Q Is there any problem in taking vitamins a year or so past the expiration date? Are there specific vitamins that would deteriorate so much that one shouldn’t take them?
MUFFIN, Oklahoma City
A This is a commonly asked question, and the answer must be qualified. Regarding drugs, the FDA has monitored what they call the shelf life extension program (SLEP) of drugs for the past 20 years for the United States Department of Defense.1 Extensive pharmaceutical stability data indicate that in 88% of the drugs tested (122 in all, representing 3005 different lots), shelf life was extended for at least one year beyond the originally indicated expiration date—and by an average of 66 months! However, there was a lot of variability during the extended period, and the FDA reported that the only way to be assured of continuing potency was through periodic testing and systematic evaluation of each lot.
Regarding supplements such as vitamins, minerals, amino acids, and other nutrients, no large study has ever been undertaken, as far as I know. (With all that testing, the cost of the SLEP study must have been staggering!) But we do know, from stress and stability studies of individual supplements, that there is a great deal of variability, just as there was in the SLEP study.
The principal factor that determines shelf life is initial quality. The supplement must have essential material as much as is reasonably possible and, by the same token, low levels of nonessential material. It must also have low levels of prooxidative residues, as little moisture as possible, and, if synthesized (as most vitamins are), great chemical stability. Herbal materials must have nearly unmeasurable levels of bacteria or be sterilized. The supplement must be packaged in opaque and secure containers in a clean or sterile, dust-free, air-conditioned, dehumidified environment and not be subjected to extremes in temperature. Finally, as you have undoubtedly seen on the labels, the supplements should be stored in a cool, dark, dry place.
Products made under the above conditions, if stored properly in unopened bottles, should last at least two years before any loss of potency occurs, and, once opened, they should hold up for at least one year.
Initial quality is paramount. For example, the vitamin C developed by Hoffmann-La Roche has been found to outlast other vitamin C products by many years (unopened samples have maintained their purity and potency for up to 20 years). Other vitamin C products have been found to darken, changing color from brown to gray to black in only a few years. This darkening reflects the formation of dehydroascorbic acid, an oxidized form of vitamin C that is undesirable to ingest. Life Enhancement Products uses only vitamins manufactured by the successor company to Hoffmann-La Roche, as well as amino acids, hormones, herbs, and other supplements from the world’s premium producers.