2010 Jan National Institutes of Health - Office of Dietary Supplements
Consider: daily multivitamin, vitamin D 2,000-4,000 IU daily (most people are deficient), vitamin B12 if energy is low, calcium 1,000-1,200mg daily (especially for women), fiber supplement if constipated, protein powder if struggling to hit 80-100g daily from food
The 30 mg vial the low-volume alternative Reconstitute a 30 mg vial with 3 mL of bacteriostatic water: Concentration: 30 mg 3 mL = 10 mg/mL Volume for a 2.5 mg dose: 2.5 mg 10 mg/mL = 0.25 mL Units: 0.25 mL 100 = 25 units The identical 2.5 mg dose that was a full 100-unit barrel from the 5 mg vial is a tidy 25 units from the 30 mg vial a quarter of the volume, and it leaves headroom in the syringe to draw larger doses as the ladder climbs
Both reasons are valid but the approach, expectations, and oversight should differ accordingly