21st Century Magnesium 250 mg
Brand: 21st Century · Form: TABLET [E0155]
Our assessment
The evidence shows that this product, 21st Century Magnesium 250 mg, provides a meaningful dose of a key mineral. However, we must be clear: the data provided only covers the ingredient calcium, not magnesium. Our assessment is therefore limited. Based on the available data, calcium is essential for bone mineralization and neuromuscular relaxation [NIH ODS]. You should know that the label lists the product as magnesium, but the supporting data we have is for calcium, which is a different mineral with its own unique role.
How it works
Think of calcium as a structural builder and signaler for your body. It supports bone density and mineral deposition, helping keep your skeleton strong. It also plays a role in neuromuscular relaxation, meaning it helps your muscles relax and your nerves send signals properly [NIH ODS]. For magnesium, the intended ingredient, data on its specific mechanism is not available from the provided sources.
Safety profile
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, the safety data shows some important risks: 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]. Calcium can also reduce the absorption of several medications, including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. Specific side effect data with report counts for this product are not available.
Our recommendation
Data not available for a specific recommendation on 21st Century Magnesium 250 mg. Since the provided information only covers calcium, not magnesium, we cannot make a confident recommendation for this product. For calcium supplements, start at the RDA (1,000-1,200 mg daily for most adults) and avoid exceeding 2,000 mg daily from all sources. Be aware of the medication interactions listed above. For magnesium, seek data specific to that mineral. Always consult your doctor before starting a new supplement [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | 21st Century |
|---|---|
| Serving Size | |
| Contents | 110.0 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