Great as always, but microbiota is a better term than flora. Show us microbiologists some phylogenetic love!

Interesting. I didn't know. Been vegetarian for 14 years now. I wonder if the bugs are dead yet.

I did find that I became lactose intolerant pretty quickly after I stopped eating dairy. I understand that lactase production would probably resume if I started eating it again gradually and tolerated the GI issues for a little while. But I don't feel any need to test that.

It took me only 3 years to have said effects, and only 6 months to overcome them when I went back to meat.

intestinal flora (this microbiologist prefers flora to microbiota) is not easy to 'change' in most people. It's an amazingly complex, and highly populated environment. 3-4 pounds of bacteria on average in the adult human gut. Hormones can alter the population, as well as long term eating changes like vegetarianism, and some antibiotics can kill off most of them with disasterous effects (look up C. diff)... The only time that the teensy amount of bacteria spread by kissing or poo eating even would be able to take hold, is when there are nutrients that current bacteria aren't using: For most people, this is at birth when they are still mostly 'sterile' and they inherit their parent's oral, gut, skin etc. flora. And perhaps... when a vegetarian starts eating meat again. Of course, perhaps their 'meat digesting' bacteria are just in low supply, and have to make a comeback when the food source... comes back. That means, strict vegetarians could be made 'sick' by a few bites of meat in years, not decades, and could recover in much less time as well.

Dear Science, who is Mr. Golob? What is your background? Can we cite some references? First, most vegetarians eat animal protein, so perhaps we're just talking about vegans? Second, you advise kissing to reconstitute flora? As if vegans and vegetarians don't kiss all the time? And not washing your hands after pooping? You'd only get your own bacteria. The bacteria starve? After years? You think the bacteria were just living on fumes for years? They can't go that long without food; the issue would need to be competition for the ecological niche.

Interesting. I have been a vegetarian for 20+ years now, but have never been militant about it. (Not Vegan, mind you... garden variety ovo-lacto).

I do all of the "due diligence" required to keep myself vegetarian 99.9% of the time. However, even with that, every rare so often (maybe a couple times a year, maybe once ever couple years)something gets by the goalie, and I find out after the fact that I consumed dead animal. Never really too much (I would notice otherwise and immediately stop).

I have never to my knowledge suffered any ill effects of this (admittedly trace) consumption. Perhaps gas, but honestly with all the beans, you'd be hard pressed to tell the difference.

My biggest gripe is just those (few) people (family usually) that won't give it a rest. That get offended that I am being "overly picky". I don't require anyone else to be vegetarian, so please don't require that I be omnivorous. I also don't require special cooking. I do just fine by tactfully doing without, if nothing is appealing to me.

I've been a vegetarian for several years now, and I can honestly say that I have said the "no thanks, I might vomit" line before to save my meat-offering hosts the awkwardness of hearing about potential GI tract difficulties.

No, you don't vomit. You do have diarrhea, REALLY stinky farts, corpse-like bad breath, and uncomfortable bloating.

I actually think I prefer a quick puke to that.

"If you were endowed with bacteria crappy at digesting, you can eat ice cream for dinner and stay skinny. (And probably pack awful-smelling farts. "

ok that explains a lot, actually. i stay skinny no matter what i eat and how much, which is nice i guess, but im bloated all the time its fucking annoying. does this article say i can reduce my farts by being more slutty?

I was a vegetarian for 17 years and started back on chicken with no problem, fish a little trouble (which shocked me -- I thought it would be easier than chicken), but the first time I ate red meat I felt stuffed and bloated so quickly, and then had diarrhea a few hours later. Yucky! I still tend to avoid red meat out of fear that the side effects might not improve.