Can I continue to take my multivitamin supplement after the expiration date? Does it become ineffective? Is it unsafe to take?
It's not uncommon: That newly purchased bottle of multivitamins – perhaps fish oil and probiotics, too – got pushed to the back of your medicine cabinet. That was two years ago.
Taking a nutritional supplement past its expiration date won't harm you. But they do lose their potency after they expire and, therefore, their effectiveness. For certain types of supplements, it's best to throw out old ones.
In Canada, supplement manufacturers are required to include expiry dates on labels. Expiration dates indicate the last day the manufacturer can guarantee a product will be at its highest level of potency.
Companies are also legally required to provide stability data that support the label claim – i.e., the product will have 100 per cent of its listed ingredients for the duration of the expiry period. To do so, manufacturers test bottled nutritional supplements in stability chambers to determine an expiry date.
Ingredients such as vitamins, omega-3 fatty acids and herbal extracts start to decompose the minute they're manufactured and continue to do so gradually over time. Exposure to heat, humidity, light and air can cause nutrients to break down even more rapidly. (Minerals, such as calcium, iron and zinc, do not degrade when stored properly.)
Some nutrients (e.g. certain B vitamins including folic acid, vitamins C and D, beta carotene) deteriorate more quickly than others. Manufacturers may beef up their strength by adding 30 to 40 per cent more than what's stated on the label. Doing so ensures that these nutrients are at 100 per cent strength at the time of expiry.
Adding a drying agent, or desiccant, to bottles of vitamin supplements – e.g., silica gel packets – slows down natural nutrient degradation by absorbing moisture. Coating tablets also helps keep vitamin supplements stable longer.
So, are you doing yourself any good taking multivitamins that expired a few months ago? It's not unsafe or dangerous to take them; they simply won't be as potent as they were before the expiry date.
According to John Doherty, vice-president of scientific and technical affairs for Jamieson Vitamins, "Once the expiry date has passed, we can't confidently guarantee how much less you're getting after three months, after six months."
Still, the potency drop-off for most vitamins is slow. If your multivitamin is only two or three months past date, you can expect its nutrient content to be pretty close to what's on the label.
That said, I don't advise taking expired prenatal multivitamins. Before and during pregnancy it's important that women ensure they consume an adequate amount of folic acid, a B vitamin that guards against birth defects such as spina bifida.
Some ingredients, though, are fragile and break down quickly after a product's expiration date. Probiotic supplements, made from live bacteria and yeasts, will be far less potent once expired. It's best to throw them out.
Ditto for oil supplements in gelatin capsules including fish oil, flax oil, cod liver oil and evening primrose oil. These fats oxidize much more readily than do vitamins and minerals sold as tablets. Once expired, toss them out.
Flavours, too, break down quickly and are usually the first ingredient to go after expiration. While your chewable vitamin C or gummy multivitamin may still have as much as 90 per cent of its original potency three months past expiry, don't expect them to taste the same.
To prevent supplements from losing potency faster, follow storage directions on the label. Store vitamins in their original containers away from heat and light. Don't remove the little silica gel packet or canister that helps remove moisture from inside the bottle. (I used to always pitch it, not realizing its purpose.)
Although many brands of probiotics are shelf-stable, it's best to store them in the refrigerator after opening to help slow their rate of dying.
If you do need to throw out vitamin supplements (or medications) that have expired, don't flush them down the toilet or throw them in the garbage. Doing so is unsafe and can harm the environment.
To dispose of them safely, take them to a pharmacy that participates in the Medication Return Program. The same goes for unused supplements that haven't yet expired.
Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto.