woman with dropper bottle

Ask Gerda: How Do You Evaluate
Supplements and Wellness Products?

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 college, 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.

If an ad or a label says that a product is efficacious or organic, the FDA and the FTC require that there is evidence that the claim is truthful. For example, consumable products labeled as “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-branded and third-party supplements we sell are substantiated by scientific research or, in some cases, by ancient medical traditions. goop’s director of science and research, Jennifer Kovacs-Nolan, PhD, spends most of her workday digging into research. To give you an idea of her line of thinking, I asked her about a few of the products she’s helped evaluate from different categories: “The products we carry from Wooden Spoon Herbs are thoughtfully formulated with traditionally used botanicals and are certified organic,” she explains. “And the Sugar Control Mints in Sweetkick’s 14-Day Sugar Reset are backed up by a clinical study on the product as well as data on the key ingredient, gymnemic acid.”

  1. Wooden Spoon Herbs ROSE-COLORED GLASSES
    Wooden Spoon Herbs ROSE-COLORED
    goop, $36
  2. Sweetkick 14-DAY SUGAR RESET
    Sweetkick 14-DAY SUGAR RESET goop, $46

    goop, $495

The vFit device is another good example. It uses heat, red light, and vibration to stimulate blood flow and promote the health of the pelvic floor. We say this because a clinical study showed benefits for a healthy bladder and sexual function. And the brand worked with the FDA to classify the vFit as a wellness device.


  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?

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

If the claims look okay, the next thing to look at is the ingredient list. Are there chemicals you don’t recognize? There’s a good chance that the Environmental Working Group 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 endocrine disruptors, such as phthalates and parabens and other potentially harmful ingredients. We also screen for artificial colors, flavors, and sweeteners.


  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.

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

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 practice (CGMP) 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 CGMP. Many go above and beyond and seek CGMP certification by a third-party auditor, including, for example, Gaia, and the manufacturing facility used by The Nue Co.

  1. The Nue Co. SKIN FILTER
    The Nue Co. SKIN FILTER goop, $60
  2. The Nue Co. VITAMIN D SPRAY
    The Nue Co. VITAMIN D SPRAY goop, $25

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 Kovacs-Nolan.


  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 CGMP is used when manufacturing dietary supplements. CGMP requires 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 CGMP can be validated by certification from an independent auditor, such as NSF or USP.

An important part of CGMP is clearly labeling when allergens such as peanuts are present. All five of goop’s vitamin protocols are made without the common allergens wheat, soy, egg, dairy, tree nuts, and peanuts. And they are

  1. goop Wellness HIGH SCHOOL GENES
    goop Wellness HIGH SCHOOL GENES goop, $90/$75 with subscription
  2. goop Wellness WHY AM I SO EFFING TIRED?
    goop Wellness WHY AM I SO EFFING TIRED? goop, $90/$75 with subscription
  3. goop Wellness THE MOTHER LOAD
    goop Wellness THE MOTHER LOAD goop, $90/$75 with subscription
  4. goop Wellness MADAME OVARY
    goop Wellness MADAME OVARY goop, $90/$75 with subscription
  5. goop Wellness BALLS IN THE AIR
    goop Wellness BALLS IN THE AIR goop, $90/$75 with subscription

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.