Herbal tea explained

Herbal teas, also known as herbal infusions and less commonly^[1] called tisanes (UK and US, US also),^[2] are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water; they do not usually contain any true tea (Camellia sinensis). Often herb tea, or the plain term tea, is used as a reference to all sorts of herbal teas. Many herbs used in teas/tisanes are also used in herbal medicine and in folk medicine. Some herbal blends contain true tea (e.g., the Indian classic masala chai).

The term "herbal" tea is often used to distinguish these beverages from true teas (e.g., black, green, white, yellow, oolong), which are prepared from the cured leaves of the tea plant, Camellia sinensis. Unlike true teas, most tisanes do not naturally contain caffeine (though tea can be decaffeinated, processed to remove caffeine).^{[3] [4]}

A number of plants, however, do contain psychoactive compounds, such as caffeine or another stimulant, like theobromine, cocaine or ephedrine. Some have the opposite effect, acting as a sedative. Some common infusions have specific names such as mate (yerba mate) and rooibos (red bush). Hibiscus tea is one type of herbal infusion, but many described as some other plant have hibiscus as the main ingredient, or a major one.^[5]

Etymology

thumb|A promotional poster for "Tisane Gauloise", by Paul BerthonSome feel that the term tisane is more correct than herbal tea or that the latter is even misleading, but most dictionaries record that the word tea is also used to refer to other plants beside the tea plant and to beverages made from these other plants.^{[6] [7]} In any case, the term herbal tea is very well established and much more common than tisane.^[1]

Furthermore, in the Etymology of tea, the most ancient term for tea was 荼 (pronounced tu) which originally referred to various plants such as sow thistle, chicory, or smartweed, and was later used to exclusively refer to Camellia sinensis (true "tea").^{[8] [9]}

The word tisane was rare in its modern sense before the 20th century, when it was borrowed in the modern sense from French. This is why some people feel it should be pronounced as in French, but the original English pronunciation continues to be more common in US English and especially in UK English.^[2]

The word had already existed in late Middle English in the sense of "medicinal drink" and had already been borrowed from French (Old French). The Old French word came from the Latin word Latin: ptisana, which came from the Ancient Greek word Greek, Ancient (to 1453);: πτισάνη (Greek, Ancient (to 1453);: ptisánē), which meant "peeled" barley, in other words pearl barley, and a drink made from this that is similar to modern barley water.^[10]

Composition and usage

See also: List of plants used in herbalism and List of culinary herbs and spices. Herbal teas can be made with any part of a plant, including fresh or dried flowers, fruit, leaves, stems, seeds or roots. These parts may be steeped fully raw (as picked) or processed in some way (such as drying, roasting, crushing, tearing / cutting, steaming, etc.).

thumb| Herbal tisanes being sold in Mauritius as medicines for various diseasesHerbal infusions may be made by pouring hot or boiling water over the plant parts and letting them steep for a period of time. The infusion temperature and time can vary depending on the type of plant part used and their properties. For example, some plant parts are covered in oils which may take some time to separate. Brewing with cold water will take much longer as well, usually several hours.

An herbal tea may be strained or not (as with mate where a special straw called a bombilla is used for drinking).

Some herbal teas are blends which include various different herbs or plant parts. Herbal infusions may also be sweetened, spiced, salted, or combined with other additives, like milk or lemon juice.

Some herbal teas are also infused in alcohol, either for medicinal purposes or to make an herbal liquor.

Herbal teas are commonly used in Herbal medicine and in traditional medical cultures, like Indian Ayurveda and Traditional Chinese medicine. Many ancient and medieval Herbal texts contain evidence for the use of various herb infusions throughout human history. Various herbal teas have been promoted throughout history as folk remedies for various diseases and in some cultures they retain their status as local folk cures.

Many companies produce herbal tea bags for such infusions or sell bottled herbal teas.

Varieties

thumb|A yerba mate infusion, popular in South AmericaHerbal teas can be made from any edible plant material, below is a list of common herbal infusions. Some herbal teas are made from plants which contain caffeine, and other herbal infusions may contain other psychoactive compounds. However, many other common herbal teas have not been shown psychoactive properties when compared to placebos, though they may still have some physical effects.

Many herbal teas on the market may also be blends which include various herbs or plant parts. These blends may also include additives, like flavorings.

Caffeinated infusions

• Cacao bean tea, which contains theobromine and a small amount of caffeine.
• Coffee-leaf tea, coffee fruit tea, and coffee blossom tea are herbal teas made using the leaves, fruits and flowers of the coffee plant
• Guayusa tea, made from the caffeinated leaves of the ilex guayusa holly, native to the Amazon rainforest
• Mate, a South American caffeinated tea made from the holly yerba mate (Ilex paraguariensis)
• Yaupon tea, caffeinated leaves of the yaupon holly, native to North America
• Tea made from Ilex cassine, which has less caffeine than yaupon, but more theobromine.

Other psychoactive infusions

• Cannabis tea, which contains the psychoactive THC. It is a common drink in India, where it is known as bhang.
• Coca tea, infusion made from coca leaves. Contains trace amounts of cocaine and similar alkaloids.^[11] In some countries where coca is illegal, products marketed as "coca tea" are supposed to be decocainized, i.e., the pharmacologically active components have been removed from the leaf using the same chemicals as manufacturing cocaine.
• Kava root tea, common in Pacific island cultures (Polynesia, Melanesia, Micronesia), which has sedative effects and anesthetic effects caused by compounds called kavalactones.^[12] The traditional form is a water-based suspension of kava roots.
• Kratom tea made from the dried leaves of the kratom tree. It has opioid-like properties and some stimulant-like effects.^{[13] [14]}
• St. John's wort tea, the plant has been shown to have antidepressant properties according to a 2017 meta-analysis.^[15]
• Ephedra tea, mainly from the plant Ephedra sinica.^[16] It contains the stimulant ephedrine. It has been used in traditional Chinese medicine, where it is called máhuáng, for more than 2,000 years.^{[17] [18]} Ephedra tea was also used by Native Americans and Mormons, hence the name "Mormon tea" and "Indian tea".
• Poppy tea, brewed from the poppy straw or seeds of several species of poppy (most commonly Papaver somniferum). Since it contains opium, it is consumed for its narcotic, sedative and analgesic properties.
• Salvia divinorum ("Sage of the diviners") tea which contains salvinorin A, a compound that induces a dissociative state and hallucinations.^[19]
• Dream herb (Calea ternifolia) an oneirogen (dream inducing herb) native to the Americas made into a tea by Mexican peoples.^[20]
• African dream root (Silene undulata) which is an oneirogen used by the Xhosa people as a sacred plant.^{[21] [22]}
• Ayahuasca, a highly psychoactive and hallucinogenic infusion brewed from the Banisteriopsis caapi vine and the leaves of the Psychotria viridis shrub. It is prepared and drunk by native peoples of the Amazon basin as a healing drug and as a spiritual shamanic brew.
• Tabernanthe iboga, which can be made into an infusion, is traditionally used by the peoples of Central Africa and in African traditional medicine as a stimulant (in low doses) or as a powerful ritual hallucinogen (in larger quantities).^{[23] [24] [25]}
• Tobacco tea, which contains nicotine and is traditionally used by the indigenous peoples of the Americas as a medicine for various ills (dizziness, headaches), as a laxative, as an emetic and as an expectorant.^[26]

Non-caffeinated and non-psychoactive infusions

thumb|Rooibos tea, a common drink in South Africa

• Anise tea, made from either the seeds or the leaves
• Asiatic penny-wort leaf, in South Asia and Southeast Asia
• Artichoke tea
• Commiphora gileadensis tea, in the Hijaz region of western Arabia.
• Bael fruit tea
• Bee balm
• Boldo, used in South America
• Burdock; the seeds, leaves, and roots have been used
• Butterfly pea flower tea (from Clitoria ternatea), also called "Blue tea" since it produces a blue infusion
• Caraway, tea made from the seeds
• Catnip, tea used as a relaxant, sedative, and to calm
• Chamomile
• Che dang, bitter tea made from Ilex leaves
• Chinese knotweed tea
• Chrysanthemum tea, made from dried flowers
• Cinnamon tea
• Clover tea, made from the blossoms
• Cerasse, bitter Jamaican herb
• Citrus peel, including bergamot, lemon and orange peel
• Dandelion coffee, which does not contain caffeine despite the name
• Dill tea
• Dried lime tea, made from dried limes common in western Asia
• Echinacea tea
• Elderberry
• European mistletoe (Viscum album), (steep in cold water for 2–6 hours)
• Essiac tea, blended herbal tea
• Fennel
• Gentian
• Ginger root can be made into herbal tea, known in the Philippines as salabat
• Ginkgo biloba
• Ginseng, a common tea in China and Korea, commonly used as a stimulant and as a caffeine substitute
• Goji berry tea
• Hawthorn
• Hibiscus (often blended with rose hip), a common tea in the Middle East or Asia
• Honeybush, similar to rooibos and grows in a nearby area of South Africa, but tastes slightly sweeter. Has a low tannin content, no caffeine.
• Horehound
• Houttuynia
• Hydrangea tea, dried leaves of hydrangeas; considerable care must be taken because most species contain a toxin. The "safe" hydrangeas belong to the Hydrangea serrata Amacha ("sweet tea") cultivar group.^[27]
• Jasmine flower tea, though it is commonly blended with tea leaves, jasmine flowers are also sometimes infused on their own
• Jiaogulan (also known as xiancao or "poor man's ginseng")
• Kapor tea, dried leaves of fireweed
• Kelp tea, East Asian tea made from kelp, known as konbu-cha in Japan
• Kuzuyu, a thick white Japanese tea made by adding kudzu flour to hot water
• Labrador tea, made from the shrub by the same name, found in the northern part of North America
• Lavender tea ^[28]
• Lemon balm
• Lemon and ginger tea
• Lemongrass tea
• Luo han guo
• Licorice root
• Lime blossom, dried flowers of the lime tree (tilia in Latin).
• Meadowsweet herb
• Mint (mint tea), made from various mints, especially peppermint and spearmint. It is also commonly mixed with green tea, as in Maghrebi mint tea. Korean mint tea is one popular pure mint herbal tea.
• Mound of termites tea in Merauke
• Moringa
• Mountain tea, common in the Balkans and other areas of the Mediterranean region. Made from a variety of the Sideritis syriaca plant which grows in warm climates above 3,000 feet. Records of its use date back 2,000 years.
• Neem leaf
• Nettle leaf
• New Jersey tea (Ceanothus americanus), which has a mild blood pressure lowering effect.^[29]
• Noni tea
• Oksusu cha, traditional roasted corn tea found in Korea
• Olive leaf tea
• Oregano tea
• Osmanthus tea, dried flowers of the sweet olive tree, are used alone or blended with tea leaves in China.
• Pandan tea
• Patchouli tea
• Pennyroyal leaf, an abortifacient
• Pine tea, or tallstrunt, made from needles of pine trees
• Qishr, Yemeni drink with coffee husks and ginger
• Red clover tea
• Red raspberry leaf
• Barley tea, East Asian drink with roasted barley
• Rosa × damascena tea, in the Middle East.
• Roasted wheat, used in Postum, a coffee substitute
• Rooibos (red bush), a reddish plant used to make an infusion and grown in South Africa. In the US it is sometimes called red tea. It has many of the antioxidant characteristics of green tea, but because it does not come from tea leaves, it has no caffeine.
• Rose hip (often blended with hibiscus)
• Roselle petals (species of hibiscus; known by other names including bissau and dah), consumed in the Sahel and elsewhere
• Rosemary
• Sagebrush, California sagebrush
• Sage
• Sakurayu, Japanese herbal tea made with pickled cherry blossom petals
• Sassafras roots were steeped to make tea, a practice which was common among Native Americans. They were also used in the flavoring of root beer until being banned by the FDA.
• Scorched rice, known as hyeonmi cha in Korea
• Skullcap
• Shallot peel tea from Kalimantan
• Serendib (tea), tea from Sri Lanka
• Sobacha
• Spicebush (Lindera benzoin) leaves used to make a tea by some native peoples of eastern North America
• Spruce tea, made from needles of spruce trees
• Staghorn sumac, fruit can be made into a lemonade
• Stevia, can be used to make herbal tea, or as a sweetener in other beverages
• Sweet potato leaf tea, a common herbal tea in Chinese medicine
• Thyme, contains thymol
• Tulsi, or holy basil
• Turmeric tea
• Uncaria tomentosa, commonly known as cat's claw
• Valerian is used as a sedative, but clinical evidence for its psychoactive properties are inconclusive.^{[30] [31] [32]}
• Verbena (vervain)
• Wax gourd in East Asia and Southeast Asia.
• Wong Lo Kat, a recipe for herbal tea from Guangdong, China since the Qing Dynasty
• Woodruff
• Yarrow

Health risks

See also: List of herbs with known adverse effects.

While most herbal teas are safe for regular consumption, some herbs have toxic or allergenic effects. Among the greatest causes of concern are:

• Comfrey, which contains alkaloids which may be harmful to the liver from chronic use, and particularly is not recommended during pregnancy or when prescription drugs are used; comfrey is not recommended for oral use.^[33]
• Lobelia, which contains alkaloids and has traditional medicine uses for smoking cessation, may cause nausea, vomiting, or dizziness at high doses.^[34]

Herbal teas can also have different effects from person to person, and this is further compounded by the problem of potential misidentification. The deadly foxglove, for example, can be mistaken for the much more benign (but still relatively toxic to the liver) comfrey. Care must be taken not to use any poisonous plants.

The US does not require herbal teas to have any evidence concerning their efficacy, but does treat them technically as food products and require that they be safe for consumption.

Fruit or fruit-flavored tea is usually acidic and thus may contribute to erosion of tooth enamel.^[35]

Adverse herb‑drug interactions

See also: Grapefruit–drug interactions and Cytochrome P450 (CYP). Some phytochemicals found in herbs and fruits can adversely interact with others and over the counter or prescription medications, among other ways by affecting their metabolism by the body. Herbs and fruits that inhibit or induce the body's Cytochrome P450 enzyme complex function can either cause the drug to be dangerously ineffective, or increase its effective absorbed dose to potentially toxic levels, respectively. Best known examples of adverse herb‑drug interactions are grapefruit or St John's wort, contraindicated for several medications including Paxlovid and oral contraceptives, but other herbs also affect the CYP enzyme family, showing herb‑drug interactions.^{[36] [37] [38]}

Contamination

See also: Health effects of pesticides. Depending on the source of the herbal ingredients, herbal teas, like any crop, may be contaminated with pesticides or heavy metals.^[39] According to Naithani & Kakkar (2004), "all herbal preparations should be checked for toxic chemical residues to allay consumer fears of exposure to known neuro-toxicant pesticides and to aid in promoting global acceptance of these products".^[40]

During pregnancy

In addition to the issues mentioned above which are toxic to all people, several medicinal herbs are considered abortifacients, and if consumed by a pregnant individual could cause miscarriage. These include common ingredients like nutmeg, mace, papaya, bitter melon, verbena, saffron, slippery elm, and possibly pomegranate. It also includes more obscure herbs, like mugwort, rue, pennyroyal, wild carrot, blue cohosh, tansy, and savin.

See also

• List of hot beverages
• Tea culture
• Health effects of tea
• Tincture, the often more concentrated plant extracts made in pure grain alcohol, glycerin, or vinegar
• Yerba mate
• Hot chocolate
• Coffee substitute
• Tea in France
• Chinese sweet tea

External links

• • • Variety of Teas review from https://www.mydraw.com/

Notes and References

1. Web site: Google Ngram Viewer . 2018-05-29.
2. Web site: tisane . Cambridge Advanced Learner's Dictionary . 2018-05-23 . 2018-05-29.
3. Web site: Herbal tea . Dictionary.reference.com . 2019-09-25.
4. Web site: Center. Garfield Medical. Different Types of Tea and Caffeine Content. 2021-01-29. Garfield Medical Center.
5. Web site: Blackberry & Blueberry infusion. Sainsbury's . 6 March 2024. A typical example, described as Blackberry & Blueberry, but has hibiscus as main ingredient, and 0.5% of the named ingredients.
6. tea . Merriam-Webster . 2018-05-29.
7. tea. Lexico. 31 May 2022. 19 November 2017. https://web.archive.org/web/20171119112348/https://en.oxforddictionaries.com/definition/tea. dead.
8. Book: Albert E. Dien . Six Dynasties Civilization . Yale University Press . 2007 . 978-0-300-07404-8 . 362.
9. Book: Bret Hinsch . The ultimate guide to Chinese tea . Bret Hinsch . 2011 . 978-974-480-129-6.
10. tisane. Lexico. 31 May 2022. 27 September 2021. https://web.archive.org/web/20210927014241/https://www.lexico.com/definition/tisane. dead.
11. Jenkins AJ, Llosa T, Montoya I, Cone EJ . 1996 . Identification and quantitation of alkaloids in coca tea . Forensic Science International . 77 . 3 . 179–89 . 10.1016/0379-0738(95)01860-3 . 2705900 . 8819993.
12. Wang . J . Qu . W . Bittenbender . H. C . Li . Q. X . 2013 . Kavalactone content and chemotype of kava beverages prepared from roots and rhizomes of Isa and Mahakea varieties and extraction efficiency of kavalactones using different solvents . Journal of Food Science and Technology . 52 . 2 . 1164–1169 . 10.1007/s13197-013-1047-2 . 4325077 . 25694734.
13. Web site: Gottlieb, Scott . 6 February 2018 . Statement from FDA Commissioner Scott Gottlieb, M.D., on the agency's scientific evidence on the presence of opioid compounds in kratom, underscoring its potential for abuse . 6 February 2018 . US Food and Drug Administration.
14. Cinosi . E . Martinotti . G . Simonato . P . Singh . D . Demetrovics . Z . Roman-Urrestarazu . A . Bersani . F. S . Vicknasingam . B . Piazzon . G . Li . J. H . Yu . W. J . Kapitány-Fövény . M . Farkas . J . Di Giannantonio . M . Corazza . O . 2015 . Following "the Roots" of Kratom (Mitragyna speciosa): The Evolution of an Enhancer from a Traditional Use to Increase Work and Productivity in Southeast Asia to a Recreational Psychoactive Drug in Western Countries . BioMed Research International . 2015 . 1–11 . 10.1155/2015/968786 . 4657101 . 26640804 . free.
15. Ng . Qin Xiang . Venkatanarayanan . Nandini . Ho . Collin Yih Xian . March 2017 . Clinical use of Hypericum perforatum (St John's wort) in depression: A meta-analysis . Journal of Affective Disorders . 210 . 211–221 . 10.1016/j.jad.2016.12.048 . 28064110.
16. Gurley B, Wang P, Gardner S . 1998 . Ephedrine-type alkaloid content of nutritional supplements containing Ephedra sinica (Ma-huang) as determined by high performance liquid chromatography . J Pharm Sci . 87 . 12 . 1547–53 . 10.1.1.460.7810 . 10.1021/js9801844 . 10189265.
17. Abourashed E, El-Alfy A, Khan I, Walker L . 2003 . Ephedra in perspective--a current review . Phytother Res . 17 . 7 . 703–12 . 10.1002/ptr.1337 . 12916063 . 41083359.
18. Book: Kee C. Huang . The Pharmacology of Chinese Herbs, Second Edition . 12 December 2010 . CRC Press . 978-1-4200-4826-1 . 9.
19. Butelman . Eduardo R . Kreek . Mary Jeanne . 2015 . Salvinorin A, a kappa-opioid receptor agonist hallucinogen: Pharmacology and potential template for novel pharmacotherapeutic agents in neuropsychiatric disorders . Frontiers in Pharmacology . 6 . 190 . 10.3389/fphar.2015.00190 . 4561799 . 26441647 . free.
20. Sałaga . Maciej . Fichna . Jakub . Socała . Katarzyna . Nieoczym . Dorota . Pieróg . Mateusz . Zielińska . Marta . Kowalczuk . Anna . Wlaź . Piotr . 2016 . Neuropharmacological characterization of the oneirogenic Mexican plant Calea zacatechichi aqueous extract in mice . Metabolic Brain Disease . 31 . 3 . 631–641 . 10.1007/s11011-016-9794-1 . 0885-7490 . 4863909 . 26821073.
21. J. F. Sobiecki . 2008 . A review of plants used in divination in southern Africa and their psychoactive effects . Southern African Humanities . 20 . 333–351 . 37305695.
22. Sanz . Camila . Zamberlan . Federico . Erowid . Earth . Erowid . Fire . Tagliazucchi . Enzo . 2018 . The Experience Elicited by Hallucinogens Presents the Highest Similarity to Dreaming within a Large Database of Psychoactive Substance Reports . . 12 . 7 . 10.3389/fnins.2018.00007 . 1662-453X . 5786560 . 29403350 . free.
23. Web site: January 23, 2019 . Iboga . live . https://web.archive.org/web/20080601024047/https://www.drugs.com/npp/iboga.html . June 1, 2008 . October 28, 2019 . Drugs.com.
24. Koenig . Xaver . Hilber . Karlheinz . January 29, 2015 . The Anti-Addiction Drug Ibogaine and the Heart: A Delicate Relation . Molecules . 20 . 2 . 2208–2228 . 10.3390/molecules20022208 . 1420-3049 . 4382526 . 26807959 . free.
25. Aubry-Lecomte, Charles Eugène, "Note sur quelque poisons de la côte occidentale d'Afrique", Revue Maritime et Coloniale, vol. XII, 1864.
26. Web site: Tobacco . 2024-06-19 . www.utep.edu . en.
27. C.J. van Gelderen; D.M. van Gelderen. 2004. Encyclopedia of Hydrangeas. Timber Press. 280 p.
28. Web site: Cooking with Lavender – Purple Haze Lavender (Sequim, WA) . dead . https://web.archive.org/web/20100417125855/http://www.purplehazelavender.com/cooking.html . 17 April 2010 . 25 August 2008 . Purple Haze Lavender.
29. J.E. Saxton ed. "The Alkaloids". A special report. Vol I The Chemical Society Burlington House, London (1971) SBN 85186 257 8
30. Boullata JI, Nace AM . Safety issues with herbal medicine . Pharmacotherapy . 20 . 3 . 257–69 . 2000 . 10730682 . 10.1592/phco.20.4.257.34886 . 36757144 .
31. Web site: 9 June 2022 . Valerian . 22 July 2022 . Drugs.com.
32. Web site: 15 March 2013 . Valerian . 2 April 2018 . Office of Dietary Supplements, US National Institutes of Health.
33. Web site: Comfrey. Drugs.com. 5 January 2018. 3 January 2018.
34. Web site: Lobelia. Drugs.com. 5 January 2018. 3 January 2018.
35. O'Toole. S.. Mullan. F.. The role of the diet in tooth wear. British Dental Journal. 224. 5. 379–383. 2018. 10.1038/sj.bdj.2018.127. 29471309. 3797429.
36. Zuo . Hua-Li . Huang . Hsi-Yuan . Lin . Yang-Chi-Dung . Cai . Xiao-Xuan . Kong . Xiang-Jun . Luo . Dai-Lin . Zhou . Yu-Heng . Huang . Hsien-Da . 2022-01-14 . Enzyme Activity of Natural Products on Cytochrome P450 . Molecules . en . 27 . 2 . 515 . 10.3390/molecules27020515 . 1420-3049 . 8779343 . 35056827 . free .
37. Cho . Hyun-Jong . Yoon . In-Soo . 2015 . Pharmacokinetic Interactions of Herbs with Cytochrome P450 and P-Glycoprotein . Evidence-Based Complementary and Alternative Medicine . en . 2015 . 1–10 . 10.1155/2015/736431 . 1741-427X . 4302358 . 25632290 . free .
38. Smith . Dallas J. . Bi . Huichang . Hamman . Josias . Ma . Xiaochao . Mitchell . Constance . Nyirenda . Kumbukani . Monera-Penduka . Tsitsi . Oketch-Rabah . Hellen . Paine . Mary F. . Pettit . Syril . Pheiffer . Wihan . Van Breemen . Richard B. . Embry . Michelle . 2023-07-12 . Potential pharmacokinetic interactions with concurrent use of herbal medicines and a ritonavir-boosted COVID-19 protease inhibitor in low and middle-income countries . Frontiers in Pharmacology . 14 . 10.3389/fphar.2023.1210579 . 1663-9812 . 10368978 . 37502215 . free .
39. 16228893 . 2005 . Naithani . V . Kakkar . P . Evaluation of heavy metals in Indian herbal teas . 75 . 1 . 197–203 . 10.1007/s00128-005-0738-4 . Bulletin of Environmental Contamination and Toxicology. 41011619 .
40. 16268119 . 2004 . Naithani . V . Kakkar . P . An evaluation of residual organochlorine pesticides in popular Indian herbal teas . 59 . 8 . 426–30 . 10.3200/AEOH.59.8.426-430 . Archives of Environmental Health . 31026817 .