A viable tool to ensure if a supplement meets the strict guidelines of the FDA is looking for a USP (US Pharmacopeia) seal on each bottle.
USP verifies the identity, strength, purity, and quality of dietary supplement finished products, dietary supplement ingredients, and pharmaceutical ingredients. Products and ingredients that pass all USP verification requirements– product and ingredient testing, and manufacturing documentation review–are awarded use of the distinctive "USP Verified" mark.
Participation is voluntary and available to manufacturers worldwide…used today in more than 130 countries around the world. If you find an USP seal, you know the following will be true:
• What's on the label is in fact in the bottle—all the listed ingredients in the declared amount.
• The supplement does not contain harmful levels of contaminants.
• The supplement will break down and release ingredients in the body
• The supplement has been made under good manufacturing practices