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Comment by sureaboutthis | Hacker News Reader

I bake all our bread, and it's sourdough, every two or three days. I wonder what effect this has on my overall health in a positive or negative way.

EDIT: To be clear, this article is about microbes on the hands of sourdough bread bakers. I'm curious about what effect these microbes on my hands have on my body, if anything. Not the ingestion of my bread.

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I also keep a starter and bake sourdough regularly.

The only thing IMHO that can be an issue is just eating too much carbs (because it's so damn good) or sensitivity to gluten. However, it is known that sourdough/pain-au-levain is more digestible than regular bread for folks with gluten intolerance. Sourdough is decidedly more acidic (that's why it's called "sour") than dough which has been risen with commercial yeast. This acid partially breaks down the gluten in the dough during fermentation.

People have been eating naturally fermented bread since the dawn of civilization. The bacteria and yeast in properly fermenting dough do an excellent job of keeping any nasty stuff out.

> However, it is known that sourdough/pain-au-levain is more digestible than regular bread for folks with gluten intolerance.

I’ve heard this many times, but I don’t know if it rises to the level of “it’s known”. It’s not even clearly known that “gluten intolerance” exists outside the context of celiac disease, and sourdough definitely does not help with celiac.

There is a theory that “gluten intolerance” is actually intolerance of certain sugars, sometimes called FODMAPs, that are found in wheat, rye, barley, and quite a few non-cereal foods. I’ve never seen a paper about this, but I could easily believe that many sourdoughs ferment those sugars, making the bread more tolerable.

Finally, a little anecdote about gluten intolerance. I know someone who claimed to be gluten intolerant. She felt much better when she avoided gluten. At one point, I baked a fresh challah, and she decided to make an exception and try the challah. After eating maybe a pound of challah all by itself, she felt terrible. And lo and behold, we had a diagnosis! Eating large amounts of bread made her feel sick! Now she eats bread in moderation and she feels okay :)

I own restaurants. I have to force myself to not roll my eyes at the numbers of people who come in with growing fear of gluten claiming to be allergic to it. One parent even asked us to prepare one child's salad with separate utensils to avoid even the slightest contact with bread. Touching bread does not cause a reaction to gluten.

So I think we should distinguish between "gluten intolerance" (which is often self-diagnosed) and "celiac disease" (actual medical condition with allergic reaction to gluten). For people with the latter, even trace amounts of gluten are harmful:

https://www.ncbi.nlm.nih.gov/pubmed/1923558

Even inhaled gluten is enough to cause immune system reaction: https://www.nejm.org/doi/pdf/10.1056/NEJMc063112

The generally accepted safe threshold of gluten intake for people with celiac disease is somewhere on the order between 6 and 30mg (depending on the study). Even that may be high, there are case studies of individuals where as little as 1mg of gluten prevented recovery of their gut:

https://www.ncbi.nlm.nih.gov/pubmed/15497770

So the parent that asked for separate utensils is not insane; sharing a bread knife between gluten-free and gluten-containing bread can be harmful already.

(A close family member and another close friend of mine have celiac disease, and it is seriously not a joke)

Minor nit: celiac disease isn’t an allergy. It’s a very different underlying mechanism with very different effects.

A slice of bread weighs about an ounce or 28 grams. There is less than 3 grams of protein in a slice of bread. About 80% of the protein is gluten which gives 2.5 grams of gluten per slice. So at the lowest exposure level, 1 milligram, this would mean making sure not to eat 1/2500th of the slice of bread. The slice of bread is about 4 inches by 4 inches by 0.5 inches giving a volume of 8 cubic inches. 1/2500th of that slice is 0.0032 cubic inches or a cubic piece >1/8 inch on each side.

Based on the above calculation, I think it's probably ok to use the same utensil as long as there are no obvious crumbs.

For a child with celiac disease, eating even a few crumbs of gluten is enough to set off the auto-immune reaction and cause intestinal damage. I agree that a lot of the fear of gluten is overblown, but there are people for whom it really does matter.

Perhaps you should consider a different line of work? One in which you aren't in a position to serve people food that can make them seriously ill. Either that, or perhaps accept reality and choose to not be condescending and flippant toward people who have genuine concerns for their health.

Agreed, this flippant attitude is more toxic than people trying to look out for themselves in a world where even the Food Pyramid is bullshit.

Celiac disease isn't funny. Some people are sensitive enough that even the type of contact you describe transfers enough gluten (from the bread to the plate to the actual food consumed) to set off a reaction. I have several friends with celiac, and one of them was recently hospitalized after a restaurant server decided to "test" their claim about having celiac. That server has since been fired by the restaurant and facing assault charges; her (now former) employer is looking at a pretty heft lawsuit.

Please let us know what those restaurants are so we can avoid them, and any future restaurants you own.

Well, I can't say to what extent people are actually intolerant to gluten or not.

But it is clear that sourdough DOES break down gluten during fermentation. Here's a lucid observational demonstration of that ...

(https://www.youtube.com/watch?v=vsCpdCsJFr4)

-- it's in French, but they have really good bread making videos.

Depends on where you'd get your bread otherwise I assume, what has been added to it, where the flour is sourced from, how it was grown. Those last factors also matter for your own bread obviously. I'm not sure how conclusive the science is on the effects of using the different types of pesticides on crops, or none at all, on the final product, and how that in turn affects health.

Probably very negligible as the baking should kill all microbes present (some might sporulate but probably not a relevant number). But Sourdough bread is super tasty so don't stop doing it!

The article is in regards to sourdough microbes that are on a bakers hands, not necessarily those that may or may not survive the baking process.

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