Unfortunately, there are many:
- Quality. As detailed in today’s Wall Street Journal, when supplements are submitted to quality testing, about 25% have problems like contamination or mislabeled dosage. In some cases, that contamination can be quite dangerous such as with lead.
- Safety. Herbal supplements aren’t subject to the same kind of testing that pharmaceutical drugs have to go through. This often means unsubstantiated claims and little information about risks associated with long term or high dosage use.
- Research quality. Many of the claims made about supplements are backed by research. Unfortunately, the fine print often reveals the research was funded by the supplement maker. The potency of plants can often vary as well – so the variety tested in the research study may not be the one included in the supplement you buy. In many instances, the studies are also very small or not well designed, which makes for less reliable results, something often missing from the scientific pedigree supplement makers list in their ads or on their websites. That many people who write about the benefits of these supplements don't have a great understanding of the research process, and what may seem in an article to be rock solid health benefits of a supplement, may be little more than anecdotal evidence.
- Reductionism. Reductionism is when a single component of a whole food found to have health benefits is put into a supplement and assumed to have the same (or greater) health benefits of the whole foods. The food is "reduced" to a single component, usually with mixed results. The classic example is beta-carotene. Studies had found that individuals who consumed higher amounts of fruits and vegetables had lower rates of lung cancer. Researchers hypothesized that this was due to the antioxidants (like beta-carotene) found in fruits and vegetables and began randomized controlled trials to see if these individual components had any health benefits in smokers. The results were surprising. Lung cancer rates were HIGHER in the groups taking beta-carotene. These results don’t mean you should go off and eat Twinkies instead of carrots, but they do suggest that extracting one component from a food doesn’t always lead to the desired result.
- Extrapolation. Extrapolation is taking a narrow set of results and applying it to broader populations. It's a common practice, particularly in health news stories, and while it makes for great headlines, it often results in over-reaching. Supplement makers do the same. A small study in mice or cells in a petri dish can have seemingly astounding results - but the problems is that these studies are in....mice and cells. Animal and cell studies are just a starting point in the research process, and more often than not the results don't pan out in good studies in humans. It is also important to note that the doses of supplements and extracts applied to animals and cells in the laboratory often exceed those that humans would (or could) consume. The big concern here is that these extracts and compounds, tested in labs, will result in the same unanticipated consequences that beta-carotene did on lung cancer when tested in humans. Of course, there is also the possibility that they will have benefit, but until they are evaluated, we just don’t know.
What we worry about are the health claims many supplement makers and other proponents make that over-reach (often by a great deal) what the science has to say about both the effectiveness and the safety of their products.
In this day of ever-growing health care costs and tight budgets, it's only natural that we want to take control over our health, and turning to supplements can seem like an easy route to take. But, it's important to know about some of the potential pitfalls with supplements so you can make good, informed decisions about your health. Most of the time, the best choice is to keep those supplements on the store shelves and go for a good walk instead. Focus on fruits, vegetables, and whole grains, trying to get a wide variety of each. A single 100% RDA daily multivitamin is also a good nutrition insurance policy for most people.