Dietary Supplements: What PTs Need Know | Modern Manual Therapy Blog - Manual Therapy, Videos, Neurodynamics, Podcasts, Research Reviews

Dietary Supplements: What PTs Need Know

Dietary Supplements: What PTs Need Know -

By Dr. Sean M Wells, DPT, PT, OCS, ATC, CSCS, CNPT, NSCA-CPT, Cert-DN

Three out of four Americans takes some form of dietary supplement every day. From multivitamins to weight loss supplements, the list of dietary supplements is long and the associated costs can be substantial. Physical therapists (PTs) work with a wide range of patient types, many of whom are actively taking supplements for health, to slow aging, or in hopes to reverse a disease state. Obviously these supplements must have some positive impact on our health, right? Doctors of physical therapy (DPTs) are becoming more holistically trained to understand the role of nutrition and dietary supplements: despite this, the answer to above question is convoluted and may even surprise you.


Dietary supplements are not regulated by the Food and Drug Administration. This is vastly different than the drugs that many of our patients are taking. The lack of regulation should be a mainstay reason why many PTs ought to educate their clients on being skeptical about dietary supplements. Regulation is vitally important to ensuring that an active ingredient is actually in the supplement, at the right dose, and is safely efficacious. 

Surprisingly many supplements fail to meet any of these standards. One research article shows how supplemental manufactures can accidently produce too much of a vitamin, which can cause hypervitaminosis and illness. In this example a manufacturer accidentally put too much vitamin D in their product, causing multiple causes of reported vitamin D toxicity. Imagine the number of unreported illnesses.

Another issue with the lack of regulation is that manufacturers may actually put real drugs in their supplements. The most popular supplements for Americans, from most to least, are for general health, physical performance, and sexual enhancement. The Journal of the American Medical Association (JAMA) published a nice review article highlighting how many sex enhancing supplements simply contain real drugs. The authors cite, "Rock Hard for Men (manufacturer unknown), sold as a “natural” supplement, actually contains 2 potent prescription drugs—a phosphodiesterase-5 (PDE-5) inhibitor, tadalafil, and a sulfonylurea, glyburide." As such, people are getting real benefits from these supplements, but unfortunately a Wall Street Journal article revealed that most of these sex enhancing supplements are simply tainted with real drugs.

Being tainted with an actual drug is a problem but contain toxic compounds is another major issue with supplements. Several researchers have shown that most milk thistle supplements are tainted with a type of mycobacterium, which can cause serious health issues. Reports of creatine containing bacteria have also been a concern for many fitness-focused patients. Many cardiac rehab patients ask me about taking fish oil supplements, many which are chock full of dioxin, mercury, or lead -- why not just eat real fish? Lack of regulation is the major driver for why we see drugs and toxins in our supplements and PTs must know about this!

Such taintedness can pose a real problem for medical doctors and DPTs when working with patients. As we work with patients these drugs can cause, unknowingly to all, severe side effects like dizziness, headache, and back pain -- all conditions commonly treated by PTs! Even a prudent DPT may not catch these side effects from a tainted supplement. Consider how many times you ask patients what supplements they are taking. Next, think about if you would even consider that the supplement would be tainted with an actual drug...the chances are slim, even for medical doctors.

The final issue with lacking regulation is that the supplement may actually cause overt harm. While this is rare it can happen. Consider the ephedra supplement trend about 20 years ago. Nearly 42% of Americans are obese, so weight loss supplements are seen as that "extra edge" for many hoping to shed pounds. Ephedra, a stimulatory dietary supplement, promised to help many lose weight by stimulating their metabolism. The supplement worked great but it also caused many cases of cardiac and neurological issues. The most commonly reported conditions, as cited in this New England Journal of Medicine Journal article, included hypertension, palpitations, stroke, and seizures. Obviously ephedra came under much scrutiny and was later banned by the International Olympic Committee (IOC) and FDA; however, many manufacturers still produce products with similar alkaloid compounds intended for weight loss.

PTs should educate clients that supplements lack regulation, may be tainted with real drugs, and could cause harm. The harm may extend beyond an expensive bottle of pills -- people die every year from dietary supplementation.


Supplements can have varying doses from bottle to bottle or even pill to pill. The variance in dosing can make it very difficult for healthcare providers to prescribe the right amount of a supplement. That is why many medical doctors and registered dieticians (RDs) recommend the use of NSF or USP certified supplements. While even these supplements are perfect they offer more rigorous independent testing with an increased cost to the consumer. 

Now, assuming you have a quality supplement how does a person or healthcare provider know the recommended dose to take? This depends on many factors, including how old the person is, what their serum or tissue concentration is of that nutrient, and the patient's size. Much of these detail exceed the scope of this blog post; regardless, blindly taking even benign supplements at moderate doses for a long period of time can still cause toxicity and issues. Take for example this vitamin D toxicity review article where the authors report cases of people taking moderate doses of vitamin D for years. The subjects developed chronic vitamin D toxicity -- it happens because we don't have data driving the appropriate dose. PTs should exercise caution when recommending supplements to clients, especially when limited data is available to drive individualized recommendations -- a safe bet is to recommend a supplement at the Recommended Dietary Intake or below, but even this may not be sufficient for those severely deficient.


It goes without saying that if you have a unregulated product with varying doses (or possibly no active ingredient at all) how do you get a desired response? Examining the literature from many systematic reviews, the data show that many dietary supplements have little to no impact on aging, cancer, heart health, pain, or performance. If there are small changes in some of these factors they are often of small magnitudes. For instance, several studies tout the benefits of green lipped mussels for joint arthritis. The reduction in knee pain scores is roughly 1 out of 10, which does not exceed MCIDs. Perhaps the patient should reduce their sugar or alcohol intake versus taking an expensive and strange substance.

In the end, PTs need to educate clients on the risk of supplementation versus the benefit. Speaking with the primary physician may help, but ultimately an RD and thorough review of the literature can show how little most supplements benefit our PT clients.

We cover more of the efficacy of supplements in our 3 courses of nutrition education for physical therapists and physical therapist assistants.  If you like what you see here then know there is more in our 3 board-approved continuing education courses on Nutrition specific for Physical Therapists. Enroll below in our new bundled course offering and save 20%, a value of $60!

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