The beneficial bacteria, Lactobacillus acidophilus, helps to maintain immune function by aiding in the digestion of proteins, B vitamins, enzymes and lactic acid. According to Phyllis Balch in her book "Prescription for Nutritional Healing," acidophilus aids in normalizing cholesterol levels, improving digestive disturbances and increasing the assimilation of vital nutrients. Antibiotics, stress and a poor diet can reduce the amount of healthy bacteria in the intestinal tract. Supplementing with store-bought acidophilus can help to increase healthy bacterial colonies in the gut. But if you have a bottle of acidophilus that has been sitting around for a while, it can be hard to tell if it is still active. Here are some tips to determine if you should take those capsules or buy a new bottle.
Check the expiration date. Most acidophilus products are guaranteed to maintain a certain potency, like 1 million cfu, up to their expiration date. This means that shortly after the expiration date, some of the acidophilus should still be viable.
Contact the manufacturer. Most acidophilus product labels will have a contact number or a website through which you can ask a representative about the product's viability before and after the expiration date. Acidophilus products often retain their properties for a short while after expiration, however it is best to follow the manufacturer's advice on whether to take the product.
Check the label. If the product label for the acidophilus says that it should be kept refrigerated, the lifespan of the bacteria may be less stable. Most acidophilus products that are shelf-stable, or unrefrigerated, have been freeze-dried to maintain their viability for longer periods of time and in greater temperature variations.
Culture the acidophilus. If you are using the acidophilus to prepare homemade yogurt, test a small amount of the acidophilus so you don't waste your ingredients if the acidophilus is no longer active.