Quality and Sources of Herbs, Supplements and Other Natural Products
Laura Pole, RN, MSN, OCNS, BCCT Senior Researcher
Nancy Hepp, MS, BCCT Project Manager
Last updated July 12, 2021.
Herbs, supplements and other natural products promoting health and wellness are a booming market, with Americans alone spending billions of dollars each year on these products.1 However, because these products are not well regulated, and because “natural products” by definition are not manufactured to precise specifications, several concerns arise with packaged supplements and other natural products:2
- Multiple names may be used for a product; for example, the terms artemisinin, annual wormwood, qing hao, qinghaosu, sweet annie, sweet sagewort and sweet wormwood all denote the same herb.
- Different products may be labeled with similar names.
- Products need to contain the correct plant part—whether root, leaf, bark, pollen, seed, fruit, flower or whole plant—to be effective.
- Two main issues regarding the safety and effectiveness of products (discussed below):
Disclosing all products you use to your healthcare team is crucial to maximizing your well-being.
In addition to quality concerns, some supplements and products can interact with pharmaceutical treatments (decreasing or increasing a drug’s main effects or side effects), surgery (decreasing blood clotting or increasing or decreasing sedative effects of anesthesia), some foods, and other supplements.
Some supplements may contain undisclosed ingredients. A study published in 2020 found that over-the-counter supplements advertised to improve memory and cognitive function may contain unapproved pharmaceutical drugs in potentially dangerous combinations and dosages.3
Disclosing all products you use to your healthcare team is crucial to maximizing your well-being. See our Dosing Guidelines page for more information on general interactions and cautions.
Quality of Supplements
The Bad News
In the United States, “the US Food and Drug Administration (FDA) does not have the authority to review dietary supplement products for safety and effectiveness before they are marketed.”4 No governmental review assures that supplements perform as claimed or even that they are safe to use: manufacturers do not need to prove either safety or effectiveness of the ingredients in their supplements. FDA does have the authority to take dietary supplements off the market if they are found to be unsafe or if the claims on the products are false and misleading. This puts the burden on the FDA and consumers to prove that supplements are unsafe or ineffective.
The FDA’s effectiveness at pursuing unsafe supplements and false claims may need improvement: a review of regulatory action in the US and Canada from 2005-2013 found that of 1560 dietary supplement-related regulatory alerts, 83 percent were identified through Health Canada and 18 percent through FDA MedWatch, even though the US has nine times as many people as Canada.5
Several investigations have found undisclosed—and sometimes unsafe—contaminants in supplements and herbal products.
Without strict oversight, the quality of herbs, dietary supplements and other natural products can vary immensely. Several investigations have found undisclosed—and sometimes unsafe—contaminants in supplements and herbal products. Contaminants can include bacteria, fungi, heavy metals, pesticides, other chemicals and pharmaceutical agents.6 Some contaminants are intentionally added (especially with herbs from Asia), while others reflect lax oversight or quality control, and yet others indicate cost-saving approaches that disregard the ultimate health and well-being of the consumer.7
Products may also not contain the active ingredients in the amounts stated on labels. In 2015, an investigation by the New York State attorney general found that supplements sold at four major retailers either could not be verified to contain the labeled substance or were found to contain ingredients not listed on the labels. Just 21 percent of supplement tests identified DNA from plant species listed on product labels.8 Other studies have also found inaccurate representations of the amount of active ingredients in some supplements, with some supplements having undetectable levels of the active ingredient.9 Supplements may also contain far more active ingredient than the label states, which can pose a hazard for consumers.
In addition to a product’s level of active ingredient, its bioavailability is also a consideration. Some ingredients are taken into the bloodstream or cross the blood-brain barrier only under certain conditions, such as co-consumption with other foods or substances. Curcumin is an example, for it is not passed from the digestive system into the blood at meaningful levels unless combined with piperine (from pepper) and/or dietary fats. Some supplements are modified to increase bioavailability.10
Similar to many foods and pharmaceutical drugs, some supplements deteriorate over time. The potency may increase or decrease with exposure to air, light, moisture or heat. Check packages occasionally for expiration dates, and store supplements and products as manufacturers recommend. Bathrooms are generally not good storage sites due to high moisture levels.11
BCCT encourages our visitors to check independent ratings of manufacturers before purchasing bargain brands—or indeed any brands—of supplements.
The Good News
Certificates of Analysis
Manufacturers who do not have their own labs for testing ingredients can get a Certificate of Analysis to assure product ingredient quality. While some sources suggest checking whether manufacturers have these COAs for each ingredient, finding this information can be difficult and burdensome for consumers.
Fortunately for consumers, some guidelines and rating systems indicate the quality of supplements for consumers:
- The FDA has published Current Good Manufacturing Practices (CGMPs) for Dietary Supplements.
- NSF International:
- Independent entities rate supplement quality:
- ConsumerLab.com (subscription required): Reviews of Supplements and Health Products
- US Pharmacopeia: USP Verified Products Listing
- NSF International: Search for NSF Certified Dietary Supplements
- Therapeutic Research Center (subscription required): Natural Medicines
- Livestrong.com: The Best Rated Whole Food Vitamins
Research evidence is available regarding the health benefits and risks of supplements:
- BCCT database of therapy summaries
- National Center for Complementary and Integrative Health: HerbList App
- Memorial Sloan Kettering Cancer Center: About Herbs, Botanicals & Other Products
- CAM-Cancer: The Summaries
- US National Library of Medicine: MedlinePlus Database
- National Institutes of Health: Dietary Supplement Fact Sheets
- PubMed: Dietary supplements search
Sources of Supplements
BCCT recommends first that patients consult knowledgeable physicians and practitioners who are experienced in using the supplements and natural products. Some practitioners sell products through their practices. Many patients view this source as a convenience, while others are skeptical that practitioners can maintain objectivity in recommending supplements when profiting from sales. You will have to determine your comfort and level of trust around purchasing supplements from a practitioner. BCCT encourages our visitors to check independent ratings of manufacturers before purchasing bargain brands—or indeed any brands—of supplements. See more about supplement quality below.
Some products are not available in certain countries or locations. When appropriate, BCCT includes a note in therapy summary pages about access.