To what extent can older people follow a plant-based diet without compromising adequate nutrition?

Increasing the proportion of plant-based proteins on our plates not only minimises the environmental footprint of our diet, but also helps to reduce the risk of certain chronic diseases such as diabetes, cardiovascular disease and cancer[1]. However, it is important to ensure the increment of plant-based products in our diet does not lead to insufficient intake of certain nutrients. Elderly people have higher requirements for proteins and amino acids (the basic components of proteins) and  plant-based foods generally contain lower levels of these compounds than animal products. In light of this, it is important to assess the extent to which it is possible to increase the consumption of plant-based foods among the elderly without causing nutritional deficiencies.

Based on data representative of the diets of French adults over 65 from the INCA3 study, the researchers modelled diets with increasing levels of plant-based foods. These diets were optimised to ensure full nutrient adequacy for 34 nutrients[2], taking into account both high and standard protein requirements. The diets were also designed to minimise the risk of chronic disease while remaining as close as possible to their normal eating habits.

Their results show that as the proportion of plant-based protein increases, the nutritional problems most likely to emerge are not linked solely to proteins or amino acids, but to other essential nutrients such as iodine, calcium, iron and vitamins A and B12. High protein requirements can also be a cause for concern in predominantly plant-based diets, due to the lower protein content of plant-based products compared with animal products.

On average, French people eat 1/3 plant-based protein and 2/3 animal-based protein. The study shows that it is possible to reverse this ratio, increasing the plant-based protein content to 2/3, without compromising nutritional adequacy among the elderly, provided that enough seafood and dairy products are consumed, in line with current general public health recommendations. Increasing the amount of plant-based food beyond that ratio would require other strategies, such as nutrient fortification or supplementation to meet the nutritional needs of this population.