The American Journal of Medicine
Volume 121, Issue 2 , Pages 91-97, February 2008

Advising Patients Who Use Dietary Supplements

Division of General Internal Medicine, The Johns Hopkins University School of Medicine, Baltimore, Md.

Article Outline

Abstract 

Public use of dietary supplements is quite prevalent, with an estimated 1 of 5 patients using such substances in an effort to maintain or promote their health. Despite their popularity, patients and physicians are often unaware of the limited regulation of these products as well as their potential risks and benefits. Lack of physician knowledge in these areas has the potential to strain the doctor-patient relationship. In this review, we present a 6-step approach to advising patients who are considering use of dietary supplements. Our framework includes a discussion of regulatory issues, efficacy and safety, potential supplement-drug interactions, and monitoring for adverse events and therapeutic effects.

Keywords: Complementary and alternative medicine, Dietary supplements, Herbal medicine

 

The passage of the Dietary Supplement Health and Education Act (DSHEA) in 1994 significantly changed the way in which herbs, vitamins, and other supplements are regulated.1 As a result of its enactment, sales of dietary supplements have soared. Consumers presently spend in excess of 23 billion dollars every year on natural products marketed to maintain or enhance health.2 In 2002, nearly 20% of the population used over-the-counter supplements.3

Clinical Significance

 


•Although about 20% of patients use dietary supplements, they often fail to disclose this to their physicians.

•Because supplement use is potentially dangerous, physicians should encourage disclosure by inquiring directly and nonjudgmentally.

•Physicians should learn about supplement safety, efficacy, and regulation and discuss these issues with their patients.

•These measures will assist the patient in making informed decisions and potentially strengthen the doctor-patient relationship.

Dietary supplements are generally regarded by patients as safe. However, a number of adverse events have been reported over the past few years from the use of these natural substances.4 Concern over herb–drug interactions has also arisen.5, 6 Surveys suggest that approximately 16% of Americans who take prescription medications also ingest supplements.7 Additionally, patients often do not disclose their alternative medicine use to their health care providers,8 thus making identification of potential adverse events difficult. It is imperative for clinicians to openly discuss dietary supplement use with their patients in an effort to prevent untoward effects and strengthen the provider–patient relationship. Additionally, supplements may provide safe and effective alternatives to prescription medications (eg, fish oil for hypertriglyceridemia) or safe options for conditions for which there are no conventional treatments (eg, echinacea for the common cold). This article reviews the fundamental issues surrounding the use of dietary supplements and presents an approach to discussing these issues with patients.

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Reasons for the Popularity of Dietary Supplements 

The reasons for the popularity of supplements are numerous. A general theme underlying a majority of alternative therapies is their emphasis on natural modes of healing. Dietary supplements are easily accessible, relatively inexpensive, “natural” substances that are purported to improve or prevent a number of conditions. Herbs and vitamins are assumed to be milder and safer than human-derived medications. For many patients, the use of supplements represents an effort to take charge of and be instrumental in their health care. In some cultures, herbs and “traditional” or “folklore” medicine are integral aspects of normal everyday life, and may be the framework within which health in general is viewed. Some patients may also turn to supplements to fill the void created by the dearth of available preventive medications, while others see them as a quick, hassle-free cure to an underlying problem. This “cure” can potentially be obtained without the need for practitioner visits, lifestyle changes, or unpleasant procedures. Thus, patients have exerted more autonomy with regards to their health care. The distrust of the traditional medical system that has developed over the recent past has likely served as an impetus for seeking out such autonomy.9

Direct-to-consumer advertising has significantly impacted supplement sales. Companies have aggressively marketed their products to the public in print, on the radio, on television, and over the Internet. Some of these ads have been shown to contain exaggerated, misleading, or blatantly incorrect information.10, 11 The Federal Trade Commission, which oversees advertising, operates under the same basic guidelines for all consumer products such that “advertising for any product—including dietary supplements—must be truthful, not misleading, and substantiated.”12 While the Federal Trade Commission provides guidance and oversight, it does not “approve” individual product ads before their use. It instead relies on advertisement surveillance for enforcement of its guidelines.13 This surveillance has led to millions of dollars of fines being levied against companies making unsubstantiated or false claims.14

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Communicating With Patients 

There has been much discussion about shared decision-making and patient autonomy with regard to treatment choices. This has become an even greater issue given the pervasiveness of direct-to-consumer advertising. The promotion of patient autonomy has been shown in some instances to improve patient care.15 It is important for physicians to avoid a policy of displaying universal disdain for the use of supplements, as this can be detrimental to the physician–patient relationship and preclude patients from fully disclosing their use of herbs and vitamins. Adler and Fosket suggested that patients did not disclose their complementary and alternative medicine use to their physicians for a variety of reasons, including anticipating their physician’s disinterest, anticipating a negative response from their physician, or assuming that their physician lacked sufficient knowledge to contribute useful information.16 Surveys have suggested that most physicians have an open attitude toward alternative therapies,17, 18 but are limited with regards to their ability to discuss complementary and alternative medicine issues due to an inadequate knowledge base.19 The following 6 steps can assist physicians in engaging patients in discussions about their supplement use and enhance the shared decision-making process.

Step 1: Inquire About Supplement Use 

Effective physician–patient communication requires uninhibited disclosure by patients as well as thorough inquisition by physicians. Many patients might not volunteer their alternative medicine use (including dietary supplements) to their physicians, but they are willing to engage in discussion if asked. Physicians have generally avoided open discussion about such matters,20, 21 possibly due to their lack of knowledge.19 It is important for physicians to be forthright regarding their level of understanding, but they also should convey a sense of interest and willingness to learn about specific herbs, vitamins, and other nutraceuticals.

Inquiring about reasons for use of specific supplements is also important. Is there a cultural context that needs to be understood regarding the supplement use? What are the patient’s beliefs about their health and how do they think the supplement will affect their health? Is it being used for treatment of a specific condition/symptom? Or is it being used for possible preventive purposes? The significance of making these distinctions revolves around further discussions of safety and efficacy. For example, there are some, albeit limited, data supporting a positive clinical effect of saw palmetto on symptoms of prostatic hyperplasia.22 There is, however, no current clinical or epidemiologic evidence that saw palmetto is effective for preventing prostate cancer.23 Discussing these issues with patients enables them to perform a more informed cost-benefit analysis with regards to their supplement use.

Step 2: Evaluate the Supplement 

When doctors encounter patients taking or requesting a prescription for a medication that they may be unfamiliar with, they often consult texts or other references in order to educate themselves and potentially benefit their patients. This degree of investigation is not common when physicians uncover supplement use, however.24 Complicating matters further, dietary supplements are often sold as combination products, known by their trade names rather than their specific active ingredients. Supplements such as Cortislim (Window Rock Enterprises, Brea, CA) and Focusfactor (Vital Basics, Inc., Portland, ME) have become popular among the public, who may be unaware of the herbs and vitamins that they are ingesting. Physicians need to be aware of and have access to references that can help sort out the composition of these products and help describe any safety and efficacy issues. A number of such references are currently available (Table 1).

Table 1. Potential Sources of Information about Dietary Supplements
Internet
National Center for Complementary and Alternative Medicine


Office of Dietary Supplementshttp://ods.od.nih.gov/
Natural Medicine Comprehensive Databasewww.naturaldatabase.com
Natural Standardwww.naturalstandard.com
Consumer Labshttp://www.consumerlab.com/results/index.asp
Memorial Sloan Kettering Cancer Center Integrative Medicinewww.mskcc.org/aboutherbs
Cochrane Library’s field group in CAM website (CD-ROM available also)http://www.cochranelibrary.com
Print
Evidence-Based Herbal Medicine. Rotblatt R, Ziment I, Eds. Philadelphia, PA: Hanley & Belfus; 2001
Herb Contraindications & Drug Interactions, 2nd edition. Brinker F. Sandy, OR: Eclectic Medical Publications; 2001
Natural Standard Herb and Supplement Reference: Evidence-Based Clinical Reviews. Ulbrich CE, Basch EM. Philadelphia, PA: Elsevier; 2005
PDR for Herbal Medicines. Greunwald J, Brendler T, Jaenicke C, Eds. Montvale, NJ: Thomson; 2004

Step 3: Discuss Regulatory Issues Surrounding Dietary Supplements 

It is imperative that we make our patients savvy consumers. Under DSHEA, supplements are not required to have Food and Drug Administration (FDA) approval before their production or distribution. Efficacy and safety studies are unnecessary before product marketing. Dietary supplements are assumed to be safe unless proven otherwise by the FDA through postmarket surveillance.25 This is in stark contrast to the regulation of drugs, which require extensive premarket safety and efficacy data and FDA approval. Additionally, until recently, regulations to ensure product content and quality have been lacking. This has lead to significant variability in the composition of supposedly similar dietary supplements and a lack of standardization.26 Cases of dietary supplement adulteration have also been reported,27as was the case with PC SPES, a product that was initially thought to be a promising for treatment of prostate cancer (PC standing for “prostate cancer” and SPES being Latin for “hope”) but was found to be adulterated with diethylstilbestrol (a synthetic estrogen), warfarin, and indomethacin.28

Unfortunately, the public appears unaware of the lack of governmental oversight of dietary supplements, and may be making uninformed choices regarding their use of these substances.29, 30 Many physicians are also unfamiliar with these regulatory issues.31 The passage of DSHEA was thought to be an act that would enhance patient autonomy. Yet, in order for an act to be truly autonomous, a substantial degree of understanding should be present.32 Physicians have a responsibility to educate their patients about supplement regulation, not to dissuade their use, but to ensure that a truly informed choice is being made.

In an effort to address issues of product quality, the FDA has just issued its final rule establishing Good Manufacturing Practices for all dietary supplement companies.33 The rule should take effect in June 2008 for large companies. Smaller companies have been given more time to comply with the regulations, which will be enforced by random FDA audits. Good Manufacturing Practices include quarantining herbs, proper identification of herbs based on their chemical composition, and pharmaceutical grade production practices. Until all manufacturers are in compliance, physicians should tell their patients who are interested in supplements to look for the symbols GMP (Good Manufacturing Practices), NSF (National Safety Foundation), or USP (United States Pharmacopeia).

Step 4: Discuss the Available Safety and Efficacy Data 

There are only limited data on the efficacy and safety of many of the dietary supplements currently available. Most clinical trials have been small, nonrandomized, or unblinded. Recently, some well-designed trials have been published that have given physicians some cogent data to discuss with their patients. Additionally, a number of systematic reviews have been published on a variety of supplements. As a complement to the resources listed in Table 1, physicians can find easily accessible information on a number of commonly used supplements by searching medical databases such as Medline and Cinahl.

In addition to side effects that can occur with the use of dietary supplements, physicians need to be aware of potential supplement-drug interactions. For example, St. John’s wort (Hypericum perforatum) has been shown to potentially decrease the levels of a number of commonly used drugs, including protease inhibitors,34 warfarin,35 and some hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins).36 Table 2 lists potential uses, efficacy, side effects, and drug interactions of a few popular supplements.

Table 2. Commonly Used Dietary Supplements
SupplementCommon UseEfficacyAdverse EffectsPotential Drug Interactions
Bitter orange (Citrus aurantium)Weight lossNo data to support effectiveness37Case reports of myocardial infarction,38 stroke,39 and syncope40Avoid use with other stimulants due to theoretical risk of cardiovascular toxicity
Black cohosh (Actaea racemosa)Menopausal symptomsSome short-term (<12 weeks) studies have suggested a benefit,41 but the most recent 1-year study did not42Mild gastrointestinal symptoms; case reports of hepatitis and fulminant hepatic failure43None known
Coenzyme Q10Heart failure, hypertension, angina, Parkinson diseaseData inconclusive for treatment or prevention of cardiovascular disease;44 early data promising for slowing the progression of Parkinson disease in high doses45Generally well toleratedMay decrease the INR in patients on warfarin46
Cranberry (Vaccinium macrocarpon)Urinary tract infections (UTI)May have a role in preventing UTIs47; no evidence to support its use for treatment of UTI48Generally well toleratedMay increase the INR in patients on warfarin49
Echinacea (E. purpurea, E. pallida, E. angustifolia)Upper respiratory infectionsVariations in types of extracts studied and conflicting results make conclusions regarding efficacy difficult50Generally well tolerated; hypersensitivity reactions have been reportedAvoid in patients taking immunosuppressants51
Ginkgo bilobaDementia, claudication, tinnitusSome data suggest modest improvement in cognitive performance in patients with dementia52Case reports of spontaneous bleeding53 and seizures54Avoid in patients using anticoagulants due to possible increased risk of bleeding
Ginseng (Panax spp; Asian ginseng, Korean ginseng, American ginseng)Diabetes, fatigueInsufficient evidence for its use at this time55, 56Generally well tolerated; case reports of hypertension, insomnia, vomiting, headache, vaginal bleeding, Stevens–Johnson syndrome, and mastalgia51May decrease INR in patients on warfarin57
Glucosamine and chondroitinOsteoarthritisMay be beneficial but effect may be dependent on preparation58Generally well toleratedNone known
Kava kava (Piper methysticum)AnxietySuperior to placebo for short-term treatment of anxiety59Sedation, rash; liver toxicity and fulminant hepatic failure have been reported60Avoid use with anxiolytics or alcohol due to risk of excess sedation
St. John’s wort (Hypericum perforatum)DepressionConflicting study results61Can cause irritability, insomnia, dizzinessAvoid use with SSRIs due to risk of serotonin syndrome; decreases levels of a number of drugs (see text)

INR=international normalized ratio; SSRIs=selective serotonin reuptake inhibitors.

Given inherent time constraints, physicians’ lack of knowledge of supplements, and limited definitive data regarding interactions, it is virtually impossible for physicians to be aware of all possible adverse reactions that may result from combining herbs and drugs. However, it is important for clinicians to be aware of available resources that can assist in protecting patients from potential untoward effects. In addition to the print and online references listed in Table 1, physicians can take advantage of the expertise of the clinical pharmacists at their hospitals or in the community. Pharmacists often have access to databases that can quickly cross-reference drugs and supplements to assess for interactions. In order to use this service at local pharmacies, it is important for physicians to advise their patients to disclose their supplement use to their pharmacist.

Step 5: Compare Risk/Benefit of Use to Available Conventional Therapies 

Patients often choose to use dietary supplements over prescription or nonprescription medications due to their awareness of potential adverse effects from medications. They may not be aware of such effects from the use of a specific supplement. Physicians should discuss the available conventional options and compare them to the benefits and risks of supplement use. Two examples highlight such an approach:

Example 1 

A 46-year-old woman with obesity, hypertension, and diabetes presents with concerns about her weight. She states that she has been exercising 5 days per week and has been fairly strict with her diet but has not been able to lose more than 5 pounds over the last 6 months. Her thyroid function is normal. She wants to start taking a supplement she found on the Internet that advertised that it was “clinically proven” to cause weight loss. By looking at the advertisement, you discover that the probable active ingredient in the supplement is bitter orange.

Although it may be easy to just say to the patient that you do not believe in weight loss supplements, this approach may be deleterious to the physician–patient relationship. After a discussion about the regulatory issues surrounding supplements, you can report that there is currently no evidence that the supplement is effective and that there have been reports of serious side effects from the active ingredient in the supplement. As an alternative (if you are comfortable recommending medications for obesity), you may wish to discuss the efficacy data for a medication such as orlistat and its potential side effects and cost. This will provide the patient with considerably more information regarding choices for treatment of her obesity.

Example 2 

A 72-year-old gentleman with a history of recent gastrointestinal bleeding due to peptic ulcer disease presents to discuss treatment options for his osteoarthritis, which predominantly affects his knees. He was told to avoid aspirin and ibuprofen after his discharge and he notes that acetaminophen does not give him relief. He wants to discuss using a glucosamine preparation.

It is much more difficult in this case to recommend conventional therapies. You want to avoid nonsteroidal anti-inflammatory medications given his recent bleeding episode. You could start him on a narcotic medication but that can cause significant toxicity as well. Despite limited evidence of efficacy, it may be reasonable to agree with his use of glucosamine sulfate, given its safety profile, and follow his symptoms. Again, you should discuss supplement regulation and the fact that not all glucosamine products are equivalent. You may even wish to recommend a specific preparation, given that a number of the positive studies were done on preparations manufactured by one company (Rotta Pharmaceuticals, Wall, NJ).58

Step 6: Monitor for Adverse Events and Therapeutic Response 

Although most dietary supplements may be safe, adverse events and drug-supplement interactions can occur (Table 2). It is important for physicians to monitor for such occurrences and report any suspected cases of significant toxicity to the FDA. This can be done by accessing the FDA MedWatch system.62 Reports can be filed online or by mail, fax, or phone (1-800-FDA-1088). Definitive proof of the toxicity of a supplement is not required before filing a report. Rechallenge to prove causation is not recommended.

In addition to monitoring for safety, physicians should also monitor for response. Readdressing treatment after a number of weeks of therapy is commonplace for conventional medications and should also occur with dietary supplements. For example, a 67-year-old woman presents for follow-up 12 weeks after starting on a glucosamine preparation for her pain from osteoarthritis of the knee. She notes no symptomatic relief or functional improvement. Even though there is some evidence for a disease-modifying benefit from glucosamine,58, 63, 64 most positive studies used pain and function as their primary outcome, and most subjects who saw benefit responded within 3 months.58 This should be discussed with the patient, so that she can make a decision whether to continue to spend money on the same supplement, spend money on a different brand, or abandon its use altogether.

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Conclusion 

The passage of DSHEA has given the public access to a plethora of products marketed to promote or maintain their health. It has also resulted in a communication gap between physicians and patients. Even today, most physicians-in-training have little exposure to dietary supplements and are ill-equipped to deal with such issues. By following a systematic process, which requires continuing education, physicians can become more comfortable discussing use of these products and bridge the gap that currently exists.

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Acknowledgments 

We thank Tieraona Low Dog, MD for her review of the manuscript.

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References 

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PII: S0002-9343(07)01136-9

doi:10.1016/j.amjmed.2007.10.031

The American Journal of Medicine
Volume 121, Issue 2 , Pages 91-97, February 2008

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