Food and nutrition.pdf

44 Diet and HealthDietetic Association summarized its views even more strongly: Plantsources of protein alone can provide adequate amounts of essential andnonessential amino acids assuming that dietary protein sources fromplants are reasonably varied and that caloric intake is sufficient to meetenergy needs. Whole grains, legumes, vegetables, seeds, and nuts allcontain essential and nonessential amino acids. Conscious combining ofthese foods within a given, as the complementary protein dictum suggests,is unnecessary.Additionally, soya protein has been shown to be nutritionallyequivalent in protein value to proteins of animal origin and, thus, canserve as the sole source of protein intake if desired.Although most vegetarian diets meet or exceed the RecommendedDietary Allowances for protein, they often provide less protein thannonvegetarian diets. This lower protein intake may be associated withbetter calcium retention in vegetarians and improved kidney function inindividuals with prior kidney damage. Further, lower protein intakes mayresult in a lower fat intake with its inherent advantages, because foodshigh in protein are frequently also high in fat.So, how has this myth of deficiency arisen? Early research (circa 1914)into protein consisted of experiments on rats. These animals were foundnot to grow as quickly when fed plant protein as when given animalprotein.Hence the idea arose that plant protein was second class, and animalprotein superior. There are a few reasons as to why this happens. Theweaning rat grows at as much faster rate than the human infant and thusrequires a much more concentrated source of nutrients, including protein.Human breast milk, for example, contains about 7 per cent of caloriccontent as protein, while rat milk contains 20 per cent protein.If rats were fed solely human milk, they would not thrive. Using thislogic one could argue that human breast milk is an inferior protein source.Obviously this is not true to humans. Humans are not rats, and results ofdietary studies on rat can therefore not be equated to humans.The second 'protein myth' arose from an unexpected quarter, a bookwritten in the late 1960s which exposed the terrible wastes inherent in ameat-centered diet.Diet for a Small Planet sold over 3 million copies, and popularizedthe idea of 'protein complementarity'.Written with best intentions, its effect was to make plant sources ofprotein again seem second class, unless carefully combined with eachother, and to make the whole subject of protein nutrition seem vastlycomplex and fraught with danger.In subsequent editions of the book, this mistake was corrected. But