**1. Introduction**

Protein is not only significant as an energy source, but also as a component of the body, such as muscle and connective tissue, and as a physiological function substance, such as enzymes, hormones, and immune antibodies.

On the other hand, the problem of food shortage (in particular, protein) due to global population growth is becoming increasingly serious. Because of the economic development of emerging countries, people who used to consume energy from "carbohydrates" such as bread and rice are now tending to consume "proteins" such as meat and seafood as a luxury item, and there are concerns about a shortage of protein supply on a global scale. Under these circumstances, the effective use of plant proteins as a protein source has been attracting attention. Plant proteins have been considered to be less adaptable to human tastes in terms of flavor and physical properties than animal proteins, but recent superior food

processing technologies have led to the marketing of "delicious" plant protein foods that are at the same level as animal protein foods.

It has been reported that plant proteins, especially soy proteins, have beneficial functions to improve and prevent lifestyle-related diseases that cannot be overcome by animal proteins, which are currently prevalent all over the world. The US Food and Drug Administration [FDA] has approved the health claim for food labelling that the consumption of 25 g of soy protein per day reduces the risk of heart disease [1]. In Japan, the Consumer Affairs Agency [formerly the Ministry of Health, Labour and Welfare] has allowed the health labelling of soy protein as a food for specified health use "to people who are concerned about cholesterol levels" [FOSHU].

The beneficial physiological effects of soy protein are presumed to be due to anti-inflammatory properties. The anti-inflammatory effect of soy protein is enhanced by its processing into peptides. Indeed, it has been reported that soy peptides suppress muscle inflammation pain relief in rheumatoid arthritis and ameliorate inflammatory bowel disease.

Recently, it is being reported that not only soy proteins, but also some legumederived proteins have excellent physiological effects that are similar to, or even absent from, soy proteins. In this chapter, the author 1] introduces the beneficial physiological effects of soy protein for MetS, CKD and inflammation; 2] reports that these effects acted complementarily when used in combination with drugs; and 3] suggests other legume-derived proteins as alternatives to soy protein as novel proteins from legumes with beneficial physiological functions.

By understanding these findings, it is hoped that plant proteins will be used more actively to contribute to the improvement of human health, as well as their value as protein nutrition, which is in short supply worldwide.
