Link to original: http://sphynxcatvp.nocturna.org/health/diet-stomach.html
We all have what is best described as "stomach trouble" now and then - whether vampire or not - and it can be due to a variety of causes, ranging from food allergies to food poisoning - if you know you are allergic to a specific food, the best bet is to avoid it - and if you are fatally allergic (as with some people who have peanut allergies) it becomes even more imperative to know WHAT is in the foods you're eating! But for situations where you have to deal with foods that you know "don't agree with you", here's a selection of ways to reduce or eliminate digestive trouble.
If you've pretty much stopped eating greasy foods for a long time, then suddenly have a greasy food meal, that will sometimes give you problems - just because your body's not used to the grease in the foods after such a long absence. Avoid red meat entirely for a few months, then have a big 1-pound slab, rare. Ho boy, will you feel THAT for the next several hours. :)
These can be to either specific normal foods (of which dairy foods - milk, cheeses, cream, etc. - are the most common problem), or in the case of genetically modified foods, to a component of the modification - just as an example, corn that has genetic components of, say, fish or something to give it bug resistance. If you're allergic to fish but not corn, you could still be affected. (And this is part of the reason that genetically modified food is such a "big deal" to some people - certain allergies, especially peanut allergies, tend to be more severe than others, potentially even life threatening. For example, say the corn has genetic components from peanuts - give that to a person who's allergic to peanuts, and they could possible die from it if it triggers the allergy, even though they haven't touched a single peanut. Things like this have happened...)
These can be from aging - no matter what age you are, pregnancy (if you're female, and almost everyone knows about the stereotypical "pickles and ice cream" cravings), perhaps even some medications will affect your hormones. Hey, Viagra's supposed to do that, and look how popular it is. :)
Yes, you too can know that special joy that comes from counting your bathroom tiles....for the third time....in one sitting. :) Food that's past it's prime should never be served....but we all know it sometimes happens anyway. Not just at home, but at restaurants too. I've had tomatoes from Certain Fast Food Chains (who shall remain nameless...just sniff those tomatoes before eating them, no matter where you get them from, k?) who seem to have a habit of using tomatoes until they're used up, regardless of whether they're actually still safe to eat. I'm sure it all depends on the managers of the place...some are more anal about food quality than others. But anyway, that can certainly cause you to have stomach problems or worse, a case of nearly nonstop diarrhea until it works out of your system. The type of bacteria responsible can vary with the food - eggs (and chicken) commonly have salmonella, pork has trichinosis, etc. I used to know someone who would eat one mildly bad chicken wing and be out of work for a week. Me? a couple trips to the bathroom later, and I'm fine. Reactions depend on your immune system.
The old standby for gas problems from beans, it may also help you digest whatever it is that normally disagrees with you. (I've had relatively good luck using Beano for non-bean digestive problems, so give it a try.) I know Beano itself is not necessarily available anywhere, some alternates would be "charcoal capsules" or "digestive enzyme combination" pills. You may need to do a web search (I recommend Google) to find your local equivalent.
Yogurts with active yogurt cultures
If you have, or think you have, a milk/lactose intolerance problem, try some of this. One yogurt, daily, should reduce the problems you have with lactose products, although it may not eliminate them completely if you have severe problems.
I like mine with cream and sugar. This can help settle an upset stomach, but you may have to experiment with brands to see what works for you - not all brands will have the same effect, and some are just plain vile. :( And stay away from that fake cream / fake sugar crap, ewwwww!
An old old old herbal remedy for an upset stomach. Buy boxes of Altoids or a similar product. You want the mints to have real peppermint OIL, not peppermint flavor. Ideally, the primary ingredient should be "Peppermint oil". :) Penguin mints have peppermint oil, but they have Nutrasweet, so I don't recommend them as a result. Penguin mints happened to have caffeine, so I know they're popular in some circles. I'd rather see caffeine added to regular Altoids instead. :)
Long-term preventive measures
Keeping a log of what you eat, in what quantities (even if you just write "meal" or "snack" or something to judge relative sizes), and in what combinations is a good way to keep track of what really aggravates your digestion. This is the best, and most basic, procedure for determining what your food allergies REALLY are. On the flip side, if the sheer number of foods that disagree with you are that many, then keep track of what DOES agree with you. Either way, you're bound to get some idea of what you can and cannot eat, and that will make a difference in the long run - once you learn what food to avoid or not avoid, eating becomes much easier. :)
Avoid junk food / fast food
Putting a lot of artificial chemicals in your system does not do anyone any good. If it has no nutritional value, your body still has to work and stress itself to process it OUT of your body. I'm not saying cold-turkey-quit - I still enjoy the occasional chocolate bar or fast-food burger - But keep it in LOW moderation. Junk food / fast food should NOT be a large chunk of anyone's diet.