Do Dietary Supplements Really Work?

Answer: It depends on the supplements. Some do and some don’t, but one thing I know for sure. The FDA does not test them to make sure supplements are what they say they are. The FDA doesn’t even test to see if they contain harmful toxins or poisons. The supplements can be grass clippings or vegetable oil for all the FDA knows. Their only concern is that the supplements are labeled properly and according to the Dietary Supplement Health and Education Act (DSHEA 1994). The supplement label can make claims that a product can build or support health, or provide a good source of supplementation. The label cannot state that the supplement can prevent, treat, or cure any condition or disease.

But before you completely lose faith in dietary supplements, know that there are some good, high-quality products out there. Some of those products voluntarily submit to rigorous testing to an agency called U.S. Pharmacopeia. It is a federally recognized nonprofit organization that tests supplements for their content and sanitary manufacturing conditions. Access to the USP Dietary Supplement Verification Program website is

Any product that passes the test bears a seal of approval that looks like this: usp seal

Beware of tricky advertisers that display a similar copy-cat seal on their labels.

Also, to retain the seal the USP annually tests the products off the shelves of random stores.

ConsumerLab is also another agency that tests products but this time without the manufacturer’s permission. Its reports disclose information such as: which multivitamins failed testing and why; which multivitamins exceed tolerable upper limits for certain nutrients; which lowcost multivitamins provide the same nutrients as more expensive popular brands; head-to-head comparisons of all multivitamins reviewed and rated; and concerns, cautions, and potential adverse effects of the products tested.

Access to reports requires membership for a cost of $33 for 1 year or $54 for 2 years; the website is

There is one thing that these labs do not test for, that is if the supplement produces a desired effect in the body. That task is left to the clinical trials and is posted in the medical journal.

And what do the various studies say about each individual supplement? Well, it depends on the product, the dose, and the condition it is treating in the study. It all gets very complicated and new studies are coming out every day proving and disproving theories. It’s also tricky to read these clinical trials because researchers with hidden agendas can doctor up the results in their favor. It takes a skilled eye and an expert in the field to detect that.

That is why I rarely read clinical trials directly. I usually read commentaries from experts in the field. Those commentaries are written as review articles and meta-analysis studies.

Sometimes the overall final opinions as to whether the supplement works or not can be found in the clinical guidelines set forth by a large group of experts who have come together and reviewed all the clinical trials and data. Sometimes these guidelines are old and need to be updated as new information becomes available, but usually, they are reliable.

There will be more blogs about which supplements are endorsed by expert doctors and which supplements are so powerful they are used in the hospital setting. Also in a future blog, I will discuss what to do if you encounter a fraudulent dietary supplement or one that produces an adverse effect and evidence that the placebo effect is alive and well.

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