Bacteria that lurk in food can make that food delicious or deadly. Why is it that some bacteria in food are safe and even beneficial, while others are harmful and can cause illness?
“Over millions of years, bacteria have evolved into different types, some of them developing a beneficial relationship with us, and some developing into more toxic forms,“ explains Maria Tucker, registered dietician and nutrition educator at Duke University. “This evolution actually resulted in some bacteria being good for us and some bacteria being bad for us.”
Fermented foods — yogurt, kefir, tempeh, miso, sourdough bread, and some cheeses, just to name a few — owe their unique and delicious flavors to bacteria that live there.
As Tucker points out, however, some microbes cause a lot of trouble. According to the World Health Organization, each year, more than 600 million people worldwide become ill after eating contaminated food. Of those, some 420,000 die. Small children and older people are most at risk.
E. coli, Shigella, and Salmonella come from fecal contamination of food. Sometimes bacteria from the intestines or skin of an animal get into meat products, Tucker says.
“That’s why you sometimes see ground beef recalls, because there was E. coli in it.”
Read the full article on Discover Magazine
November 7, 2025