[Column] Why it's good to eat cooked vegetables

When dozens of people suffer from food poisoning after eating a burger, the immediate assumption is often that the meat is undercooked. However, that’s not always the case. In a recent outbreak in the U.S., 90 individuals experienced food poisoning symptoms after consuming McDonald's hamburgers. Among them, 27 were hospitalized, and one person died.

According to the U.S. Centers for Disease Control and Prevention (CDC), the source of the outbreak was likely shredded, uncooked onions. Supplied by the American food company Taylor Farms, the onions were contaminated with E. coli O157:H7, leading to cases of food poisoning.

Other fast food chains, including Taco Bell, Pizza Hut, KFC, and Burger King, have since removed raw onions from certain menu items. Taylor Farms has recalled diced and chopped onions. According to the Ministry of Food and Drug Safety, no raw onions from Taylor Farms have been imported into Korea in the past two years—good news. However, it's important to remember that this isn’t the first time a raw vegetable has caused a foodborne illness. In 2006, 205 people were sickened and three died in the U.S. after eating spinach contaminated with E. coli O157:H7. Similarly, in 2011, a major outbreak in Germany affected nearly 4,000 people and resulted in 51 deaths due to consuming contaminated sprouts. In fact, in the past, this problem was much worse, and many people suffered from food poisoning after eating poorly washed vegetables. Therefore, vegetables were usually preserved in pickles or cooked with heat. This is why the traditional German way of cooking spinach is to chop it into small pieces and cook it into a porridge.

Why do foodborne illnesses from raw vegetables occur even in countries with safe food systems? Because vegetables grow in the ground, they are susceptible to contamination. If the soil is exposed to animal or wildlife waste from neighboring farms, it can splash around during rain or watering, causing bacterial contamination. Contaminated irrigation water can also be a problem, as well as contamination from tools or people during harvest. Additionally, contamination can occur from cooking without washing hands. Nowadays, vegetables are often pre-washed before distribution, but this doesn't completely prevent bacterial contamination. They should still be washed before consumption.

Children under the age of 5, adults over 65, and people with compromised immune systems are especially vulnerable to eating foods contaminated with E. coli. Blanching or boiling vegetables in boiling water is safer than eating them raw. You don't have to worry about destroying nutrients. The loss of nutrients, such as vitamins, is negligible when cooked for a short time. Cooking leafy vegetables reduces their volume by less than half, making it easier to eat more of them. For food to be healthy, it must first be safe.

Jeong Jae-hoon is a food writer and pharmacist. He covers a variety of subjects, including trends in food, wellness and medications. This column was originally published in Korean in Joongang Ilbo on Nov. 7, 2024. – Ed.