Lessons in Chemistry: Dietary Supplements
As a personal trainer and nutrition coach, I often get asked about dietary supplements. While it’s outside of my scope of practice to recommend supplementation, I do try to share current, credible scientific research about the supplement(s) in question.
Vitamins and minerals are critical to many bodily functions and maintaining health. With a few exceptions, we can get most of the micronutrients our bodies need from eating a well-balanced diet that includes lean meats, fish and other seafood, lots of fruits and vegetables, including leafy greens, beans, nuts and seeds. Supplementation is sometimes required to ensure that we get the right nutrients in the right amounts to maintain our good health.
Over time, I’ve created this information chart on common dietary supplements. The chart (is a work in progress—other supplements will be added over time) is by no means a definitive reference guide on supplements: it’s a summary of information from what I believe to be credible online sources, including:
Harvard’s Nutrition Source deserves special mention here: I find it to be thorough, current and accessible.
Vitamin and minerals are BIG business
The 2023 Canadian vitamin and mineral market—excluding probiotics, homeopathic remedies and performance-enhancing preparations—has been valued at $1.12B (US$). And, it’s expected to grow at a rate of about 6% annually over the next five years. Public health care plans typically don’t cover the cost of dietary supplements but some private insurance plans do, often with a doctor’s prescription. More than half of Canadians take dietary supplements on a regular basis.
Things to know about supplements
Nutrition practitioners, in Canada and the United States, use the Dietary Reference Intakes (DRIs)—a set of scientifically-based nutrient reference values for healthy populations—to assess and plan the dietary intakes of individuals and population groups. The DRIs include recommendations for the daily consumption of total energy, macronutrients (carbohydrates, protein and fat), fibre, vitamins, minerals and water.
The DRIs were established over time and are updated as required at the request of the National Academy of Sciences, a society of scholarly advisors to the U.S. government. Two of the DRI standards are intended for use by individuals to help them assess and monitor their own dietary intake. These are:Recommended Dietary Allowances (RDA) – the average daily nutrient intake level that meets the needs of nearly all (97-98%) healthy people of a particular life stage and gender group.
Adequate Intake (AI) – the recommended average daily nutrient intake level based on intakes of healthy people (observed or experimentally-derived) of a particular life stage and gender group assumed to be adequate. AI is used when scientific data are insufficient to allow for the establishment of an RDA value.
Another standard is worth noting:Tolerable Upper Intake Levels (UL) – the highest average daily nutrient intake level that is likely to pose no risk of toxicity to almost all healthy individuals of a particular life stage and gender group. Consumption above this amount may pose a health risk.
Supplements are regulated in Canada, but not as rigorously as prescription medications
Natural and non-prescription health products (NNPHPs, formerly known as NHPs) are regulated in Canada under provisions of the Food and Drugs Act and Regulations (National Health Products Regulations). There is a separate and distinct regulatory framework for prescription drugs. According to Health Canada, “NHPs are regulated in a manner appropriate for the lower-risk nature of these products” which include: herbal remedies, some sunscreens, and vitamins and minerals.
The safety of health products, including human drugs, NHPs and medical devices is a shared responsibility between:Product license holders;
Companies that conduct activities such as manufacturing, packaging, labelling and importing health products;
Retailers; and
Health Canada.
Dietary supplements sold in the United States are not regulated.
Consult your health care provider before taking supplements
I know you’ve heard this before … and it’s important! When you read about the well-documented and numerous side effects, drug and/or treatment interactions of some of the most commonly used supplements, it becomes clear that people really should consult their health care provider before taking anything other than what’s been prescribed by the person who is most familiar with your health status. Why? Because …Much of the “research” conducted on dietary supplements is done by the manufacturers of those products. To me, this is an inherent conflict of interest. But, the same could be said of prescription drugs: large pharmaceutical companies do the bulk of drug research; however, the process they go through to get a medication approved for use in this country by Health Canada is much more rigorous.
Taking dietary supplements without the knowledge and oversight of your health care provider can be downright dangerous. Some supplements:
are contra-indicated (not recommended) for people with certain health conditions, or of no use whatsoever to people with other medical conditions;
can affect the results of certain laboratory tests, for example, heart and thyroid function tests;
interact with many classes of prescription drugs used to treat common health issues;
can interfere with health care treatment, such as chemotherapy and radiation treatment;
can have adverse effects depending on a person’s age, dietary habits, level of alcohol consumption and whether they smoke; and
can reach toxic levels when consumed in large amounts.
It’s important to consider the total amount of a specific micronutrient that you are consuming daily. For example, when considering how much of a specific supplement to take, you also need to think about how much may be contained in other supplements you are taking, such as a multi-vitamin, and how much you are getting from your food. When looked at in totality, you could possibly be getting more than the Recommended Dietary Allowance.
All dietary supplements are not created equally. If you and your health care provider decide that supplementation is required, be sure to buy one that has been third party tested. This will at least confirm that the product you’re buying contains the ingredients listed on the package and in the amounts stated. Look for products that are certified by NSF, or US Pharmacopeia or another reputable independent testing organization. And be sure to do your homework on third party testing organizations: some manufacturers have set up their own “independent” testing centres.
The bottom line? Vitamins and minerals play an important role in our health. Most of us can get what we need from a nutritious well-balanced diet. For those who can’t, supplementation under a doctor’s supervision may be necessary. Just because they are naturally occurring and sold over-the-counter, doesn’t mean they’re entirely safe in all cases and under all circumstances. Learning more about these micronutrients and consulting your primary health care provider before taking them is a good idea.