Expiration dates, "use by" guidelines, or "manufactured on" notices are printed on the labels of nearly all consumable products nowadays. When it comes to dietary supplements, who determines those dates––and what do they really mean?
What's In A Date?
"Typically, the responsible party is the one listed as the manufacturer or distributor on the label of the dietary supplement product," said Andrew Shao, Interim Senior Vice President of Scientific and Regulatory Affairs at the Council for Responsible Nutrition. Manufacturers use stability studies––a series of experiments exposing a product to a range of different storage conditions––to inform their expiration date calculations.
Stability testing enables researchers to examine products when stored under ideal conditions––in the dark, at room temperature and low humidity, generally––as well as more extreme circumstances, like those that might occur during shipping and transport. Shao noted that supplement makers often use a combination of "accelerated" methods--where products are exposed to extreme conditions for a short period of time--and "real time" studies, in which the products are exposed to more normal conditions. In both cases, analytical chemists track any changes in quality that occur over a designated period.
"From a product development perspective, most products degrade over time, due to chemistry and interaction of the ingredients," explained Larisa Pavlick, Vice President of Global Regulatory and Compliance at the United Natural Products Alliance. "This is not a reflection of poor manufacturing practices—it is the nature of the ingredients," she noted.
Using stability testing, manufacturers measure a product's active ingredients at varying points in time and under varying conditions, to calculate an informed "best by" date for a given supplement.
While the Food and Drug Administration (FDA) mandates expiration date listings on all prescription drugs and over-the-counter medications, in accordance with a federal law passed in 1979, supplements are separately regulated under the Dietary Supplement Health and Education Act of 1994. DSHEA does not mandate expiration dating. In other words, supplements are not required by law to carry expiration dates.
However, many supplement makers do voluntarily choose to label products with some form of suggested "use by" date. Additionally, retail stores often require expiration dates to be listed on product packages, so most companies do provide them.
Jay Sirois, Senior Director of Regulatory and Scientific Affairs at the Consumer Healthcare Products Association, said that according to FDA, "a firm may include [expiration dating] if it is supported by valid data demonstrating that it is not false or misleading."
If an expiration date is indicated, FDA Current Good Manufacturing Practice (cGMP) regulations for dietary supplements mandate that it must be supported by stability testing data. This helps to ensure a scientific backing behind any label claims made, guaranteeing to consumers that at least 100% of the amount of any ingredients listed on a package must be present in the supplement up until the date indicated.
"Given that requirement, manufacturers must know the shelf life of their products so they know how long they can be made available to consumers and still meet 100% of label claims," Shao said. "Most reputable manufacturers make stability testing and expiration dating or shelf-life dating a routine part of their GMP process," he suggested.
Supplements are not required by law to carry expiration dates. However, many supplement makers do voluntarily choose to label products with some form of suggested "use by" date. Additionally, retail stores often require expiration dates to be listed on product packages, so most companies provide them.
Pavlick, a former FDA investigator who inspected over 200 food and supplement facilities throughout the western US, pointed out that the agency specifically requires companies to "establish specifications for identity, purity, potency, and composition, plus for any and all potential contaminants." Manufacturers must also verify that their products meet all written specifications.
"During an FDA inspection, the investigator will verify that the product meets specifications at the time of manufacturing and that any dates used on the product, whether called expiration date, 'best by' or something else, are scientifically supported. If they are not, [the manufacturers] are typically cited for not meeting specifications," she said.
Apart from facility inspections, FDA also has the ability and authority to sample products from retail shelves in order to verify that values shown in the Supplement Facts boxes match what's in the products. Pavlick noted that while FDA does not currently have the resources to monitor all nutritional supplements, it can––and does––conduct "for cause" investigations. She said that children's vitamins, for example, were specifically monitored during her tenure at the FDA.
Art and Science
Legal requirements aside, many consumers expect expiration dates on food and medicine packages. Depending on the type of product, these shelf life indicators––and the extent to which they should be strictly followed––can vary significantly.
Some nutrients are more shelf-stable than others. The degradation characteristics of single-"letter" vitamins, for instance, are fairly well known; water-soluble vitamins like vitamins B and C are generally more stable than fat-soluble vitamins like A or D. Supplement manufacturers take these known stability characteristics into consideration during product formulation.
By regulation, if a company states an expiration date, then the ingredients in a supplement must remain at label claim levels until that defined time of expiration. Because degradation occurs naturally, FDA permits manufacturers to formulate with "intentional overages"--the purposeful addition of higher ingredient quantities to account for an eventual loss in potency.
Responsible companies will account for the known degradation of vitamins and botanical constituents by responsibly overformulating their products (see, Validation Testing: Insights from Inside the Analytical Lab).
"This means that at the beginning of the shelf life, the product may have a safe and allowable intentional overage of some ingredients to allow for the product to maintain at least the values that are shown in the Nutrition Facts or Supplement Facts box" through the date of expiration, Pavlick said.
It is "an art and a science to understand the rate of degradation and safe limits for some vitamins and components," she told Holistic Primary Care, adding that reputable companies conduct "complex analytical testing at very specific time points to create degradation curves for their specific formulations."
Natural degradation can eventually affect a product's potency, but that does not necesarily make it harmful to consume post-expiration. A post-date suplement is not likely to be dangerous; it is simply less likely to deliver the expected benefit.
Storage Affects Quality
Many vitamins and other nutrients become unstable with exposure to light, air, and/or humidity.
Most supplements have shelf life of between one and two years, or an expiration date that extends one to two years post-manufacture. They are generally sold in relatively stable dosage forms, like tablets and two-piece hard shell capsules which usually maintain their quality for about two years when stored properly (see Encapsulating Quality: How Ingredient & Capsule Choices Impact Supplement Performance).
Other products, such as probiotics, liquids, and oils, are more fragile. They are highly sensitive to heat, moisture, and mold, and they have shorter shelf lives than letter vitamins. Formulas containign these less-stable ingredients are typically labeled with special storage instructions––refrigeration is a common one––plus shorter suggested "Use By" dates.
Adverse conditions will change the characteristics of nutritional products, so proper storage is of paramount importance. Sirois urged that patients always "follow any labeling instructions regarding the proper storage of a dietary supplement to ensure that the product retains its potency."
He recommended that "if there is no expiration or best by date or specific storage information included on the label, consumers should store the dietary supplement in a cool, dry place or contact the manufacturer if there is a question about product freshness or potency."
Pavlick encouraged patients to "think about the impact of opening and closing supplement bottles day after day, or storing them in a kitchen window or in a bathroom in high humidity."
"Are you mail ordering your vitamins? Do they sit in the mailbox for days in the hot sun, or left in a purse or backpack in the trunk or the backseat of a car during the summer? These storage conditions are often not considered by the consumer when we speak of product quality—yet they should be," she said.
That said, if stored correctly, certain types of products will keep for some time even after a best by date has passed. Shao explained that for the majority of supplements, the expiration date "is not a hard cut-off." While a product's composition will change over time, "that does not mean that all the ingredients have suddenly degraded after that date. So think of the expiration date as a general guideline," he suggested.
Despite the voluntary nature of supplement expiration dating, responsible manufacturers take stability testing seriously, and patients who use their products can trust that dates indicated are evidence-based.
"It would be odd for a dietary supplement product not to include a date of some kind, and such products should probably be avoided," Shao cautioned.
If an expiration date seems close to the time of purchase––for example, one month out on a bottle containing a six-month supply––that's another sign to seek a different product.
Health professionals can guide patients toward high-quality products by requesting that supplement companies provide or discuss their stability data.
Pavlick recommended some key questions to ask manufacturers:
"Do they arbitrarily assign a two-year expiration, or do they have data (to support that date)?
Are they using intentional overages?
If so, for which ingredients?
Has the potential for toxic mega-dosing been considered?"
She stressed that responsible brands will have these answers and will be happy to discuss them with you. "Be sure to ask your customer service or sales representative to put you in touch with the scientists in product development or within the quality department."
Other indicators can help guide patients towards higher-caliber products. A number of supplements have a USP verification mark or GMP registration seal on their labels, both of which provide additional information about a product's contents and safety.
The USP (United States Pharmacopeia) Dietary Supplement Verification Program is a voluntary program open to manufacturers of dietary supplement products worldwide. It provides independent third-party testing of supplement quality, purity, potency, performance, and consistency, in accordance with federally recognized US Pharmacopeia–National Formulary (USP–NF) and FDA cGMP standards.
NSF is another independent certification body that registers nutritional supplement makers who meet GMP requirements. The NSF "GMP Registered" logo assures consumers that products contain the identity, strength, composition, quality, and purity of ingredients they claim to provide.
As always, "a patient-practitioner dialogue about dietary supplements is important," Sirois said. He encouraged patients to "check with their healthcare providers and read the label before taking any dietary supplement product."