Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts

Protein-rich foods, such as meats, eggs, nuts, legumes, and dairy foods, can be important sources of micronutrients, especially those micronutrients that tend to be widely under-consumed. The source of dietary protein, animal or plant origin, is therefore a relevant consideration in the transition to healthier and sustainable diets. In this study, 1589 Australian adult diets with higher diet quality and lower environmental impact were isolated from Australian Health Survey data. These diets were primarily differentiated by lower intake of energy-dense/nutrient-poor discretionary foods. These diets were grouped according to the proportion of total protein obtained from animal and plant sources. On average, 55% of protein was from animal sources and 45% was plant derived. As the proportion of animal protein increased, total dietary protein intake also increased, and total energy intake decreased. Diets with between 60 and 80% of protein from animal sources met the greatest number of Estimated Average Requirements (EARs). Furthermore, diets with this ratio of animal protein were closest to benchmarks when assessed as a proportion of EAR met. That said, across all identified “sustainable healthy diets”, calcium, vitamins B6 and A, zinc, and magnesium were at risk of inadequate intake. This evidence suggests that a diet with around 60–80% of total protein coming from animal sources can reduce the risks of inadequate intake of micronutrients in a sustainable diet.