GNC Super Magnesium 400 mg

Our assessment

The evidence shows that GNC Super Magnesium is a straightforward magnesium supplement, but the data we have is primarily about calcium, not magnesium. Based on the available information, we cannot confirm specific benefits for this exact product. For general magnesium guidance, the data provided does not cover magnesium's effects, so we must state that specific health claims for this product are not supported by the data provided.

How it works

While the data provided focuses on calcium, not magnesium, we can explain how a mineral supplement like this works in principle. For calcium, the mechanism involves bone mineralization: it supports bone density and mineral deposition, and neuromuscular relaxation: it supports muscle relaxation and nerve signaling [NIH ODS]. For magnesium, data on its mechanism is not available in the provided information.

Safety profile

The FDA has received 592,059 total adverse event reports for all dietary supplements, but specific report counts for this product or its ingredients are not available [FDA data]. For calcium—the only ingredient with safety data provided—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]. For magnesium-specific side effects, data is not available.

Our recommendation

We recommend starting with a lower dose of a supplement and consulting your healthcare provider before adding any new supplement to your routine. Since the data provided does not include specific magnesium studies or side effect reports for GNC Super Magnesium, we cannot make a confident recommendation for this product. You should consider that calcium can reduce the absorption of several medications, including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. For personalized advice, speak with your doctor or a registered dietitian.

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