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Microbiome

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Beneficial gut bacteria help determine our ability to fight off infection, but how? Scientists discover that gut bacteria communicate with immune cells and cells lining the intestinal wall to regulate the immune system’s response to infection. Beneficial gut bacteria are responsible for attaching to the intestinal wall and signaling the cellular production of IL-10, a cytokine that tones down the inflammatory response triggered during the initial immune reaction. This regulation protects the gut from being attacked by the immune system and keeps the immune response focused on the infection. Immunity →Takeaway: The lead researcher in the study, Professor Gretchen Diehl, tells us, “A take-home message… is that a healthy microbiota is necessary to allow for a balanced response to not only protect us from infection, but also to limit potential tissue damage as the immune system attempts to eliminate pathogens.” Eat your veggies, grow a good gut garden, and reap the benefits of…

Prebiotic supplementation could replace the low FODMAPs diet as a treatment for functional gut disorders (IBS, constipation, functional dyspepsia, etc.). A 4-week study compared the effects of a prebiotic supplement plus Mediterranean-type diet, versus a placebo supplement plus low FODMAP diet for 2 weeks. Fecal microbiota composition, intestinal gas production, and digestive sensations were measured outcomes. After 4 weeks, both groups showed improvements in GI symptoms but only the prebiotic group showed significant improvements in microbial composition. (The FODMAP group actually showed an increase in pathogenic-associated bacteria). Two weeks after the intervention, improvement persisted in the prebiotic group but not in the FODMAP group. Gastroenterology →Takeaway: Based on 20+ years of clinical experience, Dr. Chutkan does not recommend the low FODMAP diet in her practice, including in those patients with functional GI disorders. The low FODMAP diet was created as a diagnostic tool for IBS, not as a therapeutic diet. While it may…

Scientists studied the sex-based differences in the intestinal barrier function and gut microbiome of 23 volunteers administered indomethacin (NSAID most commonly prescribed for rheumatoid arthritis and gout). At baseline, healthy women showed lower intestinal permeability and higher microbial diversity than healthy men. While indomethacin increased intestinal permeability in both sexes, only women experienced decreased diversity in fecal bacteria. While the microbiome and intestinal permeability returned to baseline 4 to 6 weeks after NSAID administration in both males and females, researchers conclude that women have a lower intestinal permeability, higher microbial diversity, and a less stable microbiome than men. Federation of American Societies for Experimental Biology →Takeaway: While this study looked at only 23 participants and touts some profound conclusions, it’s interesting to consider gender-based differences in the gut microbiome – and if any differences actually exist. In 2015, uBiome, one of the first companies to collect microbial data from the general population, found…

Common stool processing techniques (such as freeze thawing or blending in oxygen) for fecal microbiota transplantation (FMT) may significantly reduce efficacy of the procedure. Using a process called PMA, which differentiates between dead and live bacteria and discards the DNA data for dead bacteria, scientists found that even when using the best stool processing protocols available, approximately 50 to 80% of the bacteria in FMT stool samples were destroyed. Unfortunately the types of bacteria most negatively affected are commensal obligate anaerobes, which have strong anti-inflammatory properties. These types of bacteria produce a metabolite called butyrate that plays a key role in reducing inflammation in the body. Even when using best stool processing practices, the ability of the transplanted bacteria to produce butyrate was very low and was nearly zero when the stool was processed in oxygen. Healio →Takeaway: These findings tell us that current stool processing techniques have significant negative impacts on transplanted…

Gut bacteria play a leading role in how well cancer drugs work. Certain gut bacteria (Bifidobacterium specifically) boost people’s response to cancer treatment while others can make immunotherapy ineffective. In addition, previous studies show that those with antibiotic exposure are more likely to have a poor response rate to immunotherapy. Researchers are now testing how to manipulate gut bacteria in immunotherapy “non-responders”- using methods such as fecal microbiota transplantation, robust oral probiotics, and other medications based on the interplay between gut bacteria and the immune system. While manipulating the intestinal microbiome to treat cancer is an exciting proposition, some scientists are wary. Altering the gut microbiome can lead to harmful side effects, including other health problems. Some scientists also feel that it’s too early – we just don’t know enough about the microbiome: “A lot of findings [in microbiome research] have proven to either not stand up or be considerably more…

A ketogenic diet (KD) improves neurovascular pathways that play key roles in brain function and beneficially alters the gut microbiome.  The study included a 16-week ketogenic diet and was conducted in young, healthy mice aged 12 to 14 weeks. In addition to improved neurovascular function, a KD reduced blood glucose levels and body weight and showed markers of microbial alterations. Researchers conclude that when started early, a ketogenic diet may enhance brain vascular function, increase beneficial gut bacteria, improve metabolic function, and reduce the risk of Alzheimer’s disease (AD). Scientific Reports →Takeaway: Should we begin our children (or ourselves) on a ketogenic diet as a preventative measure for disease? Probably not! While ketogenic studies have uncovered some impressive findings – such as rapid weight loss, improved cardiovascular health markers, and efficacy for some diseases like epilepsy and MS – a long-term ketogenic diet can be problematic, if not detrimental. Adherence to the diet is extremely…

Patterned hair loss could be due to gut bacteria imbalance. Antibiotic-induced dysbiosis, characterized by an overgrowth of Lactobacillus murinus (a gut bacteria strain that depletes biotin – vitamin B7, a nutrient associated with hair growth), in mice fed a biotin deficient diet altered gut metabolic function and resulted in alopecia (or hair loss). When consuming a biotin supplement, alopecia symptoms were reversed. Cell Reports →Takeaway: This study tells us that there may be a microbial component to patterned hair loss. Yet re-establishing hair growth by restoring the microbiome can be extremely difficult for some. If you’re looking to increase the amount of bioavailable biotin in your diet focus on dietary sources first, such as nuts, sunflower seeds legumes, cauliflower, bananas, oats, and avocados. Looking for tips on how to balance your gut bacteria? Check out The Microbiome Solution for Dr. Chutkan’s Live Dirty, Eat Clean plan.

Is your microbiome test giving you an accurate picture? A recent study looked at one of the most well known markers of microbial health – bacterial diversity. The researchers found that taking 5 fecal samples over 5 consecutive days portrays a more accurate picture of microbial diversity than just 1 sample. This study also concluded that when looking at microbial composition (bacterial species and their ratios), 1 fecal sample was sufficient. In a letter to the editor, a group of researchers argue that microbial composition also varies over time. In their study of 61 infants, fecal samples were taken weekly for 6 weeks. Microbial composition varied over time, even from week to week. Researchers point out that the age of the study participants could be partly to blame. But, they ultimately conclude that calculating an average composition from fecal samples taken over a period of time could offer a more complete portrayal. Current Microbiology →Takeaway: Microbiome testing…

High processed salt intake alters gut bacteria composition and may disrupt the relationship between the microbiome and host homeostasis. While increased salt intake is a risk factor for cardiovascular disease (CVD), we’re not exactly sure why that is. A recent study gave rats either water or a salt-water solution over a two-week period and analyzed blood plasma, urine, and stool samples for TMAO (trimethylamine N-oxide – a bacterial byproduct that is linked to CVD) markers. Gut bacteria composition was also analyzed using 16S rRNA gene sequencing. Results found that high salt intakes increased TMAO and altered gut bacteria composition. Nutrition →Takeaway: The results of the study could help explain the relationship between high salt intake and an increased risk of CVD, although more research is needed. Based on this study and previous studies, a low or moderate salt intake in the diet is recommended. When looking at the Western diet, approximately 90% of…

Artificial sweeteners promote dysbiosis (imbalanced gut bacteria) in Crohn’s disease (CD) patients and may worsen the disease and its symptoms. In a series of 3 studies, scientists mixed a low dose of Splenda into the drinking water of mice (who originated from a genetic line of mice with CD). They increased the dose slightly for the second study and ten times for the third study. When compared to control groups of healthy mice that received plain water, there was an increase in Proteobacteria, E. coli, and intestinal wall immune cell reactivity – all signs of dysbiosis. Inflammatory Bowel Diseases →Takeaway: The lead researcher in the study concluded that Splenda and other artificial sweeteners should be avoided by those with Crohn’s disease, ulcerative colitis, or other digestive diseases, as they can cause inflammation and disease flare-ups. He also suggested in Newsweek that those without these conditions might not need to worry about the potential side effects of Splenda. At…