Plant-based foods can supply most of the required dietary nutrients globally, but weaknesses in nutrition security persist. Here, we assess the role of plant-based food supply (PFS) in fulfilling dietary needs for energy and 17 nutrients in China from 1997 to 2016. We estimate per nutrient the coverage (supply/demand) and source diversity (exponentiated Shannon entropy of sources). Coverage was insufficient (supply/demand<1) for selenium, calcium, riboflavin, and vitamin A. Source diversity was below 4 for vitamins A and C. From 1997 to 2016, coverage and source diversity improved little for these nutrients. Transformations like reducing avoidable nutrient losses, repurposing feed to food consumption via reducing red meat intake, and reallocating domestic crop use increased coverage by at least 18%, but hardly improved source diversity. The above PFS transformations enable the fulfilment of all nutrient needs except selenium, providing opportunities for more sustainable and healthy diets in China.