Which food is known to contain all nine essential amino acids needed by the body?

Fish and shellfish are known to contain all nine essential amino acids, making them a complete protein source. Essential amino acids are those that the body cannot synthesize on its own and must be obtained through diet. Complete proteins provide all of these essential amino acids in sufficient quantities to support various bodily functions, such as tissue repair, hormone production, and immune function.

While tofu is a good source of protein derived from soybeans and contains all essential amino acids, it is considered a complete protein for most individuals, particularly vegans and vegetarians, but fish and shellfish are more universally recognized within both animal and plant-based diets for their complete amino acid profile.

Chickpeas, although nutritious and a good source of protein, do not provide all essential amino acids in sufficient quantity on their own. They pair well with grains to form a complete protein, but they are not a complete protein source by themselves.

Walnuts, while healthy and providing some protein, do not contain all essential amino acids, focusing more on healthy fats than protein content.

In summary, fish and shellfish stand out for having a complete amino acid profile, making them the best choice among the options listed.