Can antibiotics be contributing to obesity?
I had always known that commercial farmers put antibiotics into their livestock feed, and generally have tried to buy free-range, organic or antibiotic-free chicken and beef, even though it was much more expensive and the chickens were noticeably smaller. I’ve wanted to avoid meat raised this way not because of a fear that there were lingering antibiotics in the meat itself, but because I was concerned that our family might be exposed to antibiotic-resistant pathogens by eating it.
I assumed that the reason the farmers gave their animals the antibiotics was to prevent infection because the animals lived in such close proximity to each other in the barns. Right? Wrong. It wasn’t until I researched the topic of obesity and antibiotics that I learned why the commercially-raised feed animals are given the low-dose medication and it isn’t to prevent disease. Antibiotics are added to livestock feed because it helps fatten the animals!
For many years, farmers have given their cows, chickens and pigs low, steady doses of antibiotics in the livestock feed to grow and fatten them up, without understanding why it worked. Science is now starting to take a closer look at this practice and study the impact of antibiotics on gut bacteria and weight in humans.
Antibiotics, whose sole purpose is to kill disease-causing bacteria, incidentally also shift the composition of healthy bacteria in the gut. They can kill many of the bacteria that normally thrive inside the gut, not just the disease-causing ones, changing the mix of flora in the gut. Since certain bacteria are more efficient at converting food into energy that can be used for growth and fat production, changing the mix of bacteria can increase fat production.
Two recent studies have suggested that antibiotic use impacts obesity.
The first study, reported in the International Journal of Obesity, examined eleven thousand five hundred (11,500) babies whose parents had agreed to have them participate in the study before they were born. Researchers checked the height, weight and antibiotic-use of these children at birth, and then again at 7 weeks, again at 10 months, again at 20 months, again at 38 months and finally when they were 7 years old. The researchers also tracked many other factors that they had originally suspected might be linked to obesity, such as their parents’ weight and smoking status. They found that babies who were given antibiotics during the first six months of life gained 22% more weight on average than those babies not given antibiotics during the same time frame. This same result was not found for babies given antibiotics in the second six months of their young lives.
The first few months of life are the time when a baby’s microflora are being established, after the receiving her first bacteria bacterial exposure via passage through the birth canal and later through her mother’s breast milk and her early environment. Once established, the mix of bacteria remains relatively stable. This may be why taking the antibiotics earlier in life has a bigger impact on the bacteria than it does when taken later.
Dr. Leonardo Trasande, a lead researcher on the study and a professor of pediatrics at New York University speculates that an early disruption of microbes in the gut cause over-absorption of calories and subsequent obesity. As gut microflora assist in the digestive process, it makes sense that a change in the composition of bacteria in the digestive tract, with a corresponding increase in those which are more efficient at converting food to energy, may affect how food is digested and calories absorbed.
The other study on obesity and use of antibiotics, published in August 2012 in the journal Nature, gave antibiotics, in low doses comparable to what livestock receive, to young mice and observed changes in both their body fat content and the composition of their gut microflora. The mice that were given the antibiotics had 15% higher fat content than those that were not given them. The researchers also noted changes were found in the genetic profiles of the mice given antibiotics, with unusual activity in their genes which are linked to digesting carbohydrates and regulating cholesterol levels, perhaps causing these mice to become very efficient converting food to fat.
Humans typically take antibiotics for short periods at high doses to fight infection. This is different than the way livestock receive them (for long periods at low doses). Therefore, the research on the mice may not be entirely applicable to how therapeutic antibiotic use in adult humans might impact obesity. And the fact that young babies, whose gut microbiomes are still undeveloped, have their weight impacted by antibiotic use might not necessarily mean that there would be the same effect when an adult with a more stable mix of gut bacteria takes them. More research needs to be done with adult study participants to tease out the effect that taking an antibiotic periodically to fight disease has on human weight.
And, the evidence does seem to be mounting. An article published by Mother Jones in November 2013 shows two maps of the United States plotting the frequency of antibiotic prescription per capita, per state, and also obesity rates. The correlations are stunning.
While researching this topic, I thought of something I’ve observed living here in Singapore and wondered if gut bugs were playing a role.
Antibiotics can be very effective at fighting bacterial illnesses and living in a hot and steamy climate, there is a concern about the spread of disease. In Singapore, the doctors sell prescription medications in their medical offices. Antibiotics are freely prescribed here. It is very uncommon to leave a medical appointment here without a little brown bag containing antibiotics, among other medications which may also include probiotics.
Singapore is a young nation. It became a country in 1965. Although it is extremely modern and developed, the pervasive administration of antibiotics is a relatively recent phenomenon. Many of today’s adult Singaporeans did not grow up with the same ready access to modern, Western medicine as their children now have. Traditional Chinese Medicine was, and still is to a slightly lesser degree, commonly practiced here.
It is not uncommon to see Singaporean children with heavier body weights compared to their typically lean parents. The Singaporean diet is heavy in fat (lots of fried foods) and carbohydrates (rice and noodles), but for some reason children seem to gain weight even if their parents don’t. Of course there are many possible explanations for this, such as lots of inactive time spent in the classroom or children being indulged with the sweets that they crave. But I have wondered if the brown baggies that have been so readily dispensed from the medical clinics to this young generation of Singaporeans might be playing a role in what appears to be a mini obesity epidemic in the children. This is pure speculation, of course.
Awareness of the risks of over prescription of antibiotics is growing here, as it is elsewhere. Many more doctors are now resisting their patients’ requests for antibiotics at the same time many patients are resisting the drugs, which their doctors recommend, that they feel might be unnecessary. It will be interesting to see, over time, if there are fewer heavy children here, as antibiotics are taken more sparingly.
The connection between obesity and antibiotics is one more reason, in addition to concerns about increasing antibiotic resistance in disease-causing pathogens, to use them sparingly and only when truly necessary, particularly amongst infants. Knowing that there is a link, can provide potential areas to explore for understanding why some people’s bodies so readily convert food to fat as well as providing clues to explore for future obesity treatments.
How do you know what formulary or combination of probiotics to use for a specific medical condition? Do you just read what is on the box or ask a (hopefully) knowledgeable sales person at a health food store? Most Docs I know are not “up on” probiotics. How do you know what is the best basic probiotic for general good gut flora? I note that your son’s pediatrician gave you a specific brand and probiotic combination. When I suffered from collagenous colitis (or ulcerative colitis) several years ago, even my GI doc hadn’t heard of the condition. Now it is more well known. I diagnosed myself on the internet from my symptoms and I followed what was recommended for a cure – Saccharomyces boulardi (a beneficial “good” yeast). It cured me within a week!! I HAD TRIED EVERYTHING FOR MONTHS AND NOTHING ELSE WORKED. Florastor is the most common brand name but it wasn’t the brand I used. The advantage of the Florastor brand is that it doesn’t have to be refrigerated as do so many of the probiotics. The brand I used did need to be refrigeratied; thus not easy to travel with. Costco even carries Florastor now; couldn’t believe it. On the box it states #1 Probiotic Worldwide. I gather from researching it, that it has been used for years in Europe.It virtually was a lifesaver for me!