Wednesday, October 24, 2012

Health: Antibiotics and Probiotics

Microbiome is the term used to describe a living species combined with the microorganisms that inhabit it. All animals and plants have microbiomes. The microbes that inhabit us are not just transient visitors; they are species that coevolved with us and they are an integral part of the animal that we are. Michael Specter has produced an interesting article on how we have been affecting our microbiome and what it might mean for our health. His article appeared in The New Yorker and was titled Germs Are Us.

Specter describes what can only be referred to as a revolution in medical science. For decades we have assumed that who we are is essentially determined by our genetic makeup. Sickness could then be explained by a genetic malfunction. That may no longer be an appropriate assumption.

"....another truth has emerged: while our health is certainly influenced by genes, it may be affected even more powerfully by bacteria."

We are provided this background information:

"We inherit every one of our genes, but we leave the womb without a single microbe. As we pass through the mother’s birth canal, we begin to attract entire colonies of bacteria....They are bacteria mostly, but also viruses and fungi....We are inhabited by as many as ten thousand bacterial species; these cells outnumber those we consider our own by ten to one, and weigh, all told, about three pounds—the same as our brain."

One of the medical truths we face is that we are undergoing an epidemic of certain conditions: obesity, autism, food allergies, asthma.... It is difficult to assign such rapid growth in these illnesses to genetic conditions. There is a circumstantial evidence that associates the growth in incidence of these conditions with the growth in use of antibiotics. Antibiotics were lifesavers for many, and bacteria were viewed as things to be expunged from our systems. The net effect of continued and continual use of antibiotics is to upset our microbial makeup. Evidence is accumulating that indicates serious side effects effects can ensue.

Specter provides Martin J. Blaser, chairman of the Department of Medicine at New York University as a guide to this burgeoning field of study. He explains how the practice of medicine itself can be responsible for perturbing our microbial content—our microbiome.

"For the past hundred and fifty million years, nearly all mammals have acquired their microbiome by passing through their mother’s vagina, which is colonized by an enormous range of bacterial species. Babies delivered by Cesarean section lack many microbes that are routinely transferred from mother to child. Last year, nearly a third of the four million children born in the United States were delivered by Cesarean section. (In China, the figure was closer to fifty percent.) The incidence of allergies and asthma is far higher among those children than it is for vaginal-birth babies."

Cesarean sections had the unintended effect of altering a child’s bacterial makeup.

The usage of antibiotics is dominant in producing bacterial losses that accumulate and grow over successive generations.

"By the age of eighteen, the average American child has received from ten to twenty courses of antibiotics. forty-three million courses were dispensed in 2010 alone....’Those drugs have saved countless lives, and it is very important that we not lose sight of that fact,’ Blaser said. ‘Whenever they are used, though, there is collateral damage. And we are only now fully learning how severe that damage has been’."

Blaser adds:

"The rise in obesity, celiac disease, asthma, allergy syndromes, and Type 1 diabetes. Bad eating habits are not sufficient to explain the worldwide explosion in obesity."
"We are not talking about illnesses that are increasing by ten percent....They are doubling and tripling and quadrupling. With each generation, there is a heavier impact on early-life microbiome. And it means that we are less and less able to metabolize the food we eat."

Specter focuses on one microbe as an example of how complex the task of understanding our microbiome will be: H. pylori. This bacterium also provides a cautionary tale for those who would rush in with cures.

"Heliobacter pylori may be the most successful pathogen in human history. While not as deadly as the bacteria that cause tuberculosis, cholera, and the plague, it infects more people than all the others combined. H. pylori, which migrated out of Africa along with our ancestors, has been intertwined with our species for at least two hundred thousand years."

This is the bacterium that was identified in 1982 as the cause of gastritis and peptic ulcers. This discovery led to effective treatments of these conditions using antibiotics. It was so successful that people talked about eliminating it entirely. Few people stopped to question how natural selection allowed this bacterium to survive in humans when it had such ill effects. Further research has shown that H. pylori actually provides a number of beneficial effects, particularly at a young age.

"At the beginning of the twentieth century, H. pylori occupied the stomach of nearly every person in the world. Although it remains prevalent in developing countries, where sanitation is often poor and antibiotic use less common, it is found in just five percent of children born in the United States—a dramatic change echoed in many other Western countries."

Consequences from the disappearance of H. pylori are beginning to emerge from research activities.

"Blaser and his N.Y.U. colleague Yu Chen reported that people who didn’t have H. pylori in their guts were far more likely to have had asthma as children than those who did."

"There is equally convincing evidence that destroying H. pylori could alter metabolism in ways that increase the risk of obesity. Several research groups, including Blaser’s, have found a strong relationship in humans between the bacterium and two stomach hormones, ghrelin and leptin, both of which play central roles in regulating our appetites....The more ghrelin you have in your bloodstream, the more likely you are to overeat. Leptin functions in the opposite way, suppressing appetite and increasing energy levels. For people whose stomachs are infected by H. pylori, ghrelin became far less detectable after a meal. For the others, levels of the hormone remained high, and the effects are evident."

It would seem that we have created a generation of children whose mechanism for controlling food consumption has been damaged, making it more difficult for them to avoid overeating.

If this research holds up, it has profound implications for our nation as it contends with rising healthcare costs. While potentially a medical disaster, it also holds out the promise that there might be simple and inexpensive corrective steps that could be taken.

A probiotic would be something that attempts to alter the microbiome in a beneficial manner, perhaps by introducing strains of bacteria. Products that claim to be probiotics are readily available. There doesn’t seem to be any science behind any of the products or their claims, and regulators have refused to recognize their efficacy at this point.

"....instead, probiotics are sold as dietary supplements or as foods like yogurt. This permits supplement manufacturers to make almost any claim about the benefits of the products as long as the packaging includes, usually in the tiniest possible type, this disclaimer: ‘These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease’."

The potential for making money with products labeled as probiotics has not gone unnoticed in the commercial sector. Many companies have found more lenient controls in Asian countries and are developing growing markets for their products there. An article in Bloomberg Businessweek addressed the global market that has arisen for these proclaimed probiotics.

"The global market for foods containing probiotics will probably grow 51 percent, to $42 billion, by 2016, figures Euromonitor. For fortified drinks such as Actimel and Yakult, the Asia-Pacific region is the No. 2 market after North America, generating about $18 billion in sales last year, Euromonitor says. Western Europe ranks third at $11 billion."

We seem to be emerging from a period in which we aggressively tried to kill any microbe we encountered without understanding what the consequences might be, and have entered a period in which we are being induced to stuff ourselves with all kinds of microbes without understanding what the consequences might be.


1 comment:

  1. A treatment with antibiotics may have consequences because these pharmaceutical products can’t distinguish between good and bad bacteria. This is one of the main reasons why an antibiotics treatment can lead to a serious imbalance in the gastrointestinal flora.

    Many people that have to take antibiotics may experience diarrhea as a consequence. This diarrhea is often the result of clostridium difficile overgrowth.

    Studies suggest that about 300,000 people in the US are hospitalized every single year because of a clostridium difficile infection. The results of 23 clinical studies show that taking a probiotic supplement will increase the risk of suffering from such an infection significantly.


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