Greenhouse　gas　(GHG)　emissions　from　food　are　of　great　importance　for　global　warming　effects.　Life　cycle　assessment　(LCA)　method　has　been　widely　used　in　this　field.　In　previous　studies,　food　mass　was　mainly　used　as　the　functional　unit　in　LCA,　which　cannot　cover　the　environmental　load　of　food　products　in　terms　of　nutrition　value.　Other　functional　units　are　less　applied　and　mostly　have　specific　application　scenarios.　In　this　study,　food　mass　and　nutrition　value　were　both　taken　into　consideration　in　the　development　of　a　new　food　equivalent　(FE)　unit　incorporated　in　LCA　(FE-LCA)　to　investigate　the　greenhouse　gas　(GHG)　emission　and　nutritional　level　(FEC)　of　different　food　and　dietary　structure.　GHG　emissions　from　15　food　products　based　on　either　same　mass　or　FE　measured　and　compared　by　LCA　showed　that　legumes,　grains　and　nuts　are　low-carbon　food　product,　whereas　beef　can　provide　the　highest　carbon　emission.　Grains,　legumes,　nuts　and　chicken　have　a　higher　nutritional　value　the　intake　of　anti-seasonal　vegetables　and　anti-seasonal　fruits　should　be　reduced　while　more　seasonal　foods　should　be　consumed.　From　GHG　emission　results　of　9　dietary　structures,　Argentine　diet　presented　the　highest　carbon　emission　due　to　extensive　beef　intake.　The　lowest　GHG　emission　referred　to　Vegan　diet　but　has　a　low　FEC　of　75.90　cannot　supply　the　nutritional　needs　of　human　health.　New　Nordic　Diet,　Mediterranean　Diet,　Chinese　Diet　and　Dutch　Diet　with　reasonable　GHG　emission　were　recommended.　They　were　characterized　by　a　more　balanced　consumption　of　various　food　groups　without　a　clear　preference　for　a　particular　food　group.　In　conclusion,　the　FE-LCA　method　is　the　most　suitable　method　when　evaluating　food　production.　©　2023　Elsevier　Inc.