Dietary Supplements: Sizing Up the Product and Manufacturer

If you have questions about a dietary supplement, you may want to contact the manufacturer directly.

The manufacturer should be able to answer the following questions:

  • Has your product been evaluated in scientific studies that have been published in reputable medical journals?
    • If so, are you willing to share these studies?
    • Or, is most of the product information the result of testimonials by people with diabetes who have used the product?
  • Can you explain how the product works?
    • Do you have scientific studies that verify the mechanism of action?
  • Does your company conduct a chemical analysis of the active and inactive ingredients to verify that the product contains what it says on the label?
  • Does the product break down and dissolve appropriately in the stomach?
  • Does your company specify storage or stability instructions such as what temperature to store the product, whether light may affect the product, or whether it should be stored in a dark place?
    • Do you list an expiration date for the shelf life of the product?
  • Do you specify any side effects or possible interactions with other supplements or prescription drugs or disease states?
    • Do you specify which patients should not use the product?

Difficult to Evaluate Products

Even when armed with these questions and the best intentions, it is difficult to evaluate the safety and effectiveness of products.

Unfortunately, many of the scientific studies done on dietary supplements are unreliable. For example, studies may include only small numbers of patients. Some scientists never examine the actual contents of the studied products, so their results could be unintentionally skewed.

It's always best to talk with your health care provider about questions regarding the effectiveness and safety of a product, rather than trying to troubleshoot on your own.


This material is adapted from The American Diabetes Association Guide to Herbs & Nutritional Supplements, written by Laura Shane-McWhorter, PharmD, BCPS, FASCP, BC-ADM, CDE, and published by the American Diabetes Association, ©2009.

  • Last Reviewed: February 20, 2014
  • Last Edited: April 7, 2014

Articles from Diabetes Forecast® magazine:

Diabetes Forecast