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BONE HEALTH & STRENGTH

Calcium

Ca — Element #20

also known as Calcium carbonate, Calcium citrate, Calcium phosphate, Calcium gluconate

Calcium is the most abundant mineral in the human body, with 99% stored in bones and teeth as hydroxyapatite. It is essential for skeletal structure, muscle contraction, nerve signal transmission, and blood clotting. Dietary calcium must be maintained throughout life to prevent bone loss and osteoporosis.

  • Supports bone mineralization and maintenance of bone density across all life stages
  • Required for normal muscle contraction, including cardiac muscle function
  • Plays a critical role in nerve impulse transmission and neuromuscular signaling
  • Necessary for the blood coagulation cascade (cofactor for clotting factors)
  • Helps regulate intracellular signaling and enzyme activation
  • May modestly reduce risk of colorectal adenoma recurrence

Active in Ca²⁺ ion.

Tolerable Upper Intake Level (UL): 2,500 mg/day for adults 19–50; 2,000 mg/day for adults 51+
Excessive intake linked to hypercalcemia, kidney stones, and possibly increased cardiovascular risk from supplements
Calcium supplements (carbonate form) reduce absorption of levothyroxine, bisphosphonates, and some antibiotics — separate by at least 2 hours
High calcium intake can inhibit absorption of iron, zinc, and magnesium when taken simultaneously

NIH ODS — Calcium · MedlinePlus — Calcium · NIH ODS — Calcium Consumer Fact Sheet · Britannica — Calcium

Works with
Vitamin D Calcium requires vitamin D for efficient intestinal absorption; supplementing calcium without adequate vitamin D substantially reduces bone-health benefit. Magnesium Calcium and magnesium work together in muscle contraction and relaxation; target dietary ratio is approximately 2:1 Ca:Mg.
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The curious few.
50 founding spots left

Know what you're putting in your body.

158 herbs, nutrients, and compounds. What the science says, what tradition knew, and what to watch for. Founding members keep this running.

$60 /year

Founding rate — locked for life. Regular price after launch: $96/year.

  • ✓ Full access to all 158+ entries
  • ✓ Print-ready reference card for every herb
  • ✓ Monthly curated set — 5 herbs, one body system
  • ✓ The Sunday Letter — weekly research digest
  • ✓ Bookmarks synced across devices
  • ✓ Founding rate locked forever
Become a founding member

Cancel any time. No questions asked.