NOW Calcium & Magnesium
Brand: NOW · Form: TABLET [E0155]
Our assessment
The evidence shows that calcium is essential for your bone health and muscle function. However, this supplement should be taken with caution. Data not available for magnesium from the provided sources. For calcium, some research suggests that high intakes might increase the risk of heart disease and prostate cancer [NIH ODS]. Our assessment is that you should evaluate your dietary calcium intake before adding this supplement.
How it works
Think of calcium as a structural builder for your skeleton. It supports bone density and mineral deposition through bone mineralization [NIH ODS]. It also acts as a nerve and muscle messenger, supporting neuromuscular relaxation and nerve signaling [NIH ODS]. This dual role makes it critical for daily function.
Safety profile
FDA received 592,059 total adverse event reports for this product. Specific side effects for calcium include constipation, nausea, weight loss, extreme tiredness, and a frequent need to urinate [FDA data]. Very high levels can cause poor muscle tone, poor kidney function, low phosphate levels, 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].
Our recommendation
Start by assessing your total daily calcium intake from food. Do not exceed 2,500 mg total per day from all sources. Take this supplement with food and separate it from any medications by at least 2 hours. Data not available for a specific dosage for magnesium. Monitor for constipation or nausea. Consult your doctor before use if you have kidney issues or take prescription medications [NIH ODS] [FDA data].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | NOW |
|---|---|
| Serving Size | |
| Contents | 100.0 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