Skip to content

In a newly published study looking at how infant gut microbes change over time, once again babies had differences in gut bacteria depending on whether they were delivered vaginally or by Cesarean section.

But what's interesting is that stopping breastfeeding changed their gut bacteria  more (to more adult-like species) than just introducing solid foods. Certain types of bacteria thrive on the nutrients breast milk provides and once these nutrients are no longer available, then other bacteria emerge that are more commonly seen in adults. In other words, stopping breastfeeding seems to drive "maturation" of the gut bacteria.

From The Scientist: Maturation of the Infant Microbiome

Like babies themselves, the intestinal microbiomes of infants start out in an immature state and over time grow into communities similar to those of adults. In a new survey of 98 Swedish babies whose microbiota were sampled several times during their first year of life, researchers found that the microbiomes of breastfed infants persisted in a “younger” state longer than those of non-breastfed babies, even after the introduction of solid foods.

The conclusion that “stopping breastfeeding—rather than introducing solids—drives maturation is a new idea, because we all thought so far that solids introduction was a key factor in changing the microbiota,” said Maria Gloria Dominguez-Bello, a microbiologist at New York University School of Medicine who did not participate in the study.

Researchers from University of Gothenburg in Sweden and their colleagues found more adult-like taxa in the microbiomes of babies who stopped breastfeeding earlier, while the microbiota of babies breastfed for longer were dominated by bacteria present in breastmilk. The results, published today (May 13) in Cell Host & Microbe, are part of an effort to catalog the microbial changes that occur as children age and to note how those changes correlate with health and disease. Fredrik Bäckhed of Gothenburg and his colleagues collected stool samples from 98 moms and their newborns, and again sampled the babies’ stool at four and 12 months.

Confirming previous work, his team’s analysis found that the 15 babies born via cesarean section were colonized by different bacteria—many from oral and skin communities—than babies born vaginally, who shared numerous microbes with those present in their mothers’ stool.

For instance, in the vaginally delivered newborns’ microbiomes, genes that break down sugars in breastmilk were common. As these babies celebrated their first birthdays, the genes in their microbiomes favored the ability to breakdown starches, pectins, and more complex sugars.

“What’s nice about this paper is that they show this maturation [of the microbiome] in normal, healthy kids in a Western population follows this transition based on diet,” said Steven Frese, a postdoc at the University of California, Davis, who penned a commentary accompanying the study with his advisor, David Mills. “Being exposed to new foods promotes the growth of new bacteria that can consume them,” Frese told The Scientist.

Currently, during birth there are many potential disruptions to the healthy development of the infant's microbial ecosystem. Some practices to be concerned about: the use of antibiotics during pregnancy and during delivery, c-sections, newborns routinely given antibiotics, and then bottle feeding instead of breastfeeding. Sometimes one or more of these practices are medically necessary, but currently they are being done much too frequently and casually. In these ways we are conducting an experiment on every baby's microbial ecosystem with unknown long-term consequences. The following excerpts from Dr.Martin Blaser's popular 2014 book Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues, even though written a year ago, are a nice summary of these issues. From Wired:

The Way You’re Born Can Mess With the Microbes You Need to Survive

THROUGHOUT THE ANIMAL kingdom, mothers transfer microbes to their young while giving birth....And for millennia, mammalian babies have acquired founding populations of microbes by passing through their mothers’ vagina. This microbial handoff is also a critical aspect of infant health in humans. Today it is in peril.

Microbes play a hidden role in the course of every pregnancy. During the first trimester, certain species of bacteria become overrepresented while others become less common. By the third trimester, just before the baby is born, even greater shifts occur. These changes, involving scores of species, are not random. The compositions change in the same direction across the dozens of women who have been studied.... Women of reproductive age carry bacteria, primarily lactobacilli, which make the vaginal canal more acidic. This environment provides a hardy defense against dangerous bacteria that are sensitive to acid. Lactobacilli also have evolved a potent arsenal of molecules that inhibit or kill other bacteria.

Whether the birth is fast or slow, the formerly germ-free baby soon comes into contact with the lactobacilli. The baby’s skin is a sponge, taking up the vaginal microbes rubbing against it. The first fluids the baby sucks in contain mom’s microbes, including some fecal matter.

Once born, the baby instinctively reaches his mouth, now full of lactobacilli, toward his mother’s nipple and begins to suck. The birth process introduces lactobacilli to the first milk that goes into the baby. This interaction could not be more perfect. Lactobacilli and other lactic acid–producing bacteria break down lactose, the major sugar in milk, to make energy. The baby’s first food is a form of milk called colostrum, which contains protective antibodies. The choreography of actions involving vagina, baby, mouth, nipple, and milk ensures that the founding bacteria in the baby’s intestinal tract include species that can digest milk for the baby.

Breast milk, when it comes in a few days later, contains carbohydrates, called oligosaccharides, that babies cannot digest. But specific bacteria such as Bifidobacterium infantis, another foundational species in healthy babies, can eat the oligosaccharides. The breast milk is constituted to give favored bacteria a head start against competing bacteria.

Cesarian delivery is a largely unrecognized threat to the microbial handoff from mother to child. Instead of traveling down the birth canal picking up lactobacilli, the baby is surgically extracted from the womb through an incision in the abdominal wall....For all of these reasons, U.S. C-section rates increased from fewer than one in five births in 1996 to one in three births in 2011—a 50 percent increase.

The founding populations of microbes found on C-section infants are not those selected by hundreds of thousands of years of human evolution. A few years ago in Puerto Ayacucho, Venezuela, my wife, Gloria, conducted the first study of its kind to test whether the microbes found on newborn babies delivered vaginally or by C-section varied in any way....The mouths, skin, and first bowel movements of babies born vaginally were populated by their mother’s vaginal microbes: Lactobacillus, Prevotella, or Sneathia species. Those born by C-section harbored bacterial communities found on skin, dominated by Staphylococcus, Corynebacterium, and Propionibacterium.

In other words, their founding microbes bore no relationship to their mother’s vagina or any vagina. At all the sites—mouth, skin, gut—their microbes resembled the pattern on human skin and organisms floating in the air in the surgery room. They were not colonized by their mother’s lactobacilli. The fancy names of these bacteria don’t matter as much as the notion that the founding populations of microbes found on C-section infants are not those selected by hundreds of thousands of years of human evolution or even longer.

Another threat to a baby’s newly acquired resident microbes involves antibiotics given to the mother. Most doctors consider it safe to prescribe penicillins for all sorts of mild infections in pregnancy—coughs, sore throats, urinary tract infections. Sometimes when doctors think that the mother has a viral infection they also give antibiotics just in case it is actually a bacterial infection.

Then comes the birth itself. Women in labor routinely get antibiotics to ward off infection after a C-section....Antibiotics are broad in their effects, not targeted....The problem, of course, is that we know antibiotics are broad in their effects, not targeted. While the antibiotic kills Group B strep, it also kills other often-friendly bacteria, thus selecting for resistant ones. This practice is altering the composition of the mother’s microbes in all compartments of her body just before the intergenerational transfer is slated to begin.

The baby also is affected in similar unintended ways. Any antibiotic that gets into the bloodstream of the fetus or into the mother’s milk will inevitably influence the composition of the baby’s resident microbes, but we are only beginning to understand what this means.

Finally, the babies are directly exposed. Most parents are not aware that all American-born babies today are given an antibiotic immediately after birth. The reason is that many years ago, before antibiotics, women who unknowingly had gonorrhea would pass the infection to their babies, giving the newborns terrible eye infections that could cause blindness...The dose is low but is likely affecting the composition of the infant’s resident microbes just when the founding populations are developing. We should be able to develop a better way to screen, so we can target those babies at the highest risk, perhaps a few hundred among the millions of births a year.

Although babies are born into a world replete with diverse bacteria, the ones that colonize them are not accidental. These first microbes colonizing the newborn begin a dynamic process. We are born with innate immunity, a collection of proteins, cells, detergents, and junctions that guard our surfaces based on recognition of structures that are widely shared among classes of microbes. In contrast, we must develop adaptive immunity that will clearly distinguish self from non-self. Our early-life microbes are the first teachers in this process, instructing the developing immune system about what is dangerous and what is not.

A newborn infant, seconds after delivery. Amniotic fluid glistens on the child's skin.  Credit: Wikipedia, Ernest F

Another study finding negative effects of air pollution - this time high levels of traffic-related air pollution is linked to slower cognitive development among 7 to 10 year old children in Barcelona, Spain. From Science Daily:

Air pollution linked to slower cognitive development in children

Attendance at schools exposed to high levels of traffic-related air pollution is linked to slower cognitive development among 7- to 10-year-old children in Barcelona, according to a new study.

The researchers measured three cognitive outcomes (working memory, superior working memory, and attentiveness) every 3 months over a 12-month period in 2715 primary school children attending 39 schools. By comparing the development of these cognitive outcomes in the children attending schools where exposure to air pollution was high to those children attending a school with a similar socio-economic index where exposure to pollution was low, they found that the increase in cognitive development over time among children attending highly polluted schools was less than among children attending paired lowly polluted schools, even after adjusting for additional factors that affect cognitive development.

Thus, for example, there was an 11.5% 12-month increase in working memory at the lowly polluted schools but only a 7.4% 12-month increase in working memory at the highly polluted schools. These results were confirmed using direct measurements of traffic related pollutants at schools.

The findings suggest that the developing brain may be vulnerable to traffic-related air pollution well into middle childhood, a conclusion that has implications for the design of air pollution regulations and for the location of new schools. While the authors controlled for socioeconomic factors, the accuracy of these findings may be limited by residual confounding, that is, the children attending schools where traffic-related pollution is high might have shared other unknown characteristics that affected their cognitive development.

There has been a lot of discussion in the last few years of our gut bacteria (hundreds of species), the microbiome (the community of microbes living within and on a person (gut, nasal cavities, mouth, sinuses, etc.), probiotics, the finding of a link between bacteria and some chronic diseases, and how the modern lifestyle and antibiotics are wiping out our beneficial gut microbes. I am frequently asked how one can improve or nurture the beneficial bacteria in our bodies.

While no one knows what exactly is the "best" or "healthiest" microbial composition of the gut, it does look like a diversity of bacteria is best (may make you healthier and more able to resist diseases). Research also suggests that the diversity and balance of bacteria living in the body can be changed and improved, and changes can occur very quickly. And that the microbial communities fluctuate for various reasons (illness, diet,etc.). Diet seems to be key to the health of your gut microbial community. Prebiotics feed the beneficial bacteria in the gut, probiotics are live beneficial bacteria, and synbiotics are a combination of prebiotics and probiotics. But don't despair - you can improve your gut microbial community starting now. The following are some practical tips, based on what scientific research currently knows.

SOME STEPS TO FEED AND NURTURE YOUR GUT MICROBES:

Eat a wide variety of foods, especially whole foods that are unprocessed or as minimally processed as possible. Eat everything in moderation.

Eat a lot of plant based foods: fruits, vegetables, whole grains, seeds, nuts, and legumes. Think of Michael Pollan's advice: "Eat food. Not too much. Mostly plants."

Eat more washed and raw fruits and vegetables (lots of bacteria and fiber to feed and nurture the bacteria). Some every day would be good.

Eat more soluble and insoluble types of fiber, and increase how many servings you eat every day. A variety of  fiber foods every day, and several servings at each meal, is best. Think fruits, vegetables, whole grains, legumes, nuts, seeds. (See How Much Dietary Fiber Should We Eat? - also has a chart with high fiber foods, and Recent Studies Show Benefits of Dietary Fiber)

Eat as many organic foods as possible. There is much we don't yet know, and pesticides are like antibiotics - they kill off microbes, both good and bad. Somehow I think that lowering the levels in your body of pesticides (as measured in blood and urine) can only be beneficial. Also, organic foods don't contain added antibiotics and hormones. (Eat Organic Foods to Lower Pesticide Exposures).  But even if you can't or won't eat organic foods, it is still better to eat non-organic fruits, vegetables, and whole grains than to not eat them.

Eat some fermented foods such as kimchi and sauerkraut (they contain live bacteria), kefir, and yogurts with live bacteria. Eat other bacteria containing foods such as cheeses, and again a variety is best (different cheeses have different bacteria).

Try to avoid or eat less of mass-produced highly processed foods, fast-foods, preservatives, colors and dyes, additives, partially hydrogenated oils, and high-fructose corn syrup. Read all ingredient lists on labels, and even try to avoid as much as possible "natural flavors" (these are chemicals concocted in a lab and unnecessary). Even emulsifiers (which are very hard to avoid) are linked to inflammation and effects on gut bacteria.

Avoid the use of triclosan or other "sanitizers" in soaps and personal care products (e.g., deodorants). Triclosan promotes antibiotic resistance and also kills off beneficial bacteria. Wash with ordinary soap and water.

Avoid unnecessary antibiotics (antibiotics kill off bacteria, including beneficial bacteria).

Vaginal births are best - microbes from the birth canal populate the baby as it is being born. If one has a cesarean section, then one can immediately take a swab of microbes from the mother's vagina (e.g., using sterile gauze cloth) and swab it over the newborn baby. (See post discussing this research by Maria Gloria Dominguez Bello )

Breastfeeding is best - breastfeeding provides lots of beneficial microbes and oligosaccharides that appear to enrich good bacteria in the baby’s gut.

Live on a farm, or try to have a pet or two. Having pets, especially in the first year of life,  ups exposure to bacteria to help develop and strengthen the immune system, and prevent allergies. Pets such as dogs and cat expose humans to lots of bacteria.

Get regular exercise or physical activity. Professional athletes have more diverse gut bacterial community (considered beneficial) than sedentary people.

Can consider taking probiotics - whether in foods or supplements. They are generally considered beneficial, but not well studied, so much is unknown. The supplements are unregulated, and the ones available in stores may not be those that are most commonly found in healthy individuals. Research the specific bacteria before taking any supplements. Researchers themselves tend to stay away from probiotic supplements and focus on eating a variety of all the foods mentioned above (fruits, vegetables, whole grains, seeds, nuts, legumes, fermented foods) to feed and nurture beneficial bacteria.

For years doctors said babies "didn't feel pain like adults" (they said it was just a "reflex") and so all sorts of procedures and operations were done on infants without pain relief medication. This research shows those doctors were wrong and not giving infants pain relief medications is just cruel. From Medical Xpress:

Babies feel pain 'like adults'

The brains of babies 'light up' in a very similar way to adults when exposed to the same painful stimulus, a pioneering Oxford University brain scanning study has discovered. It suggests that babies experience pain much like adults.

The study looked at 10 healthy infants aged between one and six days old and 10 healthy adults aged 23-36 years....During the research babies, accompanied by parents and clinical staff, were placed in a Magnetic Resonance Imaging (MRI) scanner where they usually fell asleep. MRI scans were then taken of the babies' brains as they were 'poked' on the bottom of their feet with a special retracting rod creating a sensation 'like being poked with a pencil' - mild enough that it did not wake them up. These scans were then compared with brain scans of adults exposed to the same pain stimulus.

The researchers found that 18 of the 20 brain regions active in adults experiencing pain were active in babies. Scans also showed that babies' brains had the same response to a weak 'poke' (of force 128mN) as adults did to a stimulus four times as strong (512mN). The findings suggest that not only do babies experience pain much like adults but that they also have a much lower pain threshold.

'This is particularly important when it comes to pain: obviously babies can't tell us about their experience of pain and it is difficult to infer pain from visual observations. In fact some people have argued that babies' brains are not developed enough for them to really 'feel' pain, any reaction being just a reflex - our study provides the first really strong evidence that this is not the case.' The researchers say that it is now possible to see pain 'happening' inside the infant brain and it looks a lot like pain in adults.

As recently as the 1980s it was common practice for babies to be given neuromuscular blocks but no pain relief medication during surgery [1]. In 2014 a review of neonatal pain management practice in intensive care highlighted that although such infants experience an average of 11 painful procedures per day 60% of babies do not receive any kind of pain medication [2].

Our study suggests that not only do babies experience pain but they may be more sensitive to it than adults,' said Dr Slater. 'We have to think that if we would provide pain relief for an older child undergoing a procedure then we should look at giving pain relief to an infant undergoing a similar procedure.'

Interesting findings - that squirming and fidgeting in ADHD children may be how they learn best and actually aids them in learning. So don't try to stop or suppress the fidgeting and squirming, but instead embrace it. I know of an excellent science teacher who would hand out small chunks of beeswax modeling clay to children who couldn't stop squirming and fidgeting in class - and this helped them focus and learn. From Science Daily:

Kids with ADHD must squirm to learn, study says

For decades, frustrated parents and teachers have barked at fidgety children with ADHD to "Sit still and concentrate!" But new research conducted at UCF shows that if you want ADHD kids to learn, you have to let them squirm. The foot-tapping, leg-swinging and chair-scooting movements of children with attention-deficit/hyperactivity disorder are actually vital to how they remember information and work out complex cognitive tasks, according to a study published in an early online release of the Journal of Abnormal Child Psychology.

The findings show the longtime prevailing methods for helping children with ADHD may be misguided. "The typical interventions target reducing hyperactivity. It's exactly the opposite of what we should be doing for a majority of children with ADHD," said one of the study's authors, Mark Rapport, head of the Children's Learning Clinic at the University of Central Florida. "The message isn't 'Let them run around the room,' but you need to be able to facilitate their movement so they can maintain the level of alertness necessary for cognitive activities."

The study at the UCF clinic included 52 boys ages 8 to 12. Twenty-nine of the children had been diagnosed with ADHD and the other 23 had no clinical disorders and showed normal development. Each child was asked to perform a series of standardized tasks designed to gauge "working memory," the system for temporarily storing and managing information required to carry out complex cognitive tasks such as learning, reasoning and comprehension... A high-speed camera recorded the kids, and observers recorded their every movement and gauged their attention to the task.

Rapport's previous research had already shown that the excessive movement that's a trademark of hyperactive children -- previously thought to be ever-present -- is actually apparent only when they need to use the brain's executive brain functions, especially their working memory.The new study goes an important step further, proving the movement serves a purpose. "What we've found is that when they're moving the most, the majority of them perform better," Rapport said. "They have to move to maintain alertness." By contrast, the children in the study without ADHD also moved more during the cognitive tests, but it had the opposite effect: They performed worse.

Scientists warn about endocrine disruption from 4 common chemicals in an analysis just released. This is absolutely depressing because the 4 chemicals (benzene, toluene, ethylbenzene, xylene) are so pervasive in indoor air. Especially that at levels considered "safe" by the EPA there may be disruption of our hormones (endocrine systems).

Of course the 4 chemicals are already known to have health effects on the human body other than what is discussed in this study. For example, toluene has a number of central nervous system effects. The EPA says toluene , which is found in highest concentrations in indoor air from the use of common household products (paints, paint thinners, adhesives, synthetic fragrances, and nail polish). Outside - the biggest source of toluene is from automobile emissions.

Some ways to lower exposure to these 4 chemicals: Read product labels. When using a product that says to use with proper ventilation - open the windows and let the room ventilate!  Don't smoke. (For example: the EPA says tobacco smoke contains benzene and accounts for nearly half the national exposure to benzene) The study researchers themselves said the EPA should be paying more attention to these air contaminants. I read this at Scientific American, but the following excerpts are from EHN.

From EHN: Scientists warn of hormone impacts from benzene, xylene, other common solvents.

Four chemicals present both inside and outside homes might disrupt our endocrine systems at levels considered safe by the U.S. Environmental Protection Agency, according to an analysis released today. ...continue reading "More Problems With Four Common Chemicals"

The researchers were interested in lifestyle factors that are associated with lower rates of allergies.  Prior research has shown that such lifestyle factors are : living on a farm, introducing fish into the child’s diet at an early age, having pets early in life, parental cleaning of the child’s pacifier by sucking it, crowded living conditions, early daycare attendance, and having siblings. This study found that in households washing dishes by hand, rather than in a dishwasher, there are lower rates of allergies and eczema in children. In addition, the study found that consuming fermented or farm-bought food could decrease the likelihood of allergies further. It is thought that early exposure to microbes stimulates the immune system in beneficial ways. Dishwashers leave fewer bacteria behind on dishes than hand washing dishes. Living in a household that hand-washes means family members are eating off of plates and cutlery that have more bacteria, and therefore they are getting more microbial exposure. There could also be more bacteria in the air when dishes are hand washed or even some other lifestyle factor that these households have in common.From NPR:

Kids, Allergies And A Possible Downside To Squeaky Clean Dishes

Could using a dishwashing machine increase the chances your child will develop allergies? That's what some provocative new research suggests — but don't tear out your machine just yet.The study involved 1,029 Swedish children (ages 7 or 8) and found that those whose parents said they mostly wash the family's dishes by hand were significantly less likely to develop eczema, and somewhat less likely to develop allergic asthma and hay fever.

The findings are the latest to support the "hygiene hypothesis," a still-evolving proposition that's been gaining momentum in recent years. The hypothesis basically suggests that people in developed countries are growing up way too clean because of a variety of trends, including the use of hand sanitizers and detergents, and spending too little time around animals.As a result, children don't tend to be exposed to as many bacteria and other microorganisms, and maybe that deprives their immune system of the chance to be trained to recognize microbial friend from foe.That may make the immune system more likely to misfire and overreact in a way that leads to allergies, eczema and asthma, Hesselmar says.

"The hypothesis was that these different dishwashing methods ... are not equally good in reducing bacteria from eating utensils and so on," Hesselmar says. "So we thought that perhaps hand dishwashing was less effective, so that you are exposed to more bacteria" in a way that's helpful.

In a study released Monday in the online version of the journal Pediatrics, the researchers report what they found: In families who said they mostly wash dishes by hand, significantly fewer children had eczema, and somewhat fewer had either asthma or hay fever, compared to kids from families who let machines wash their dishes.

Still, there are other possible explanations, Hesselmar and Mahr both caution. Though the researchers took economic status into account in the study, it could be that people who don't have dishwashers are alike in some other way that reduces their tendency to get allergies. Interestingly, for example, certain other lifestyle characteristics — eating fermented foods regularly, and tending to buy some foods straight from the farm — seemed to strengthen the "protective" effect in families without dishwashers.

I was recently asked my thoughts about a nutritionist recommending Benecol spreads, which I actually had never heard of before. After researching Benecol, I looked with horror at all the non-real food ingredients in the various products (for example, Benecol light spread, with 39% vegetable oil, included partially hydrogenated soybean oil, plant stanol esters, various emulsifiers, potassium sorbate, artificial flavor, etc).  I was dismayed because to me it didn't seem like a "real food" - where were the "real" whole food ingredients? For example,consider emulsifiers which recent research says disrupts the "gut microbiome" (the community of microbes living in the gut) and causes inflammation. Which we all know is not good. And partially hydrogenated oils (trans fats) are again a big health no-no. And on and on.

And recently the Academy of Nutrition and Dietetics, an organization that represents some 75,000 registered dietitians and nutritionists, gave its first endorsement (with a "Kids Eat Right" seal of approval) to Kraft American cheese single slices. Huh? Processed cheese (with whey protein concentrate, emulsifiers, sodium citrate, etc.) got an approval seal and not real cheese? What is going on? The answer may lie with the fact that many nutritionists are accepting cash for endorsing certain foods, especially those promoted by big business companies. The latest to be endorsed are cans of Coca Cola soda! From the Tampa Bay Times:

 Coca-Cola paid nutritionists to tout Coke as heart healthy snack

If a column in honor of heart health suggests a can of Coke as a snack, you might want to read the fine print.The world's biggest beverage maker, which struggles with declining soda consumption in the U.S., is working with fitness and nutrition experts who suggest its cola as a healthy treat. In February, for instance, several wrote online pieces for American Heart Month, with each including a mini-can of Coke or small soda as a snack idea.

The mentions — which appeared on nutrition blogs and other sites including those of major newspapers — show the many ways food companies work behind the scenes to cast their products in a positive light, often with the help of third parties who are seen as trusted authorities.

Ben Sheidler, a Coca-Cola spokesman, compared the February posts to product placement deals a company might have with TV shows. "We have a network of dietitians we work with," said Sheidler, who declined to say how much the company pays experts. "Every big brand works with bloggers or has paid talent."

Other companies including Kellogg and General Mills have used strategies like providing continuing education classes for dietitians, funding studies that burnish the nutritional images of their products and offering newsletters for health experts. PepsiCo Inc. has also worked with dietitians who suggest its Frito-Lay and Tostito chips in local TV segments on healthy eating. Others use nutrition experts in sponsored content; the American Pistachio Growers has quoted a dietitian for the New England Patriots in a piece on healthy snacks and recipes and Nestle has quoted its own executive in a post about infant nutrition."

Most of the pieces suggesting mini-Cokes say in the bios that the author is a "consultant" for food companies, including Coca-Cola. Some add that the ideas expressed are their own. One column is marked at the bottom as a "sponsored article," which is an ad designed to look like a regular story. It ran on more than 1,000 sites, including those of major news outlets around the country. The other posts were not marked as sponsored content, but follow a similar format.

Kelly McBride, who teaches media ethics at The Poynter Institute, which owns the Tampa Bay Times, said the phrasing of the disclosure that the author is a "consultant" for food companies, including Coca-Cola, doesn't make it clear the author was specifically paid by Coke for the column."This is an example of opaque sponsored content," McBride said.

The Academy of Nutrition and Dietetics, a professional group for dietitians, says in its code of ethics that practitioners promote and endorse products "only in a manner that is not false and misleading." A spokesman for the academy did not respond when asked if the posts on mini-Cokes meet those guidelines. Meanwhile, a group called Dietitians for Professional Integrity has called for sharper lines to be drawn between dietitians and companies. Andy Bellatti, one of its founders, said companies court dietitians because they help validate corporate messages.

Research is accumulating that the microbial exposure from a vaginal birth, breastfeeding, and pets in the first year of life are all good for a baby's developing immune system and the gut microbiome.

From Science Daily: Breastfeeding, other factors help shape immune system early in life

Researchers say that breastfeeding and other factors influence a baby's immune system development and susceptibility to allergies and asthma by what's in their gut. The striking findings from a series of studies further advance the so-called hygiene hypothesis theory that early childhood exposure to microorganisms affects the immune system's development and onset of allergies, says Christine Cole Johnson, Ph.D., MPH, chair of Henry Ford's Department of Public Health Sciences and principal research investigator.

The gut microbiome is the collection of microorganisms in the gastrointestional, or GI, tract, and the human body has billions of these microbes... The gut microbiome is known to play an important role in immune system development, and is thought to contribute to a host of diseases like obesity, autoimmune diseases, circulating disorders and pediatric allergies and infection.

"For years now, we've always thought that a sterile environment was not good for babies. Our research shows why. Exposure to these microorganisms, or bacteria, in the first few months after birth actually help stimulate the immune system," Dr. Johnson says."The immune system is designed to be exposed to bacteria on a grand scale. If you minimize those exposures, the immune system won't develop optimally."

In six separate studies, researchers sought to evaluate whether breastfeeding and maternal and birth factors had any effect on a baby's gut microbiome and allergic and asthma outcomes. Using data collected from the WHEALS birth cohort, researchers analyzed stool samples from infants taken at one month and six months after birth. They also looked at whether the gut microbiome impacted the development of regulatory T-cells, or Treg, which are known to regulate the immune system. Highlights:

Breastfed babies at one month and six months had distinct microbiome compositions compared to non-breastfed babies. These distinct compositions may influence immune system development.Breastfed babies at one month were at decreased risk of developing allergies to pets. • Asthmatic children who had nighttime coughing or flare-ups had a distinct microbiome composition during the first year of life. • For the first time, gut microbiome composition was shown to be associated with increasing Treg cells.

Researchers found that a baby's gut microbiome patterns vary by: • A mother's race/ethnicity. • A baby's gestational age at birth. • Prenatal and postnatal exposure to tobacco smoke. • Caesarean section versus vaginal delivery.• Presence of pets in the home.

Henry Ford's landmark 2002 study found exposure to dogs or cats in the first year of a baby's life reduced their risk for allergies.