Among vegans in New Zealand, meals that contain about twice as much legumes as grains show higher protein quality based on the DIAAS metric, compared to meals primarily made of grains, fruits, and...

We analyzed the available evidence and found that meals with a 2:1 legume-to-grain ratio are associated with higher protein quality in vegans, based on one specific observation. The evidence we’ve reviewed comes from a single assertion that looked at vegans in New Zealand, where meals containing roughly twice as many legumes as grains showed better protein quality when measured using the DIAAS metric — a method that estimates how well the body can absorb and use dietary protein [1]. This finding was contrasted with meals made mostly of grains, fruits, and sugary foods, which had lower scores. No studies or assertions in our review contradicted this pattern. We don’t know if this holds true for vegans in other regions, or if the same ratio works the same way across different ages, activity levels, or overall diets. The DIAAS metric is more precise than older methods like PDCAAS, but it’s still just one way to measure protein quality, and it doesn’t tell us everything about long-term health outcomes. We also don’t know whether this ratio is optimal, or if even higher legume amounts would make a difference. What we’ve found so far suggests that combining legumes and grains in a 2:1 ratio may help improve the protein quality of vegan meals, at least in this one group. For vegans looking to get the most out of their plant-based protein, including more beans, lentils, or chickpeas compared to rice, bread, or pasta could be a simple way to support better protein use — but more research is needed to confirm this applies more broadly.