21st Century One Daily Active
Brand: 21st Century · Form: TABLET [E0155] On Market
Our assessment
The evidence shows that this supplement contains calcium, a mineral essential for bone health. However, the data reveals significant safety considerations. Calcium supports bone mineralization and neuromuscular function [NIH ODS]. For most adults, getting calcium from food is preferred, but supplements can fill gaps when dietary intake is low.
How it works
Think of calcium as a building block for your skeleton. It works through bone mineralization to support bone density and mineral deposition, and it also helps with neuromuscular relaxation — meaning it supports muscle relaxation and nerve signaling [NIH ODS]. Your body needs a steady supply to keep these systems running smoothly.
Safety profile
FDA has received 592,059 total adverse event reports across all supplements, though specific numbers for this product are data not available. Some research suggests that high calcium intakes might increase the risk of heart disease and prostate cancer [NIH ODS]. 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 assessing your dietary calcium intake before adding a supplement. If you take this product, be aware of the potential for side effects at high doses and the interactions with common medications. Consult your doctor or pharmacist to check if calcium is right for you, especially if you have kidney issues or take thyroid or antibiotic medications [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 100.0 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