Beverages and food items labeled with "zero" -- intended to indicate they are sugar-free -- have faced criticism in Korea, as their promoted benefits often lead consumers to overconsume them, believing they contain no ingredients that could negatively impact health.

In recent years, zero-labeled items have emerged among Korean consumers, largely driven by the increasing demand for healthier sugar-free snacks. These products provide a similar sweetness as those made with regular sugar by using artificial sweeteners, but with fewer calories and a reduced impact on blood sugar levels.

This trend has spread across the market, leading food and beverage providers to produce a range of sugar-free items, spanning from carbonated beverages to alcoholic spirits, candies, ice creams, and cookies. However, there are increasing concerns about such zero-labeled items as those artificial sweeteners often cause health problems after consumption.

Sugar-free doesn't mean harmless

Earlier in June, Compose Coffee, a low-cost coffee chain, released an announcement warning consumers about excessive consumption of their newly launched "zero drinks," including Zero Sugar Peach Iced Tea, Zero Sugar Chamomile Refresh, and Zero Sugar Green Grape Green Tea. This came after many customers complained of stomachaches from consuming these drinks, more so than with those made with regular sugar, believing they were less likely to cause weight gain.

The company explained that overconsumption of maltitol, erythritol and sucralose, the artificial sweeteners used in their beverages, could lead to stomachaches, advising consumers not to have more than one cup per day. Nonetheless, they ultimately stopped selling the products due to public relations concerns.

Maltitol, erythritol and sucralose are commonly used ingredients in sugar-free items because they are much sweeter than regular sugar for the same amount and have lower or zero calories, along with other non-sugar sweeteners such as allulose and xylitol.

While concerns about the health benefits of such non-sugar sweeteners as replacements for regular sugar were often raised previously, many experts and organizations now suggest that these artificial sweeteners could be viable alternatives in terms of reducing sugar consumption. However, they also warn that there is still much to learn about these sweeteners.

"Since artificial sweeteners emerged as a popular ingredient to replace sugar, many studies have supported their benefits in reducing sugar consumption," said Lee Eun-hee, a professor of consumer economy at Inha University. "However, there are also some studies that raise concerns about their unknown effects. So, consumers should not be too reassured just because these products contain less sugar."

Sugar-free products can spike blood sugar too

Lotte Wellfood, the confectionery wing of Lotte Group, has also joined the sugar-free race, with a "Zero" lineup that ranges from candies and cookies to ice creams and chocolates. With a copy on the products highlighting "zero sugar, zero sugar-related ingredients," all of the Zero lineup products use maltitol as their primary sweetener.

However, some artificial sweeteners, including maltitol, convert to sugar during digestion, consequently leading to an increase in blood sugar levels.

Maltitol, sorbitol, erythritol and xylitol -- all of which end with 'tol', indicating they are sugar alcohols -- have glycemic index (GI) levels of up to 36, 9, 2, and 13, respectively, while regular sugar has a GI of 68. The glycemic index is a value used to measure how much specific foods increase blood sugar levels.

The company explains that the use of maltitol was the best choice for their non-sugar products, especially chocolates, cookies, and dairy products and that an increase in blood sugar levels is practically unavoidable for these items.

"Among various non-sugar artificial sweeteners, maltitol is the best sweetener for making cookies and dairy ice creams. And, maltitol indeed raises blood sugar more slowly than regular sugar does," a Lotte official said. "It's hard to avoid an increase in blood sugar levels despite using non-sugar sweeteners because snacks inevitably use other carbohydrate ingredients such as flour, which also convert to sugar during digestion."

Other than the Zero lineup products, such as sorbet-type ice creams and beverages, Lotte uses other artificial sweeteners instead of maltitol. For similar reasons, other food companies focus on neither flour nor dairy products for their sugar-free offerings.

Is the 'zero' marketing deceptive?

Some consumers have raised complaints that the marketing of non-sugar products is overly exaggerated as certain artificial sweeteners like maltitol in those products still increase blood sugar levels.

Park Jeong-suk, a professor of food and nutrition at Baekseok Culture University, also warns about the potential risks of items marketed as sugar-free.

"Amid increasing demand for healthy food items, many products are now marketed as zero sugar, but some of them are found to raise blood sugar levels. This can be particularly dangerous for diabetic patients who need to manage their blood sugar carefully," Park said.

However, Lotte's Zero lineup's claim of "no sugar" is essentially correct, as they technically do not use sugar as an ingredient.

According to food item regulations in Korea, products must contain less than 5 grams of sugar per 100 grams to be labeled as lower sugar products, and less than 0.5 grams of sugar per 100 grams to be labeled as no sugar products.

Also, the Ministry of Food and Drug Safety advises that the appropriate consumption amount of sugar alcohols is 50 to 100 grams per day, and all of Lotte's Zero lineup products contain 8.3 to 26 grams of maltitol per serving. Currently, the company only warns that overconsumption of their products could lead to stomachaches.

In the meantime, Citizens United for Consumer Sovereignty, a consumer rights group in Korea, argues that zero sugar marketing can be deceptive if the products have similar effects to those using sugar.

In May, the consumer rights group demanded an apology from Lotte Chilsung, the beverage wing of Lotte Group, for misleading consumers over the calorie content of the new product, Saero Soju.

Saero Soju is one of those trend-driven products designed to capitalize on the growing popularity of the zero-sugar trend in the alcohol market. HiteJinro and Muhak, other distillers, have also relaunched their Jinro Soju and Joeun Day as sugar-free soju.

Saero Soju qualifies as zero calorie because it has below 0.5 grams of sugar per 100 milliliters, but so does regular soju, with an average of around 0.12 grams. Most of the calories in soju come from alcohol, and Saero Soju has a lower calorie count than its rivals because other sojus are stronger.

"If it is not possible to create a truly zero-calorie soju, the product should be renamed and marketed as low-calorie or using alternative sweeteners," said the Citizens United for Consumer Sovereignty, citing that those zero soju products' calorie content was not significantly different from other regular soju.