Sword-swallowers, such as Dan Meyer claim to be putting a real metal sword down their throats.
Are they really pushing a piece of metal down their throats, or are they some sort of magic trick with fake swords?
Sword swallowers are indeed placing a real metal sword down their throats and into their stomachs. It is (obviously) extremely dangerous and risky, which is part of what makes it so captivating to see.
Quoting from their FAQ:
Q: "Don't you use a gimmick, a fake sword that curls or folds up?" "Don't you swallow a sheath first, or use a plastic tip on your sword?"
A: No. Many people think that sword swallowers use a fake sword (known as a "gaff" in the business) that curls or folds up into the handle, but this is simply not the case for real sword swallowers.
Photos from the same site shows an X-ray of a swallowed sword:
This clip from Discovery Health shows Dan Meyer swallowing a sword and being X-rayed.
HowStuffWorks also has a nice article explaining that it is real and how it works:
There is a trick to real sword swallowing, but it doesn't involve illusions or preemptively-swallowed metal tubes. Instead, it involves lots of physical and psychological preparation. For some performers, learning to swallow a sword can take years. In this article, we'll examine what it takes to swallow a sword and why sword swallowing is an extremely dangerous practice.
There is also a 2006 study from the British Medical Journal which acknowledges that sword swallowers swallow real metal swords and looks at the side effects:
Sword swallowers know their occupation is dangerous. The Sword Swallowers' Association International (SSAI, www.swordswallow.org) recognises those who can swallow a non-retractable, solid steel blade at least two centimetres wide and 38 centimetres long. As we found only two English language case reports of injury resulting from sword swallowing,1 2 we explored the technique and side effects of this unusual practice. - Source
So yes, sword swallowers swallow real swords.
Quite real. Brian Witcombe and Dan Meyer are authors of a BMJ paper "Sword swallowing and its side effects" where they asked 110 sword swallowers about medical conditions related to sword swallowing of whom 46 responded.
Sore throats seem to be a common problem, but more serious problems such as intestinal bleeding are in there too.
Thirteen respondents did not volunteer any medical information, but 19 described sore throats, usually when they were learning to swallow, after performing too frequently, or when they were swallowing multiple or odd shaped swords. Lower chest pain, often lasting days, followed some performances and was usually treated by abstaining from practice. They rarely sought medical advice. Six suffered perforation of the pharynx or oesophagus. Three of these had surgery to the neck, one having a 1.5 cm laceration at the level of D2 and a pneumothorax, one a pinhole laceration at C6 and surgical emphysema, and the other having a pharyngeal tear. The perforations were treated conservatively in three patients, one of whom had a second perforation with aspiration of a neck abscess after further injury. Three others also had probable perforations, one of whom was told that a sword had “brushed” the heart, and one had pleurisy and another pericarditis after injury, suggesting extraoesophageal trauma. No one underwent thoracotomy, although one had a breadknife removed transabdominally. Sixteen mentioned intestinal bleeding, varying in quantity from melaena or finding some blood on a withdrawn sword to large haematemases necessitating transfusion. No members of the association had died from sword swallowing, but the cost of medical care was a concern with three members receiving medical bills around $23 000-$70 000 (£12 000-£37 000, €18 000-€55 000).