Anti-biotics and the guts.

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Pus on the brain.  Caused by bacterial meningitis.

Pus on the brain. Caused by bacterial meningitis.

I like anti-biotics.  They kill nasty bugs that shouldn’t be there.  Provided the problem is caused by some horrible microbe, then anti-biotics are a Good Thing.  They aren’t so good if they are given to cows to make them grow more quickly.  And, on an individual basis, it is an excellent idea to build up our immune system so we can fight the Empire of Evil Bacteria on a daily basis and not go running to the docs because we can’t throw off our latest cold.1

Being prescribed a course of anti-biotics to make us better seems so simple.  Take all the pills and the job is done.  Unfortunately, the anti-biotic can be indiscriminate in what ‘biotics’ it kills, taking out the good guys, the lactobacillus and bifidobacterium as well as the e coli or whatever.  The hopeful idea amongst the docs is that our guts restore the levels of the good stuff in a couple of weeks.  Sadly, this isn’t always the case. The anti-biotic factors that affect its devastation on the human gastrointestinal tract, wonderfully shortened to GIT, are the type of anti-biotic and how it circulates around.  I am concentrating on oral anti-biotics.  Injected ones cause problems because they circulate round and round.   And the problems relating to anti-biotics are not just that our guts are open to more pathogens taking hold, as we will see.

Taking a single course of anti-biotics can lead to four different problems:2

  1. An overgrowth of nasties already present in the GIT, for example clostridium difficile or yeasts.
  2. A reduction in the production of SCFAs (short chain fatty acids), which can directly lead to electrolyte imbalances. 3  SCFAs increase the blood flow in the colon and the liver, which helps the absorption of nutrients in the small intestine and they also help maintain the mucosal barrier that lines the GIT.  So it isn’t a good idea to have any reduction of these.
  3. An increased susceptibility to intestinal pathogens.  Less of them are needed to cause a problem and they hang around the GIT for longer.
  4. A reduction in the therapeutic value of some herbs, eg willow bark, senna, soy or rhubarb.  This is because activity of these herbs is dependant upon bacterial enzymatic metabolism in the colon.

This final point also applies to dietary lignans.  Lignans bind to oestrogen receptors and scavenge the free radicals that cause breast cancer and heart attacks.  When the dietary lignans have been processed in the guts by the good bacteria, they circulate round the plasma or serum, and are called enterolactone. The best sources of lignans are flax, sesame seeds, brassicas, eg broccoli, and red wine.  The footnoted study done on 2,753  Finnish men and women found that 12 – 16 months after taking anti-biotics, people still had lower serum levels of enterolactone than those who had not taken any anti-biotics.  The strongest suppression came from the anti-biotics called macrolides; these are the anti-biotics usually ending in …..mycin.  So erythromycin, clarithromycin are examples of macrolides. They are prescribed to treat  the ‘cocci’ infections: streptococci, staphylococci, pneumococci, enterococci and so on.4  Frequently, the people in the study had only taken one course of these anti-biotics to have their enterolactone levels suppressed for months afterwards.  We clearly have a problem here.

The problems caused by the macrolides are partly attributable to their recirculation through the liver and bile, so instead of being excreted rapidly, they go round and round, bashing away at our good bacteria.

The other anti-biotics that cause the worst gut damage are the broad spectrum ones such as amoxicillin, oxytetracycline or tetracycline.  All anti-biotics cause damage to our poor guts, but some are definitely worse than others.

The answer is to maintain a healthy immune system at all times and, should we have to take a course of anti-biotics, reinoculate the gut with the highest standard of pro-biotics afterwards.  So not Yakult, then.  However, if dairy tolerant, eating full fat, live yogurt is a good idea or drinking keffir, a drink made from fermented milk – ideally fermented with keffir grains.

  1. Building the immune system does not mean washing our hands with anti-bacterial soaps! – or drinking unfiltered tap water because we are told Corporation Pop is good to drink.  It isn’t. []
  2. Hawrelak J A, Myers S P. The causes of intestinal dysbiosis: a review.  Altern Med Rev. 2004;9:180-197 []
  3. Electrolyte imbalances: the billions of cells in our bodies both contain and swim in fluid that is rich in electrolytes: potassium, magnesium, sulphate and phosphate inside and sodium, chloride and bicarb outside.  The balance is essential to life and maintained by the pumping action of the cell membranes. []
  4. Kilkkinen A et al.  Use of oral anti microbials decreases serum enterolactone concentration.  Am. J. Epidemiol. (2002) 155 (5); 472-477 []

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