Just what the title says. I love the stuff, but no matter what form–oat groats from scratch, Quaker instant, oatmeal cookies–it gives me hideous heartburn about 45 minutes to an hour after I eat it. Plain oatmeal does it just as badly as a homemade oatmeal cookie. 
After working out this morning I had half a cup of Cracklin’ Oat Bran cereal with almond milk, and sure enough I was bolting for the Tums half an hour later when I felt it coming on.
Everything I read says it should be the opposite, and that a diet high in fiber should help keep heartburn at bay. I can eat the greasiest, spiciest meal on the face of the planet and be just fine, nothing gives me heartburn like oatmeal. What gives?
Well, your reaction is certainly paradoxical, as fiber is generally recognized as reducing the frequency of GERD in some patients.
However, I can hypothesize that with some individuals, the bulk of the fiber may distend the stomach as the fiber swells with liquid, thus expanding the stomach and relaxing the sphincter which is supposed to be a one-way valve to prevent acid from migrating back up into the esophagus.
Again, that’s my wild-ass hypothesis.
Probably best to consult your doctor about this (standard disclaimer I know but good advice nonetheless).
Dunno if this helps but…
That said following some links from the page above it lists foods with little potential to cause heartburn. I won’t quote it here because it is a table but oatmeal is listed among the low risk foods.
http://heartburn.about.com/cs/dietfood/a/heartburnfoods1.htm <-- Link to the table.
In addition, you might want to consult your physician about your symptoms. It’s possible that you don’t have heartburn alone but perhaps complicated by other GI conditions.
Thanks for the responses, I guess a check in with the doc is in order.
On preview, I didn’t really intend this to be a ‘medical advice for mixie’ thread, but somehow thought there was a factual answer for why oatmeal would cause heartburn for some people. I guess I’m just a lone, oatmeal-refluxing freak though 
Just wanted to let you know you are not alone. I rarely experience heartburn except when I eat oatmeal or granola cereal. For some time I thought the granola mixed with yogurt was the culprit. I began eating plain old fast cook oatmeal and experienced the same hearburn issue.
Whoa, zombiness!
Thanks for the anti-oatmeal support. As it turns out, I cut all grains out of my diet a little while ago, and within 48 hours, all the heartburn/reflux and associated nausea that I had been experiencing for a couple of decades on a low-fat, whole-grain based diet stopped cold. Bacon, eggs, and spinach for breakfast, steak and broccoli with butter for dinner, and now my CBC/Chem panel results are hanging on the fridge with a gold star, and my blood pressure is down from 142/94 to 118/72. Life is good ;0)
Err… meaning to say that it turned out I always had acid reflux in conjunction with a whole-grain-heavy, low-fat meal, but before that had always associated it with dinner. I thought I just always had heartburn at night, no matter what. We always had rice, or barley, or pasta. Whole oats seem to bring it on the fastest and most predictably, but now that I’ve isolated grains in general, I can generally predict the onset of heartburn if I have a cookie or some good, crusty bread or something as a treat.
Oh, you are so not alone! I’ve been tryin to have at least 1/2 a c up of oatmeal a day for breakfast and just recently, like within the last 4 days, I have started to get heartburn, too. I thought it was the coffee - tho that’s been in my routine for 6+ months now - but even with drinking tea and eating my oatmeal I’m gettin the heartburn 
So, I’ll check w/ the doc when I go Tues based on all the posts I’m seeing here. Thanks, everyone!
For what it’s worth, I have the same problem from eating rice. I’ve mentioned it to doctors, and nobody has heard of this before. So I just eat rice very sparingly.
I’ve learned that oatmeal eaten alone makes my stomach go all weird (not heartburn pain, exactly) 45 minutes to an hour after breakfast. However, eating protein such as poached eggs or an omelet with the oatmeal makes the symptoms disappear. Whole-grain rye bread etc. does not act like this, so there’s something evil in the oatmeal itself, not just the fiber.
Interesting. I have reflux and there have been a few occasions where I haven’t felt good after eating oatmeal, kind of like heartburn yet not.
Oatmeal does the exact same thing to me and I find myself asking the same question as well. I’m sitting here at work right now, still suffering at 10:00pm from a large bowl of plain oatmeal that I ate at 12:30pm this afternoon! And that is the reason I asked why this is happening to me from something that is suppose to be good for me. You are definitely not alone in this.
Wow, so another fellow oatmeal-cryptoniter! I figured I was just strange, well I am to be honest…, strangER than other people because oatmeal, wheat bread (any wheat -brown bread), and lastly cream of wheat (GOD WHYYYY) give me the worst heartburn ever.
The only reason I signed up was to spread some knowledge: Baking Soda.
Remember, don’t make a bad habit out of it as it has a lot of sodium, but when you’re having one of those nightmare heartburn episodes grab about 1 tablespoon of baking soda (not powder) and mix it with some water. The less water, the more concentrated it will taste… the more water the less nasty it is but you have to drink all of it. So one is a shot of nasty and the other is a longer dilution of nasty haha.
Anyway, mix it really well and just drink it. I can almost guarantee you that your heartburn will DIE within a few seconds to a few minutes.
Whole grains give me heartburn, reflux, and diarrhea. It got so bad for me at one point that I was diagnosed with IBS. But it turns out that if I stay away from certain foods, I am symptom free. 
Some of us do not need extra dietary fiber. If you aren’t constipated, you’re getting enough. Some of us also have reactions in our upper digestive tract to certain compounds in foods that many people digest perfectly - who knows why - but I know a lot of heartburn and GERD sufferers who saw big improvements when they stopped eating grain products.
One tablespoon is WAY too much! On the box of baking soda it recommends 1/2 teaspoon, which is plenty.
Cite?
Oats do the same to me, the only thought I had was that I might be mixing up a bowl with too little milk to dilute the mixture.
That’s possible. I eat oatmeal for breakfast practically every morning (with nuts, bananas, a dash of maple syrup, hemlock seeds, chia, wheat germ, ground flax seed, and a frozen mixed berry from Costco’s (defrosted first, of course). With a cup of Joe, of course. After this meal, I always have to defecate. That’s a good thing I think. If the oatmeal gets a little thick while I’m eating it, I will add some more soymilk. I don’t use milk, just soymilk. I have eaten the oatmeal at McDonald’s with no after-effects. However, a person with whom I run and with whom I stop at McDonald’s after the run, did complain of those problems and has refused to eat oatmeal since.
[Wilford Brimley] Oatmeal — in your case, it’s not the right thing to do. [/WB]