This is Part 2 (of 4) in the Supplement Savvy series by Jeremy Appleton, ND, CNS. Other articles include:
Part 1: Understanding Food and Supplement Labels
Part 3: Finding Authentic Herbal Supplements
Part 4: Quality and Purity
When you take a 500 mg tablet of acetaminophen (a popular over-the-counter drug for pain relief), you expect the tablet to contain 500 mg of acetaminophen. It had better contain 500 mg, because the efficacy of the product and your safety depend on it. Each drug has a so-called “therapeutic window”: the dose-range in which it is safe and effective. Take too little and you do not achieve the desired effect; take too much and, depending on the ingredients, you could risk poisoning yourself. With over-the-counter and prescription drugs, we trust that we are getting the amount of ingredients stated on the label. Most of the time, that trust is warranted because federal regulations require pharmaceutical manufacturers to adhere to fairly rigorous standards of quality assurance (QA) and quality control (QC), a topic to be covered in the next article in this four-part series.
Manufacturers of dietary supplements should also adhere to “pharmaceutical” standards of QA and QC, but federal regulations do not require them to do so. There is a separate, less rigorous, set of regulations governing the manufacture of dietary supplements. As a result, consumers need to be more proactive in seeking out companies with superior quality processes and not simply trust that their supplements meet the claims made on the label.
Product purity (i.e., lack of contamination or adulteration) and product potency (i.e., the product contains the stated amount of active ingredient) are two central issues of product quality that should concern everyone who takes a dietary supplement. This article will take a look at product potency.
Percent Elemental
If two different products both claim to contain 500 mg of an ingredient, it seems safe to assume that they both provide the same amount of that ingredient. But product potency is not always so clear cut as that. Minerals, for example, come in different chemical forms (for example, calcium citrate versus calcium carbonate). These forms contain differing percentages of the elemental ingredient in their molecule. A greater percentage of the elemental mineral means that fewer tablets are needed to achieve the desired intake. For example, in calcium carbonate, elemental calcium accounts for about 40% of the compound; in comparison, calcium citrate provides just 24% elemental calcium. So 500 mg of calcium carbonate provides 200 mg of elemental calcium, whereas the same amount of calcium citrate provides 120 mg of calcium. Ordinarily, the label should make it clear how much elemental mineral you are getting per dose.
To complicate matters, some forms of nutrients are better absorbed than others. So for people willing to take more pills to achieve a given amount of calcium, calcium citrate may be a better choice because it is reported to absorb better. However, it requires more pills per day because each pill contains less calcium.
Tests of Potency
Laboratory evaluation of nutritional and botanical ingredients is a developing science, and there is not always consensus on the best way to identify and measure certain active ingredients. Therefore, two products claiming to contain 99% of a particular ingredient might not, in fact, both contain 99% even if lab tests confirmed it in both cases. This can happen when different testing methodologies are used. There are many testing methods, many more laboratories, and a dizzying variety of ingredients to test for. There has been a push in the dietary supplement industry in recent years to standardize testing methods for some of the most prominent ingredients used in supplements
For example, quantitative analysis of chondroitin sulfate—an ingredient poopular in supplements for joint health—has been difficult because there is wide variance in the molecular weight of its polymers, poor ultraviolet light absorbance, and a strong tendency for the substance to form ionic bonds. Many lab methods have been used to characterize chondroitin sulfate. However these methods may not work well when used on finished products, which contain other potentially interfering ingredients. A single laboratory validation of a method for quantifying chondroitin sulfate in dietary supplement ingredients has been accomplished and will hopefully be adopted across the entire supplement industry. Nevertheless, this is just one high-profile ingredient. For dozens if not hundreds of others, no consensus exists regarding how best to test them.
Consumers cannot be expected to possess the level of knowledge to necessary to critically evaluate issues of product potency. To be honest, most people who work in the industry do not even appreciate the problems inherent in guaranteeing that a supplement has in it what the label says it does. But a consumer can ask a few well-placed questions of a supplement company’s technical director in order to determine if they have appropriate quality control procedures in place:
- Are your ingredients and finished products evaluated by a laboratory for purity, potency and identity of active ingredients?
- Are your laboratory’s analytical methods validated for the ingredients tested? (The answer to this question may be no, and that may be acceptable. But it is best to ask and find out.)
- Do you follow FDA Good Manufacturing Practices for dietary supplements?
- Can you provide lot-specific certificates of analysis validating the identity, purity and potency of your products?
If a supplement company is unwilling or unable to answer these questions, or to at least find out the answers and get back to you in a timely manner, it is time to choose another supplement company.
In Part 3: Finding Authentic Herbal Supplements, of this four-part series, we will examine how to determine which herbal supplements are the real thing.
