GNC Magnesium 250

Our assessment

The evidence shows that GNC Magnesium 250 is a product aimed at supporting basic mineral intake, but the data provided does not contain specific information on magnesium itself. The only ingredient data available is for calcium. Our assessment: without data on the magnesium content or its specific effects, we cannot confirm the product's primary benefits. If you are taking this for magnesium, you should know that the provided data only covers calcium, which is a different mineral with its own set of considerations [NIH ODS].

How it works

Based on the data for calcium, this mineral plays a role in bone mineralization, helping to support bone density and mineral deposition. It also supports neuromuscular relaxation, aiding muscle relaxation and nerve signaling [NIH ODS]. For the magnesium component, data on its mechanism is not available.

Safety profile

Data not available for magnesium specifically. For calcium, the data shows that high 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]. The FDA received a total of 592,059 adverse event reports across all products, but report counts specific to this product are not available [FDA data].

Our recommendation

Because the data provided does not include information on magnesium, we cannot recommend GNC Magnesium 250 for its intended purpose. If you are seeking a magnesium supplement, you should look for products with clear, data-backed evidence for that ingredient. If you are specifically interested in calcium, be aware of the potential risks and interactions with medications like bisphosphonates, tetracycline antibiotics, and levothyroxine [NIH ODS]. Consult with your healthcare provider before starting any new supplement.

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