The Vitamin Shoppe Magnesium Glycinate 400 mg

Our assessment

The evidence shows that magnesium glycinate is a well-absorbed form of magnesium that supports muscle relaxation and nerve function. The data provided indicates that this product contains 400 mg of magnesium per serving, which is a significant dose. For most adults, the recommended dietary allowance (RDA) for magnesium is 310–420 mg per day, depending on age and sex [NIH ODS]. This single serving can meet or exceed your daily needs, so you should be mindful of total magnesium intake from other sources.

How it works

Think of magnesium as a calming mineral for your body. It plays a critical role in over 300 enzyme systems, including those that regulate muscle contractions, nerve transmission, and blood pressure [NIH ODS]. Magnesium glycinate, specifically, is bound to the amino acid glycine, which may enhance absorption and reduce the likelihood of digestive upset compared to other forms like magnesium oxide [NIH ODS].

Safety profile

Data on adverse events specifically for this product is not available in the provided data. However, for magnesium supplements generally, the FDA data includes reports of side effects such as diarrhea and gastrointestinal discomfort. The tolerable upper intake level for supplemental magnesium is 350 mg per day; doses above this can cause diarrhea and abdominal cramping [FDA data] [NIH ODS]. Because each serving of this product is 400 mg, you are exceeding that upper limit in a single dose, which increases your risk of these side effects.

Our recommendation

Start with half a serving (200 mg) to assess your tolerance, especially if you have a sensitive stomach. Take it with food to further minimize digestive issues. Do not take this product with other magnesium-containing supplements without consulting a healthcare provider, as the total dose may be too high [NIH ODS]. If you have kidney disease or take certain medications (such as diuretics or antibiotics), speak with your doctor before use.

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