How Pharmacies and Retailer Shops Convey Information on Health Products to Their Customers

Abstract

Introduction

Natural health products are frequently used by many people. However, many of these individuals do not discuss these products with their physicians, and instead seek information about the products from pharmacies or natural health product retailers. Previous research has shown that not all pharmacists are comfortable answering questions about these products as they receive little training in this area; natural health product retailers are unregulated and receive training at their own discretion. This study aimed to evaluate the accuracy of the information provided by pharmacies and natural health product retailers pertaining to use, adverse effects, and potential drug interactions for four currently popular products: garlic, peppermint, black licorice, and apple cider vinegar.

Methods

The literature surrounding these products was reviewed and compared to information provided by pharmacies and natural health product retailers. The interviews were conducted by an investigator who presented as a potential client to closely mimic real-world interactions. Statistical analysis was limited to generating proportions and 95% confidence intervals for statements made about each product.

Results

Overall, 10% of statements that were made regarding the uses for the four natural health products were consistent with the evidence-based literature, 40% of statements were consistent with the common use of the products, 47% of statements were inconsistent with the literature and 3% of statements reflected general opinions about the product. There was variation in the accuracy of statements depending on which product was discussed. When discussing adverse effects associated with the products 38% of statements made by pharmacists and 44% made by NHP retailers were consistent with the literature. Sixty-nine percent of pharmacists and 44% of NHP retailers correctly identified potential drug interactions for the products.

Discussion

The majority of statements were consistent with common use but few evidence-based statements were made and a large proportion of statements that were inconsistent with literature were made. Most interviewees required prompting to discuss adverse effects and potential drug interactions.

Conclusions

This study highlights a need for increased training of pharmacists and natural health product retailers to ensure that they are familiar with these popular natural health products and can provide accurate information to clients regarding use, adverse effects, and possible drug interactions.

Introduction

Natural health products (NHP) are defined as vitamins, minerals, homeopathic products, herbal supplements, traditional therapies, amino acids, probiotics, and some personal care products. ¹ Surveys have indicated that 60% of the population use NHP and this number is steadily increasing, especially in persons of older age and with chronic health conditions.^2–4 Patients use NHP both as treatments and as preventative therapies. ⁵ Patients may begin taking NHP for a variety of reasons, including dissatisfaction with pharmacotherapies, as a part of traditional cultural practices, concerns over resistance to medications, and a belief that NHP are safer and have fewer adverse effects than pharmacotherapies.^3,5 NHP are usually not covered under drug benefit programs and patients pay out of pocket for these therapies. ³

In North America, NHP are regulated by the FDA, Health Canada and the Federal Commission for Protection against Sanitary Risk (COFEPRIS), although there have been issues in the past with product contamination, adulteration and deceptive advertising in some markets.^1,5 Due to the fact that NHP can be purchased over the counter, many patients self-prescribe. ² Even with the large number of patients taking NHP, few of these individuals inform their doctors of their use. ⁶ Patients may not share this information with their doctor because they are not specifically asked about their use, because they fear judgment, or because they have had a prior negative experience with a physician regarding NHP.^2,3,6 This is particularly concerning since NHP have the potential for adverse effects and drug interactions, much like prescription and OTC pharmacotherapies.

Research has shown that patients are more likely to seek advice about NHP from pharmacists or NHP retailers, than their doctor.^2,4 This means it is important that pharmacists and NHP retailers provide accurate information about the use, adverse effects, and potential drug interactions of the NHP that they sell. Pharmacists undergo educational training in pharmacology and other relevant areas as part of their postgraduate education; this training involves some study of NHP and how to provide counseling to patients regarding them. ⁴ Pharmacists are also regulated by a national governing body. ⁴ NHP retailers are hired by the retailer they work for; their backgrounds vary as each retailer has discretion about what qualities they look for in applicants. Any training that NHP-retailers receive is also at the discretion of the retailer they work for as NHP-retailers are not a regulated profession. ⁴ NHP retailers do not require specific training above that provided by the store they work in, and pharmacists receive little training in counseling surrounding NHP and often feel ill prepared to discuss these products. ⁴ Therefore, it would be important to assess the accuracy of the information provided to patients from these providers.

Garlic, peppermint, black licorice, and apple cider vinegar are popular commonly used NHP (Table 1). Garlic and peppermint are two products that have been used for a long period of time and are well studied. Garlic has some evidence for benefit in the prevention of the common cold and reducing blood pressure; it has also been commonly used for reducing cholesterol and managing peripheral vascular disease, albeit without strong evidence.^7–10 Garlic can result in the adverse effects of halitosis, diarrhea, emesis, and hypersensitivity, and can have interactions with warfarin or other anticoagulants or antiplatelet agents resulting in increased risk of bleeding.^7–10

Table 1.

Evidence-Based Use, Common Use, Adverse Effects, and Possible Drug Interactions Associated With Popular NHPs Garlic, Peppermint, Black Licorice and Apple Cider Vinegar.

	Uses	Adverse Effects	Interactions
Garlic	Evidence-based: prevention of common cold, reduction in blood pressure Common use: reduction of cholesterol, improve peripheral vascular disease	Halitosis, diarrhea, emesis, hypersensitivity	Anticoagulants or antiplatelet agents – increased risk of bleeding
Peppermint	Evidence-based: reduce pain/discomfort in IBS Common use: reduce nausea/emesis	Dyspepsia, hypersensitivity	Cyclosporine (inhibits CYP3A4)
Black licorice	Evidence-based: treatment of benign prostatic hypertrophy, reduction of insulin resistance, prevent postoperative sore throat Common use: liver disease, treat stress or menopausal symptoms, treat infection	Hypertension, hypokalemia, hypersensitivity	Cyclosporine and methotrexate (induce CYP3A4)
Apple cider vinegar	Evidence-based: none Common use: reduce inflammation, antibacterial, antifungal, treat delayed gastric emptying, weight management	Hypersensitivity, otherwise unknown	Unknown

Information was obtained by reviewing available literature for each product. common use is popular use but where there is an absence of evidence to support that use.

There is evidence that peppermint can reduce the pain and discomfort associated with irritable bowel syndrome (IBS) and is also commonly used to reduce nausea.^11,12 Peppermint can have the adverse effects of dyspepsia, hypersensitivity, and inhibition of the CYP3A4 enzyme resulting in potential drug interactions with medications such as cyclosporine.^11,12

Black licorice and apple cider vinegar have been studied less thoroughly and only more recently have become popular. Black licorice has some evidence for use in the treatment of benign prostatic hypertrophy, reducing insulin resistance and in preventing postoperative sore throat. Common uses include the management of liver disease, to reduce stress or menopausal symptoms and to treat infections.^13–20 Black licorice can have severe adverse effects associated with hypertension, hypokalemia and hypersensitivity as well as cause the induction of CYP3A4 enzymes resulting in drug interactions with medications such as cyclosporine and methotrexate.^13–20

Apple cider vinegar has no evidence in the scientific literature to support its use, however it is commonly used as an anti-inflammatory, an antibacterial or antifungal product, to treat delayed gastric emptying and for weight management.^21–25 The adverse effects of apple cider vinegar are largely unknown aside from hypersensitivity; the potential for drug interactions is unknown.^21–25

Methods

A review of the literature was conducted to identify the evidence for the use, adverse effects and drug interactions pertaining to garlic, peppermint, black licorice, and apple cider vinegar. Garlic and peppermint are well established NHP, and so multiple Cochrane Reviews were evaluated and adopted as the literature base for these products. As black licorice and apple cider vinegar are less well studied, all available primary studies and meta-analyses were reviewed for the literature base of these products. The information obtained regarding use was categorized as either evidence-based or a reflection of common use.

A list of all possible pharmacies and NHP retailers within the city of Hamilton, Ontario was generated (farmers markets and online-only establishments were excluded). A random number generator was used to determine which establishments would be visited for an interview. No more than two of the same chain of store were visited. The selection process was repeated until eight pharmacies and eight NHP stores were visited; visits occurred between November 2019 and March 2020. When visiting the stores, the researcher presented themself as a potential client, identified the products to be discussed and approached the first available sales associate in the pharmacy or NHP-retailer and asked if someone could provide them with more information about the products. This allowed an opportunity for the most knowledgeable person to be called if desired, and most closely mirrored how lay people may shop for products. The researcher then stated that some of their friends had recommended the products to them and wondered if they could receive more information about them. The interviewee was then allowed to speak uninterrupted about the product; if they did not mention uses, adverse effects or interactions these were prompted by a direct question once. If the interviewer was asked about their own medical health, they said that they were healthy and occasionally took Tylenol (acetaminophen) or Advil (ibuprofen) as needed. The interviews were recorded with a concealed audio recorder, to assist in the recollection of data collected after leaving the store. Once the data was extracted from the recording and anonymized, the audio recording was destroyed; no identifying data were included in the data analysis aside from whether the store was a pharmacy or an NHP-retailer. Overall, the interactions were designed to mimic a usual or customary interaction between a customer and a sales associate or pharmacist.

The data were analyzed by comparing it to information provided in the literature regarding each product. Statements pertaining to use that were made in the interviews were categorized as being either evidence-based, consistent with the common use of the product, inconsistent with the literature, or as a general opinion about the product. Similarly, statements were assigned as either in agreement or disagreement with the literature with respect to adverse effects and possible drug interactions for each product.

Analysis of this descriptive data was limited to generating proportions and where applicable 95% confidence intervals.

Results

Overall, 10% of the statements made regarding the use of the four NHPs were consistent with the evidence-based literature for the products and 40% of the statements were consistent with the common use of those NHP (Table 2). At pharmacies, the described use for the products was consistent with the evidence-based literature in 8% of interviews whereas NHP-retailers described evidence-based use in 11% of interviews. Statements consistent with the common use of the products were made 45% of the time in pharmacies and 37% in NHP-retailers. Statements inconsistent with either evidence-based or common use were made in 47% of interviews (39% of pharmacy interviews and 52% of NHP-retailer interviews). Three percent of statements were expressions of a general opinion about the product by the individual being interviewed (all occurred at pharmacies.) Garlic and apple cider vinegar were discussed in both pharmacies and NHP-retail stores. Black licorice and peppermint were only discussed at the NHP-retailers as these two products were not available in the pharmacies that were visited. The overall observed differences between pharmacies and NHP-retailers were not significant.

Table 2.

Percentage (95% CI) of Interviews Where Statements Concerning the Use of the NHP Were Consistent With Evidence-Based Literature, Common Use, Were Not Consistent With Literature or Were a General Opinion of the Individual Being Interviewed.

NHP Uses	Pharmacy	NHP Retailer	Total
Evidence-based	8% (3-19)	11% (6-19)	10% (6-16)
Common use	45% (32-59)	37% (28-48)	40% (32-48)
Not consistent with literature	39% (26-53)	52% (42-62)	47 (39-55)
Opinion	8% (3-19)	0% (0-4)	3% (1-7)

Percentages reflect all statements made for all NHP studied.

Statements about recommended uses for garlic are depicted in Figure 1. Statements reflecting common use were the most frequent followed by statements that were not consistent with the evidence in the literature. Only 21% of statements were consistent with the evidence-based literature (9% of pharmacy statements and 35% of NHP-retailer statements). Pharmacies offered a general opinion about garlic (9% of statements) whereas no NHP-retailers offered a general opinion regarding the use of garlic.

Figure 1.

Percentage of statements regarding the use of garlic that were evidence-based, consistent with common use, not consistent with literature, or general opinions. A. All interviews. B. Pharmacies. C. NHP-retailers.

When discussing peppermint, most statements were not consistent with the literature (53%). Common use was described in 33% of the statements and evidence-based use in 14% of statements (Figure 2). No statements reflecting the interviewees’ opinion of peppermint supplements were made.

Figure 2.

Percentage of statements regarding the use of peppermint that were evidence-based, consistent with common use, not consistent with literature, or general opinion for interviews conducted at NHP-retailers.

In interviews regarding black licorice, none of the statements made by NHP-retailers were consistent with the evidence-based use of black licorice however 36% of the statements made were consistent with the common use of black licorice (Figure 3). Statements not consistent with the literature were made in 64% of the interviews and none of the interviewed NHP retailers expressed an opinion on the use of black licorice.

Figure 3.

Percentage of statements regarding the use of black licorice that were evidence-based, consistent with common use, not consistent with literature, or general opinion for interviews conducted at NHP-retailers.

When discussing the use of apple cider vinegar there were very few statements made that were consistent with evidence-based use, whereas 40% of the statements were consistent with the common use of apple cider vinegar (Figure 4). Pharmacists offered a general opinion on apple cider vinegar in 7% of interviews whereas no NHP retailers offered such an opinion.

Figure 4.

Percentage of statements regarding the use of apple cider vinegar that were evidence-based, consistent with common use, not consistent with literature, or general opinion. A. All interviews. B. Pharmacies. C. NHP-retailers.

When discussing adverse effects associated with the products statements consistent with the literature were made in 38% (95% CI 24-56) of discussions with pharmacists and 44% (95% CI 28-60) by NHP-retailers. Statements on adverse effects varied considerably across the products, and between pharmacies and NHP-retailers. Thirteen percent of pharmacists and 50% of NHP-retailers correctly identified possible adverse effects of garlic, 50% of NHP-retailers identified possible adverse effects of peppermint, 25% of NHP-retailers identified possible adverse effects of black licorice, and 63% of pharmacists and 50% of NHP-retailers correctly identifying adverse effects associated with apple cider vinegar.

Statements about possible drug interactions also varied across the various products studied. Sixty-three percent of pharmacists and NHP-retailers correctly identified possible interactions with garlic, 37.5% of NHP-retailers identified possible interactions with peppermint or with black licorice and, 75% of pharmacists and 38% of NHP-retailers correctly identified possible interactions with apple cider vinegar. Overall, 69% (95% CI 44-86) of pharmacists and 44% (95% CI 28-60) of NHP-retailers correctly identified possible interactions with the products.

During the interviews, 25% of the pharmacists had to be prompted to discuss the uses of the products whereas 38% of NHP-retailers needed a prompt. A large portion of the interviews required prompting to discuss possible adverse effects (94% of pharmacists and 78% of NHP-retailers) and to discuss possible drug interactions (69% of pharmacists and 91% of NHP-retailers).

Discussion

This research showed that the majority of statements about the use of the studied NHPs reflected the common use of the products or were inconsistent with the evidence-based literature surrounding the product, and only a minority of statements reflected the evidence-based supported uses described in the literature. Many statements about adverse effects were also inconsistent with the literature. Most of the statements about possible drug interactions made by pharmacists were correct, with a lesser number of correct statements made by NHP-retailers.

The results of this study are very similar to the studies conducted by Brazier & Levine and Sim & Levine in 2002 and 2010, respectively. Brazier & Levine evaluated the accuracy of information provided verbally and in written resources by pharmacies and NHP-retailers for St. John's wort, valerian and gingko biloba and showed that 67% of verbal statements regarding uses and 54% of statements regarding adverse effects were correct for these products. ²⁶ In 2010, Sim & Levine evaluated the accuracy of information provided by pharmacies and NHP-retailers concerning potential drug interactions with St. John's wort and echinacea, showing that 53% of respondents correctly identified drug interactions associated with St. John's wort however only 7% correctly identified drug interactions with echinacea. ²⁷ Although the studies by Brazier & Levine and Sim & Levine studied different NHPs, the results with regard to accuracy of statements are similar. Our study expanded on these studies to differentiate evidence-based uses from common uses and focused on currently popular products. Overall, all the studies show that there is increased need for training pharmacists and NHP-retailers to provide accurate information about NHPs.

NHPs typically have less evidence surrounding their use as they are not regulated to the same rigorous standard as pharmaceutical products.^1,2,5 This may explain why many statements were consistent with the common use of products, but few statements were consistent with the evidence-based use for the products. Previous studies have shown that pharmacists are often uncomfortable providing information about NHPs as it is not a subject that is heavily focused upon in their training. ⁴ NHP-retailers are not regulated health professionals and so any information or training they receive would be done at the retailers’ discretion and would not be uniform across all retailers.^2,4 This would explain why such a large portion of the statements made about the use of these products were not consistent with the literature. With respect to stating their opinions about the use of potential health products, as regulated health professionals, pharmacists may be more comfortable providing their opinion on a product compared to NHP retailers who are not regulated and may have even more limited training.

Garlic and peppermint are the supplements that had more evidence surrounding them whereas black licorice and apple cider vinegar had less evidence.^7–25 This may explain why there was a larger proportion of statements made about black licorice and apple cider vinegar that were not supported by the literature. Even though peppermint is one of the better studied products, it is surprising that such a large proportion of statements were inconsistent with the literature regarding its uses. Garlic has also been well studied and this product had many statements regarding evidence-based use in addition to common use, but also generated multiple statements that were inconsistent with the literature. The observation that even the products that were more thoroughly studied did not receive consistently correct answers regarding their uses, suggests that there is a gap in training surrounding NHP for pharmacists and NHP-retailers.

Adverse effects and possible drug interactions are also important considerations when taking any medicinal product. NHP are not regulated the same way as pharmaceutical products and it is often difficult to find information on these topics.^1,2,5 Additionally, due to NHP not being recognized as medicinal products it is common for assumptions to be made that these products do not have any adverse effects or possible drug interactions. ⁶ This is reflected in the great variation across products with regards to the information provided by pharmacists and NHP-retailers. Both pharmacists and NHP-retailers struggled to correctly identify adverse reactions associated with the products, but the majority of pharmacists were able to identify some possible drug interactions with the products. This may be due to pharmacists being familiar with the cytochrome enzymes that are responsible for many drug interactions and the awareness of the many types of prescription drugs that patients may access. ⁴

During the interviews, it was uncommon for a pharmacist or NHP-retailer to require prompting to discuss the uses of the products, but the majority required prompting to discuss the adverse effects and possible drug interactions. Lay individuals searching for information about a product may not directly ask about adverse effects or possible drug interactions when inquiring about a NHP, yet this is important information that individuals should receive to make an informed choice about using a product. ⁶

Conclusions

Overall, this study showed that information provided by pharmacists and NHP-retailers reflected evidence-based use of four popular products in only 10% of interactions, whereas common use was described in 40% of interactions. There was no significant difference between pharmacies and NHP-retailers when evaluating information about uses of the products. Information on adverse effects and drug interactions with the products had variability between pharmacies and NHP-retailers as well as between products studied.

This study reflects the importance of improving the training of pharmacists and NHP-retailers surrounding NHPs. Given that patients are more likely to seek information about NHPs from pharmacists or NHP-retailers than from their doctors, it is important that the information provided by these sources is accurate.^2,3,6 Pharmacists believe that they do not receive adequate training on the topic of NHP. ⁴ Further, as NHPs are not regulated like pharmaceutical products there is often a paucity of research surrounding their use and guidelines focus on “common uses” rather than “evidence-based” uses.^1–5 In the end, for patients to be able to make informed decisions about their use of these products it is important to ensure that the individuals selling the products have sufficient knowledge that they can communicate to the consumer regarding the product's uses, adverse effects and potential drug interactions.

This descriptive study was limited by the fact that it examined only four popular products, surveyed eight pharmacies and eight NHP-retailers, and was limited to stores within one geographic region. This may limit the generalizability of the results to other markets. The small sample size also limits the statistical analyses that could be performed. Future research should consider examining other popular NHPs at a larger number of stores and in multiple different geographical locations.

Supplemental Material

sj-docx-1-npx-10.1177_1934578X231210251 - Supplemental material for How Pharmacies and Retailer Shops Convey Information on Health Products to Their Customers

Supplemental material, sj-docx-1-npx-10.1177_1934578X231210251 for How Pharmacies and Retailer Shops Convey Information on Health Products to Their Customers by Kelsey MacEachern and Mitchell Levine in Natural Product Communications