanie Strathdee, the UCSD professor who helped save her husband's life with
phages and now is co-director of UC San Diego's Center for Innovative
Phage Applications and Theraputics.
Dr Strathdee added, "I think that, if you can show you can induce or inhibit
phages reliably, then you can pursue this landscaping kind of approach where you can select what you want to grow and keep other things from growing."
Dr Strathdee noted that the findings in the SDSU paper, while promising, are not yet conclusive. The study, for example, tested only four bacteria among what are thought to be up to 1,000 different species present in the gut, meaning that broader testing will be necessary to understand whether findings with the four species tested are more broadly applicable. And, because the SDSU experiments were done under lab conditions, results might be different when tested inside the human body.
Dr Strathdee further added, "It's a very complex system once you're testing inside the body, so we don't really know fully what the effects would be there. But it's pretty neat to think that maybe someday,
dietary changes could be prescribed to improve health not just using
phages to treat disease but also to promote health."
Reference: Dietary prophage inducers and antimicrobials: towards landscaping the human gut mircobiome, lance Boiling, Danieal A.Cuevas, Juris A. Grasis, Han Suh Kang, Ben Knowles, Kyle Levi, Published 13th January 2020, Gut Microbes Journal
https://doi.org/10.1080/19490976.2019.1701353
