Calcium (Citrate / Carbonate)
Bones & teethFunction & benefits
Calcium is needed for the maintenance of normal bones and teeth and contributes to normal blood clotting, nerve signalling and normal muscle function (EFSA-authorised claims).
Dosage & how to use
| Recommended dose | 500–800 mg elemental calcium daily |
| Best time to take | With meals (carbonate only with a meal); the body absorbs no more than 500 mg per dose |
| Frequency | Split into two doses |
Best forms to choose
Calcium citrate is the best choice: it is absorbed with or without food and does not depend on stomach acid; carbonate is cheaper but must be taken with a full meal and can cause gas and constipation.
Important warnings
The EFSA upper limit for adults is 2500 mg a day from all sources
Chronic excess without balancing vitamin D3, K2 and magnesium may raise the risk of vascular calcification and kidney stones
Drug interactions
It competes with iron, zinc and magnesium for absorption; take it two hours apart from them. It reduces the absorption of levothyroxine, antibiotics (fluoroquinolones and tetracyclines) and bisphosphonates; take it 2–4 hours apart.
Related supplements
- Glucosamine & Chondroitin ComplexBone & joint health
- Hydrolyzed Collagen PeptidesJoints & skin
- Vitamin K2 (Menaquinone-7 / MK-7)Bones & blood vessels
- Pure MSM (Methylsulfonylmethane)Joints & connective tissue
Scientific references
- EFSA Journal 2012;10(7):2814 (Tolerable Upper Intake Level of calcium)
- NIH Office of Dietary Supplements (ODS): Calcium Fact Sheet
Content last updated: 17 October 2026 · Based on published sources and research (EFSA / NIH / PubMed)
⚖️ Medical disclaimer: The information and data provided here are for health education and nutritional guidance only. They are not a medical diagnosis and never replace a direct consultation with your doctor or pharmacist. Always consult your doctor before starting any supplement, especially during pregnancy or breastfeeding or when taking long-term medication.