It still makes no sense to me. There are numerous spices. But given that this is a Chinese study, maybe "spicy" means five-spice powder, or maybe just Sichuan pepper. And of course, health claims have also been asserted for several Indian spices. Personally, I'd go for a Goan/Sichuan hybrid :)
Edit: OK, I see "mainly chili peppers". So are chili peppers more commonly used in China than Sichuan pepper?
I don't understand; Sichuan pepper (花椒, huajiao) isn't spicy. Wikipedia confirms:
"Sichuan pepper's unique aroma and flavour is not hot or pungent like black, white, or chili peppers. Instead, it has slight lemony overtones and creates a tingly numbness in the mouth (caused by its 3% of hydroxy alpha sanshool) that sets the stage for hot spices."
Chinese cooking uses many different kinds of spicy peppers, however. For instance, heaven-facing peppers (朝天椒, chaotianjiao) are pretty common in Sichuan cooking. Maybe that's what you mean?
