21st Century Highly Absorbable Calcium Citrate
Brand: 21st Century · Form: SUPPLEMENT FORM, OTHER [E0172] On Market
Our assessment
The evidence shows that calcium is a critical mineral for your bone health, but the decision to supplement requires careful consideration of your diet and medical history. While 21st Century Highly Absorbable Calcium Citrate provides a well-absorbed form of calcium, you should first assess your total daily calcium intake from food and any medications you take [NIH ODS].
How it works
Calcium supports bone mineralization, helping to maintain bone density and mineral deposition. It also plays a role in neuromuscular relaxation, which helps your muscles relax and your nerves send signals properly [NIH ODS].
Safety profile
Data not available for this specific product. However, the FDA has received a total of 592,059 adverse event reports across all products. High calcium intakes might increase the risk of heart disease and prostate cancer. 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].
Our recommendation
Start by checking your total daily calcium intake from food and supplements to ensure you do not exceed recommended levels. Be aware that calcium supplements can reduce the absorption of bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin. Take this supplement at least two hours apart from these medications [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 120.0 Caplet(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