How to read vitamin labels

1. Look for the number

Health Canada’s Natural Health Products Directorate approves dietary supplements-everything from vitamins and minerals to herbal remedies-for sale. You’ll know a product has been green-lighted if it has an eight-digit Natural Product Number (NPN) or a Drug Identification Number (DIN), which appear on all drugs, including
over-the-counter and prescription drugs. NPNs are replacing DINs on natural health products. “If you don’t see either number, then check with your pharmacist,” says Leonard Piché, registered dietitian and nutritional scientist at the Brescia University College at The University of Western Ontario.

2. Check your source

Vitamins and minerals come from a variety of sources. Some sources are more potent than others or may be more readily absorbed. So the next time you’re buying a calcium supplement, for example, take note of the source: Is it calcium citrate or calcium carbonate? (These are different salts of the same compound.) Calcium citrate is often recommended over calcium carbonate. If you’re unsure of which to choose, your healthcare provider or pharmacist can help.

3. Know your units

Knowing how much you should be taking can be difficult because of the different units of measurement used. The most important are micrograms (mcg) and milligrams (mg). That’s because most health professionals base their 
recommendations on the Dietary Reference Intakes (DRIs), a set of nutrient requirements determined by Health Canada and given in these metric units. But you may occasionally see IU (for “International Unit”) on a label. This is an international standard of measurement primarily used for vitamins A, D, and E. There are multiple sources for these vitamins, each with a different strength or potency. IUs make it possible to compare one source with another. Unfortunately, there’s no easy rule for converting IU into metric units because the conversion factors vary from one vitamin to the next. Ask your pharmacist.

To complicate things further, you may also see two relatively new units of measurement on labels: RAE and ATE. These indicate the potency of vitamins A and E, respectively, and are slowly replacing IUs.

4. Read the label’s warnings

Manufacturers are required to provide about 20 different pieces of information on supplement labels, says Piché. Pay close attention to whether there are warnings about side effects, drug interactions, or other precautions you should take, such as avoiding certain foods or drugs while you’re taking the supplements. Lastly, read the health claim, a short statement that declares what the product can do. For vitamin C, it may read “an antioxidant for the maintenance of good health” or “helps in wound healing.” Health Canada allows manufacturers to make claims like these only if they have good evidence to back them up.

Remember to get your doctor’s okay

Years of research on our eating habits show that Canadians often fall short on getting enough of certain vitamins and minerals from their diets alone. Taking a vitamin or mineral supplement can be a healthy safeguard. But as with other forms of medication, taking too much can actually be harmful, and a small number of people will also have adverse reactions to some supplements. So talk to your health professional before taking any pills.

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