Many medicinal plants have been reported to manage hypertension (Al Disi et al. 2016; Rawat et al. 2016; Landazuri et al. 2017). Although some of the reported medicinal plants have verifiable scientific evidence regarding their pharmacological activity, many medicinal plants are still being studied, and information obtained from indigenous users provides valuable insights for scientific research into such medicinal therapies (Mordeniz 2019). The results obtained in this study showed that participants used various medicinal plants to manage hypertension (Table 2).
The participants described the knowledge and sources of medicinal plants used to manage hypertension to emanate from the community and passed down from generation to generation. The World Health Organization (WHO) (2015) describes traditional medicine as the total knowledge and practices of indigenous people used to diagnose, prevent, treat, or manage diseases. In many communities such as Saudi Arabia, Pakistan, India, and China, knowledge of medicinal plants has been received from ancestors and communities (Petrovska 2012; Inoue et al. 2019). This reliance on medicinal plants was reported in older people who inherited the knowledge from their ancestors, as reported by participants in this study. Even though medicinal plants have been used for generations, and most of the knowledge is passed from one generation to another, the challenge is often that such information is not adequately documented. Hence, some vital ingredients are likely to be lost along the line over the years (Baharvand-Ahmadi et al. 2016; Meresa et al. 2017; Malik et al. 2018; Petrovska 2012). The dynamics of migration from rural to urban communities by the younger generation, the advent of education, and the knowledge of Western therapies play vital roles in the plant knowledge being lost (Malik et al. 2018). In addition, the outright lack of interest in some younger generations could play a significant role in the ineffective transmission of medicinal plant knowledge from older folks. For instance, a lack of interest in indigenous therapies among young people has been reported (Malik et al. 2018). This lack of interest by young people is making transmission of indigenous knowledge from older people difficult, especially because younger people have ease of access to readily available Western medications (Malik et al. 2018). The results from the present study will serve as useful baseline documentation of medicinal plants, particularly those perceived to be helpful in the management of hypertension in Belize.
The duration of medicinal plants in the management of hypertension was also explored in this study. The study participants stated that using medicinal plants for less than a year to as many as ten years and beyond to manage their hypertension, possibly because of generational use, availability, and culture. The desire to use medicinal plants to manage a variety of diseases has significantly increased. Although many factors are responsible for this, the main reasons are the perceived safety of medicinal plants and their cheapness compared to Western medications (Ekor 2014; Shaikh et al. 2020). In Belize, for instance, the provision of Western medications from government-owned hospitals is accessible and free to all hypertensive patients. However, because the use of medicinal plants in Belize is a deeply rooted culture in almost all ethnic groups, especially among the Maya, Kechi, Garinagu, and East Indians, the habit is difficult to let go of even with freely accessible Western medications. The desire to maintain the originality of cultural and ethnobotanical practices among natives has strengthened cultural and ethnic identities from the colonial era (Mans et al. 2017a; b). In addition, the extensive rainforest of Belize and biodiversity provide the right environment and atmosphere for the use of many medicinal plants to treat hypertension and other diseases.
The plant parts used for hypertension therapy by the participants were also assessed. The majority of the participants in this study reported using the leaves of a medicinal plant to manage their hypertension. The results observed in the current study support the research on ethnobotanical antihypertensive plants used in northern Pakistan (Malik et al. 2018). The study reported that stem, root, flower, bark, leaves, seed, aerial parts, fruit, and whole herbal plant were used by indigenous Pakistani people for the management of hypertension. Their report further indicated that most respondents (55.1%) reported using leaves to manage their hypertension. Similar studies have shown that leaves are the highest plant part used compared to other medicinal plants, with 57% and 36% reported by Boadu and Asase (2017) and Baharvand-Ahmadi et al. (2016), respectively.
Additionally, the preparation methods of medicinal plants used for the management of hypertension in Belize were evaluated. In order to ensure the quality and consistency of medicinal plants, methods of preparation, quality control, and standardization of medicinal plants are fundamental (Nafiu et al. 2017). As noted in this study, hot water extraction of leaves resonates with previously reported studies, where participants indicated hot water extraction as the most used preparation method (Malik et al. 2018). Different preparation methods for medicinal plants have been described to include infusions, decoctions, boiling, teas, syrups, concoctions, powders, and chemical extractions (WHO 2015; Nafiu et al. 2017; Shaikh et al. 2020). Variations in medicinal plants, the identity of the plants, and adulteration have been reported to be some of the factors that affect medicinal plant preparation (Nafiu et al. 2017). When a plant part is boiled in water until the volume is approximately half, the extract is considered decoction. Similarly, soaking a plant part in water at room temperature for more than an hour is called infusion. Juice is made from medicinal plants by blending the fresh part of the medicinal plant with water (Malik et al. 2018). The lack of standardization in the preparation of medicinal plants was observed in this study. For instance, only a few (6) participants indicated the number of leaves they used to prepare medicinal plant therapies for hypertension. Some participants indicated mature or large-sized leaves, while others did not. The sizes of leaves of different medicinal plants vary according to the developmental stage of the tree. In addition, only a few (5) participants indicated the amount of water used to boil the medicinal plant part. The duration of boiling the medicinal plant mentioned by a few (4) participants ranged from 15 to 20 min of boiling. Despite the lack of standardized reporting on the preparation methods for medicinal plants used to manage hypertension observed in this study, decoctions of medicinal plants for hypertension are standard practices reported globally (Baharvand-Ahmadi et al. 2016; Boadu and Asase 2017; Malik et al. 2018). The results seen in the current study support these findings.
Furthermore, the methods of administering medicinal plant therapies for hypertension management were evaluated in this study. The majority of the participants reported the oral route as the main route for administering medicinal plants in hypertension management. Boadu and Asase (2017), in a study of herbal medicines used in the treatment of human diseases in Ghana, reported oral administration as the typical route for herbal administration. Other routes of medicinal plant administration have been described to include topical, rectal, inhalational, and drops. The active ingredient in a medicinal plant and the disease being treated usually determines the route of administration (Busia 2016; Boadu and Asase 2017). Boadu and Asase (2017) further reported that medicinal plants' absorption of alkaloids is readily absorbed from the gastrointestinal tract system, while the best routes for administering essential oils of terpenoids are nasal and dermal routes. Even though infusions can be administered rectally and nasally, most infusions and decoctions have been reported to be best administered orally (Busia 2016; Boadu and Asase 2017).
The primary issue with the dosing of medicinal plants is knowing the correct concentration to use. Such challenges were encountered in this study, where no standardized dosing was reported among participants. The time of the year herbs or plants are harvested presents a unique challenge in the concentration of active ingredients found in medicinal plants. For instance, during the rainy season, the active ingredients found in plants and herbs are diluted due to the availability of rain, whereas in the dry seasons, plants seem to conserve water as such have a higher concentration of active ingredients compared to the rainy season (Lawson and Rands 2019; Nascimento et al. 2019). Depending on the season, plant or herb is harvested for medicinal usage; therefore, what is extracted and used varies. Additionally, the extraction method, the amount of water used for the extraction, and the size or weight of the leaves could all play a role in the dosage and potency that the patient eventually consumed. The results observed in this study resonate with previously published studies where the season and time when medicinal plants are harvested affect their concentration (Nare et al. 2018; Lawson and Rands 2019; Nascimento et al. 2019). In this study, participants reported drinking "half or full glass" and that they drink the extracted therapy "every day, all day or when they feel the pressure."
Participants' opinions on the effectiveness of medicinal plants and the duration of their use in hypertension management were assessed. The majority of the participants believe that medicinal plants are effective in lowering blood pressure. Many medicinal plants have traditionally shown great potential in managing various diseases, and historically, many Western medications have been discovered from medicinal plants (Petrovska 2012; Al Disi et al. 2016; Mordeniz 2019). Nevertheless, with the growing use of medicinal plants in both developed and developing nations, there is still insufficient knowledge about how they produce their mechanism of action in treating or preventing disease progression (Ekor 2014; Shaikh et al. 2020). In Belize, traditional and cultural beliefs on medicinal plants are robust and have been preserved from the pre-colonial era. Subsequently, ethnic heritage is passed on to generations as a means of strengthening communities. This tradition has also been reported in South Africa (Mphuthi and Pienaar 2017; Nare et al. 2018) and Suriname (Mans et al. 2017b). Some of the claims on the biological efficacy of the medicinal plants by the participants in this research have been scientifically verified in a few studies (Somparn et al. 2014, 2018; Anggraeni et al. 2018). Although very few scientific studies on antihypertensive medicinal plants uniquely native to Belize are currently available, the reports from hypertensive patients in this study give insight and raise the need for extensive scientific documentation and evaluations of medicinal plants native to Belize. A comprehensive pharmacological evaluation of these medicinal plants native to Belize will provide further guidelines for their practical usage and prevent the unforeseen risks of adverse effects to public health. Ultimately, although large ranges of antihypertensive medications are available for managing hypertension, no cure has been found (Esler et al. 2010; Bakris n.d). The choice of medicinal plants as a substitute for the management of hypertension may have its value, especially since it is related to cultural perceptions. However, no cure has been reported with medicinal plants or any medication to treat hypertension (Esler et al. 2010). Lifestyle modification and the administration of scientifically approved antihypertensive medications are still the best recommendations for managing hypertension (Bakris n.d). The inability of medicinal plants to cure hypertension, as reported by the participants in this study, supports previously reviewed studies (Baharvand-Ahmadi et al. 2016; Malik et al. 2018; Boadu and Asase 2017).
Just as important, the participants' opinions on the safety and adverse effects of medicinal plants used to manage hypertension were explored. The majority of the participants indicated that the medicinal plants are safe and only produce mild to moderate adverse effects (Fig. 1). The primary concern in the use of medicinal plants is that of safety. The global increase in the awareness of medicinal plants results from their ease of accessibility, cheapness, and the perception of their safety because they are natural (Ekor 2014). For instance, in many communities where medicinal plants are used as therapies, it is common for people to try medicinal plants before coming to the hospital (Ekor 2014; Mphuthi and Pienaar 2017), which is also a common practice in Belize because of cultural beliefs linked to their African and East Indian ancestry. In so doing, some patients may be tempted to combine medicinal plants with Western medications to treat diseases. While therapies using medicinal plants have always been reported to have potential efficacy, most such remedies remain untested, with their use remaining poorly monitored (Ekor 2014; Shaikh et al. 2020). The resulting consequences are inadequate knowledge of their possible adverse reactions, mode of action, possible contraindications, and possible interactions with the already existing Western pharmaceuticals and functional foods that can promote the rationale and safety of medicinal plants. Consequently, the utilization of medicinal plants and supplements has expanded tremendously in recent years, with over 80% of individuals depending on them as part of primary healthcare (Ekor 2014; Al Disi et al. 2016; Shaikh et al. 2020). Although medicinal plants have demonstrated promising potential, the efficacies of a decent number of such therapies remain untested, and their utilizations are either inadequately checked or not observed by any means (Ekor 2014; Shaikh et al. 2020). Consequently, it results in insufficient information on medicinal plants' biological activity, potential adverse responses, contraindications, and interactions with existing pharmaceutical products. It is crucial for studies into their activities and for regulatory bodies to put in place measures for the safety of public health (Ekor 2014; Shaikh et al. 2020). Additionally, concerns with medicinal plants' adverse effects and interactions are because medicinal plants have not been refined and processed for toxicity; therefore, drug-herb or herb-herb interactions and adverse effects are likely to occur (Ekor 2014; Shaikh et al. 2020). The general perception that medicinal plants are safe because they are natural has been reported (Ekor 2014; Baharvand-Ahmadi et al. 2016; Boadu and Asase 2017; Malik et al. 2018; Shaikh et al. 2020; Husaini et al. 2020). The results of this study support these previous studies.
Next, the availability and cost of medicinal plants used in the management of hypertension were assessed. The majority of the participants indicated that the medicinal plants they used were readily available and affordable. The patient's choice to use indigenous therapies is informed by availability, religion, cultural beliefs, the cost of those therapies, and the perceived efficacy of such herbs in treating the ailment (Petrovska 2012; Ekor 2014; Al Disi et al. 2016). Medicinal plants are affordable and readily available, making them the first line of treatment in many communities (Ekor 2014; Shaikh et al. 2020). Furthermore, high morbidity and mortality rates with most diseases have always been associated with high hospitalization rates and an increase in the cost of therapy (McPhail 2016). In addition, long-term management of diseases such as hypertension and other comorbidities has been reported to be the greatest challenge for patients and healthcare givers (McPhail 2016). Hypertension and related diseases have been reported to have a high cost of management, especially as prescribed Western medications are expected to be taken for life (Kastor and Mohanty 2018). In addition, the cost of Western medications, cultural beliefs, and the perception that medicinal plants are harmless because they are natural are excellent incentives to make people with hypertension explore alternative methods for hypertension management (Ekor 2014; Shaikh et al. 2020). The report by hypertensive patients on the cost of medicinal plants in Belize confirms its ease of availability, accessibility, affordability, and perhaps effectiveness as a drive for usage. This study resonates with previously published studies on the availability and affordability of medicinal plant therapies to manage hypertension and other diseases (Baharvand-Ahmadi et al. 2016; Malik et al. 2018; Boadu and Asase 2017).
Lastly, the concomitant use of medicinal plants and Western medications for the management of hypertension was evaluated among participants. A few participants reported that they combine medicinal plants with Western medications in the management of their hypertension. The wide acceptance and usage of medicinal plants in different cultures provide a growing habit of concurrent herb-drug use, which raises the concern of pharmacokinetic interactions (Parvez and Rishi 2019). In many communities, administering medicinal plant extracts in combination with therapeutic drugs is a common practice, raising the potential for herb-drug interactions. Furthermore, the rising interest in natural products for disease management has reawakened natural product research in drug discovery, necessitating pharmacokinetic studies of phytochemicals, including their potential for drug interactions (Parvez and Rishi 2019; Kahraman et al. 2020). Although therapies involving these agents have shown promising potential with the efficacy of many medicinal plant products, thereby establishing clear therapeutic use potentials. However, many of these indigenous products are yet to be scientifically tested, and a large portion of them are either not monitored or poorly monitored scientifically (Shaikh et al. 2020; Kahraman et al. 2020). The lack of adequate knowledge of indigenous products, especially their pharmacokinetics and pharmacodynamics with existing Western medications and other food products, calls for caution and a more rational approach in their usage (Kahraman et al. 2020). Accordingly, the availability of Western medicines in the market follows rigorous laboratory and clinical investigations and goes through stringent regulatory scrutiny; it cannot be said of medicinal plants. A wide variety of acclaimed herbal products currently lack sufficient scientific data on the safety or efficacy of such products (Parvez and Rishi 2019; Kahraman et al. 2020). The concomitant use of Western medications and medicinal plants reported in this study could result in drug-herb interactions that could result in clinical outcomes that are beneficial, unwanted, or toxic. To make matters worse, most individuals consuming both Western and medicinal plants do not provide vital documentation of such usage, thereby making clinical decisions on interactions complicated (Parvez and Rishi 2019; Kahraman et al. 2020). The same challenge might be the case in Belize.
