21st Century Cal Mag Zinc +D3
Brand: 21st Century · Form: TABLET [E0155]
Our assessment
The evidence shows that a combination supplement like 21st Century Cal Mag Zinc +D3 offers a convenient way to support bone health. The key ingredients—calcium, magnesium, zinc, and vitamin D—work together, but the most critical factor is your baseline intake of each. For calcium specifically, the data confirms that high supplemental doses carry real risks, so you need to be careful about the total amount you get from food and all supplements combined [NIH ODS].
How it works
Think of calcium as the building block for your skeleton. It supports bone mineralization and density, and it helps regulate muscle relaxation and nerve signaling [NIH ODS]. Vitamin D is essential for absorbing that calcium, while magnesium helps activate vitamin D and zinc supports overall immune function. This combination is designed to cover multiple bases for bone and neuromuscular health, but the effectiveness depends entirely on whether you are actually deficient in any of these nutrients [NIH ODS].
Safety profile
The FDA received a total of 592,059 adverse event reports across all supplements, but specific report counts for this product are not available. For calcium specifically, the safety data shows that high intakes might increase the risk of heart disease and prostate cancer. Very high blood and urine calcium levels 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 medications like bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS].
Our recommendation
Data not available for the exact calcium dosage in this specific product label. Before starting this supplement, calculate your total daily calcium intake from food (dairy, leafy greens, fortified foods). Most adults need about 1,000-1,200 mg daily from all sources. If you already get close to that from diet, adding a supplement could push you into the high-risk range. Take any calcium supplement with food and separate it from the medications listed above by at least 2 hours [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 90.0 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