Replacing animal-based protein sources with plant-based alternatives reduced both the quality and quantity of protein intake among older adults. Notably, the reductions were significant only when all animal-based foods were eliminated--i.e., in a vegan scenario -- a simulation study found. The authors suggest switching to a ratio of 40:60 (animal vs plant), in line with recommendations of the Dutch Health Council, which says that ratio is better for health and for the environment.

Researchers assessed the impact of a more sustainable eating pattern on protein quantity and quality using data from 607 adults ages 65-79. The data came from two 24-hour dietary recalls on two non-consecutive days.

In their simulation, the authors replaced certain foods in the original diet from a list of similar plant-based alternatives to create scenarios for two flexitarian diets (40% and 80% meat and fish were replaced), one pescetarian diet (meat was replaced, but not fish or other animal products), one vegetarian diet (meat and fish were replaced, but not other animal products), and one vegan diet (fish, meat, and all animal products were replaced).

Compared to the original diet (∼62% animal-based), usable protein intake decreased by about 5% in the flexitarian, pescetarian and vegetarian scenarios. In the vegan scenario, however, both total protein intake and usable protein were lower, leading to nearly 50% less usable protein compared to the original diet.

In the original diet, the protein intake of 7.5% of older men and 11.1% of  older women did not meet the recommended daily requirements. This deficit increased slightly in the flexitarian, pescetarian, and vegetarian scenarios. But in the vegan scenario, 83.3% of men and women had a protein intake below recommendations, potentially increasing the possibility of muscle loss and vulnerability to various health conditions.

To download the full article, published in the Journal of Nutrition, Health and Aging with examples of replaced foods for each scenario, click here