Medicinal Plants and Herbal Food Ingredients in the 21st Century - Benefits and Safety

The global inventory of plant diversity consists currently of about 350,000 species, with most current estimates expecting around 420,000 plant species to exist. This tremendous diversity accounts for a wide range of phytochemicals, and a high variation of compound composition even within one single species, depending on growth conditions (soil, climate, nutrient status etc.), and harvest practices and timing, not even taking intraspecific variation into account. While traditional plant use and medicine preparation normally takes these details into account, they are often seen as of marginal importance in the herbal trade. In the USA botanical supplements are supposed to be labeled, with the requirement to include the correct scientific name. However, in practice this does not prevent accidental or deliberate adulterations or can contain heavy metal contaminations. The most problematic occurrence in herbal medicine trade is however linked to the purchase and use, either in medication or research, of botanicals that are either accidentally or purposefully wrongly identified or are simply collected under a vernacular name without any subsequent taxonomic treatment, and often without having any vouchered material that could later be used for the verification of plant identity. Substitution of common, non-toxic species with toxic species has been reported frequently in literature. Good examples for life threatening adulterations are replacements of Plantago major L. with Digitalis lanata Ehrh., Illicium verum Hook. f. with Illicium anisatum L., or Arctium lappa L. with Atropa belladonna L. A much more frequent occurrence is however the often-deliberate adulteration of botanicals with more common and cheaper species, which, although generally not toxic, might completely lack efficacy. Bulk herbs are readily available unprocessed, which allows for the retention of material for a botanical voucher, although material in trade often does not contain all plant parts, i.e., fruits and flowers are often missing from bulk material, and as such botanical identification can be difficult. In contrast, raw botanicals are also often provided in ground or powdered form, which makes morphological identification very difficult or virtually impossible. While microscopic and organoleptic methods do sometimes allow separating correct species from adulterants, if the material is only crushed or very coarsely ground, such an identification or powdered material or extracts is impossible. For this reason, the only possibility to later identify the source of a certain botanical securely is to count on botanical voucher specimens that can be directly linked to the material in trade. This is where plant taxonomy and trained taxonomists play an irreplaceable role in the herbal supplement industry. The need for the use of botanical methods in ethnopharmacology is nothing new whatsoever and calls from botanists for a broader inclusion of botanical taxonomy in the discipline have been published for decades. Likewise, it has been documented frequently that vernacular names for species can change dramatically.

Example 1 - not even the species of grass used for the most common baskets in Madagascar was correctly known scientifically.

Madagascar harbors a great diversity in terms of vegetation and endemic species. The island is composed of a multitude of natural ecosystems, which harbor a unique and globally important flora. Baskets made from plant fibers are a common sight all over Madagascar and are also important in international fair-trade. Any online search for baskets from Madagascar will yield a large number of sales sites. Baskets have long been important in the Malagasy economy. While the Malagasy flora has a tremendous diversity, most commercially available baskets are made from raphia palm (Raphia farinifera (Gaertn.) Hyl, Arecaceae) fibers, with other palm species contributing to the basket portfolio. In central Madagascar, however, baskets used locally, as well as sold in markets in the capital Antananarivo, are almost entirely made of grass and come in a wide variety of sizes. The grass material used is locally known as "Harávola." To our great astonishment, none of the Missouri Botanical Garden staff in Madagascar knew which grass species was or were used to manufacture these baskets, and some other utensils seen in local markets. Based on a literature search, a first mention of grass material used in manufacturing was found in a report on Madagascar economic plants from Royal Botanical Garden Kew, where Stipa madagascariensis Baker (accepted name: Loudetia simplex ssp. stipoides Bosser) was listed as "making native baskets and hats." The most complete checklist of grasses of Madagascar did not mention any use for Loudetia sp. but described Lasiorhachis viguieri (A. Camus) Bosser as "Les feuilles sont utilisées en vannerie et servent à tresser des chapeaux et des paniers"—The leaves are used in basket-making and serve to weave hats and baskets. No detailed descriptions of artifacts, or imagery to indicate which species was used for what, were however available in literature. Based on the appearance of artifacts, we hypothesized that several grass species were involved in basket and utensil manufacturing.

Example 2 - many different species are sold as bay leaf!

The accurate identification of bay leaf in natural products commerce may often be confusing as the name is applied to several different species of aromatic plants. The true “bay leaf”, also known as “bay laurel” or “sweet bay”, is sourced from the tree Laurus nobilis, a native of the Mediterranean region. Nevertheless, the leaves of several other species including Cinnamomum tamala, Litsea glaucescens, Pimenta racemosa, Syzygium polyanthum, and Umbellularia californica are commonly substituted or mistaken for true bay leaves due to their similarity in the leaf morphology, aroma, and flavor. Substitute species are, however, often sold as “bay leaves”. As such, the name “bay leaf” in literature and herbal commerce may refer to any of these botanicals. The odor and flavor of these leaves are, however, not the same as the true bay leaf, and for that reason they should not be used in cooking as a substitute for L. nobilis. Some of the bay leaf substitutes can also cause potential health problems. Therefore, the correct identification of the true bay leaf is important. The present work provides a detailed comparative study of the leaf morphological and anatomical features of L. nobilis and its common surrogates to allow for correct identification.

Example 3 - Many different and confused species are sold as anti-diabetics

Peru is what Peruvian anthropologist Lupe Camino calls the “health axis” of the old Central Andeanculture area stretching from Ecuador to Bolivia. In particular in the North of the country the traditional use of medicinal dates back as far as the first millennium B.C. Both healers, and the wider population, often buy their medicinal plants in local markets, but there is very little comparative information available about which plants are sold under which vernacular name at any given time, for which indication, and which dosage information and information about side effects is given by vendors. For this study we used two traditionally used species groups “Hercampuri” Gentianella spec. (Gentianaceae) and “Pasuchaca” Geranium spec. (Geraniaceae.), found in the Mercado Aviación in Lima, as small, clearly circumscribed plant group frequently used to treat symptoms of diabetes as a test case to study the taxonomy, indications, dosage, indicated side effects, and additional species used as admixtures and hypothesized that: 1. A wide variety of different species is sold under the same common name, and often several common names exist for one species. 2. There is no consistency in the dosage, or a relationship between dosage and species marketed under one name. 3. However, there is consistency in the knowledge about usage and side effects. Our surveys in Mercado Aviación in Lima yielded four species of Gentianella, two of Geranium, and three additional species from three genera used as common additives that were sold as anti-diabetic. These results indicate that even in case of only a few plant species, used for a very clearly circumscribed application, patients run a considerable risk when purchasing their remedies in the market. The possible side effects in this case are the more serious because diabetes has to be treated long term, and as such the patients are ingesting possible toxic remedies over a long period of time. Much more control, and a much more stringent identification of the material sold in public markets, and entering the global supply chain via internet sales, would be needed.

Example 4 - Plant use to remedy COVID-19.

Plants are the basis of life on Earth as we know it and the study of plants is essential to protect our future. Securing our future requires protecting plant biodiversity and the development of climate-resilient crops. Increasing science communication about exciting advances in our knowledge of plants and their importance to society may be a strategy to counteract this. Recent studies demonstrate that the COVID-19 pandemic has boosted awareness of the therapeutic value of interacting with plants and their positive effect on human well-being.

During a very complex and confusing time, in which public health services in multiple countries have been completely overwhelmed, and in some cases even collapsed, these first-line household responses have been quintessential for building physical, mental, and social resilience, and for improving individual and community health.  Urban diasporas and rural households seem to have repurposed homemade plant-based remedies that they use in normal times for treating the flu and other respiratory symptoms or that they simply consider healthy foods. The most remarkable shift in many areas has been the increased consumption of ginger and garlic, followed by onion, turmeric, and lemon. Our preliminary inventory of food medicines serves as a baseline for future systematic ethnobotanical studies and aims to inspire in-depth research on how use patterns of plant-based foods and beverages, both “traditional” and “new”, are changing during and after the COVID-19 pandemic. We call attention to the importance of ethnobiology, ethnomedicine, and ethnogastronomy research into domestic health care strategies for improving community health.

References

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