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Testing products for quality
January 1999

Testing is done as an integral part of the manufacturing process to ensure quality. It is performed by the manufacturer and also by independent labs on its behalf.

Testing is also done off-the-shelf by completely independent third parties to test the quality of products being sold. There have been several initiatives to test supplements independently. ConsumerLab.com is a private testing organization that licenses a quality seal for products that pass testing. Some other initiatives are done by trade associations like the National Nutritional Foods Association (NNFA) and American Botanical Council (ABC). Sporadic testing is done as part of an investigative news report, the results of which have been published in media such as The LA Times, Consumer Reports, and The New York Times.

In addition to testing for marker compounds to verify the presence of particular biologically active components, testing is performed to test for dosage accuracy; contaminants such as heavy metals, bacteria, and pesticide residue; compliance with US Pharmacopoeia (USP) tests for disintegration, dissolution, and shelf-life standards; and bio-availability.

Complexity of testing

Testing dietary supplements is much more complex than for drugs. Pharmaceuticals are usually manufactured by extracting single active ingredients from raw materials and then blending those ingredients into a unique, often patentable, formula. In contrast, botanical products have complex chemical structures. Exactly which active ingredient(s) provide a health benefit is often unknown and thus controversial.

Testing technology itself is complex. Different methods can be used to test for the same ingredient, giving different outcomes. Even for a single product, testing can be so difficult that it can take over six months for the manufacturer to figure out how to test its own product.

Furthermore, different manufacturers use different formulas and procedures for creating the same type of supplement. These different formulas and procedures call for different test methods. This makes testing to compare different brands especially difficult.

For more about identifying ingredients, see standard terminology: the important first step in evaluating health benefits.

Many useful methods have been developed by manufacturers and independent test labs to analyze and ensure the quality of botanicals. But these methods vary among manufacturers and labs. In order to compare botanicals, it is important to have a common understanding of how to test a given type of dietary supplement.

Test standards

In order to perform product tests on multiple brands of a given type of supplement, standards are needed to establish what ingredients, or marker compounds, for which to test. Otherwise, reliable testing can only be performed on single name brands. Among the questions that must be answered are:

  • Which of the active components should be included?

  • What test methods accurately measure the existence of those ingredients?

  • How much of these components should be present?

  • What ratios of these components should be present?

  • Will the presence of one component offset the test of another so as to yield a false-negative?

  • Can a test be offset if the product is doctored thus yielding a false-positive?

Toward this end, an industry consortium called the Institute for Nutraceutical Advancement is working to create standard test methods under its Methods Validation Program (MVP) so that different brands can be tested using the same methods. They aim to make standards as broad and inclusive as possible so that they are valid for every product.

So far their efforts have concentrated on development of methods for testing raw materials. It will be years before industry-wide standards are available for finished products. Thus reports of dietary supplement testing should be evaluated with this in mind.

See also: dosage amounts, standard terminology, contamination, label: ingredients and recommended dosages, dissolution and bioavailability, and interviews with Mark Lange and Loretta Zapp of the Institute for Nutraceutical Advancement.

More about standards & regulations:

Industry standards

Creating a quality model for dietary supplements

Different types of standards

Pros and cons of standards

Competing standards

Testing products for quality

Dosage recommendations

Good manufacturing practices (GMPs)

Self-regulatory quality standards


Government regulations

FDA safety monitoring

Federal Trade Commision (FTC)

State laws

Health benefit claims

RDA, DV, and other recommended intake values

Funding of research at the National Institutes of Health (NIH)

Possible future FDA regulations

Possible future Codex regulations


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(c) Copyright 1999-2003 Dietary Supplement Quality Initiative. For permission to reprint, please contact our editor.