Macronutrients in the Cemetery: Every culture that evolved around field agriculture rather than pastoralism had something equivalent to beans and corn: a source of plant protein like beans, and a source of calories like corn. Just think how important corn, or the tortilla, is in the Mexican diet. To be properly and nutritionally prepared, however, corn must be soaked in an alkaline solution and dried before it is ground. The nixtamalization process unlocks micronutrients and balances the proteins supplied by beans. Add squash and you've got the "three sisters" of the pre-Columbian American diet. Woodmere Memorial Park.