Capsaicin is the fiery substance responsible for giving chili peppers their kick, and the ferocity of this is measured in Scolville Units (SU). This scale was first developed by Wilbur Scolville in 1912, using a fearless panel of tasters. It is now measured less subjectively using High Performance Liquid Chromatography (HPLC). The inoffensive Bell peppers score 0, the finger-like scarlet Jalapenos range from 2,500 to 8,000, while the crinkled Scotch Bonnet & Habernero peppers linger at the top with piquancy from 100,000 to 325,000 SUs.

The claim for the most ferocious chili pepper currently resides with two chili farmers in Dorset, England. Vindaloos aside, we Brits are not known for our spicy cuisine but nevertheless the Dorset Naga chili, a relative of the Scotch Bonnet, was analyzed by the American Spice Trade Association and found to be an eye-watering 923,000 SUs.

Chilies have long been reported to benefit health and wellbeing. When ingested, capsaicinoids interact with the trigeminal nerve, which has pain receptors in the mouth and stomach. Stimulation of these receptors is associated with the release of endorphins, which can result in sensations of both euphoria and analgesia following a chili binge.

It is commonly thought that chilies can boost metabolic rate and fat oxidation, and therefore help with weight loss. This theory has been investigated in a number of studies but results are inconclusive.

One experiment in men showed that energy expenditure following a chili-laced meal was higher for an initial 30 minutes, but after 3 hours, total energy expenditure was equal for chili and non-chili meals.

In another study, obese and lean women were compared, and higher rates of thermogenesis and energy expenditure were seen in lean women following a spicy meal. This unfortunately suggests capsaicin may only assist those that are already slim in losing weight.

Studies in Japanese and Caucasian subjects have shown that adding a certain amount of chili to a meal leads to decreased appetite and subsequent lower intake of energy from that meal.

Body weight aside, a study by Ahuja et al published last year showed that consumption of chilies may help to control blood sugar levels after a meal. It has also been shown that capsaicin can reduce the hardening of cholesterol in the arteries, and so slow the process which leads to heart disease.

All varieties of peppers contain hefty amounts of vitamin C, with a red bell pepper providing the same amount as a glass of orange juice for a 1/5 of the calories. Peppers are also rich in anti-oxidant carotenoids such as lutein, which may be important in reducing heart disease risk.

A large red bell pepper is probably your best option as it has the highest anti-oxidant, potassium and folate content and as it lacks spice, it's easier to eat more. Lace this with a jalapeno for your capsaicin kick.

Of course spicy options are plentiful in China, and choosing Sichuan or Hunan dishes (xiangcai湘菜) guarantees your chili hit. Try spiced baby chicken (mala ziji, 麻辣子鸡) or fish flavored pork and chilies (yuxiang rousi, 鱼香肉丝). Be kind to your heart and avoid the very oily dishes such as fish boiled in oil with red chilies (shuizhuyu, 水煮鱼).

This nutrition-related column is written by Nina Lenton, a qualified dietitian living in Beijing and working at Bayley and Jackson Medical Center. Contact her at nina.lenton@bjhealthcare.com.

(China Daily 07/25/2007 page14)