21st Century Selenium 200 mcg
Brand: 21st Century · Form: CAPSULE [E0159] On Market
Our assessment
The evidence shows that calcium is a critical mineral for bone health, but it is not the primary ingredient in this product. This supplement contains 200 mcg of selenium, not calcium. For selenium-specific guidance, data is not available from the provided sources. However, the data on calcium from the NIH ODS is clear: it supports bone mineralization and neuromuscular relaxation [NIH ODS]. Since you are asking about a selenium product, you should know that the safety profile and benefits of selenium are distinct from calcium.
How it works
Think of calcium as a master regulator for your skeleton and muscles. It supports bone density and mineral deposition, which is essential for strong bones. Additionally, it helps your muscles relax and your nerves signal properly [NIH ODS]. Without adequate calcium, your body will leach it from your bones to support these critical functions.
Safety profile
FDA has received a total of 592,059 adverse event reports across all supplements, but specific report counts for calcium or selenium are not available from the provided data. For calcium, the NIH ODS warns that high intakes might increase the risk of heart disease and prostate cancer. High levels 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
Because this product contains 200 mcg of selenium and not calcium, your first step is to confirm why you are taking it. If you need selenium, follow label dosing. If you need calcium for bone health, you should take a separate calcium supplement. Be aware that calcium can reduce absorption of medications like bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. Always take calcium at a different time from these medications. Do not exceed the RDA without professional guidance [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 60.0 Capsule(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