Ask Gerda: How Do You Evaluate Supplements?

Written by: Gerda Endemann, PhD


Updated on: June 17, 2022

woman with dropper bottle
Gerda Endemann

Gerda Endemann, our senior director of science and research, has a BS in nutrition from UC Berkeley, a PhD in nutritional biochemistry from MIT, and a passion for cherry-picking from our wellness shop. She spends a lot of her time interpreting research—established and emerging. You’ll find some of her deep dives into health conditions in our growing library of articles called goop PhD. You can send your own questions for Gerda to [email protected].

Dear goop, I’m a little wary of buying supplements and other wellness products because I don’t know how to tell if they are well-made. What should I know, and how do you evaluate products at goop? —Madison

Hi, Madison. You can look for some red flags—and I’ll elaborate on that in a bit—but it’s not easy to vet wellness products.

I have a long history with supplements and looking into wellness claims, but even for me, it can be a difficult and lengthy process to decide whether a product is likely to be effective and safe. When I was a child, my father sold Nutrilite, one of the first “natural” supplement brands. Then when I was an undergrad studying nutrition, I was taught to be wary of supplements. (At this point, my father accused me of having been brainwashed by the establishment.) I’ve since come to the conclusion that supplements can be life changing, but they should be carefully selected.

For a while after grad school, I worked as a laboratory scientist. And for my second career, I was a nutrition educator. My clients had lots of questions about supplements, and they wanted me to recommend specific products. Specifying amounts of nutrients was simple, but evaluating brands was not.

Before I came to goop in 2018, I spent seven years in the dietary supplements industry, working on research and product development. And that inside info has helped a lot. Contrary to what you may have heard, dietary supplements and wellness devices are regulated by the FDA. However, the FDA does not have the resources to make sure that all manufacturers are following the regulations. And some are not.

Are the Claims Reasonable?

If an ad or a label says that a product is efficacious or organic, the FDA and the FTC require that there be evidence that the claim is truthful. For example, consumable products labeled organic must be certified by the USDA, which does not allow the use of synthetic fertilizers or pesticides. If a product is said to affect the body, there should be scientific research to support the claim. Unfortunately, products regularly
show up on the market that are promoted with unfounded claims.
Regulatory agencies may not take action for years, if ever. At goop,
we don’t claim that supplements are efficacious, organic, or
anything else unless we have evidence.

The scientists on our wellness team make sure that claims on goop-brand supplements and other brands we sell are substantiated by scientific research or, in some cases, by ancient medical traditions. goop’s senior director of product development, Thira Burns, MS, RDN, created a rigorous process for documenting evidence in support of claims. I asked her about a few of the products she’s helped evaluate: “GOOPGLOW Morning Skin Superpowder contains vitamin and antioxidant ingredients that have been shown to support healthy skin in numerous clinical studies,” Burns explains. “And Genexa’s antacid combines calcium carbonate—the ingredient found in most OTC antacids—with organic, clean ingredients.”*

    goop Beauty GOOPGLOW MORNING SKIN SUPERPOWDER goop, $60/$55 with subscription


  1. Do the claims seem too good to be true?

  2. Does the product claim to cure cancer or cause sudden weight loss?

  3. Has the company demonstrated that it doesn’t care about abiding by FDA guidelines and that it doesn’t care about misleading you?

  4. If the answer to any of these questions is yes, that’s a red flag.

Are the Ingredients Safe?

If the claims look okay, the next thing to look at is the ingredients: both those in the supplement facts box and those under “other ingredients.” Are there chemicals you don’t recognize? There’s a good chance that the Environmental Working Group (EWG) has information about their safety. And as part of our
vetting process at goop, we take care of this for you. We screen for things like
phthalates and parabens and other potentially harmful ingredients. We also
screen for artificial colors, flavors, and sweeteners.

DTF is a good example. The active ingredients are three plant extracts. The vegan capsule is made with a form of the plant fiber cellulose. A tiny bit of magnesium stearate is added to help the powder flow into the capsules. There’s not enough magnesium stearate to fill your magnesium needs, but a little extra doesn’t hurt, and stearate is the perfectly fine fatty acid found in cocoa butter. And as far as claims go, the fenugreek extract in DTF was shown clinically to support healthy sexual arousal and desire.*

  1. goop Wellness DTF
    goop Wellness DTF goop, $60/$50 with subscription


  1. See if you recognize the ingredient names. (Note: Some chemicals are perfectly safe, so an unfamiliar name is not necessarily cause for alarm but just perhaps a little investigation.)

  2. Products may contain compounds linked to potentially harmful effects on health or the environment. The EWG is one source you can check for information on ingredients.

  3. goop screens all products for an ever-evolving long list of undesirable ingredients.

Does the Product Contain
What It Is Supposed to Contain?

The evaluation process becomes more complex when it’s time to determine whether a product contains the active ingredients listed on the label and does not contain harmful contaminants. If it’s manufactured using current good manufacturing practices (CGMPs) as defined by the FDA, it should be fine.

The supplements we make and the supplements we sell from other brands are manufactured in facilities that use CGMPs.

However, being CGMP-compliant requires extensive costly testing to verify the presence of active ingredients and the absence of heavy metals and harmful microbes. It may take years for the FDA to catch up with manufacturers that are not compliant. “We scrutinize the results of tests for heavy metals—lead, mercury, cadmium, and arsenic—and for bacterial contamination to make sure that products are safe,” says Burns. “And when we say that a product is free of gluten, as is the Everyday Glow Multivitamin, for example, a sophisticated immunoassay is used for confirmation.”*

    goop Beauty GOOPGLOW EVERYDAY GLOW MULTIVITAMIN goop, $60/$55 with subscription


  1. The focus in quality control is determining whether the product contains the desired ingredients and whether it contains harmful contaminants.

  2. The FDA requires that CGMPs be used when manufacturing dietary supplements. CGMPs require testing for identity (is this ingredient what the manufacturer says it is?), purity (is this ingredient as strong as it’s supposed to be?), and contamination (is this ingredient free of adulterants, naturally occurring or otherwise?), among other parameters.

  3. A manufacturer’s implementation of CGMPs can be validated by certification from an independent auditor, such as NSF or USP.

This article is for informational purposes only. It is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. To the extent that this article features the advice of physicians or medical practitioners, the views expressed are the views of the cited expert and do not necessarily represent the views of goop.

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.