Ultra-processing breaks down whole foods into components and recombines them with additives, flavors, colors and emulsifiers, often making them high in calories, salt, sugar and fat. A 2024 study published in eClinicalMedicine examined the consumption of ultra-processed and minimally processed foods among 200,000 adults with various dietary patterns, including regular red meat eaters, low red meat eaters, flexitarians, pescatarians, vegetarians and vegans. Food frequency questionnaires and food diaries were used to determine diet type and ultra-processed food intake.

Across all diet types, ultra-processed foods made up roughly one-fifth to one-quarter of total daily food intake. Vegetarians and vegans consumed slightly more ultra-processed foods than regular red meat eaters. Low red meat eaters, flexitarians and pescatarians ate modestly fewer ultra-processed foods than regular red meat eaters. All other groups ate more minimally processed foods than regular red meat eaters.

These findings challenge the assumption that plant-based diets inherently contain fewer processed foods. Vegetarian diets included slightly more ultra-processed foods than meat-heavy diets, while diets with modest amounts of meat or fish had the lowest ultra-processed food levels.

The authors noted that plant-based diets vary in quality depending on the degree of processing. While meat and dairy alternatives are often perceived as sustainable, many are highly processed. Simply replacing meat with packaged plant products may not yield the expected health or environmental benefits.