New Zealand Natives and the Gut Microbiome

  

Posted: May 2023
Author: Phil Rasmussen | M.Pharm., M.P.S., Dip. Herb. Med.; M.N.I.M.H.(UK), F.N.Z.A.M.H.

New Zealand Natives for Gastrointestinal Conditions and the Gut Microbiome

Many of our native plant medicines have the ability to help in the management of gastrointestinal ailments¹. While these have diverse actions, and undoubtedly act concomitantly to prevent and treat such conditions, their direct effects on the gut microbiome are likely to be contributory.

Intestinal microbiota also play an important role in the activation and metabolism of medicinal plant phytochemicals, as they do with the breakdown of proteins, carbohydrates, and fats in foods, into simpler and bioavailable molecules. A diverse and healthy microbiome is thus needed to ensure optimal processing and presentation of medicinally active phytochemicals.

Apart from probiotics, live microorganisms that confer a health benefit when administered in adequate amounts, prebiotics are ingredients that stimulate increased beneficial microbial activity in the digestive system to improve health. Additionally, specific primary or secondary components of plants or mushrooms can exert a positive effect on the microbiome community, and health outcomes.

Native plants and the microbiome

Regular ingestion of herbal teas such as Camellia sinensis (green tea), kuding tea, and Scutellaria baicalensis (baical skullcap) can exert beneficial effects on the gut microbiota. This includes an increased number of unique bacterial genera, and changes in the relative abundances of particular species^2,4. Catechins and insoluble fibre contribute to these benefits and exert a prebiotic-like effect on gut microbiota⁵. Supplementation with certain tannins also increases the diversity and abundance of butyrate-producing and probiotic bacteria, and amino acid metabolism⁶. In fact, the antioxidant and disease preventative properties of many polyphenolic rich plants may correlate with effects on gut bacterial species⁷.

Many native plants from Aotearoa, New Zealand are very rich in polyphenolic compounds and are likely to produce similar benefits. While the larger ones have poor oral bioavailability, they can facilitate significant changes in the abundance of bacterial species, associated with positive health outcomes. Microbiota-mediated hydrolysis of tannins is being recognised as producing smaller, bioavailable and bioactive metabolites, with many beneficial effects on health⁸.

Controlling infections

While antibiotics are used to eradicate harmful bacteria, they can negatively impact beneficial bacteria. Plants with a narrower spectrum of antimicrobial activity can provide a more targeted action, and thus reduced adverse events⁹.

The microbiota is also involved in reducing and preventing colonization by enteric pathogens through the process of competitive exclusion and the production of antimicrobial substances. Plants that enhance production of bacteriostatic and bactericidal substances by the microbiota offer potential interventions to counteract some pathological infections¹⁰.

Leptospermum scoparium (mānuka), Kunzea ericoides (kānuka), Phormium tenax (harakeke), Pseudowintera colorata (horopito), Phyllocladus trichomanoides (tanekaha), Podocarpus totara (totara) and Laurelia novae-zelandiae (pukatea), all exhibit good activity against specific pathogens.

Animal studies show the microbiome to have a positive impact not only on gut physiology, but also host immunity. Part of the mechanism of Echinacea purpurea immunomodulatory effects may involve its influences on the gut microbiota. This is supported by improvements in immunosuppressed ducks in conjunction with increased abundance of beneficial intestinal bacteria¹¹.

Antibacterial and antifungal actions are prominent activities of many native plants, and traditional use for gastrointestinal tract infections was common. Tannin-rich native species, such as mānuka, can treat dysentery and diarrhoea, and have intrinsic antibacterial properties. The powerful astringent and antimicrobial effects, produced by infusions and hydroethanolic liquid extracts of mānuka’s leaves and stems, make it a useful component for gastrointestinal infection treatment.

In its living state, mānuka has around 200 different bacteria within its leaves, stems, and roots. They make up a rich endophyte community, several of which themselves produce antifungal or antibacterial compounds as part of their competitive survival¹². Ingestion of preparations made from its leaves and stems will deliver a range of phytochemicals, with the potential to modulate the gut microbiome and provide digestive system benefits. The often symbiotic relationships between endophytes and plants, and those between microbes and humans, appear to have much in common.

Hebe stricta (koromiko) is another effective remedy used for diarrhoea and dysentery among Māori and European settlers, including New Zealand soldiers during World War II. Rebalancing different microbial species within the gut is probably involved in the anti-diarrhoeal and anti-inflammatory properties.

Intestinal mucosa tonics

Damage to the integrity of the intestinal biofilm can result in intestinal permeability, a condition widely described as ‘leaky gut’. When this occurs, the immune system can become weakened or dysregulated, making conditions such as irritable bowel syndrome or inflammatory bowel disease more likely.¹³ Inflammatory bowel conditions such as ulcerative colitis, Crohn’s and irritable bowel syndrome are associated with secretion of proinflammatory cytokines, poor maintenance of the epithelial barrier, and dysbiosis^{14, 15}.

Piper excelsum (kawakawa) is a plant widely used for gastrointestinal inflammation and has many pronounced digestive system benefits. As with other Piperaceae species, influences on gastrointestinal absorption and gut permeability have been shown for kawakawa and some of its amide constituents, including piperine and piperdardine¹⁶. Lignans are also prominent constituents and, given other lignans interact with gut microbiota, microbiome modulations through these phytochemicals may also take place.

Other plants with broad-ranging effects on the digestive system are Pseudowintera colorata (horopito) and Dodonaea viscosa (akeake). Key phytochemical constituents of these herbs exhibit astringent, anti-inflammatory and antimicrobial properties. This can undoubtedly impact population levels of some microbiome species in a negative manner, and others in a potentially facilitatory manner. An Indian variety of Dodonaea viscosa has been shown to be gastroprotective in animal studies¹⁷.

Polysaccharides

These are another type of secondary metabolite with limited oral bioavailability but are increasingly being recognized for the complex interactions they have with gut microbiota. This includes gut microbiota composition modulation, metabolism of polysaccharides to short chain fatty acids by the gut microbiota, and polysaccharide-induced gut microbiota metabolite production, such as trimethylamine, tryptophan and lipopolysaccharides¹⁸. Amelioration of antibiotic-associated diarrhoea, through a prebiotic effect of polysaccharides from the medicinal fungus Poria cocos (hoelen), has recently been reported¹⁹.

Hoheria populnea (hoheria), is a native tree rich in polysaccharides. Like slippery elm and other polysaccharide hydrocolloid rich plants, hoheria can help reduce symptoms of dyspepsia or gastritis when taken either as an infusion or hydroethanolic liquid extract. As with many other polysaccharide-rich plants or medicinal fungi, beneficial effects on the gut microbiome also seem likely.

Bitters

Medical herbalists are generally taught that it is the stimulatory effects of bitter-tasting plants on the gastrointestinal system that accounts for their many beneficial and tonic-like actions. We now know that activation of bitter receptors is involved in the regulation of appetite, insulin sensitivity, airway innate immunity, and other physiological processes. The ability of strong-tasting bitter plants to positively influence the gut microbiome community is being increasingly revealed^{20, 21}.

Native plants such as Dysoxylum spectabile (kohekohe) and Phyllocladus trichomanoides (tanekaha) make excellent bitter substitutes to classical European bitters such as Gentiana lutea (gentian) and Artemisia absinthium (wormwood). These also, undoubtedly, produce complex and, in all likelihood, beneficial actions on the gut microbiome.

Summary

Humans have a wide variation in the makeup of their gut microbiome. This potentially results in variations in microbial metabolism of many phytochemicals, and thus their therapeutic activities. However, there are a multitude of ways in which the ingestion of plants can produce health benefits, with some form of involvement of these bacteria.

A better understanding of the human gut microbiome seems certain to provide innovative targets for the incorporation of New Zealand native plants into the prevention and treatment of several gastrointestinal conditions.
 

References:

1. Rasmussen PL. Treating digestive conditions using New Zealand native plants. Phytomed seminar, October 2009.
2. Morishima, S., Kawada, Y., Fukushima, Y., Takagi, T., Naito, Y., & Inoue, R. (2023). A randomized, double-blinded study evaluating effect of matcha green tea on human fecal microbiota. Journal of clinical biochemistry and nutrition, 72(2), 165–170.
3. Vamanu E, Dinu LD, Pelinescu DR, Gatea F. Therapeutic Properties of Edible Mushrooms and Herbal Teas in Gut Microbiota Modulation. Microorganisms. 2021;9(6):1262.
4. Shen J, Li P, Liu S, et al. The chemopreventive effects of Huangqin-tea against AOM-induced preneoplastic colonic aberrant crypt foci in rats and omics analysis [published correction appears in Food Funct. 2021 Mar 15;12(5):2336-2337.
5. Thumann, T. A., Pferschy-Wenzig, E. M., Aziz-Kalbhenn, H., Ammar, R. M., Rabini, S., Moissl-Eichinger, C., & Bauer, R. (2020). Application of an in vitro digestion model to study the metabolic profile changes of an herbal extract combination by UHPLC-HRMS. Phytomedicine : international journal of phytotherapy and phytopharmacology, 71, 153221.
6. Correa PS, Mendes LW, Lemos LN, et al. Tannin supplementation modulates the composition and function of ruminal microbiome in lambs infected with gastrointestinal nematodes. FEMS Microbiol Ecol. 2020;96(3): fiaa024.
7. Morisette A, Kropp C, Songpadith JP, et al. Blueberry proanthocyanidins and anthocyanins improve metabolic health through a gut microbiota-dependent mechanism in diet-induced obese mice. Am J Physiol Endocrinol Metab. 2020;318(6): E965-E980.
8. Sallam IE, Abdelwareth A, Attia H, et al. Effect of Gut Microbiota Biotransformation on Dietary Tannins and Human Health Implications. Microorganisms. 2021;9(5):965.
9. Chou, S., Zhang, S., Guo, H., Chang, Y. F., Zhao, W., & Mou, X. (2022). Targeted Antimicrobial Agents as Potential Tools for Modulating the Gut Microbiome. Frontiers in microbiology, 13, 879207.
10. Clavijo, V., & Flórez, M. J. V. (2018). The gastrointestinal microbiome and its association with the control of pathogens in broiler chicken production: A review. Poultry science, 97(3), 1006–1021.
11. Lin R, Zhi C, Su Y, et al. Effect of Echinacea on gut microbiota of immunosuppressed ducks. Front Microbiol. 2023;13:1091116
12. Wicaksono WA, Jones EE, Monk J, Ridgway HJ. The Bacterial Signature of Leptospermum scoparium (Mānuka) Reveals Core and Accessory Communities with Bioactive Properties. PLoS One. 2016;11(9): e0163717.
13. Fukui H. Increased Intestinal Permeability and Decreased Barrier Function: Does It Really Influence the Risk of Inflammation?. Inflamm Intest Dis. 2016;1(3):135-145.
14. Wu X, Chen H, Gao X, Gao H, He Q, Li G, Yao J, Liu Z. Natural Herbal Remedy Wumei Decoction Ameliorates Intestinal Mucosal Inflammation by Inhibiting Th1/Th17 Cell Differentiation and Maintaining Microbial Homeostasis. Inflamm Bowel Dis. 2022 Jul 1;28(7):1061-1071.
15. Aldars-García L, Chaparro M, Gisbert JP. Systematic Review: The Gut Microbiome and Its Potential Clinical Application in Inflammatory Bowel Disease. Microorganisms. 2021;9(5):977.
16. Obst K, Lieder B, Reichelt KV, et al. Sensory active piperine analogues from Macropiper excelsum and their effects on intestinal nutrient uptake in Caco-2 cells. Phytochemistry. 2017;135:181-190.
17. Arun M, Asha VV. Gastroprotective effect of Dodonaea viscosa on various experimental ulcer models. J Ethnopharmacol. 2008;118(3):460-465.
18. Zhang D, Liu J, Cheng H, et al. Interactions between polysaccharides and gut microbiota: A metabolomic and microbial review. Food Res Int. 2022;160:111653.
19. Xu H, Wang S, Jiang Y, et al. Poria cocos Polysaccharide Ameliorated Antibiotic-Associated Diarrhea in Mice via Regulating the Homeostasis of the Gut Microbiota and Intestinal Mucosal Barrier. Int J Mol Sci. 2023;24(2):1423.
20. Xiong X, Cheng Z, Wu F, et al. Berberine in the treatment of ulcerative colitis: A possible pathway through Tuft cells. Biomed Pharmacother. 2021;134:111129.
21. Zhao, A., Jeffery, E. H., & Miller, M. J. (2022). Is Bitterness Only a Taste? The Expanding Area of Health Benefits of Brassica Vegetables and Potential for Bitter Taste Receptors to Support Health Benefits. Nutrients, 14(7), 1434