Study: Commonly Used Mouthwash Could Make Saliva Significantly More Acidic

Toby Leigh wrote . . . . . . . . .

The first study looking at the effect of chlorhexidine mouthwash on the entire oral microbiome has found its use significantly increases the abundance of lactate-producing bacteria that lower saliva pH, and may increase the risk of tooth damage.

A team led by Dr Raul Bescos from the University of Plymouth’s Faculty of Health gave a placebo mouthwash to subjects for seven days, followed by seven days of a chlorhexidine mouthwash.

At the end of each period, the researchers carried out an analysis of the abundance and diversity of the bacteria in the mouth – the oral microbiome – as well as measuring pH, saliva buffering capacity (the ability to neutralise acids in the mouth), lactate, glucose, nitrate and nitrite concentrations.

The research, published in Scientific Reports, found using chlorhexidine mouthwash over the seven days led to a greater abundance of species within the families of Firmicutes and Proteobacteria, and fewer Bacteroidetes, TM7 and Fusobacteria. This change was associated with an increase in acidity, seen in lower salivary pH and buffering capacity.

Overall, chlorhexidine was found to reduce microbial diversity in the mouth, although the authors cautioned more research was needed to determine if this reduction in diversity itself increased the risk of oral disease.

One of the primary roles of saliva is to maintain a neutral pH in the mouth, as acidity levels fluctuate as a result of eating and drinking. If saliva pH gets too low, damage can occur to the teeth and mucosa – tissue surrounding the teeth and on the inside of the mouth.

The research also confirmed findings from previous studies indicating that chlorhexidine disrupted the ability of oral bacteria to turn nitrate into nitrite, a key molecule for reducing blood pressure. Lower saliva and blood plasma nitrite concentrations were found after using chlorhexidine mouthwash, followed by a trend of increased systolic blood pressure. The findings supported earlier research led by the University that showed the blood pressure-lowering effect of exercise is significantly reduced when people rinse their mouths with antibacterial mouthwash rather than water.

Dr Bescos said: “There is a surprising lack of knowledge and literature behind the use of these products. Chlorhexidine mouthwash is widely used but research has been limited to its effect on a small number of bacteria linked to particular oral diseases, and most has been carried out in vitro.

“We believe this is the first study to look at the impact of 7-day use on the whole oral microbiome in human subjects.”

Dr Zoe Brookes and Dr Louise Belfield, Lecturers in the Peninsula Dental School at the University of Plymouth, are co-authors of the study.

Dr Belfield said: “We have significantly underestimated the complexity of the oral microbiome and the importance of oral bacteria in the past. Traditionally the view has been that bacteria are bad and cause diseases. But we now know that the majority of bacteria – whether in the mouth or the gut – are essential for sustaining human health.”

Dr Brookes added: “As dental clinicians, we need more information on how mouthwashes alter the balance of oral bacteria, so we can prescribe them correctly. This paper is an important first step in achieving this.

“In the face of the recent COVID-19 outbreak many dentists are now using chlorhexidine as a pre-rinse before dental procedures. We urgently need more information on how it works on viruses”

Source: University of Plymouth


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Many Common Medicines Could Alter Your Microbiome

Some widely used drugs alter the population of microbes in the gut, and a number raise the risk of antibiotic resistance, a new Dutch study shows.

The gut microbiome includes at least 1,000 species of bacteria and is influenced by a number of different factors, including medication. Research suggests that changes in the gut microbiome are associated with obesity, diabetes, liver diseases, cancer and neurodegenerative diseases.

“We already know that the efficiency and the toxicity of certain drugs are influenced by the bacterial composition of the gastrointestinal tract and that the gut microbiota has been related to multiple health conditions; therefore, it is crucial to understand which are the consequences of medication use in the gut microbiome,” said lead researcher Arnau Vich Vila, from the University Medical Center Groningen.

In this study, the researchers examined 41 commonly used drug categories and assessed 1,883 fecal samples from people who did and didn’t take the drugs, including some with irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).

Eighteen of the drug categories had major effects on the gut microbiome, and eight increased the risk of antimicrobial resistance.

The categories with the biggest impact on the microbiome were:

  • Proton pump inhibitors (PPIs), used to treat indigestion, peptic ulcer, H. pylori eradication, gastro reflux and Barrett’s esophagus.
  • Metformin, used to treat type 2 diabetes.
  • Antibiotics, used to treat bacterial infections.
  • Laxatives, used to treat and prevent constipation.

The gut microbiomes of PPI users had higher levels of upper gastrointestinal tract bacteria and increased fatty acid production, and metformin users had higher levels of potentially harmful E. coli bacteria.

Seven other drug categories were associated with significant changes in bacterial populations in the gut, according to the researchers.

For example, the use of SSRI antidepressants by people with IBS was associated with increased levels of the potentially harmful bacteria species Eubacterium ramulus.

Meanwhile, the use of oral steroids was associated with high levels of methanogenic bacteria linked with obesity and an increase in body mass index (an estimate of body fat based on weight and height).

The study was to be presented Wednesday at the UEG (United European Gastroenterology) annual meeting, in Barcelona. Such research is considered preliminary until published in a peer-reviewed journal.

“Our work highlights the importance of considering the role of the gut microbiota when designing treatments and also points to new hypotheses that could explain certain side-effects associated with medication use,” Vila said in a meeting news release.

Source: Healthday

Are Personalized Diets Ready for Prime Time?

Debbie Koenig wrote . . . . . . . . .

When Howard Wolinsky was diagnosed with type 2 diabetes, he expected to kiss bagels goodbye — too many carbs. But a personalized diet based on his own gut microbiome offered a pleasant surprise: “It turns out those little bugs in my guts seem to like bread, if it’s combined with fats and proteins,” he says.

Wolinsky’s diet came from DayTwo, a company that uses research from the Weizmann Institute of Science in Israel to create customized advice for people with diabetes. From his home in suburban Chicago, Wolinsky, 71, sent the company a stool sample and a completed questionnaire, and he got back guidance about precisely which foods would spike his blood glucose and which would keep it steady. He was also taking an oral medication for his diabetes.

“I could have a bagel, with cream cheese and lox,” he says. “That combination got a really good rating on the DayTwo scale.” He was amazed to find that when he followed DayTwo’s advice, his blood sugar remained within a normal range. It didn’t spike the way it would for foods outside their recommendations.

News Flash: Diets Aren’t One-Size-Fits-All

DayTwo has plenty of company in the personalized diet business. At least a dozen outfits offer nutrition advice customized to your body, based on DNA or blood tests, microbiome profiling, or a combination of those. Several promise weight loss, while others focus on specific conditions or just general “wellness.” Each uses its own proprietary process, and for some, the science behind it gets murky. Costs range from under $100 to nearly $1,000 for different services. DayTwo, for example, charges $499 for a microbiome testing kit, personalized app, orientation call with a registered dietitian, and microbiome summary report.

Earlier this year, a new study about personalized diets made headlines. Called the Predict Study, it found that different people respond to exactly the same food in different ways — even identical twins, who have almost the same genetic makeup. So, a muffin that spikes one person’s blood glucose might not affect someone else’s. The study captured data by closely monitoring how 1,100 people, more than half of them twins, responded to various foods, including prepared items provided to them. Researchers tracked details like blood sugar, insulin, and triglycerides (fat) as well as sleep patterns, activity levels, and gut bacteria. Using that data, they began to create a model to predict how anyone might respond to a particular food, based on their own microbiome and DNA.

The Weizmann Institute’s research took a similar approach, analyzing the blood sugar responses of 800 people after more than 45,000 meals. They found wide variations in their glucose levels after eating, even when meals were standardized.

Eric Topol, MD, a cardiologist and author of Deep Medicine: How Artificial Intelligence Can Make Healthcare Human Again, tried a version of the Weizmann test. He provided a stool sample and for 2 weeks wore a glucose sensor. He monitored his food, sleep, and physical activity. “Certain foods gave me prominent spikes in my glucose, and I’m not a diabetic,” says Topol, editor-in-chief of Medscape, WebMD’s site for health care professionals. “A lot of my favorite foods were incriminated, while others that I’d never think of eating were recommended, things like bratwurst or cheesecake. I tried cheesecake just to see, and sure enough, my glucose didn’t budge.”

These discoveries go against conventional advice like the federal Dietary Guidelines for Americans and most popular diet plans. Instead of broad rules about food groups, the results suggest that each of us could be eating foods to support the specifics of our own bodies. Still, even if evidence mounts that personalized diets significantly help people identify “ideal” foods, those who eat a well-balanced diet have also been found to have improved health, decreased diabetes, heart disease, etc.

“We’re so driven by this dull idea that everyone has the same needs, that there’s a perfect proportion of carbs and fats for everybody,” says Tim Spector, MD, a professor of genetic epidemiology at King’s College London. Spector was the principal investigator of the Predict Study and is co-founder of Zoe, the company funding the research. “You have to tear up the rule book and start again.”

Enter the Gut Microbiome

Your microbiome is made up of trillions of tiny organisms called microbes that live in and on your body. Each of us has a unique mix of microbes in our guts, and the balance affects your risk of conditions like obesity and diabetes. That’s one reason scientists are focusing on the gut for custom-made diets.

A personalized diet aims to steer you toward foods that encourage the right mix in your unique microbiome.

“We believe the microbiome plays a role, because out of all the things we measured in identical twins, what differed most were the microbial species and what they did,” says Spector. “The other differences that aren’t due to genes or microbes, we’re still trying to tease apart.”

Wolinsky’s experience has him convinced. “It seems so strange that making microbes in my gut happy can affect my health and my weight, but I do believe it helps,” he says.

The Genetic Component

What we eat has an effect on our genes — there’s an entire field of study devoted to it, called nutrigenetics — but does that mean we should eat or avoid specific foods based solely on our DNA?

Right now, numerous companies claim to provide a diet made just for your DNA. But the Predict Study shows that genes alone don’t create a full picture. Using identical twins and their matching DNA allowed Spector and his colleagues to account for the effect of genetics. Even when they ate the exact same meals, twins often had wildly different responses. “Yes, genetics plays a role,” Spector says. “But it’s a very small role, compared to the things that make us individual.”

Topol agrees. “There isn’t anything proven yet with DNA. So let’s be clear about that,” he says. “The only real breakthrough in recent years has been capturing all of a person’s data, including their gut microbiome data.”

Conflicting, Confusing Results

Differing approaches to the kind of testing and the data being collected led to advice that can be hard to follow. In addition to consulting DayTwo, which focuses on helping people with diabetes manage their blood sugar, Wolinsky also got a personalized diet from Viome, a company that promises to help you “optimize” your microbiome for increased energy and well-being. The results were often at odds with each other: DayTwo gave butter, duck, and tuna an A+ score for Wolinsky, while Viome suggested he avoid those foods.

“It seems your microbiome should be your microbiome. But it’s not that simple,” he says. “So I was dubious.” He could confirm DayTwo’s recommendations with a finger-stick blood glucose test, and its program is targeted toward people with diabetes. He stuck with DayTwo’s advice.

Topol points out that because DayTwo is so focused on blood sugar, the results may not be promoting overall health. Remember that his results recommended bratwurst? “As a cardiologist, I still can’t go near that,” he says.

What We Don’t Know

While experts say the research is promising, the era of personalized diets has barely begun. Numerous questions remain. The biggest: Is it worth it?

“What we don’t know is whether we should live our lives like this. Should we radically change our diets to avoid glucose spikes? It’s intuitive that we wouldn’t want to have them, but we need more proof that this will make a difference,” says Topol.

The second phase of Spector’s research, Predict 2, aims to expand the database by collecting data from at-home volunteers in the United States. Participants of different races, ages, and lifestyles will be tested and tracked for 10 days to enrich the data — and the at-home aspect means the results will reflect real life. Ultimately, he hopes to create a commercial app through Zoe that will allow users to get up-to-the-minute advice about what they should eat.

But we’re nowhere near understanding the long-term effects of following a personalized diet. “It’ll take years to see its effect on weight reduction or heart disease. Nobody knows yet that reducing glucose peaks will do this,” says Spector. “Once we’re into the hundreds of thousands of participants, it’ll be easy to track.”

Another unknown is how practical such detailed diet plans will be. If your report says you should stay away from, say, steak, but your spouse’s says the opposite, does that mean cooking two dinners? Eating for your specific microbiome may require changing the way you approach family meals and socializing.

“Plus, we already have a pretty good sense of what constitutes a healthy diet: lots of fruits, vegetables, and whole grains with minimal red meat,” says Joe Schwarcz, PhD, director of the McGill University Office for Science and Society. “What’s the point of adding more info when people aren’t even following what we know to be true?”

Should You Try It?

At this point, none of the personalized diets on the market gather enough information about you to pinpoint what you should eat for overall health — you’ll only get a partial picture. And there’s no consensus about what they should be gathering.

“I find the genetic factors and the microbiome effects too confusing at this point to make any solid recommendations,” says Schwarcz. “People are putting the cart before the horse.”

Source: WebMD

Could Red Wine Boost Your Microbiome?

Steven Reinberg wrote . . . . . . . . .

A little pinot noir now and then might help keep the bacteria in your tummy healthy and happy, a new study suggests.

As little as one glass of red wine a week can increase the diversity of the good bacteria in your microbiome, which can help lower bad cholesterol and keep your weight down, researchers say.

“The more people drink, the higher the diversity. But even small amounts, such as one glass of red wine every week, shows a benefit,” said study first author Caroline Le Roy. She’s a research associate in the department of twin research and genetic epidemiology at King’s College London.

Le Roy cautioned that while the findings in the study were robust, they can’t prove that red wine improves the microbiome, only that the two are associated.

It’s not the alcohol that has this effect, but rather the polyphenols in red wine. Polyphenols help feed the good bacteria in the microbiome, the researchers explained.

Polyphenols are also found in fruits and vegetables, and include antioxidants.

For the study, Le Roy and her colleagues looked at the effect of beer, cider, red wine, white wine and whiskey on the gut microbiome of 916 female twins.

Only red wine resulted in a more diverse microbiome, the investigators found.

The microbiome is a collection of bacteria in the gut that has an important role in health. A healthy microbiome helps digest food and keeps some diseases at bay.

An unhealthy microbiome can lead to poor functioning of the immune system, weight gain and high cholesterol, Le Roy said.

A microbiome with lots of different bacteria is a healthy microbiome, she added.

Le Roy’s team found that red wine improved the number of different bacteria in the microbiome, compared with those who didn’t drink wine.

The researchers were able to confirm their findings in three other groups in Britain, the Netherlands and the United States, which brought the total number of participants to nearly 3,000.

Moreover, the results remained constant even after accounting for factors such as diet, socioeconomic status and age.

Samantha Heller, a senior clinical nutritionist at NYU Langone Medical Center in New York City, thinks that drinking red wine may be a marker of a healthy lifestyle, so the health benefits may be due to other factors.

“Do they, in general, lead healthier lives, such as not smoking, eating more of a plant-based diet and exercising?” she asked.

Wine comes from grapes, which like a lot of plant foods, are rich in polyphenols, Heller said.

But polyphenols are also found in vegetables, fruits, grains, nuts, legumes and teas that don’t contain alcohol, she noted.

“In addition, plants are our only source of dietary fiber, which is the favorite food for the microbes that live in our gut. When they are healthy, they help keep our bodies healthy,” Heller said.

While drinking small amounts of red wine has apparent health benefits, there are also unhealthy effects of drinking too much, such as liver disease, certain cancers, pancreatitis and a depressed immune system, she said.

“Guzzling red wine, or any alcoholic beverage, is not the miracle we have been led to believe,” Heller said.

For those who drink, the American Heart Association recommends an average of one to two drinks per day for men, and one drink per day for women (one 12-ounce beer, 4 ounces of wine, 1 ounce of 100 proof spirits).

“Let’s be honest, most of us probably drink more than that. If you do not drink alcohol, there is no reason to start,” Heller said.

The report was published in the journal Gastroenterology.

Source: HealthDay


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Walnuts Impact Gut Microbiome and Improve Health

Diets rich in nuts, such as walnuts, have been shown to play a role in heart health and in reducing colorectal cancer. According to a new study from the University of Illinois, the way walnuts impact the gut microbiome—the collection of trillions of microbes or bacteria in the gastrointestinal tract—may be behind some of those health benefits.

Walnuts are just one in a line foods that contain dietary fiber and have interested scientists for their impact on the microbiome and health. Dietary fiber acts as a food source for gut microbiota, helping the bacteria to do their jobs—breaking down complex foods, providing us nutrients, or helping us feel full, for example.

Fruits, vegetables, whole grains, nuts, and legumes are important plant sources of dietary fiber. Eating a variety of these foods helps promote a diverse gut microbiota, which in turn helps to support health.

Findings from the study, published in The Journal of Nutrition, show that consuming walnuts not only impacted the gut microbiota and microbial derived secondary bile acids, but also reduced LDL-cholesterol levels in the adults participating in the study; good news for cardio, metabolic, and gastrointestinal health.

“We found that when you consume walnuts it increases microbes that produce butyrate, a beneficial metabolite for colonic health. So the interaction of walnuts with the microbiome is helping to produce some of those health effects,” says Hannah Holscher, assistant professor of food science and human nutrition at U of I, and lead author of the study. “It is about getting to the ‘black box’ that is all the microbes in our GI tract to see how they are interfacing with the food we eat and having downstream health effects.

“Some of those health effects are hypothesized to be related to the metabolites bacteria produce,” she adds.

For the controlled-feeding study, 18 healthy male and female adults consumed diets that either included 0 grams of walnuts or 42 grams—about a third cup or a palm-full of walnuts—for two, three-week periods. Fecal and blood samples were collected at the beginning and end of each period to assess secondary outcomes of the study, including effects of walnut consumption on fecal microbiota and bile acids and metabolic markers of health.

Walnut consumption resulted in higher relative abundance of three bacteria of interest: Faecalibacterium, Roseburia, and Clostridium.

“The microbes that increased in relative abundance in this walnut study are from one of the Clostridium clusters of microbes, and there’s increased interest in those because they have the ability to make butyrate,” Holscher says. “Unfortunately in this study we didn’t measure butyrate, so we can’t say that just because these microbes increased that butyrate did increase. We still need to answer that question.

“There is a lot of interest in Faecalibacterium because it has also been shown in animals to reduce inflammation. Animals with higher amounts also have better insulin sensitivity. There is also growing interest in Faecalibacterium as a potential probiotic bacteria, and so we are trying to follow up on foods that help support Faecalibacterium.”

The findings also show, with walnut consumption, a reduction in secondary bile acids compared to the control. “Secondary bile acids have been shown to be higher in individuals with higher rates of colorectal cancer,” Holscher explains. “Secondary bile acids can be damaging to cells within the GI tract, and microbes make those secondary bile acids. If we can reduce secondary bile acids in the gut, it may also help with human health.”

Previous research that prompted this microbial research showed that the amount of energy (calories) derived from walnuts after we eat them is less than previously thought.

“When you do calculations to determine how much energy we predicted we would get from eating walnuts, it didn’t line up with the energy that was absorbed,” Holscher says. “You’re really only absorbing around 80 percent of the energy from walnuts that labels say. That means that the microbes get access to that extra 20 percent of calories and the fats and fiber left in them, and so what happens then? Does it produce a positive health outcome, or a negative health outcome? Our study provides initial findings that suggest that the interactions of microbes with the undigested walnut components are producing positive outcomes.

“We need more research to look at additional microbial metabolites and how those are influencing health outcomes, instead of just characterizing the changes in the microbiome,” Holscher says.

Source: University of Illinois College of Agricultural, Consumer and Environmental Sciences


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