Main source of all nutrients for people comes from agricultural products (Welch &
Graham, 2004). According to Grusak and Cakmak (2005), average
mineral requirement from plant food source to human is as follows:
Calcium (Ca) (12 mg/g food), Copper (Cu) (0.015–0.03 mg/g
food), Iron (Fe) (0.15 mg/g food), Magnesium (Mg) (3.5 mg/g food)
and Zinc (Zn) (0.15 mg/g food).