The way the body absorbs plant-based proteins can vary depending on the form of the food. Tofu, for example, is digested nearly as well as meat, although its overall protein quality is slightly lower. Research from INRAE in France and Agroscope in Switzerland has shown that cooked soybean seeds are not as well digested, but tofu is almost as effective as meat in this regard. A 2021 study published in Food Chemistry by Yohan Reynaud, Didier Rémond, and colleagues found that seitan and tofu had very high protein absorption rates—97% and 95%, respectively—followed by peas (94%) and soy milk (92%). Meat products showed similar absorption rates, with essential amino acids being absorbed at 97-99%, according to a 2020 study in British Journal of Nutrition by Hans Stein's team at the University of Illinois. The lower absorption rate of whole soy seeds is due to the structure of the seed itself, which makes it harder for enzymes in the body to break down the proteins. A 2024 study by Laila Hammer, Lotti Egger, and colleagues at Agroscope found that only 52 to 63% of proteins in cooked soy seeds are digested. In contrast, soy milk and tofu show much higher digestion rates, with 84-91% and 95-98%, respectively. Protein quality is measured using the DIAAS (Digestible Indispensable Amino Acid Score), which assesses whether a food provides all the essential amino acids in the right proportions. Tofu scores 97 and soy milk 117 in the INRAE study, while peas peak at 60 and seitan at 28, mainly due to a lack of lysine. Animal proteins tested in Illinois reached scores of 99 to 130. Pauline Pied, a dietitian-nutritionist, explains that "well digested" means the body can recover most of the protein components, while "good quality" means the protein has all the necessary components in the right quantities. Tofu is not the best source of protein but remains one of the best plant-based options. Pauline Pied notes that soy has "almost all the beads in the right quantities," while animal proteins have all the necessary components. Other plants may lack one component, but not the same one. By consuming both cereals and legumes throughout the day, the body can complete the protein profile. Regarding muscle protein synthesis, a meta-analysis published on April 27, 2026, in Journal of the Academy of Nutrition and Dietetics found that before the age of 55, the responses to plant and animal proteins are similar. After the age of 65, the advantage of animal proteins becomes more pronounced. However, a 2025 meta-analysis from Queen's University in Belfast, published in Nutrition Reviews, found that soy performs equally well as milk for muscle mass in some trials. Pauline Pied notes that muscle protein synthesis decreases with age, and seniors who reduce meat should aim for 1 g of protein per kilo of body weight per day, along with eggs and dairy products, and remain physically active. The Portuguese authors of the 2026 study caution that the trials are few and most animal data come from milk. Further studies are needed to refine these conclusions, as digestibility measurements mainly come from pigs or laboratory simulations. A trial in Maastricht with seniors has not yet delivered results. ANSES also recommends not over-consuming soy due to its isoflavones. Pauline Pied emphasizes the importance of balanced protein intake and physical activity for optimal health.