mineral · for brittle nails
Calcium
The most abundant mineral in the body, essential for bone and teeth structure, muscle contraction, nerve signaling, blood clotting, and enzyme function.
How strong is the research?
Not verified evidence
683 women past menopause took calcium citrate or a placebo for a year. Their nails were no less brittle, and no better in texture.
Different group studied
1 paper read, 1 against.
Tested as: Calcium citrate, 1 g elemental calcium daily
Who was studied: 683 healthy women past menopause, in a bone trial. They were not picked for nail problems, or for low calcium.
We found 1 study on this. We have not finished reading them yet, so we are not ready to say either way.
How much to take
1000 mg
Before you take it
- NIH ODS Tolerable Upper Intake Level (UL): 2,500 mg/day for adults 19–50; 2,000 mg/day for adults 51+, covering combined dietary and supplemental calcium intake
- Supplemental calcium (not dietary) is associated with modestly increased cardiovascular event risk in some meta-analyses (Bolland et al., BMJ 2010 and 2011); subsequent meta-analyses and expert panels are conflicting — a 2021 independent meta-analysis (Wang et al., Nutrients; 14 RCTs, n=28,935) found no significant increase in CVD mortality up to the UL
- Supplemental calcium is linked to increased kidney stone risk in susceptible individuals; the Women's Health Initiative RCT (n=36,282; 1,000 mg/day for 7 years) reported higher kidney stone incidence in the supplemented arm
- Drug interaction — quinolone antibiotics (e.g., ciprofloxacin): chelation reduces antibiotic absorption; take antibiotic at least 2 hours before or 4–6 hours after calcium supplement
- Drug interaction — levothyroxine: calcium carbonate reduces levothyroxine absorption; avoid within 4 hours of the thyroid dose
- Drug interaction — dolutegravir (HIV medication): calcium substantially reduces dolutegravir blood levels via chelation; FDA advises calcium 2 hours before or 6 hours after dolutegravir
- Drug interaction — lithium: long-term concurrent use may elevate hypercalcemia risk
- Calcium carbonate causes more constipation and gastrointestinal side effects than calcium citrate, particularly in older adults with reduced stomach acid
- Hypercalcemia from excessive supplementation, or combined with high-dose vitamin D or underlying conditions (e.g., hyperparathyroidism), can cause cardiac arrhythmias, renal insufficiency, poor muscle tone, nausea, polyuria, and fatigue
When to take it
Best taken: split