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Anna Crist

student researcher , University of Oregon

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Purell now, Bacteri-ell later?

The hygiene hypothesis, the idea that “too much cleanliness prevents the development of a well-balanced immune response”(Sironi and Clerici, 2010), has received a lot of support and also criticism. It has recently been challenged by the hypothesis of “early immune challenge”, which states that a lack of appropriate immune stimulation during early childhood might account for the increased development of allergies in industrialized countries (Kramer et al, 2013). This proposal places less emphasis on excessive hygienic practices and focuses more on the insufficient exposure to specific environmental microbes, particularly those from non-urban environments, as the reason behind the rise of atopic disease. While different, both hypotheses point to the beneficial health affects of some microbes.

What do you think is the reason for increased allergy levels in industrialized countries? Do you think that a concoction of the “right” microbial species in the form of a lotion, drink, or inhalant (aka "Bacteri-ell") could be a future replacement for natural exposure to beneficial microbes?
Instead of using hand sanitizers like Purell, do you see a future where people from some regions of the world are unsanitizing their hands with “Bacteri-ell”?


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    Apr 29 2013: I think it’s important to get microbes from nature into our houses and into us. The bacteria we are exposed to right when we are born sets up our bacterial species composition that persists and evolves throughout the years. What effect this has on human health is still poorly understood. There are however studies which show that bacterial compositions do have some effects on health. For instance, it has been shown that obese people have a different gut bacterial compositions than those who are not. In one study, rats that were genetically predisposed to obesity, when given fecal transplants from rats that were not overweight, lost their excess weight and kept it off. Studies like this one have been cited to encourage the ingestion of probiotics, however, it’s still unclear if these (after passing through the acidic conditions of the stomach) are effective at colonizing the already colonized human gut.

    In many industrialized nations, various food items are irradiated, which goes a long way towards preventing foodborne pathogens but also kills good bacteria as well, so we are likely not getting exposed to the amounts and types of bacteria we evolved with. I do see a future when we will be lathering up with and ingesting more bacteria but until then, I’d say were better off safe than sorry and not going overboard with cleanliness (unless we know we’ve been exposed to pathogens) and making sure we get enough outings in nature wouldn’t hurt.
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      Apr 30 2013: In reference to gut bacteria, the food we ingest has an effect on the bacteria in it as the bacteria do on us. Essentially, we eat food and take what we can/need from it, then the bacteria digest the majority of what we don't.
      For instance, if a lactose intolerant person (lacking the ability to produce lactase, the enzyme that breaks down lactose, a sugar in dairy products) drinks milk or eats a slice of cheese, they don't digest it, but the microbes in their gut do. The digestion of lactose by gut bacteria then causes excess gas and abdominal cramps. What they ate directly affected the activity of those microbes. In contrast, when we eat foods that are lower in fiber our cholesterol levels rise.
      Fiber has a two fold effect on our health. First, it swells in our large intestine and works like a scrubbing pad on its walls. Second, it feeds the majority of good bacteria that reside in out gut. Both of these effects work in unison to maintain lower LDL cholesterol and promote a healthy cardiovascular system as well as a healthy digestive system.
      My point is, there are almost always natural ways of changing the biodiversity of our personal microbiome and we should take advantage of them.
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        Apr 30 2013: I definitely agree with you about finding the more natural ways of accruing the biodiversity of microbes that we need. Why try and use synthetic ways when a natural way is there?
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      Apr 30 2013: I think it is really interesting that there are differences in gut microbes between obese people and those who are not. Do you think this is genetically linked or do obese people house these microbes because of their lifestyle? I also agree that taking the natural way to help change our personal microbiome may be a better solution than possibly introducing a "baceri-ell" that could then cause more problems since we know so little about microbes.
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        Apr 30 2013: I think the mice in the study I mentioned were reared the same way, so same diet and everything but the experimental group was genetically predisposed to obesity. I tried looking for the paper but couldn't find it. Here's an interesting article that mentions a similar study though: http://blogs.scientificamerican.com/brainwaves/2012/09/12/the-food-fight-in-your-guts-why-bacteria-will-change-the-way-you-think-about-calories/
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          May 1 2013: I also have read a study of sterile mice vs normal mice and the effects that microbes have on body weight. The sterile mice were fed autoclaved food while the normal mice received non-sterilized food. The mice without microbes were significantly obese and nutrient-deficient. With all the sterile food products in today's world, no wonder we see problems in diet and an increase in problems linked to our microbiomes. When sterile mice were inoculated with gut flora from the non-sterile mice, a decrease in body fat was seen and the mice were indeed healthier.

          Looking back in history we see a trend of preserving food by the addition of bacteria and other cultures. There are so many beneficial microbes used in food processing including: beer, wine, bread, yogurt, cheese, keifer, and kombucha. These cultures have been an integral part of the human gut flora and have benefited humans for centuries. Not to mention the digestion of the probiotic cultures themselves is extremely nourishing for your body.

          For instance, when I was young my mom gave us kombucha (this took away heartburn and stomach aches almost instantly). My mom said it was a Chinese mushroom, but actually it is a biotic mat of anaerobic and aerobic bacteria. Our family has cultured this probiotic for years and the diversity of the different scobies is astounding. Depending on what kind of scoby you aquire does make a difference in the flavor and properties of your kombucha. Most people think of probiotics as just yogurt or acidophilus, but really humans have been using them for years to survive and treat medical issues. Why throw this method out with the bathwater? We should listen to our history, not fight against it.
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        May 1 2013: Everything in your gut microbiota is influenced by lifestyles that you engage in after birth. Originally for the environment of the gut, it is sterile and must be colonized. This is why as soon as you first feed the baby it starts to gain some microbes, and as he continues to process more food, more microbes begin to colonize this new environment. This is why as you raise your child, deciding what you feed them causes massive shifts in how their gut microbiota will form
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          May 1 2013: Also, it is interesting to observed the differences in mothers who breastfeed their children vs ones that give them formula. Children fed formula do not receive the beneficial enzymes and microbes in breast milk often develop serious allergies and colic. There are some probiotics in formula, but I still don't think they are better than nature's version. I agree with everyone in saying, maybe nature is just the best answer.

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