The 3 common vitamins that have a higher potential for deficiency since they can’t be stored are vitamin C, B-complex and vitamin K. Vitamin C and B-complex (thiamine, niacin, riboflavin, folic acid, B-6, B12) are all water-soluble, so other than B12, they need to be replaced daily. While vitamin K is a fat-soluble vitamin, we store very little and therefore it also needs regular replenishment. According to government surveys, the necessary nutrients Americans fall short of most are calcium, magnesium, zinc, iron, vitamins B6, C & E and folate, which is why we recommend you eat the best you can (pick one of our very healthy diets on the Sharecare MILI platform) and take a daily multivitamin & mineral formula to cover all your bases.