LAUSR

Neither the Western diet nor the Mediterranean diet resembled actual human diets. The Western diet was made from ingredients and not whole foods. Such ingredients are common in ultraprocessed foods, typical of a Western diet, but to our knowledge, no study has reported more than 60% of ultraprocessed foods in actual human diets. The Mediterranean diet was also composed mainly from ingredients, with a few minimally processed foods: applesauce and tomato paste. One whole food was on the list (banana [tropical]). Most foods characteristic of a Mediterranean diet (olives, extra-virgin olive oil, fish, legumes, nuts, fruits, vegetables, and small amounts of cheese and yogurt) are whole or minimally processed foods. The monkeys receiving the Mediterranean diet were consuming a “cookie dough” made from fish meal and oil, nut flour, casein, whey powder, dried egg whites, bean flours, dextrin, and cellulose. Hence, this experimental diet was not similar to diets traditionally consumed in the Mediterranean area. Comparing two diets based on their nutritional content is insufficient for assessing health effects. A growing body of evidence has supported the idea that the food matrix is important for the health-promoting potential of foods. For example, processing of nuts and grains affects the digestibility and, thereby, the uptake of nutrients (2), and studies have shown that the degree of processing affects the health-promoting properties of foods (3). Moreover, the dynamics of availability and uptake also affects the structure and function of the gut microbiome, in turn, influencing the metabolism of the organism. Acellular nutrients especially have the potential to promote growth of pathobionts in the small intestine, thereby causing gut inflammation, which is linked with several metabolic disturbances. In our 2018 review, we discussed these factors in detail (4).