thesedeterminehowmuchoftheproteinthebodycanuse.
Whileitistruethatanimalfoods,especiallyeggsandmilk,
have a very well-balanced amino acid composition, plant
foodslikesoybeansandnutsalsocontaina broadrangeof
thesenutrients.Moreoverbyeatingdifferent kindsofplant
proteinsatthesametimeitiseasytoputtogetheramealthat
providesproteinentirelyequivalenttothatofanimalprotein.
Thisprincipleiscalled“proteincomplementarity,”butyoudo
not need to know much about nutrition to apply it. The
peasant whoeats his beans or lentils with riceor corn is
practicing protein complementarity. So is the mother who
gives her child a peanut butter sandwich on whole wheat
bread—acombinationofpeanutsandwheat,bothofwhich
contain protein. The different forms of protein in the different
foodscombinewitheachotherinsuchawaythatthebody
absorbsmoreproteiniftheyareeatentogetherthanifthey
wereeatenseparately.Evenwithoutthecomplementaryeffect
ofcombiningdifferentproteins,however,mostoftheplant
foodsweeat—notjustnuts,peas,andbeans,butevenwheat,
rice,andpotatoes—containenoughproteininthemselvesto
provideourbodieswiththeproteinweneed.Ifweavoidjunk
foodsthatarehighinsugarorfatsandnothingelse,aboutthe
onlywaywecanfailtogetenoughproteinisifweareona
diet that is insufficient in calories.^36
Proteinisnottheonlynutrientinmeat,buttheotherscanall
easilybeobtainedfromavegetariandietwithoutspecialcare.
Onlyvegans,whotakenoanimalproductsatall,needtobe
especiallycarefulabouttheirdiet.Thereappearstobeone,
andonlyone,necessarynutrientthatisnotnormallyavailable
fromplantsources,andthisisvitaminB12,whichispresent
ineggsandmilk,butnotinareadilyassimilableforminplant
foods.Itcan,however,beobtained fromseaweeds suchas