21st Century Calcium 500 + D3
Brand: 21st Century · Form: TABLET [E0155] On Market
Our assessment
The evidence shows that 21st Century Calcium 500 + D3 is a straightforward combination supplement. The primary ingredient, calcium, is well-studied for supporting bone health and nerve function [NIH ODS]. However, you should be aware that data on the specific D3 content in this product is not available, so we will focus on the calcium component which is the main active ingredient based on the provided label.
How it works
Think of calcium as a building block for your bones and a signal messenger for your muscles and nerves. It supports bone mineralization, which helps maintain bone density, and it is essential for proper muscle relaxation and nerve signaling [NIH ODS]. The "D3" in the name suggests it includes vitamin D, which typically helps your body absorb calcium, but specific data on the D3 dosage is not available in our records.
Safety profile
Based on FDA data, there have been 592,059 total adverse event reports for this product, though this number may include reports for various formulations. For calcium specifically, high intakes may increase the risk of heart disease and prostate cancer [NIH ODS]. Side effects from high levels of calcium in the blood include poor muscle tone, poor kidney function, low phosphate levels, 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 several medications including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS].
Our recommendation
If you are considering this supplement for bone health, start by reviewing your total daily calcium intake from food and other supplements. Because high calcium intake carries significant risks, including potential heart issues, do not exceed the recommended dietary allowance without medical supervision [NIH ODS]. Take calcium supplements with food to improve absorption, and be sure to separate them from any medications listed in the interactions by at least 2 hours [NIH ODS]. For personalized advice, consult your healthcare provider to determine if this supplement is appropriate for you.
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 90.0 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