21st Century Calcium 500+D3 plus Extra D3
Brand: 21st Century · Form: TABLET [E0155] On Market
Our assessment
The evidence shows that this combination of calcium and vitamin D3 is well-supported for bone health, but you need to be careful with dosing. The data confirms that calcium supports bone mineralization and neuromuscular function [NIH ODS]. However, the "extra D3" in this product means you should check your total daily intake from all sources.
How it works
Think of calcium as a building block for your bones. It supports bone density and mineral deposition, and it also helps your muscles relax and your nerves signal properly [NIH ODS]. The added vitamin D3 helps your body absorb that calcium more effectively.
Safety profile
FDA received a total of 592,059 adverse event reports for this product category. High calcium intakes may increase the risk of heart disease and prostate cancer [NIH ODS]. Side effects from high levels include constipation, nausea, weight loss, extreme tiredness, frequent urination, abnormal heart rhythms, and a high risk of death from heart disease [NIH ODS]. Data not available for side effect report counts specific to this product.
Our recommendation
Start by checking how much calcium you already get from food and other supplements. Calcium can reduce absorption of medications such as bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin, so take this supplement at a different time than those medications [NIH ODS]. Speak with your healthcare provider before starting, especially if you have kidney concerns or a history of heart disease.
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 400.0 Tablet(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