antinutrient

noun

an·​ti·​nu·​tri·​ent -ˈn(y)ü-trē-ənt 

variants or anti-nutrient

: a naturally-occurring substance (such as saponin or tannin) found in plant-derived foods that interferes with absorption or proper functioning of nutrients in the body

Oxalate is called an "anti-nutrient" because it binds with calcium and some other minerals so they cannot be absorbed.

—Chris Rosenbloom, The Atlanta Journal-Constitution

also : a substance (such as refined sugar or alcohol) that has little nutritive value and that typically depletes the body of more nutrients than it provides when metabolized