There is a report that your stomach acid is so strong that it can dissolve a razor blade. I'd hate to be the guy to test that assumption, but it is true that the hydrochloric acid in your stomach is some strong stuff. While your blood has a pH of around 7.4, your stomach acid has a pH of 1. That means it is a strong acid indeed. But surely, if your stomach acid could dissolve the metal of a razor blade, it would dissolve itself? Surely not! It turns out, according to at least one study, that stomach acid can do a pretty good number on a razor blade.
Of course, if there was a razor blade in your stomach, it would do a lot of damage. So, researchers did not have someone ingest a razor blade to test this. Instead they studied metal corrosion by stomach acid in vitro, meaning "outside the body in a simulated environment." According to the study by Paul K. Li, et al. corrosion of razor blades occurs fairly rapidly in the normal stomach. Now, I think that this is a stretch, because a stomach with a razor blade in it probably wouldn't be a normal stomach for long, and the oesophagus wouldn't be very happy, either. Nevertheless, according to the research, double-edged blades become fragile and easily-breakable within 24 hours, having only 63% of their original mass. You should note, however, that the stomach acid had no effect on pennies within this time-frame, nor did it cause disc batteries to spring a leak within the same amount of time.
It would be a stretch to say that stomach acid would have a large effect on a big chunk of steal within 24 hours, and of course, things do not sit in your stomach for that long. Razor blades are already very thin and flexible pieces of metal, so to corrode them enough to be brittle is perhaps not as much a feat as it seems. We do not know how long it would take to completely dissolve one.
Regardless, stomach acid, it appears, can begin to dissolve a razor blade in a reasonable time period, perhaps underscoring just how awesome our digestive system is. But if the acid is so strong, how can your stomach hold it without the acid eating right through? If you eat a steak, it will be nothing more than a liquid slurry of mushy nastiness in no time. And your stomach is, essentially, meat, right? At least, it is made of proteins. Well, the truth is that your stomach acid would happily digest your stomach if given a chance. And, when things don't go right, we get things like ulcers, which are open sores or raw areas in the stomach. When this happens, it is because a large enough amount of acid has come into contact with the stomach wall on a regular enough basis.
Normally, however, the stomach has a protective lining. This lining consists of a layer of mucosal protein (just think mucus) that is covered with molecules of sugar, held together tightly through the magic of chemical bonds. The sugars are really good at resisting the acid. You have a bunch of specialized epithelial cells that produce this mucous stuff.
It's not perfect protection, and some stomach acid gets through now and again. Now, there is a lot of blood flow in the stomach wall, so that helps to neutralize and wash away some of the acid, but it still does damage and it destroys some of the cells of the stomach. In fact, a whole lot of your stomach cells get destroyed, all the time. Thankfully, they are such busy little buggers when it comes to reproducing themselves. They do NOT take days off, at least normally. When cells are damaged, newly generated cells move up to take their place. In fact, the entire stomach lining is replaced about every three days.
When things go wrong and the mucus lining is damaged, and more acid than normal gets through, damage can occur faster than cells can be renewed, and thus a sore, or even a hole, can form. This is called an ulcer. People used to think that ulcers were caused by a bad diet. Spicy foods or fatty foods were often blamed, as well as cigarette smoking, alcohol consumption, and just a predisposition for producing excess stomach acid. While there is not a lot of evidence that food habits or stress causes ulcers, some of these other factors may be at work. Mostly, though, these earlier beliefs about the causes of ulcers were a matter of correlation. It is true that the pain and discomfort of ulcers can get worse when we eat spicy foods, drink alcohol, or during periods of stress.
The theory now is that the most common cause of an ulcer is a bacterial infection. It usually happens when the stomach becomes infected with a bacteria called Heliobacter pylori (H. pylon). Most of us already have these bacteria in our digestive tract. These bugs can secrete an enzyme around them that protects them from the stomach acid, and then they can invade the mucosal layer, taking up residence there and weakening the stomach lining, allowing too much acid to leak through, resulting in an ulcer. That is why one of the standard treatments for ulcers, today, is an antibiotic.
