If you’ve spent any amount of time in southern China, there’s a decent chance you’ve tried lo foh tong, or at least smelled it. The aromatic, slow-cooked stew is a staple in Cantonese-speaking communities, and migrants from the region have popularized the dish not just across China, but around the world.

Among the keys to lo foh tong’s popularity are its supposed health effects. The very name, lo foh tong, which literally translates to “old fire soup,” conjures images of traditional Chinese medicine and so-called food therapies. There’s no set recipe; instead, cooks whip up different combinations of on-the-bone meat, beans, vegetables, fruit, and medicinal herbs depending on the local weather, season, and the diner’s constitution. In spring, the soup should be adjusted to help eaters ‘expel dampness’; in summer it should chill; in fall it should moisturize; and in winter it must provide needed nourishment. One of the few constants is time: lo foh tong should be simmered for hours in a clay or earthenware pot — hence the name.

But if most Chinese think of lo foh tong as a classic Cantonese dish with restorative effects, it — or at least its name — is actually a relatively recent innovation. The growing popularity of lo foh tong over the past several decades is closely entwined with China’s appetite for so-called yangsheng, a diverse set of wellness ideas vaguely grounded in traditional Chinese medicine.

The foods we eat have always been closely linked to class and wealth: In China, the rich historically favored thick stews, while the poor settled for simple broths. It wasn’t until the late Qing dynasty (1644-1911) and the early Republican period that so-called slow-cooked soups — which split the difference between stews and broths — became a daily staple of southern urbanites, especially in the commercial center of Guangzhou.

At the same time, the emergence of newspapers provided a new platform for the broader public to learn about and exchange information on diet and health. For example, in the 1920s, a writer for the Guangzhou Republic Daily’s “Food Talk” column promoted the advantages of the new soups by drawing on concepts from TCM. “The taste of stewed duck with white gourd (soup) and stewed duck with lychee and lotus (soup) are both clear and rich, making them an ideal choice for a hot summer’s day,” the author wrote.

Despite rationing and shortages, the practice of slow-cooking soups continued to simmer in Guangdong throughout the Mao era. But it wasn’t until the 1980s that the term lo foh tong really took off. Starting with the “reform and opening-up” period, material conditions began to improve, especially along the coast, and residents started paying more attention to nutrition and health.

At the same time, the proliferation of Western medicine led to a renewed interest in TCM, traditional food therapy, and TCM nutrition. As TCM grew increasingly commercialized in the ’80s and ’90s, traditionally trained physicians started releasing food therapy cookbooks and opening factories and stores to produce and sell remedies.

Homemade medicinal soups were already very common, but TCM shops boosted the trend with premade soup bases supposedly capable of improving kidney function, regulating body moisture, or “dispelling wind and replenishing energy.” With so many choices, customers could find whatever they wanted and the soup bases sold like hot cakes, with shops at some points selling over 50 packs a day.

The name “lo foh tong” was a conscious attempt to cash in on this trend. As a wave of businesspeople from Hong Kong and Macao began investing in and opening restaurants and hotels in Guangzhou and surrounding Guangdong province, they found they needed signature dishes with catchy names. In Cantonese, the term lo foh originally referred to the TCM practice of using a small flame to slowly reach the desired heat. Lo foh tong thus not only emphasizes the slow cooking and rich flavor of the soup, but also naturally calls to mind the healthful effects of TCM medicinal cuisine and yangsheng.

But is lo foh tong is really good for you? Since 1999, articles have periodically popped up in Chinese outlets warning diners that the soups may be carcinogenic. These pieces typically cite a speech made by an American oncology professor claiming that food cooked for long periods can produce carcinogens.

Despite making several attempts, I was never able to locate the source of this claim. Still, most researchers recognize that lo foh tong, if not carcinogenic, is at least problematic. Boiling food for long periods of time produces purine, so those suffering from high levels of uric acid, excess blood lipids, kidney diseases, or obesity are advised to avoid it.

Within Guangdong, however, lo foh tong continues to be seen as a symbol of Cantonese tradition and cultural identity. “When we from Guangdong talk about slow-cooking soup, we’re talking about (simmered) lo foh tong, not those boiled ones,” said 76-year-old Wei. “Our ancestors passed it on to us, and even if the doctors say that boiling is better than slow-cooking, you can’t possibly boil bones or chicken — there’s no flavor to it!”

Others are less certain. Wang, a 53-year-old businessperson in Guangzhou, told me that she continues to make lo foh tong, even though her doctors warned her it could exacerbate her uric acid levels. But she’s cut down on the number of pots she makes a week from seven to two or three, and shortened the simmering time by half.

Guangdong’s affinity for slow-cooked stews is tied to South China’s damp and hot climate and longstanding cultural beliefs about the curative powers of food therapy. But lo foh tong as health food is largely a media and commercial creation, driven by business interests and sold to increasingly health-conscious diners, despite the lack of any scientific evidence that it is effective. Whether or not this specific business model is sustainable in the long term remains to be seen.

Translator: David Ball; editors: Cai Yiwen and Kilian O’Donnell; portrait artist: Zhang Zeqin.

(Header image: A bowl of “lo foh tong” (left) and cooking pots in Guangzhou, Guangdong province. Tuchong & VCG)