Inside the rice grain, the starch occupies cells whose walls are made of indigestible cellulose (itself another form of starch). Between these cells are a number of useful proteins; a cupful of cooked rice supplies about 9 per cent of an average adult’s daily protein requirement, although several necessary amino acids are missing. These are made up, in most diets, by proteins from other sources, usually meat but often legumes (e.g. the rice and bean dishes of C. America and the Caribbean, and the Risi e bisi of Venice). Vegetarians often derive their ‘complementary’ proteins from soya beans.