Ultra-processed foods should be treats only

Dear Doctor: Is it true that eating ultra-processed foods raises your risk of cancer? I really don’t want to give up my comfort foods, like a handful of potato chips or an order of chicken nuggets every few weeks.

Dear Reader: If those chips and chicken nuggets make it onto your plate only occasionally and in limited quantities, you’re probably OK. But for people whose diets are high in ultra-processed foods, there’s no end to the bad news. Not only have recent studies tied these foods to an increased risk of cancer, they have been shown to play a role in heart disease, stroke and Type 2 diabetes.

So what is ultra-processed food? Cooking, canning, drying and freezing are ways to process various foods to make them edible, enhance flavor and preserve them for future use. But ultra-processed foods go several steps further. These are foods that have been repeatedly manipulated to alter their appearance, shape, flavor and texture, and that have been amped up with lots of added sugars, salt, hydrogenated fats, modified starches and artificial flavorings. Ultra-processed foods include everything from the packaged sweet and savory treats in the snack aisle, to convenience foods like canned soups and frozen entrees, to canned and bottled beverages, to much on the menus in fast-food chains.

The ingredient labels of these products start with recognizable foods like corn or wheat or potatoes, but quickly veer into the world of inorganic chemistry with a list of preservatives, colorings, stabilizers and additives. The nutritional information, meanwhile, is long on fat and sodium, and short on vitamins, minerals and fiber.

With an entire branch of food science dedicated to making these foods irresistible and addictive flavor bombs, it’s little wonder that studies show that up to half of calories consumed in the U.S. come now from ultra-processed food. And consumers pay a steep price. Close to 40% of Americans are obese. Type 2 diabetes has become an epidemic. As you mentioned in your letter, a small study found evidence that this type of eating is associated with a rise in cancer risk. Specifically, researchers associated a 10% increase in the proportion of ultra-processed foods in the diet with a 10% increase in the risk of cancer. The same study found that diets high in minimally processed foods like fruits, vegetables, milk and lean proteins, including fish, were associated with a lower cancer risk.

When it comes to diet, we’re realists. We want our patients to commit to eating habits that they can maintain over the long haul. For those in good health, we think a split of 80% being good about diet and 20% “cheat” is OK. For those with diabetes, hypertension or any kind of cardiac issues, the ratio drops to a minimum of 90% healthful eating and a maximum of 10% treat eating. When eating less healthful choices, our advice is to opt for whole food versions of your favorite treats and steer clear of ultra-processed foods.

Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.