英语翻译notuntilbeginningofthetwentiethcenturywasitrecognizedthatcertainsubstanceswereessentialinthediettopreventorcurecomedisease.thesesubstancesarenowknownasvitamins.theyarevitalforgrowth,goodhealth,andmainten

　　英语翻译

　　notuntilbeginningofthetwentiethcenturywasitrecognizedthatcertainsubstanceswereessentialinthediettopreventorcurecomedisease.thesesubstancesarenowknownasvitamins.theyarevitalforgrowth,goodhealth,andmaintenanceofthenormalfunctionsofthebody.awell-balanceddietshouldprovideallthevitaminswenormallyrequire.thoseofuswhoarefortunateenoughtobeabletobuysufficientfoodshouldnotsufferfromvitamindeficiency.however,forvariousreasons,somepeopledonotmaintainabalanceddiet.peopleoftenlosetheirappetitebecauseofillness.peoplelivingalonemaynotbothertoeatpropermeals,peopleonadietmaynoteatsufficientquantitiesofnecessaryfoods.