Dietary supplements like multivitamins are a way for you to incorporate extra vitamins and minerals into your daily diet. While dietary supplements aren't for everyone, if you are pregnant, a vegetarian or have a medical condition that keeps you from getting enough nutrients from your daily diet, you might need a dietary supplement to give your body the nutrients it needs. But if you have had some supplements in your medicine cabinet for a few years, take caution -- those supplements may not be as strong as they used to be.
The components of dietary supplements can start to break down when exposed to air, changing temperatures and humidity. Some supplement components -- such as vitamin C -- can be highly reactive and start to break down quickly. Other supplements may take several years to break down. Some dietary supplements, such as fish oil, also can become rancid with time. Signs your supplements have gone rancid include discoloration, smell and changes in shape.
The United States Food & Drug Administration requires dietary supplement manufacturers substantiate the claims concerning potency. The FDA applies a "substantiation standard" that requires manufacturers to prevent evidence that supplements are as potent as the listings on the label. This is why manufacturers put an expiration date on the label -- because this is the amount of time the manufacturer can guarantee the supplement lives up to its label and meet FDA requirements.
Expiration dates tend to be conservative for dietary supplements, according to Jigsaw Health. This is because manufacturers take into account shelf time, shipping time and storage. For this reason, the expiration date might be slightly padded. Remember the expiration date is the amount of time a manufacturer can guarantee a supplement's potency. After this time, the supplement is not always harmful to you, but may not be as strong as it once was. If you require a certain vitamin intake, an expired supplement may not help you meet your desired level.
How you store your supplements can affect their expiration dates. If you stored your dietary supplement in a warm or humid area, it is possible they could lose their potency faster than the expiration date reads. To maintain supplement potency, it's important to store your medication in a cool, dry place away from the sunlight. Keep the lid placed tightly over the supplement to prevent air from degrading the vitamin potency. If your supplement requires refrigeration, keep it in a designated area in your refrigerator.