21st Century Calcium 600
Brand: 21st Century · Form: SUPPLEMENT FORM, OTHER [E0172] On Market
Our assessment
The evidence shows that calcium is essential for bone health, but the form and dose matter. For the 21st Century Calcium 600 supplement, our assessment is that it provides a meaningful amount of calcium, but you need to be careful about total daily intake from all sources. The data confirms that calcium supports bone mineralization and neuromuscular relaxation [NIH ODS]. However, this supplement contains 600 mg per serving, which is a significant portion of the recommended daily intake.
How it works
Think of calcium as the building block for your bones. It works through bone mineralization to support bone density and mineral deposition. It also plays a role in neuromuscular relaxation, helping your muscles relax and your nerves signal properly [NIH ODS]. This is why calcium is critical for everything from strong bones to normal heart rhythm.
Safety profile
The FDA has received 592,059 total adverse event reports across all supplements, though specific counts for this product are not isolated in the data. Important risks: Some research suggests that high calcium intakes might increase the risk of heart disease and prostate cancer. High levels of calcium in the blood and urine can cause poor muscle tone, poor kidney function, low phosphate levels, constipation, nausea, weight loss, extreme tiredness, frequent need to urinate, abnormal heart rhythms, and a high risk of death from heart disease [NIH ODS]. Calcium can also reduce the absorption of several medications, including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS].
Our recommendation
Start by calculating your total daily calcium from food and other supplements. Do not exceed 2,000–2,500 mg total per day. Take this supplement with food for best absorption, and separate it from any thyroid medication or antibiotics by at least 2 hours [NIH ODS]. If you have a history of kidney stones, heart disease, or prostate cancer, consult your doctor before starting. Data not available on the specific inactive ingredients or manufacturing quality of this brand.
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 75.0 Caplet(s) |
| Market Status | On Market |
How to Read This Label
Supplement labels contain several key sections regulated by the FDA:
- Serving Size — The recommended amount per dose. Always check this — some products require multiple capsules per serving.
- Amount Per Serving — Shows the quantity of each nutrient in the product, typically in IU (International Units), mg (milligrams), or mcg (micrograms).
- % Daily Value (%DV) — Indicates how much a nutrient in a serving contributes to a daily diet. 5% DV or less is low; 20% DV or more is high.
- Other Ingredients — Lists inactive ingredients like fillers, binders, and capsule materials (e.g., gelatin, cellulose, magnesium stearate).
- Suggested Use — The manufacturer's recommended directions for taking the supplement, including timing and dosage.
Source: FDA Dietary Supplement Labeling Guide