Joe's spray was neat capsaicin, the active ingredient of chilli peppers, and his canister the kind commonly carried by hikers in the Rocky Mountains to fight off grizzly bears. Anyone who finds a chicken madras hot would have been an innocent abroad among the aficionados who flocked to the West Dean Chilli Fiesta at West Dean Gardens, north of Chichester in West Sussex.

To the sound of samba music, about 5,000 people filled the lawns. Wreathed in the aroma of spices, the chilli crowd swapped stories of peppers they'd survived, discussed SHU ratings (the official measure of chilli hotness) and pondered the latest harvest reports from Malaya and Yucatan.

"The whole chilli culture has become much more sophisticated," said draughtsman Michael Calley, 50, from west London. "Ten years ago it was still all about blokes being macho, but there's now a much greater understanding of what chillies offer and how they work in cooking."

Jayne Forgan, 39, a teacher from Dorking, enthused: "There are more than 200 varieties and I'm growing 11. Everyone says chillies are not just tasty but good for you."

At Max Samuel's Caribbean speciality stall, Hot Flavours, I tried a dip made from Scotch Bonnets, once considered the hottest peppers around. The stuff was served with wafers that you could snack on happily – until your body went critical and they whisked you off to Sellafield for safe disposal. The Scotch Bonnet packs around 500,000 SHUs – Scoville Heat Units, named after Lincoln Scoville, the US chemist who, in 1912, developed a measure of the heat given off by capsaicin.

Michael Micheau, an American based in Britain, enjoys a cult following among chilli buffs for his championing of the dreaded Naga chilli, originally from Bangladesh but now grown on his farm in Dorset, which rates upwards of 800,000 SHUs.

He gave me a taste of one. The pain was bad enough, but when I sneezed it was like that scene from The Deer Hunter where Robert De Niro turns a flame-thrower on the Viet Cong. If I'd been able to see anything through the tears it would have been people fleeing with their clothes on fire.

Mr Micheau can't grow them fast enough. The British, once enslaved to the world's blandest diet, are now in the grip of chilli mania.

The fiesta stalls offered everything from chilli ice cream to chilli chocolate, and here's why. When capsaicin hits the tongue, tiny nerve centres known as neurotransmitters register it and a panic alert goes out. The brain then turns on a "sprinkler system"; you salivate, your nose runs and you break into a sweat. But best of all, a powerful natural painkiller, endorphin, is released, giving what chilli fans experience as a kind of high.

There was still the ultimate chilli to try. The bhut jolokia, from northern India, has an SHU of over a million and is acknowledged to be the world's hottest.

Gerald Fowler, head of the Chilli Pepper Company, produced one and I bit it; seconds later, you could have extracted my teeth and I wouldn't have felt it. The corners of my mouth gushed what seemed like radioactive drool that sizzled as it hit the grass, and through the waves of agony I had an urge to phone my wife, to say goodbye and apologise for all the bad things I'd done.

I didn't think anything worse could exist, but as I reeled away I saw a sight yet more terrifying. The queue for the beer tent.