21st Century Calcium 500 + D3
Brand: 21st Century · Form: TABLET [E0155]
Our assessment
Our assessment: This supplement provides a solid foundation for bone health by combining 500 mg of calcium with vitamin D3. The evidence shows that adequate calcium intake is essential for bone mineralization and neuromuscular function [NIH ODS]. For most adults, this can be a helpful way to meet part of your daily needs, especially if your diet falls short.
How it works
Think of calcium as the building block for your bones. It supports bone density and mineral deposition, while also playing a key role in muscle relaxation and nerve signaling [NIH ODS]. The vitamin D3 in this formula helps your body absorb that calcium more effectively, making the two nutrients work as a team.
Safety profile
FDA received 592,059 total adverse event reports across all supplements. For calcium specifically, high intakes may increase the risk of heart disease and prostate cancer in some research [NIH ODS]. Side effects from excessively high blood or urine levels include constipation, nausea, weight loss, extreme tiredness, frequent urination, abnormal heart rhythms, and a high risk of death from heart disease [NIH ODS]. Calcium can also reduce the absorption of medications such as bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. Data on side effects specific to this product is not available.
Our recommendation
This supplement can be a reasonable choice if you need extra calcium, but it should not replace a balanced diet. Be mindful of your total daily calcium intake from all sources, including food and other supplements, to avoid exceeding safe levels. If you take any of the medications listed above, separate your calcium dose by at least two hours. Always consult your healthcare provider before starting a new supplement, especially if you have a history of kidney stones, heart conditions, or prostate concerns [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 400.0 Tablet(s) |
| Market Status | Off 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