21st Century Calcium Citrate Calcium + Soy
Brand: 21st Century · Form: TABLET [E0155] On Market
Our assessment
The evidence shows that calcium is a critical mineral for bone health, but it must be taken with care. For the product 21st Century Calcium Citrate Calcium + Soy, the key active ingredient is calcium citrate. Our assessment is that this supplement can be effective for supporting your bone density, but you need to be aware of the safety risks and potential medication interactions [NIH ODS].
How it works
Calcium works in two primary ways in your body. First, it is essential for bone mineralization, meaning it helps deposit minerals into your skeleton to keep your bones dense and strong. Second, it supports neuromuscular relaxation, which is vital for proper muscle relaxation and nerve signaling throughout your body [NIH ODS].
Safety profile
Data not available for side effects specific to this product. However, for calcium supplements in general, FDA has received 592,059 total adverse event reports across all supplements. High calcium intakes can cause serious issues: some research suggests a potential increased risk of heart disease and prostate cancer. High levels of calcium in your blood and urine can lead to 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] [FDA data].
Our recommendation
We recommend you take this supplement only if you are not meeting your calcium needs through diet. Be cautious: calcium can reduce the absorption of several medications, including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. If you take any of these medications, separate your calcium dose by at least 2 hours. Start with a low dose and do not exceed the RDA without a doctor's supervision. Talk to your healthcare provider before starting, especially if you have a history of kidney stones, heart disease, or prostate cancer [NIH ODS].
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