# item.guide
Side-by-Side Comparison Essential Vitamins & Minerals

Calcium (Elemental Ca) vs. Vitamin B9 (Folate & Folic Acid)

Comparing 2 standards across 9 specifications. 9 key differences identified.

Comparing:
Calcium (Elemental Ca)
Vitamin B9 (Folate & Folic Acid)

Calcium is the most abundant mineral in the human body (1.0–1.2 kg), with 99% sequestered in hydroxyapatite bone lattice and 1% tightly regulated at 8.5–10.5 mg/dL serum for cardiac contractility, nerve signaling, and blood coagulation. Adult RDA is 1,000–1,200 mg/day.

View full Calcium (Elemental Ca) spec sheet →

Vitamin B9 comprises natural dietary folates (polyglutamates) and synthetic folic acid (monoglutamate). Adult RDA is 400 µg DFE, with a Tolerable Upper Limit of 1,000 µg/day synthetic folic acid, essential as a single-carbon donor in thymidylate DNA synthesis and neural tube closure.

View full Vitamin B9 (Folate & Folic Acid) spec sheet →

Specification Comparison Table

9 Parameters
Parameter / Spec
Nutrient Type
Essential Macromineral Water-Soluble Pteroylglutamate Vitamin
Adult RDA / RDI
1,000 mg / day (Men 19–70, Women 19–50) / 1,200 mg (Women 51+, Men 71+) 400 µg DFE / day (600 µg DFE pregnancy / prevents neural tube defects)
Tolerable Upper Limit (UL)
2,500 mg / day (Adults 19–50) / 2,000 mg / day (Adults 51+) (Avoid nephrolithiasis / vascular calcification) 1,000 µg / day (Synthetic folic acid only; masks B12 deficiency neuropathy)
Chemical Forms
Calcium Carbonate (40% elemental Ca / requires stomach acid), Calcium Citrate (21% elemental Ca / acid-independent), Hydroxyapatite (6S)-5-Methyltetrahydrofolate (5-MTHF, active circulating form), Tetrahydrofolate (THF), Folic Acid (Pteroylmonoglutamic acid, synthetic)
Primary Biological Function
Hydroxyapatite bone/dental structure [Ca10(PO4)6(OH)2], Troponin-C actin-myosin muscle contraction, Factor IV blood clotting cascade, Exocytosis neurotransmitter release 1-Carbon transfer reactions, dUMP -> dTMP methylation (Thymidine DNA synthesis), Methionine-Homocysteine cycle, Erythropoiesis
Deficiency Condition
Osteoporosis, Osteopenia, Rickets (children), Tetany (Trousseau's and Chvostek's signs of hypocalcemia) Neural Tube Defects (Spina bifida, anencephaly in fetuses), Megaloblastic Macrocytic Anemia, Elevated Homocysteine
Top Whole Food Sources
Parmigiano-Reggiano, Sharp Cheddar, Whole Milk, Sardines with bones, Kale, Tofu (Calcium-set), Fortified Plant Milk Beef Liver, Spinach, Asparagus, Brussels Sprouts, Roman Lentils, Chickpeas, Fortified Flours
Parathyroid Hormone (PTH) Homeostasis
Serum Ca2+ drop triggers PTH secretion, stimulating renal 1-alpha-hydroxylase to produce active Calcitriol (1,25-OH-D3) and osteoclast bone resorption
MTHFR Genetic Polymorphism
Homozygous MTHFR C677T variant reduces folate reduction activity by ~70%, benefiting from direct 5-MTHF supplementation