How much chilli is too much? Anyone who's ever accidentally found themselves in tears, clutching for a glass of water after a mouthful of something hot will know it can take very little, depending on the dish and our tastes.

Some of us love the hot stuff, while others can barely handle a few sprinkles of spice. And some innocent-looking chillies can pack a serious punch.

A young American man may be asking himself why he took on the California reaper - the world's hottest chilli pepper - in a chilli-eating competition recently. According to a BMJ report, he ended up in hospital with a so-called "thunderclap" headache after eating it.

"His symptoms started immediately after he had eaten the chilli, with dry heaves. But he then developed severe neck pain and crushingly painful headaches … over the next several days," the case report says.

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Doctors concluded several arteries in his brain had constricted, leading to the headaches.

This is thought to be the first case of chillies being linked to such effects, although cayenne pepper has been linked to sudden constriction of coronary arteries and heart attacks.

This is a good example of the expression "the dose makes the poison". Anything - even water - can be toxic if we have too much.

Chillies, though, for most of us, are perfectly safe and may have some pretty nifty health benefits.

As with all colourful vegetables, fresh chillies contain vitamin C and carotenoids - useful antioxidants. We're unlikely to get much of these from chillies, of course, considering we'd usually eat a very small amount.

Chillies also have capsaicin, the component which gives them their heat. This has been the subject of some interesting research.

While capsaicin can cause digestive distress due to the burning sensation it creates, some research has found that over time, chilli can actually help lessen the pain of heartburn.

One small study found that 3 grams of chilli each day for six weeks improved heartburn in patients with acid reflux; it's thought this is because capsaicin can temporarily desensitise pain receptors, lessening the burning feeling.

Capsaicin has similar effects when applied topically in creams for arthritis, nerve pain and back pain.

There's even a bit of evidence linking capsaicin to weight loss. This seems to be through either appetite suppression - making us want to eat less - or through fat burning, although evidence is a bit mixed.

Evidence is also mixed when it comes to capsaicin and cancer. There have been some studies showing potential anti-cancer benefits of the compound, and some showing no benefit. Research is ongoing.

Where the jury is not out, is on chillies' culinary benefits. They spice up almost every kind of dish, adding flavour, heat and contrast. Using chillies can add flavour without resorting to salt.

Their heat is cooling in summer and warming in winter. When I'm not sure what a dish needs to make it perfect, chillies are almost always the answer.

Niki Bezzant is editor-at-large for Healthy Food Guide www.healthyfood.co.nz