GNC Pro Performance Amino Complex 4400

Our assessment

The evidence shows that GNC Pro Performance Amino Complex 4400 contains calcium as a key ingredient. Our assessment is that this supplement is primarily a source of amino acids, but the added calcium provides a secondary benefit. For most adults, the total calcium you get from food and this supplement combined should be evaluated to avoid exceeding recommended levels.

How it works

Calcium is a mineral essential for bone mineralization, meaning it supports bone density and mineral deposition [NIH ODS]. It also plays a role in neuromuscular relaxation, helping your muscles relax and your nerves signal properly [NIH ODS]. When you take this supplement, the calcium works alongside amino acids to support recovery and overall body function.

Safety profile

FDA received a total of 592059 adverse event reports across all supplements, though specific reports for this product are not isolated [FDA data]. For calcium specifically, high intakes may increase the risk of heart disease and prostate cancer [NIH ODS]. Side effects from excessive calcium include constipation, nausea, weight loss, extreme tiredness, frequent need to urinate, and abnormal heart rhythms [NIH ODS]. Calcium can also reduce the absorption of medications like bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS].

Our recommendation

Start by reviewing your total daily calcium intake from all sources. If you already consume dairy or fortified foods, this supplement may push you above safe levels. Take this product with food and separate it from any medications by at least 2 hours to avoid absorption issues [NIH ODS]. Data not available on the exact calcium dose per serving, so check the label carefully.

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