I was a youngster in ecology class when I first learned about ecotones, those areas where one biome transitions into the next. Consider the spot where fresh water flows into salt water or the edges of a meadow. The professor said these areas were often the most biologically diverse. It’s called the edge effect, the way the transition area contains traits of both sides, the way populations from either side share the space.
My teacher was talking about the great outdoors, but I immediately thought of the border town where I grew up. The United States on one side and Mexico on the other; two cities smashed up against a bridge over a river. The edge effect weaves the two cities into one. Of course the tastiest place to note this edge effect is in the food and drink.
Whether at a fast food or a sit down restaurant, standard drink selections in my hometown were sweet tea, Coca-cola, and aguas frescas. Literally translated as “fresh waters”, aguas frescas are actually herbal teas, technically decoctions, sweetened with sugar. They’re made from fruits, seeds or grain and in Mexico each state has their own traditional flavor. In the southwestern United States the three common flavors are Horchata (cinnamon rice water), Tamarindo (a tea of Tamarind pods), and Jamaica (pronounced Ha-my-kah, a tea of Hibiscus calyces – the collective sepals of a Hibiscus sabdariffa). Aguas frescas originated as household refreshments, often a way to use up ripe fruit. They are served by street vendors in Mexico and at most taquerias in the southwestern U.S. Mexican grocers in the U.S. sell the dried calyces by the pound in open bins alongside the beans and rice.
Imagine my delight when I stumbled across an article discussing the healing properties of Hibiscus. The article cited research published in a 2009 issue of the Journal of Human Hypertension. In the study researchers concluded that an infusion of H. sabdariffa “had positive effects on BP [blood pressure] in type II diabetic patients with mild hypertension”.1 My curiosity peaked, I began to read more about this household herb.
I learned that humans utilize many species of hibiscus. Hibiscus rosa sinensis is the popular landscaping species. It is used in Chinese and Indian herbology. Hibiscus cannabinus is studied for its fiber content. Rope and paper made from this plant is called kenaf. The vegetable okra is Hibiscus esculentus. The mallow family (Malvaceae) to which Hibiscus belongs contains other popular plants such as marshmallow, cotton, hollyhock, and tilia (linden).
Much of the research conducted on Hibiscus sabdariffa focuses on the dried calyx, but also on the seed and leaf. A recent study examined the traditional use of the calyx tea as prevention for kidney stones. The researchers reported that the extract “significantly lowered the deposition of stone-forming constituents in the kidneys and serum of urolithiatic rats”– rats treated to produce calcium oxalate kidney stones. 2
Many studies attribute the activity of H. sabdariffa to its anthocyanins, the pigments that give the calyx its red/blue color. Called “red sunscreen” by one researcher, these compounds are thought to protect sensitive plant tissue from the damage of oxidation caused by ultraviolet rays. 3 These antioxidants may help to explain how hibiscus and other anthocyanin-rich plants have activity in seemingly unrelated areas. For example in a study on liver-damaged mice, an extract of hibiscus proved to elevate glutathione levels (a compound necessary for detoxification by the liver).4 In another study it lowered triglyceride levels in humans.5 In diabetic patients the antioxidant properties are thought to inhibit “the expression of certain factors associated with insulin resistance” and researchers concluded that an extract of H. sabdariffa showed “potential to be an adjuvant for diabetic therapy”.6,7 Antioxidants may also protect the cells of the immune system. When researchers exposed cultured human immune system cells to radiation, an extract of H. sabdariffa protected the cells’ ability to function. Researchers stated that the extract “possesses significant immunoprotective effect”.8
Originally from Africa, Hibiscus sabdariffa is the basis of drinks, jellies, tarts, and side dishes in all the tropical and subtropical regions where it is now cultivated and in many areas, naturalized. Its attributes for health continue to be studied and surely nutraceuticals and functional foods are in the works, if not already in the marketplace.
Becki Garza is a community herbalist, biology teacher, and plant lover. She runs her own online herbal store, La Yerberia which literally means “the herb shop” in Spanish. Becki is an advocate for plants, medicinal or otherwise, and continues to teach through presentations, writings, and consultations.
- Mozaffari-Khosravi H, Jalali-Khanabadi B-A, Afkhami-Ardekani M, Fatehi F, Noori-Shadkam M. The effects of sour tea (Hibiscus sabdariffa) on hypertension in patients with type II diabetes. Journal of Human Hypertension. 2009;23:48–54.
- Laikangbam R, Devi M. Inhibition of calcium oxalate crystal deposition on kidneys of urolithiatic rats by Hibiscus sabdariffa L. extract. Urological Research. 2012;40(3)211-218.
- Lee D, Gould K. Why leaves turn red. American Scientist. 2002;90(6):524-531.
- Lee C, Kuo C, Wang C, Wang C, Lee Y, Hung C, Lee H. A polyphenol extract of Hibiscus sabdariffa L. ameliorates acetaminophen-induced hepatic steatosis by attenuating the mitochondrial dysfunction in vivo and in vitro. Bioscienc, Biotechnology, and Biochemistry. 2012;76(4):646-51.
- Hernández-Pérez F, Herrera-Arellano A. Therapeutic use Hibiscus sabadariffa extract in the treatment of hypercholesterolemia. A randomized clinical trial. Revista médica del Instituto Mexicano del Seguro Social. 2011;49(5):469-80.
- Peng C, Chyau C, Chan K, Chan T, Wang C, Huang C. Hibiscus sabdariffa Polyphenolic Extract Inhibits Hyperglycemia, Hyperlipidemia, and Glycation-Oxidative Stress while Improving Insulin Resistance. Journal of Agricultural and Food Chemistry. 2011; 59(18)9901–9909.
- Sini J, Umar I, Inuwa, H. The beneficial effects of extracts of Hibiscus sabdariffa calyces in alloxan-diabetic rats: Reduction of free-radical load and enhancement of antioxidant status. Journal of Pharmacognosy and Phytotherapy. 2011;3(10)141-149.
- Okoko T, Ere D. Hibiscus sabdariffa extractivities on cadmium-mediated alterations of human U937 cell viability and activation. Asian Pacific Journal of Tropical Medicine. 2012;5(1)33-36.