NOW Calcium & Magnesium
Brand: NOW · Form: TABLET [E0155]
Our assessment
The evidence shows that this supplement provides two essential minerals, but you must be careful with dosing. Calcium supports bone density and neuromuscular function, while magnesium works alongside it for muscle relaxation and nerve signaling [NIH ODS]. However, the data highlights significant risks if you take too much calcium over time.
How it works
Think of calcium as a structural builder for your bones and a signal manager for your nerves and muscles. It supports bone mineralization and helps your muscles relax after contracting [NIH ODS]. Magnesium assists in this process by supporting proper nerve signaling and muscle function. Together, they help maintain your body's mineral balance.
Safety profile
FDA received 592,059 total adverse event reports for products containing these ingredients. You must be aware that high calcium intakes might increase the risk of heart disease and prostate cancer [NIH ODS]. 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]. 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 and other supplements. Do not exceed the upper limit of 2,500 mg per day from all sources combined [NIH ODS]. Take this supplement with food to improve absorption, and separate it from any medications listed in the safety profile by at least two hours. If you have a history of kidney stones, heart disease, or prostate cancer, consult your doctor before using this product [NIH ODS].
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