Carbonato de Calcio
Also known as: Carbonato de Calcio, limestone, Calcium carbonate
Overview
Calcium carbonate is a widely utilized mineral supplement, primarily sourced from natural deposits like limestone and oyster shells. It serves as a fundamental dietary calcium source, crucial for maintaining bone health, preventing and treating calcium deficiencies, managing osteoporosis, and addressing secondary hyperparathyroidism. Characterized by its high elemental calcium content (approximately 40% by weight) and cost-effectiveness, it is also commonly employed as an antacid. Extensive research, including numerous randomized controlled trials, systematic reviews, and meta-analyses, has consistently evaluated its efficacy and safety. The evidence base is robust, with multiple large-scale studies affirming its role in enhancing bone mineral density (BMD) and reducing fracture risk, particularly when co-administered with vitamin D.
Benefits
Calcium carbonate supplementation offers significant benefits, primarily in enhancing bone mineral density (BMD) and reducing fracture risk, especially in older adults and individuals prone to osteoporosis. A 2015 systematic review and meta-analysis of randomized controlled trials (RCTs) demonstrated that calcium supplements, including calcium carbonate, modestly but significantly increase BMD and decrease fracture incidence when combined with vitamin D. Furthermore, a 2017 meta-analysis reported that calcium combined with vitamin D supplementation effectively reduces hip fracture risk, particularly in older populations. Beyond bone health, calcium carbonate is effective in correcting secondary hyperparathyroidism, showing comparable efficacy to calcium citrate in post-bariatric surgery patients. The most significant benefits are observed in older adults, postmenopausal women, patients receiving glucocorticoid therapy, and those who have undergone bariatric surgery. While the improvements in BMD are modest (e.g., 1-2% increase), the reduction in fracture risk (relative risk reductions of 10-20%) is clinically relevant, with benefits typically becoming apparent after at least one year of consistent supplementation.
How it works
Calcium carbonate functions by providing elemental calcium, which is essential for the mineralization process of bones. Upon ingestion, it increases serum calcium levels, which in turn suppresses the secretion of parathyroid hormone (PTH). This suppression helps to reduce bone resorption, thereby promoting bone health. Calcium absorption primarily occurs in the small intestine and is significantly enhanced by the presence of gastric acid, which is crucial for the dissolution and absorption of calcium carbonate. At a molecular level, calcium interacts with calcium-sensing receptors and plays a vital role in the activity of bone remodeling cells, specifically osteoblasts (which build bone) and osteoclasts (which resorb bone).
Side effects
Calcium carbonate is generally considered safe when consumed within recommended dosages. The most common side effects, affecting more than 5% of users, include gastrointestinal discomfort, constipation, and bloating. Uncommon side effects, observed in 1-5% of individuals, can include hypercalcemia, though this is rare with normal dosing. Rare side effects, occurring in less than 1% of users, may involve the formation of kidney stones and vascular calcification, typically associated with excessive intake. Calcium carbonate can interact with certain medications, potentially reducing the absorption of antibiotics (such as tetracyclines and fluoroquinolones), bisphosphonates, and thyroid hormones. Contraindications for its use include pre-existing hypercalcemia, a history of nephrolithiasis (kidney stones), and severe renal impairment. Caution is advised for patients with kidney issues or those predisposed to kidney stone formation.
Dosage
For adults, the optimal daily dosage of elemental calcium from calcium carbonate typically ranges from 1000 to 1200 mg, often administered in divided doses. A minimum effective dose is generally considered to be 500 mg of elemental calcium per day. To minimize the risk of adverse effects, the maximum safe dose should generally not exceed 2000-2500 mg of elemental calcium daily. Calcium carbonate is best taken with meals, as gastric acid is required for optimal absorption. Its absorption can be reduced in individuals with achlorhydria (lack of stomach acid) or those using proton pump inhibitors. It is available in various forms, including tablets and chewables. To maximize its benefits for bone health and ensure proper calcium absorption, co-supplementation with vitamin D is highly recommended.
FAQs
Is calcium carbonate safe long-term?
Yes, calcium carbonate is generally safe for long-term use when taken within recommended doses and under appropriate monitoring to prevent potential side effects.
Should calcium carbonate be taken with vitamin D?
Yes, co-supplementation with vitamin D is highly recommended as it significantly improves calcium absorption and enhances the overall efficacy of calcium carbonate for bone health.
When is the best time to take calcium carbonate?
Calcium carbonate is best taken with meals. The presence of stomach acid, stimulated by food, is crucial for its optimal dissolution and absorption in the digestive tract.
How soon can I expect to see results from calcium carbonate supplementation?
While individual responses vary, significant benefits on bone mineral density and fracture risk reduction typically become apparent after at least 6 to 12 months of consistent supplementation.
Is calcium carbonate superior to calcium citrate?
Both calcium carbonate and calcium citrate are effective calcium sources. Calcium carbonate requires stomach acid for absorption, making it ideal with meals. Calcium citrate is better absorbed in low-acid conditions, such as for individuals on acid-reducing medications.
Research Sources
- https://www.bmj.com/content/351/bmj.h4183 – This systematic review and meta-analysis by Tai et al. (2015) examined multiple RCTs on calcium supplements, including calcium carbonate, with or without vitamin D, in older adults. It found statistically significant increases in bone mineral density (BMD) and reductions in fracture risk, despite some heterogeneity among studies, supporting the overall high quality of evidence.
- https://jamanetwork.com/journals/jama/fullarticle/2667071 – Zhao et al.'s 2017 meta-analysis in JAMA analyzed fracture incidence across trials involving calcium, vitamin D, and combined supplementation. It concluded that calcium plus vitamin D significantly reduced hip fracture risk, particularly in older adults. The study's large sample sizes and robust sensitivity analyses strengthened its conclusions regarding the efficacy of combined supplementation.
- https://www.scielo.br/j/abcd/a/VQqHVM66bHF4XnctQhDSwQN/ – Baretta et al.'s 2015 RCT compared calcium carbonate and calcium citrate in bariatric surgery patients for secondary hyperparathyroidism. The study found both forms equally effective in maintaining bone mineral density and biochemical markers, despite a small sample size, providing evidence for their equivalence in this specific population.
