Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
17 Nov

The Problems with Antibiotics: They Kill the Good Guys and Make You Fat

Whenever I think about antibiotics, I stymie my inner Star Wars fan and admit that it’s a good thing the Force isn’t real and Art Ayers is not actually a wizened microbiologist version of Ben Kenobi. Otherwise, he’d be internally wincing every few seconds as another round of antibiotics commences somewhere in the world and a few billion flora cry out in terror and are suddenly silenced, never to be heard from again.

I jest, sort of, but this much is true: every time you take antibiotics, billions of domesticated gut flora die. As I mentioned last week, antibiotics are designed not to target human cells, but the same cannot be said for the commensal bacteria living in our guts. See, most antibiotics don’t discriminate between “good” and “bad” bacteria. They target bacteria. They aren’t us, they are foreign entities, but we wouldn’t be us without them. We need them to function properly. It’s a bit like bringing in an exterminator to kill the bugs infesting your house, and the guy ends up killing your dog and making your cat act funny, along with killing the insects. The job is done, and he technically did what you requested, but now you have to tell your kid that Buddy moved to a farm upstate to go be a sheepdog and figure out how to deal with your cat peeing on the sofa and scratching up your stomach (leaky gut, get it?). Not very fun, and not what you bargained for.

The results of a 2010 study on the lasting effects of antibiotics on one’s gut flora are rather scary. Over a 10 month period, three individuals – humans – each went on two courses of ciprofloxacin, an extremely commonly prescribed antibiotic often used to treat bone and joint infections, respiratory tract infections, gastroenteritis, endocarditis, urinary tract infections, cellulitis, infectious diarrhea, anthrax infection, typhoid fever, and skin infections to name more than a few. In other words, it’s regarded as a trusty all-purpose antibiotic, effective across all species (vets often prescribe cipro). So, what happened to the patients’ gut flora populations after taking cipro?

Three to four days into the treatment schedule, gut diversity was lost and composition was altered. What flora remained became more homogenized, and the various ratios of the more than 400 species of bacteria that live in the gut became lopsided. One week after the conclusion of each treatment, gut flora had recovered, but only slightly. It was a shade of its former self. Diversity improved, but not to original levels. Composition began to normalize, but it was incomplete. Things were stable and the diversity/composition protected from further change, but the state of flora being protected was not the same pre-cipro state.

The authors admit that these are uncharted waters. They don’t know, nor do they pretend to know, the lasting effects of hosting an altered microbiome. They don’t use the words “good” or “bad” to describe bacteria. They just know that it’s altered, and – as much as a ten month trial can tell us – perhaps for good.

I dunno – I have an inkling of an idea that maybe, just maybe, forever altering our gut flora isn’t such a hot idea. I think the researchers would agree, but they can’t say anything without knowing for sure, of course. But my inkling isn’t exactly unfounded. We do have some evidence that altered gut flora are associated with weight gain. We even have evidence that antibiotics cause weight gain. Let’s take a closer look.

Foremost, of course, is the widespread usage of antibiotics to “increase the growth” of livestock. I use quotes because what they’re really doing is making the livestock fat by disrupting the microbiome of their guts. One study even determined that eliminating routine administration of antibiotics to livestock for the purposes of increasing weight gain wouldn’t affect dietary protein availability in developing nations. My guess as to why? Antibiotics are increasing body fat accumulation on these animals, rather than purely inducing sheer hypertrophy of muscle meat – unless you know of any bodybuilders who cycle penicillin and cipro – and the resulting weight gain is coming more from fat than protein.

Other animals offer more avenues of understanding the obesity-promoting effects of altered gut flora. Like, say, mice:

A team of researchers transplanted gut bacteria from obese mice into lean mice. The lean mice enjoyed a 60% increase in body fat and a rapid, 14-day descent into insulin resistance following the gut flora alteration.

In a later study, members of that same team induced obesity in mice through diet. As they fattened, a specific type of Firmicutes bacteria bloomed – it began to overgrow in the gut. Transplanting this Firmicute into lean mice made the lean mice fat. Lean mice who received transplants from lean donors did not get fat.

Oh, and there’s also some cool evidence in humans. Those same researchers who showed that lean mice have different gut flora than fat mice and that transferring fat mice flora to lean mice made the lean mice fat studied whether this was true in humans. It is. Just like the mice, lean human guts contain more flora from the bacterial phylum of Bacteroidetes and less from the Firmicutes phylum, whereas obese human guts contain flora more heavily weighted toward Firmicutes. Furthermore, both mice and humans with “obese” gut flora (high in Firmicutes) derive more energy from food and have an increased ability to “harvest energy.”

Okay. So it seems pretty clear that gut bacteria plays a role in obesity, and there’s strong evidence that it’s a causal role. But the studies up until now have only shown that altering gut bacteria by adding flora from obese animals to the guts of lean animals makes them gain weight. The question, then, becomes whether altering gut flora via antibiotic usage can have similar effects on weight.

One Martin Blaser, an NYU microbiome researcher, believes he has the answer. Citing the 2010 study mentioned earlier and another that he authored himself, he speculates that not only does antibiotic usage permanently change our gut flora, it also promotes obesity. Blaser examined the effect of antibiotics on Helicobacter pylori, a common member of the human gut biome. While there’s evidence that H. pylori increases the risk for ulcers and gastric cancer, making it a popular target for physicians (even in asymptomatic patients) wielding a hammer made of antibiotics, it’s also been living in human guts for at least 58,000 years. You might imagine that casually flouting such an extended co-history together could have some unintended consequences. You’d be right.

Blaser used US veterans who were scheduled for upper GI endoscopies (close examination of the upper gastrointestinal tract). Of the 92 vets, 38 had no H. pylori, 44 tested positive for H. pylori, and 10 were indeterminate. 23 of the H. pylori positive were given antibiotics, and all but two had total eradication of H. pylori. So, what happened to the 21 subjects who were initially replete in H. pylori but who eradicated them through antibiotics?

They gained the most weight. Their BMIs increased by 5%, give or take 2%. The other vets had no weight change.

Leptin levels increased by 20%.

Postprandial ghrelin increased sixfold.

The ghrelin increase is the most interesting effect to me. It does a number of things, the foremost of which is to increase hunger. High levels also increase abdominal fat. So, after taking antibiotics and losing all their H. pylori, patients weren’t as satisfied after meals, they gained more weight, and the weight they gained was likely concentrated in the abdomen. Bad stuff all around. I’ve written about the dangers of belly fat before; it’s not just a matter of LGN.

Man, antibiotics as growth promoters in livestock really make sense when you put it all together. They give you all sorts of awesome stuff:

More efficient conversion of feed into energy. Lower food costs.

Higher ghrelin levels that promote greater accumulation of visceral fat. More marbling.

Now I’m kinda wishing that Art Ayers actually was a Jedi master and he could use Force Debugging to remove specific strains of bacteria from the gut (Force Choke wouldn’t work because most gut flora are anaerobes and thus don’t require oxygen; also, they have no necks).

More problems next week, plus some solutions. Thanks for reading.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. I just started taking Aldoctone and Clairithromycin for acne. I’ve been eating paleo for a little over a year now, and I currently have the worst skin of my life…though I don’t believe there’s a correlation. What can I do for suspected hormonal acne? I haven’t taken antibiotics in over 10 years until recently! I’m desperate for a cure for this mess! Help!

    Holly wrote on January 14th, 2013
    • Thats just how spiro works (makes you break out like crazy first). Maybe quit eating paleo… Its not for everyone and you’re probably suffering from nutritional deficiencies. If your antibiotic isnt working then switch to a new one.

      Lila wrote on March 23rd, 2013
  2. I was having stomach buring in May 2011. Went to the doctor, who took blood and told me I had H. Pylori. I was put on the PrevPac and my body has been messed up ever since. I have suffered from vaginal yeast ever since taking the PrevPac for almost 2 years now. Doctors keep treating the yeast but, it never works, it always come back. They need to treat the route of the problem in the Gut, but how is this done??? So desperate for help that I can not find.

    Christine wrote on March 25th, 2013
  3. The Cipro study is not alarming at all, their gut started to recover 4 days after, and at a week improvements had continued.

    Taken unnecessarily? Likely a bad idea, but you have to consider cost/benefit in many cases.

    I believe it’s very likely that cows given antibiotics are more densely muscled than their non-antibiotic counterparts. The big beef industry is concerned with the muscle-meat, and to some degree the marbling within..not so much the straight lard.

    Roddy wrote on June 22nd, 2013
  4. What would you recommend to correct the weight gain from antibiotics? In 2008 I had strep that turned into rheumatic fever I was prescribed penicillin shots every month. I was 18 at the time and before penicillin weighed 114. I was on penicillin for 5 years and over time slowly gained weight. Iam now 163lbs have been off pencillin for 9months and can not lose the weight. I have tried everything and have never been a un healthy eater and excersise everyday. My doctor has not helped and laughs at the idea that it could be from the antibiotic. Any advice will be greatly apperciated.

    Sara wrote on May 24th, 2014
  5. You can’t say that, across the board, antibiotics cause weight gain in ALL patients. Diet and lifestyle are factors also. I’ve taken antibiotics for acne on and off for years and I’m underweight. I mostly only eat healthy foods and have an active lifestyle

    Ashley wrote on January 19th, 2015
  6. What about long-term use of several rounds of 4 different Abx for Lyme disease? I noticed a huge increase in body fat and I counter the Abx with Probiotics, am on a strict elimination diet to keep the yeast on the down low, and physically active. HOW do I get rid of this? Can’t stand it. I am finishing my 5th month of Abx use and will be switching to Samento and Banderol for another 6 months. I’m doing all the right things, but have noticed a significant increase in visible body fat. I’m at a loss. I have a cert in Applied Clinical Nutrition as it pertains to reversing the disease process and have been successful working with others, but can’t seem to get on top of this because of the abx.

    Cindi wrote on March 11th, 2015
  7. Antibiotics can make the disease become worse as the virus get stronger and stronger when you consume the antiobiotics. The best way to cure the diseases is through natural remedies provided by nature such as eating fruit and vegetables

    Kangen wrote on March 11th, 2016
  8. I had a severe infection in my bone after a dentist did a root cannel and missed the forth root. As such a pocket of infection was sealed in. It festered for years until I got very, very ill and had to have multiple surgeries and go on two months of the strongest does of penicillin. Two months! I’ve been taking probiotics and eating brine fermented foods as a way to protect my gut health. But I am worried that after such intense antibiotic treatment my gut microbes will be forever changed and I will put on weight among other problems. In my case I had to have the antibiotics. I was told the infection would have moved to my brain and then…well, that would have been pretty dire. But I wish there was more I could do to help my gut flora recover. I hate to think it won’t return to the way it was.

    Gill wrote on March 29th, 2016

Leave a Reply

If you'd like to add an avatar to all of your comments click here!

© 2016 Mark's Daily Apple

Subscribe to the Newsletter and Get a Free Copy
of Mark Sisson's Fitness eBook and more!