What is the best recommendation for a client who wants to ensure adequate protein quality on a total vegetarian diet?

A mixture of plant proteins is the best recommendation for ensuring adequate protein quality on a total vegetarian diet because different plant proteins contain varying profiles of essential amino acids. While some plant sources may be low in one or more essential amino acids, combining various protein sources—such as legumes, grains, nuts, and seeds—can help achieve a complete amino acid profile. For example, rice, which is low in lysine, can be complemented by beans, which are rich in lysine, effectively providing all essential amino acids the body requires.

The other options do not adequately support the goal of a balanced total vegetarian diet. Relying solely on soy products may not provide enough variety or meet the full amino acid profile needed, as it's important to consume a diverse array of protein sources. Including dairy products could conflict with the definition of a total vegetarian diet, which excludes animal products. Lastly, avoiding all sources of protein would lead to nutritional deficiencies and is not a viable recommendation for anyone, regardless of dietary preference. Thus, using a combination of plant proteins is the optimal strategy for those following a total vegetarian diet.