21st Century Calcium Citrate +D3 Maximum
Brand: 21st Century · Form: TABLET [E0155]
Our assessment
The evidence shows that this product combines calcium and vitamin D3 to support bone health. Our assessment: for most adults, this supplement can help meet daily calcium needs, but you must pay close attention to total intake from all sources to avoid exceeding safe limits [NIH ODS].
How it works
Calcium acts as a master regulator for bone mineralization, helping deposit minerals into your skeleton to maintain bone density. It also supports neuromuscular relaxation, which is essential for proper muscle function and nerve signaling [NIH ODS].
Safety profile
FDA received 592,059 total adverse event reports across all products. Regarding calcium specifically, high intakes may increase the risk of heart disease and prostate cancer. Signs of excessive calcium 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] [FDA data]. Calcium can also reduce absorption of bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS].
Our recommendation
Start by checking your total daily calcium intake from food and other supplements. Do not exceed the tolerable upper intake level without medical supervision. Take this supplement with food and separate it from thyroid medication or antibiotics by at least 4 hours [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 120.0 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