By David Kiefer, MD, Editor
There are two primary methods to determine which of your patients might be using dietary supplements (DS). The first and most obvious approach is to simply ask them; more and more health care providers are including the use of integrative therapeutics as part of every history for every clinic visit. This is also now basic training in most clinical programs, as well as the "H," or "Hear," in the oft-used H.E.R.B.A.L. mnemonic.1 The second main option for answering the question "Who is using what DS?" is to rely on the many surveys that have made their results known in the medical literature. Surveys and other population reviews have painted a relatively clear picture of the typical person who has decided to incorporate DS as part of his/her treatment approach for a variety of medical conditions or for general health. Having this image in mind and trying to match it with one’s own patient population can be useful in predicting patterns of integrative medicine use and guiding relevant communication.
Numerous surveys have been done to ferret out the demographic(s) using DS. This article is a review of representative general surveys, including commonly cited nationwide or regional research efforts. The goal was to focus on DS use in the Untied States, split into several categories as outlined below. It was beyond the scope of this review to comment on specific supplement use (i.e., calcium, specific vitamins, or specific herbal medicines) for specific diagnoses; articles to this effect are a common part of PubMed publications and topics covered by Integrative Medicine Alert.
World Dietary Supplement Use
Providing some context to U.S. DS use, this component of integrative therapy is common throughout the world. The term "dietary supplement" is not universally used throughout the world, so it is difficult to pin down exact figures for world DS use; some foods, for example, are eaten regularly for their therapeutic benefit, much as herbal medicines or capsules would be ingested in the United States. Nonetheless, some surveys have estimated that herbal medicine, one component of DS, is a common treatment throughout the world. More specifically, it is estimated that 80% of people rely on traditional medicine, which is mostly herbal medicine, to meet their primary health care needs.2,3
Dietary Supplement Use in the General Population in the United States
U.S. DS use prevalence data list percentages less than the above-mentioned world estimate. For example, one of the most well-known surveys, The National Health and Nutrition Examination Survey (NHANES), has had several iterations, the most recent of which, from 2007-2008, asked 3364 people aged 20-69 about both their nutrition and food intake and their dietary supplement use.4 In this survey, "supplement" included vitamins and minerals, and the products were verified verbally or visually. This analysis found that 47.7% of study participants reported taking at least one dietary supplement in the past 30 days. The typical dietary supplement user in this population was non-Hispanic, white, female, older, with more education, and in a "food secured" household. Given the popularity of vitamin use and resulting supra-RDA dosing in the study population, the authors make a case for concern about the over-fortification of the food supply for certain nutrients, the details of which they leave to FDA policy makers and future research.
The National Health Interview Survey (NHIS) is another survey method that was used to measure dietary supplement use from 1999 onward.5 The researchers asked non-institutionalized adults about their "herb and non-vitamin supplement" use, ever, in the past 12 months, or in the past 30 days, with some slight differences in the way the questions were worded between 1999, 2002, and 2007. Whereas there was an increase in DS recent use (in the last 12 months) between 1999 (9.6% of adults) and 2002 (18.9%), there was a slight decrease in use by 2007 (17.7%). Subgroup analyses seemed to indicate that this drop in herbal use was in adults aged 18-64, people with financial constraints, women, nonwhites, and Hispanics, whereas people aged ≥ 65 years had a significant increase in herbal usage between 2002-2007. The lower percentages listed here when compared to NHANES are likely due to the fact that vitamins and minerals were not included.
Specifically with respect to herbal medicines, an analysis of the Alternative Health Component to the 2002 NHIS found that 19% of U.S. adults used "natural herbs with medicinal properties" for their own health and treatment.6 Herbal users were likely in the age group 45-64, uninsured, female, "non-Hispanic" other, and located in the Western United States. Subsequent analyses of this database from 2007 found that 17.7% of adults used "nonvitamin, nonmineral natural products."7
DS Use in Children
Again, using the NHIS from 2007, adults answered questions about DS use in children in the household.8 The adults were asked whether or not the child used supplements in the past 30 days, and the diagnosis for which supplements were taken. DS included 45 herbal medicines and non-vitamin, non-mineral supplements (NVNM), 20 multivitamin mineral supplements, and single-vitamin mineral supplements. Overall, 37% of children were using some form of DS, and this use was equal between boys and girls, but more likely in Caucasians and Asians, those children in better health, children with higher parental income and education, and children living in the Western United States. Multivitamin mineral supplements were the most common DS used in children. All told, the authors extrapolated to the U.S. population by saying that they estimated 1.5 million children used NVNM supplements in 2007, and that there was a concern about adverse effects from this class of supplements in this demographic. A parallel analysis of the same dataset further clarified the specifics of DS use in children ages 4-17 and found 3.9% used "herbs or dietary supplements" in the past 12 months, most commonly echinacea and omega-3 fatty acids.9 The authors were optimistic about the overall DS use situation given the "good safety profile" of the two leading products, but still emphasized the importance of inquiring about DS use in every clinical encounter.
DS Use in Older Adults
Data to this effect can be gleaned from some of the aforementioned studies, but one study commissioned by the AARP and the National Center for Complementary and Alternative Medicine (NCCAM) deserves mention.10 A telephone survey of 1559 adults aged 50 and older found that 42% used "herbal products or dietary supplements."
Ethnic and Racial Differences in DS Use
When trying to learn about the totality of DS use, the medical literature speaks to the importance of considering ethnic and racial patters of use. One systematic review of herbal medicine use articles found rates of "natural products" use of 17% for African Americans, 30% for Latinos, and 30% for Asians,11 the latter two above the overall U.S. rates. These are compiled rates, but the individual studies document a range of results based on variability in inclusion criteria, demographics, health conditions, U.S. geographic location, and countries of origin. Depending on the exact characteristics of the study population(s), DS use prevalence may vary significantly. For example, herbal medicine use by Latinos, as documented in the medical literature, ranges from 4-100%. For clinicians working with racial or ethnic minorities, or immigrant populations, these and other results have led most experts to recommend a thorough DS intake and documentation of traditional medicine use in these populations.12
Nuances about DS use
Most surveys about DS use have included some discussion about disclosure to health care providers. Invariably, disclosure rates are low, setting up a situation that has room for improvement in DS efficacy and safety. For example, the AARP/NCCAM study documented that only 31% of people had discussed complementary and alternative medicine (CAM) with their health care provider.10 Men and those > 65 years of age were less likely to disclose CAM use. This survey, however, did not split out DS disclosure from CAM as a whole. Other surveys, though, support low DS disclosure rates, especially in minority populations.13,14,15 These rates range from 33-79%.
Related to the low disclosure rates, and an issue addressed by some of the national DS use surveys, is the phenomenon of adverse plant-pharmaceutical interactions (APPI). With such common DS use, and, especially in older people, the concomitant use of pharmaceuticals, the risk of APPI is not insignificant. In one survey, for people taking herbal medicines, 72% were also taking prescription drugs and 84% were taking over-the-counter preparations.6 In addition, research in multi-ethnic herbal medicine users showed that 40% believed that combining plants with pharmaceuticals had a synergistic effect.16 Even though APPI may be rare, mild, or self-limiting,17 it is enough of a concern among researchers and clinicians that the term "polyherbacy" is being used to refer to people using multiple DS, putting them at risk potentially as much as with situations involving "polypharmacy."18
The bottom line is that your patients are using DS and routinely should be asked about them. This is especially true for adult patients who are female, aged ≥ 45 years, non-Hispanic white, and uninsured. However, people of almost every ethnic group, age, and part of the United States show not insignificant DS use. Disclosure rates are negligible for most people. Although many different types of DS are being used for a variety of diagnoses, this extensive topic is beyond the scope of this article. This review of some of the primary recent published surveys confirms what most clinicians already know, namely that DS use is common (and increasing) and needs to be a part of every clinical encounter. The literature can guide our efforts at learning about patient DS use, or confirm our hunches, but focused communication with patients about this topic is key when it comes to assuring that people are using DSs safely and appropriately.
Asking about, or "hearing" (as with H.E.R.B.A.L.), DS use is a crucial part of every clinic visit. This step can be incorporated into any health care system by using an electronic medical record tool (many of which now allow this section to be populated), enlisting the help of ancillary staff, or adding a quick extra question or two to a typical medical/health history. The extra few seconds of data gathering do not compromise the clinic flow of even the busiest health care provider, and yield a rich trove of information that will improve patient care, communication, and satisfaction.