Skip to content

Category: healthy living

Published on

I've been seeing research report after report looking at how our lifestyle determines how we'll age - whether we'll be active and healthy well into our 80s or in terrible shape and dying young. Mind you, these are not "definites" because nothing can give you a guarantee, but they are ways we can improve our odds in living the long and healthy life that we want. From Medical Xpress:

A healthy lifestyle adds years to life

Live longer thanks to fruit, an active lifestyle, limited alcohol and no cigarettes. This is the conclusion of a study by public health physicians at the University of Zurich who documented for the first time the impact of behavioural factors on life expectancy in numbers. 

...Brian Martin and his colleagues from the Institute of Social and Preventive Medicine (ISPM) at the University of Zurich have examined the effects of these four factors – both individual and combined – on life expectancy. An individual who smokes, drinks a lot, is physically inactive and has an unhealthy diet has 2.5 fold higher mortality risk in epidemiological terms than an individual who looks after his health. Or to put it positively: "A healthy lifestyle can help you stay ten years' younger", comments the lead author Eva Martin-Diener.

"The effect of each individual factor on life expectancy is relatively high", states Eva Martin-Diener. But smoking seems to be the most harmful. Compared with a group of non-smokers, smokers have a 57 percent higher risk of dying prematurely. The impact of an unhealthy diet, not enough sport and alcohol abuse results in an elevated mortality risk of around 15 percent for each factor.

According to Martin an unhealthy lifestyle has above all a long-lasting impact. Whereas high wine consumption, cigarettes, an unhealthy diet and physical inactivity scarcely had any effect on mortality amongst the 45 to 55-year-olds, it does have a visible effect on 65 to 75-year-olds. The probability of a 75-year-old man with none of the four risk factors surviving the next ten years is 67 percent, exactly the same as the risk for a smoker who is ten years younger, doesn't exercise, eats unhealthily and drinks a lot.

From Medical Xpress:

Picking up healthy habits in your 30s and 40s can slash heart disease risk

The heart is more forgiving than you may think—especially to adults who try to take charge of their health, a new Northwestern Medicine study has found. When adults in their 30s and 40s decide to drop unhealthy habits that are harmful to their heart and embrace healthy lifestyle changes, they can control and potentially even reverse the natural progression of , scientists found. On the flip side, scientists also found that if people drop  or pick up more bad habits as they age, there is measurable, detrimental impact on their coronary arteries.

For this paper, scientists examined healthy lifestyle behaviors and coronary artery calcification and thickening among the more than 5,000 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study who were assessed at baseline (when participants were ages 18 to 30) and 20 years later.The healthy  assessed were: not being overweight/obese, being a nonsmoker and physically active and having low alcohol intake and a healthy diet. 

By young adulthood (at the beginning of the study), less than 10 percent of the CARDIA participants reported all five healthy lifestyle behaviors. At the 20-year mark, about 25 percent of the study participants had added at least one healthy lifestyle behavior. Each increase in healthy lifestyle factors was associated with reduced odds of detectable  and lower intima-media thickness—two major markers of cardiovascular disease that can predict future cardiovascular events. Adulthood is not too late for healthy behavior changes to help the heart."

"That loss of healthy habits had a measurable negative impact on their coronary arteries," Spring said. "Each decrease in healthy lifestyle factors led to greater odds of detectable  calcification and higher intima-media thickness.

Spring said the healthy changes people in the study made are attainable and sustainable. She offers some tips for those who want to embrace a  at any age:Keep a healthy body weight; Don't smoke; Engage in at least 30 minutes of moderate to vigorous activity five times a week; No more than one alcoholic drink a day for women, no more than two for men; Eat a healthy diet, high in fiber, low in sodium with lots of fruit and vegetables.

From Science Daily:

Adults who lose weight at any age could enjoy improved cardiovascular health

Weight loss at any age in adulthood is worthwhile because it could yield long-term heart and vascular benefits, suggests new research. For the first time, the findings indicate that adults who drop a BMI category -- from obese to overweight, or from overweight to normal -- at any time during adult life, even if they regain weight, can reduce these cardiovascular manifestations. The findings are from a study examining the impact of lifelong patterns of weight change on cardiovascular risk factors in a group of British men and women followed since birth in March 1946. 

Published on

This article summarizes some of the same things I've been posting here. From NY Times:

We Are Our Bacteria

We may think of ourselves as just human, but we’re really a mass of microorganisms housed in a human shell. Every person alive is host to about 100 trillion bacteria cells. They outnumber human cells 10 to one and account for 99.9 percent of the unique genes in the body.

Our collection of microbiota, known as the microbiome, is the human equivalent of an environmental ecosystem. Although the bacteria together weigh a mere three pounds, their composition determines much about how the body functions and, alas, sometimes malfunctions. Like ecosystems the world over, the human microbiome is losing its diversity, to the potential detriment of the health of those it inhabits.

Dr. Martin J. Blaser, a specialist in infectious diseases at the New York University School of Medicine and the director of the Human Microbiome Program, has studied the role of bacteria in disease for more than three decades. In his new book, “Missing Microbes,"Dr. Blaser links the declining variety within the microbiome to our increased susceptibility to serious, often chronic conditions,  from allergies and celiac disease to Type 1 diabetes and obesity. He and others primarily blame antibiotics for the connection.

The damaging effect of antibiotics on microbial diversity starts early, Dr. Blaser said. The average American child is given nearly three courses of antibiotics in the first two years of life, and eight more  during the next eight years. Even a short course of antibiotics like the widely prescribed  Z-pack (azithromycin, taken for five days), can result in long-term shifts in the body’s microbial environment.

But antibiotics are not the only way the balance within us can be disrupted. Cesarean deliveries, which  have soared  in recent decades, encourage the growth of microbes from the mother’s skin, instead of from the birth canal, in the baby’s gut, Dr. Blaser said in an interview.

This change in microbiota can reshape an infant’s metabolism and immune system. A recent review of 15 studies involving 163,796 births found that, compared with  babies delivered vaginally, those born by cesarean section were 26 percent more likely to be overweight and 22 percent more likely to be obese as adults. 

The placenta has a microbiome of its own, researchers have discovered, which may also contribute to the infant’s gut health and help mitigate the microbial losses caused by cesarean sections.

Further evidence of a link to obesity comes from farm animals. About three-fourths of the antibiotics sold in the United States are used  in  livestock. These  antibiotics change the animals’ microbiota, hastening their growth. When mice are given the same  antibiotics used on livestock, the metabolism of their liver changes, stimulating an increase in body fat, Dr. Blaser said.

Even more serious is  the increasing number of serious disorders now linked to a distortion in the microbial balance in the human gut. They include several that are becoming more common in developed countries: gastrointestinal ailments like Crohn’s disease, ulcerative colitis and celiac disease; cardiovascular disease; nonalcoholic fatty liver disease; digestive disorders like chronic reflux; autoimmune diseases like multiple sclerosis and rheumatoid arthritis; and asthma and allergies.

Published on

Study after study is suggesting that exposure to lots of diverse bacteria and microorganisms (think farms with animals) is healthy for the developing immune system. From Science Daily:

Growing up on livestock farm halves risk of inflammatory bowel diseases

New research conducted at Aarhus University has revealed that people who have grown up on a farm with livestock are only half as likely as their urban counterparts to develop the most common inflammatory bowel diseases: ulcerative colitis and Crohn's disease. 

"It is extremely exciting that we can now see that not only allergic diseases, but also more classic inflammatory diseases appear to depend on the environment we are exposed to early in our lives," relates Vivi Schlünssen, Associate Professor in Public Health at Aarhus University.

"We know that development of the immune system is finalized in the first years of our lives, and we suspect that environmental influences may have a crucial effect on this development. The place where you grow up may therefore influence your risk of developing an inflammatory bowel disease later in life."

However, the researchers have a theory that the body may be dependent on exposure to a wide variety of microorganisms to develop a healthy immune system -- in the same way as has been established in studies on allergies and asthma.

"We know that the difference in the microbial environment between city and country has increased over the past century, and that we are exposed to far fewer different bacteria in urban environments today than we were previously. This may in part explain our findings," says Signe Timm.

Over the past 40-50 years, incidence of the diseases has sky-rocketed in Northern Europe -- including Denmark -- as well as in Canada and the United States, although they are still relatively rare in developing countries.

Published on

Here are some more articles that I found regarding psychobiotics or the use of probiotics to affect behavior and treat psychiatric disorders.  A probiotic is a microorganism introduced into the body for its beneficial properties. Even though the articles are from 2013, they all give slightly different information about this emerging and exciting new field. Please note that psychotropic means having an effect on how the mind works (and it usually refers to drugs that affect a person's mental state). Remember that this area of research and terminology used is in its infancy. From Medscape (November 2013):

Probiotics a Potential Treatment for Mental Illness

Probiotics, which are live bacteria that help maintain a healthy digestive system, are now often promoted as an important part of dietary supplements and natural food products. "Many of the numerous health-improvement claims have yet to be supported scientifically..."

They note that the term "psychobiotic" was created as recent studies have begun to explore a possible link between probiotics and behavior.  "As a class of probiotic, these bacteria are capable of producing and delivering neuroactive substances such as gamma-aminobutyric acid [GABA] and serotonin, which act on the brain-gut axis," they write.

For this review, the investigators sought to examine studies that assessed whether ingesting these bacteria "in adequate amounts" could potentially lead to an effective treatment for depression and other stress-related disorders. In 1 of the preclinical studies examined, mice that ingested L rhamnosus showed reduced anxiety scores and "altered central expression" on both the GABA type A and type B receptors.

And a study of human patients with chronic fatigue syndrome showed that those who consumed an active strain of L casei 3 times a day had significantly higher improvement scores on anxiety measures than did those who received matching placebo. This provides "further support for the view that a probiotic may have psychotropic effects," write the researchers.

Still, Dr. Dinan called for caution. "What is clear at this point is that, of the large number of putative probiotics, only a small percentage have an impact on behavior and may qualify as psychobiotics," said Dr. Dinan. He added that for now, the field needs to wait for large-scale, placebo-controlled trials to provide definitive evidence of benefit and to detect which probiotics have psychobiotic potential.

Dr. Camille Zenobia wrote this in August 2013. From Real Clear Science:

Can 'Psychobiotic' Bacteria Affect Our Mood?

But what about your brain? Apparently, bacteria influence what’s going on up there, too. Within the last several years, a blossoming field of study called “microbial endocrinology” has provided some provocative insights about the relationship between our GI microbiota and our mood and behavior.

Studies in the field of microbial endocrinology have implicated GI microbes as a factor that can regulate the endocrine system. This could have both good and bad effects since the endocrine system is responsible for the production of hormones and coordinates metabolism, respiration, excretion, reproduction, sensory perception and immune function.

From Nov. 2013 Popular Science:

Forget Prozac, Psychobiotics Are The Future Of Psychiatry

The answer lies in the fact that many psychiatric illnesses are immunological in nature through chronic low level inflammation. There is a plethora of evidence showing the link between gut microbiota and inflammation and studies on probiotic strains have revealed their ability to modulate inflammation and bring back a healthy immunological function.  In this regard, by controlling inflammation through probiotic administration, there should be an effect of improved psychiatric disposition.

The authors bring up another reason why psychobiotics are so unique in comparison to most probiotics.  These strains have another incredible ability to modulate the function of the adrenal cortex, which is responsible for controlling anxiety and stress response. Probiotic strains, such as Lactobacillus helveticus and Bifdobacterium longum have shown to reduce levels of stress hormones and maintain a calmer, peaceful state.  There may be a host of other probiotic bacteria with the same ability although testing has been scant at best.

Finally, the last point in support of psychobiotics is the fact that certain strains of bacteria actually produce the chemicals necessary for a happy self.  But as these chemicals cannot find their way into the brain, another route has been found to explain why they work so well.  They stimulate cells in the gut that have the ability to signal the vagus nerve that good chemicals are in the body.  The vagus nerve then submits this information to the brain, which then acts as if the chemicals were there.  

Published on

Overall, this is further evidence that eating natural, real foods  (in moderation) and avoiding supplements is best for health. Don't want to feed any cancers. From Science Daily:

How antioxidants can accelerate cancers, and why they don't protect against them

For decades, health-conscious people around the globe have taken antioxidant supplements and eaten foods rich in antioxidants, figuring this was one of the paths to good health and a long life.Yet clinical trials of antioxidant supplements have repeatedly dashed the hopes of consumers who take them hoping to reduce their cancer risk. Virtually all such trials have failed to show any protective effect against cancer. In fact, in several trials antioxidant supplementation has been linked with increased rates of certain cancers. In one trial, smokers taking extra beta carotene had higher, not lower, rates of lung cancer.

Two cancer researchers have proposed why antioxidant supplements might not be working to reduce cancer development, and why they may actually do more harm than good. Their insights are based on recent advances in the understanding of the system in our cells that establishes a natural balance between oxidizing and anti-oxidizing compounds. These compounds are involved in so-called redox (reduction and oxidation) reactions essential to cellular chemistry.

Drs. Tuveson and Chandel propose that taking antioxidant pills or eating vast quantities of foods rich in antioxidants may be failing to show a beneficial effect against cancer because they do not act at the critical site in cells where tumor-promoting ROS (reactive oxygen species) are produced -- at cellular energy factories called mitochondria. Rather, supplements and dietary antioxidants tend to accumulate at scattered distant sites in the cell, "leaving tumor-promoting ROS relatively unperturbed," the researchers say.

Quantities of both ROS and natural antioxidants are higher in cancer cells -- the paradoxically higher levels of antioxidants being a natural defense by cancer cells to keep their higher levels of oxidants in check, so growth can continue. In fact, say Tuveson and Chandel, therapies that raise the levels of oxidants in cells may be beneficial, whereas those that act as antioxidants may further stimulate the cancer cells. Interestingly, radiation therapy kills cancer cells by dramatically raising levels of oxidants. The same is true of chemotherapeutic drugs -- they kill tumor cells via oxidation.

Published on

Obviously children on farms are exposed to a lot of dirt and animals, both teaming with microorganisms. But I wonder, and it's not discussed, is whether people living on dairy farms are drinking raw milk, which contains lots of microorganisms. After all, the point of milk pasteurization is to kill off bacteria. Will we go back to drinking raw milk to try to prevent allergies? From Science Daily:

Children on dairy farms run one-tenth the risk of developing allergies; Dairy farm exposure also beneficial during pregnancy

Children who live on farms that produce milk run one-tenth the risk of developing allergies as other rural children. According to researchers at The University of Gothenburg in Sweden, pregnant women may benefit from spending time on dairy farms to promote maturation of the fetal and neonatal immune system.

The occurrence of allergic diseases has risen dramatically in Western societies. One frequently cited reason is that children are less exposed to microorganisms and have fewer infections than previous generations, thereby delaying maturation of the immune system.

A study by researchers at Sahlgrenska Academy, University of Gothenburg, monitored children until the age of three to examine maturation of the immune system in relation to allergic disease. All of the children lived in rural areas of the Västra Götaland Region, half of them on farms that produced milk. The study found that children on dairy farms ran a much lower risk of developing allergies than the other children.

"Our study also demonstrated for the first time that delayed maturation of the immune system, specifically B-cells, is a risk factor for development of allergies," says Anna-Carin Lundell, one of the researchers. Children with an allergic disease at the age of 18 and 36 months had a higher percentage of immature B-cells in their blood circulation at birth and during the first month of life. 

"We need to identify the specific factors on dairy farms that strengthen protection against allergies and appear to promote maturation of the immune system as early as the fetal stage," Ms. Lundell says.

Published on

Research reports and articles on the benefits of exercise have been piling up. Here are some worth looking at. From Science Daily:

Sitting too much, not just lack of exercise, is detrimental to cardiovascular health

Cardiologists have found that sedentary behaviors may lower cardiorespiratory fitness levels. New evidence suggests that two hours of sedentary behavior can be just as harmful as 20 minutes of exercise is beneficial.

From Science Daily:

Out of shape? Your memory may suffer

Here's another reason to drop that doughnut and hit the treadmill: A new study suggests aerobic fitness affects long-term memory. "The findings show that lower-fit individuals lose more memory across time," said a co-author. The study is one of the first to investigate young, supposedly healthy adults. 

From Science Daily:

Less exercise, not more calories, responsible for expanding waistlines

Sedentary lifestyle and not caloric intake may be to blame for increased obesity in the US, according to a new analysis. A study reveals that in the past 20 years there has been a sharp decrease in physical exercise and an increase in average body mass index (BMI), while caloric intake has remained steady. 

From Science Daily:

Older adults: Build muscle and you'll live longer

The more muscle mass older Americans have, the less likely they are to die prematurely, new research shows. The findings add to the growing evidence that overall body composition -- and not the widely used body mass index, or BMI -- is a better predictor of all-cause mortality. "In other words, the greater your muscle mass, the lower your risk of death," said the study's co-author. "Thus, rather than worrying about weight or body mass index, we should be trying to maximize and maintain muscle mass."

From Medical Xpress:

Keeping active pays off in your 70s and 80s

Older people who undertake at least 25 minutes of moderate or vigorous exercise everyday need fewer prescriptions and are less likely to be admitted to hospital in an emergency, new research has revealed.

Researchers from the Universities of Bath, Bristol and UWE-Bristol looked at data from 213 people whose average age was 78. Of people studied, those who carried out more than 25 minutes of moderate to vigorous physical activity per day – such as walking quickly, cycling or swimming - received 50 per cent fewer prescriptions than those who were more active over a four to five year period.

Such physical activity leads to a higher metabolism and better circulation, reducing the risk of conditions and diseases common in older age such as high blood presure, type 2 diabetes, coronary heart disease, and strokes.

From Everyday Health:

The Best Anti-Aging Medicine? Exercise

Everyone knows that exercise is good for you — it helps manage weight, improves muscle and bone strength, and even lifts your spirits. It can also add years to your life.“People have been looking for the secret to a long and healthy life for millennia,” said Neil Resnick, MD, chief of the division of geriatrics and director of the University of Pittsburgh Institute on Aging. “It turns out the most powerful intervention is exercise.”

A recent study conducted at Harvard found that exercise can be at least as effective as prescription drugs when it comes to preventing common conditions such as heart disease, stroke, and diabetes.

Exercise at any age is beneficial. From Science Daily:

Seniors who exercise regularly experience less physical decline as they age

Older adults in retirement communities who reported more exercise experienced less physical decline than their peers who reported less exercise, although many adults -- even those who exercised -- did not complete muscle-strengthening exercises, which are another defense against physical decline.

Published on

New discoveries of what is going on in our intestines, plus a new vocabulary to understand it all. Yes, it all is amazingly complex. Bottom line: we have complex communities (bacteria, bacterial viruses or bacteriophages, etc.) living and interacting in our intestines. And only with state-of-the-art genetic analysis (DNA sequencing) can we even "see" what is going on. I highlighted really important items in bold type. From Medical Xpress:

Researchers uncover new knowledge about our intestines

Researchers from Technical University of Denmark Systems Biology have mapped 500 previously unknown microorganisms in human intestinal flora as well as 800 also unknown bacterial viruses (also called bacteriophages) which attack intestinal bacteria.

"Using our method, researchers are now able to identify and collect genomes from previously unknown microorganisms in even highly complex microbial societies. This provides us with an overview we have not enjoyed previously," says Professor Søren Brunak who has co-headed the study together with Associate Professor Henrik Bjørn Nielsen.

So far, 200-300 intestinal bacterial species have been mapped. Now, the number will be more than doubled, which could significantly improve our understanding and treatment of a large number of diseases such as type 2 diabetes, asthma and obesity.

The two researchers have also studied the mutual relations between bacteria and viruses. Previously, bacteria were studied individually in the laboratory, but researchers are becoming increasingly aware that in order to understand the intestinal flora, you need to look at the interaction between the many different bacteria found.

And when we know the intestinal bacteria interactions, we can potentially develop a more selective way to treat a number of diseases. "Ideally we will be able to add or remove specific bacteria in the intestinal system and in this way induce a healthier intestinal flora," says Søren Brunak.

From Science Daily:

Revolutionary approach to studying intestinal microbiota

Analyzing the global genome, or the metagenome of the intestinal microbiota, has taken a turn, thanks to a new approach to study developed by an international research team. This method markedly simplifies microbiome analysis and renders it more powerful. The scientists have thus been able to sequence and assemble the complete genome of 238 intestinal bacteria, 75% of which were previously unknown. 

Research carried out in recent years on the intestinal microbiota has completely overturned our vision of the human gut ecosystem. Indeed, from "simple digesters" of food, these bacteria have become major factors in understanding certain diseases such as obesity, type 2 diabetes, or Crohn's disease. Important and direct links have also been demonstrated between these bacteria and the immune system, as well as with the brain. It is estimated that 100,000 billion bacteria populate the gut of each individual (or 10 to 100 times more than the number of cells in the human body), and their diversity is considerable, estimated to around a thousand different bacterial species in the intestinal human metagenome. However, because only 15% of these bacteria were previously isolated and characterized by genome sequencing, an immense number of the microbial genes previously identified still need to be assigned to a given species.

An analysis of 396 stool samples from Danish and Spanish individuals allowed the researchers to cluster these millions of genes into 7381 co-abundance groups of genes. Approximately 10% of these groups (741) corresponded to bacterial species referred to as metagenomic species (MGS); the others corresponded to bacterial viruses (848 bacteriophages were discovered), plasmids (circular, bacterial DNA fragments) or genes which protected bacteria from viral attack (known as CRISPR sequences). 85% of these MGS constituted unknown bacteria species (or ~630 species).

Using this new approach, the researchers succeeded in reconstituting the complete genome of 238 of these unknown species, without prior culture of these bacteria. Living without oxygen, in an environment that is difficult to characterise and reproduce, most of these gut bacteria cannot be cultured in the laboratory. 

The authors also demonstrated more than 800 dependent relationships within the 7381 gene co-abundance groups; this was the case, for example, of phages which require the presence of a bacterium to survive. These dependent relationships thus enable a clearer understanding of the survival mechanisms of a micro-organism in its ecosystem. 

Published on

Some good foods to eat for their health benefits. The following articles are from Science Daily:

Almonds reduce the risk of heart disease, research shows

Eating almonds can reduce the risk of heart disease by keeping blood vessels healthy, research has shown. Research found that they significantly increase the amount of antioxidants in the blood stream, reduce blood pressure and improve blood flow. These findings add weight to the theory that Mediterranean diets with lots of nuts have big health benefits... "Our study confirms that almonds are a superfood. Previous studies have shown that they keep your heart healthy, but our research proves that it isn't too late to introduce them into your diet -- adding even a handful (around 50g) every day for a short period can help.

Could grapefruit be good for your kidneys?

A natural product found in grapefruit can prevent kidney cysts from forming, new research indicates. Naringenin, which is also present in other citrus fruits, has been found to successfully block the formation of kidney cysts, an effect that occurs in polycystic kidney disease, by regulating the PKD2 protein responsible for the condition. With few treatments currently available, symptoms include high blood pressure and loss of kidney function, and lead to the need for dialysis.

More evidence that dark chocolate is good for you. From Science Daily:

Polyphenols could yield small benefit for people with PAD

In a small study, people with artery problems in their legs (peripheral artery disease) walked a little longer and farther when they ate dark chocolate -- a food rich in polyphenols.The authors suggest that compounds found in cocoa -- polyphenols -- may reduce oxidative stress and improve blood flow in peripheral arteries....Many other polyphenol-rich foods would offer less added sugar, saturated fats, and calories than dark chocolate, such as cloves, dried peppermint, celery seed, capers, and hazelnuts, to name a few.

Published on
Lactobacilli

The human vagina is another microbial community that is nowhere as simple as earlier thought - and it's not just Lactobacillus bacteria.

From The Scientist: Characterizing the “Healthy” Vagina

For years, researchers characterized the microbial community of women’s vaginas as being dominated by Lactobacillus bacteria, which ferment carbohydrates to lactic acid, yielding a low pH that is toxic to many pathogenic microbes. When levels of Lactobacillus drop, the pH becomes more neutral, and the risk of infection rises.

But with research revealing notable variation among women’s vaginal microbiomes, as well as some interesting dynamics of the microbial communities within a single organ, “that dogma is changing a little bit,” said Gregory Buck of the Vaginal Microbiome Consortium at Virginia Commonwealth University (VCU).

The composition and stability of the vaginal microbiome varies by race, age, even within an individual—and it’s quickly become clear that the formula for a “normal,” “healthy” microbial community cannot be computed by ratios of bacterial species. “In the past we’ve made some generalizations about what kinds of bacteria are found in the vagina, what kinds of bacteria are good or healthy or protective,” said microbial ecologist Larry Forney of the University of Idaho. “What the research is showing is there are tremendous differences between women in terms of the kinds of bacteria that are present and the changes in the communities that occur over time.”

In June 2010, Forney, Jacques Ravel of the University of Maryland School of Medicine, and their collaborators published a survey of the vaginal microbiomes of nearly 400 women and found that the majority harbored bacterial communities dominated by one of four Lactobacillus strains. More than a quarter of the women studied, however, did not follow this pattern. Instead, their vaginas had fewer Lactobacillus and greater numbers of other anaerobic bacteria, although the bacterial communities always included members of genera known to produce lactic acid.

In many ways, the microbiome of these women resembled the bacterial communities of women suffering from bacterial vaginosis (BV), an infection characterized by an odorous vaginal discharge, Buck noted. “By looking at the microbial components, you’d say they have BV, but they have no clinical symptoms,” he said. “These people are not unhealthy.”

The researchers also found that the composition of a woman’s vaginal microbiome was linked to her race. Eighty percent of Asian women and nearly 90 percent of white women harbored vaginal microbiomes that were dominated by Lactobacillus, while only about 60 percent of Hispanic and black women did. Moreover, vaginal pH varied with ethnicity as well, with Hispanic and black women averaging 5.0 and 4.7, respectively, and Asian and white women averaging 4.4 and 4.2. 

This raises questions about the role of the commensal bacteria and risk of preterm labor , which has been linked to BV—and to low levels of Lactobacillus in particular—and is one-and-a-half times more common among African American women than Caucasian women.

Meanwhile, the researchers continue to sort through 40,000 swabs from more than 6,000 women to better characterize the bacterial communities living in the vagina. But Fettweis and her colleagues face a common problem in microbiome research. “In many samples, only a fraction of [the genetic sequences] align to anything we have in our databases,” she said. “So I think there’s still a lot of work to be done in terms of actually understanding: What are these organisms?”

Another question facing researchers probing the vaginal microbiome is how it is initially colonized. “Where do [the bacteria] come from?” said Forney.

Many suspect that the process occurs during vaginal childbirth. But the adolescent microbiome does not resemble that of a sexually mature woman, having far less Lactobacillus, leading some to suspect that there may be a second colonization of the vagina later in life. And if the birthing process is important to establish the vaginal microbiome, what happens in the case of C-sections? “We have more questions than answers,” Forney said.

The microbiome is also not stable later in life. It is now well known that the vaginal microbiome changes after menopause, containing fewer Lactobacillus than the vaginas of reproductive-aged women, with the notable exception of women on hormone-replacement therapies.

Moreover, recent research has revealed that the composition of the vaginal microbiome can change in as little as 24 hours.

The temporal dynamics of the vaginal microbiome raise important questions about developing microbiota-based diagnostics and therapeutics, said Forney. “If you perform a diagnostic test, would you get a different result tomorrow or the day after? In some cases, yes. How do you incorporate that into [a] decision about whether some kind of intervention is required?”