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A prized herb in Traditional Chinese Medicine, Rehmmania can help us with the chronic stresses of modern life

Rehmannia

Rehmannia glutinosa Orobanchaceae

Rehmannia is a medicine to consider when in need of balance and support. It aids in the recovery from periods of prolonged stress and overwork whilst offering protection to the systems of the body most affected, increasing our resilience, vigour and vitality.

Sustainability status

Not currently on risk lists but complete data may be missing on the status of the species. Commonly cultivated though may be sourced from the wild. Only source cultivated supplies or from certified sustainable wild collection. Read more about our sustainability guide.

Sustainability Status
Key benefits
  • Blood tonic
  • Adrenal tonic
  • Immunomodulation
  • Hormone balancing
  • How does it feel?

    The dried and fresh preparations of the herb are cooling in nature, tasting sweet and bitter. The prepared or cured form has a warmer tendency and is sweet and nourishing to taste.

  • What can I use it for?

    A wonderful nourishing medicine that can be used to support in times of high stress, rehmannia is a highly esteemed adaptogenic medicine (a substance that supports the bodies resilience to the damaging effects of stress) used for centuries in ancient China.

    The adrenal glands produce ‘stress hormones’ in response to various challenges (including physical stressors like cold and hunger as well as psychological or emotional ‘stress’. These hormones are essential for the balanced function of our body’s systems. However with prolonged periods of stress, sometimes these hormonal  responses are disturbed, and can create long term problems in the body.

    Adaptogens like rehmannia protect the systems of the body that are most affected by disturbed stress responses, such as the nervous and immune systems.

  • Into the heart of Rehmannia

    In 7th Century China rehmannia was said to be among the most highly valued medicinal plants, having the ability to remove excess heat throughout the body (heat translating as metabolic activity and inflammation).

    In the TCM understanding of excess heat, yin deficiency (yin loosely in this case, referring to coolness and substance) is thought to be the primary cause.

    Yin deficiency presents itself as hot inflammations such as skin conditions, joint pain, aversion to heat, feverishness, hot flushes, thirst and other diseases of a hot and inflammatory nature.

    Rehmannia is also used to support those with adrenal fatigue. This occurs when an individual has been exposed to prolonged high levels of stress hormones, possibly from trauma, over working or challenging personal circumstances.

    The presenting symptoms of adrenal fatigue are often physical and mental fatigue, but beneath that are classic yin deficiency symptoms, such as insomnia, night sweats, premature grey hair, lower back pain, joint pain, loss of libido, dry skin and hair.

    In TCM rehmannia is also traditionally used often in combination with astragalus as a tonic to slow ageing, both improving memory, longevity and overall health.

    Please note: In TCM the concept of yin and yang serve as the foundation for understanding health and disease. The energetic or elemental characteristics of both translate to a TCM practitioner by the nature of their balance (or imbalance). In disease either one or the other may be in excess or deficiency.

    Yin means the more substantial energies, coolness, feminine, darkness, rest and right, yang meaning light energies, warmth, masculine, activity and left. Yin deficiency is a deficiency of coolness (which leaves yang in excess – causing heat and inflammation).

  • Traditional uses

    Rehmannia’s two different preparations have their own unique energetic qualities and applications.

    Uncured is both bitter and sweet, producing a cooling effect upon the body, some of the specific applications for this medicine are to reduce heat and inflammation. As a bitter medicine this action may be due to the mechanism of bitters upon the liver (bitter compounds in herbal medicines are known for their stimulating effect upon the liver. A dysfunctional liver can generate higher levels of blood toxicity which can lead to hot skin inflammations and other inflammatory conditions).

    Cured rehmannia has a deeper, richer, slightly warm and nutritive action. The applications for this form of its medicine are more towards weakness in the body; in promoting ‘blood’ (xue – a dense form of qi) it has been applied for anaemia, dizziness, tinnitus and for regulating the menstrual cycle. Both an adaptogen and tonic this form of rehmannia would be best suited for convalescence from illness.

  • Traditional actions

  • What practitioners say

    Endocrine system: A plant with a long standing reputation as an adrenal tonic. The adrenal hormones deal with many important coping functions in the body, and are essential for wider health. However with prolonged periods of stress, these hormones can lead to chronic problems.

    To support its reputation as an adaptogenic medicine, studies have found that rehmannia affects the metabolism of cortisol (a stress hormone which is released by the adrenal cortex), making it less likely to disrupt the stress response (2). 

    Digestive system: Rehmannia has been found to be effective in reducing blood sugar levels (11). With a strong thread of reference in traditional written herbals for use as a supportive medicine for diabetics (2).

    Immune system: The immune system is directly affected by excess stress hormones, therefore it is common to see symptoms of a compromised immune system where adrenal fatigue and prolonged stress is concerned. 

    Supporting the adrenal glands and lowering stress hormones in the body allows the immune system to function in natural balance, reducing inflammation and increasing overall resilience to illness. 

    Rehmannia is also indicated in autoimmune diseases to reduce inflammations and can be used in cases of rheumatoid arthritis, urticaria, asthma and other autoimmune conditions (2). 

    In conjunction with astragalus, rehmannia has been shown to demonstrate anti-allergy effects, both promoting balanced immune function and reducing inflammation (2).

    Nervous system: Rehmannia has a neuroprotective effect, it is sometimes used in cases of memory loss, particularly when associated with ageing. 

    With its anti-inflammatory and antioxidant effects rehmannia is both protective against neurotoxicity and is also trophorestorative (restoring nutrient balance in the cells of the nervous system) (3, 4). 

    In the same context there is some support for the use of Rehmannia in treatment of inner ear diseases such as tinnitus and hearing loss (5).Eliminatory system: A preparation of astragalus and rehmannia is used to support those with chronic nephritis and for increasing kidney function for those with kidney failure (2).

  • Research

    An in vivo study showed that several constituents of Rehmannia exhibited renoprotective effects (9).

    In TCM, rehmannia and astragalus are commonly prepared together in tonics and formulas to increase longevity and enhance immune function. In 2018 an in vivo study found that this combination prolonged cellular survival and other measures of health (6). 

    In a systematic review of the activity of catalpol, the most abundant iridoid glycoside in rehmannia there was evidence for this phytochemical of neuroprotective activities against Alzheimer’s disease, Parkinson’s disease, stroke, and depression (10).

    In a data analysis carried out in 2014, four of the active compounds isolated from the air-dried roots of Rehmannia (ionones and ionone glycosides) were shown to exhibit moderate hepatoprotective activities (7).

    As with much of the current research into herbal medicine, there is a large majority of in vivo (animal) studies available to back up what we know about these plants. However, on both ethical accounts and relevance to practice, it is clear that more human studies are required.

  • Did you know?

    Rehmannia root was traditionally prepared by steaming it ten times and drying it in the sun nine times. In TCM the root is often steamed in rice or millet wine until both the insides and outsides turn black and moist. The prepared form of rehmannia has a highly rich and deep flavour.

Additional information

  • Botanical description

    Rehmannia, is a rhizomatous, basal-leaved, rosette-forming, herbaceous perennial that flowers in late spring to early summer with pendant, tubular, foxglove-like, reddish-brown to yellowish-brown flowers with dark purple veins. 

    Flowers (each to approx 2” long) bloom in few-flowered spike-like terminal racemes or singly from leaf axils on purplish stems rising to 1’ tall from a basal rosette of coarsely toothed, obovate to oblong, rosulate leaves (to 3-5” long). 

    Seeded capsules for the fruits in mid to late summer. Rehmannia has a thick tuberous orange root approximately 3 – 6cm in diameter. This species is native to mountainous slopes and open woodland areas of China.

  • Common names

    • Chinese foxglove
    • Di Huang
  • Safety

    Anti diabetes medications: As Rehmannia can effect blood sugar levels it is recommended if taking medications that lower blood sugar levels that you consult your health professional or a medical herbalist before taking Rehmannia. Blood sugar levels should be monitored closely and medications may need to be reduced.

    Antihypertensive medications: As Rehmannia can affect blood pressure, it is recommended if taking medications that lower blood pressure that you consult your health professional or a medical herbalist before taking Rehmannia

  • Dosage

    Decoction: Add 10 – 30g dried plant to 300 – 400ml water, decoction (simmer) for one hour. Strain and take two to three cups a day.

    Tincture: Take 4 – 12ml in a little water, per day.

  • Constituents

    • Saccharides – polysaccharides, oligosaccharides, stachyose and monosaccharide
    • Irodoid glycosides- catalpol, dihydrocatalpol,  phenol glycoside, catapol, ajugol, rehmanniosides, rhemaglutins
    • Ionone
    • Mannitol
    • Flavonoids
    • Amino acids
  • References

    1. Zhang R X et al. 2008. Rehmannia glutinosa: Review of botany, chemistry and pharmacology. Journal of Ethnopharmacology. Issue 117. Elsevier.
    2. Mills. S, Bone. K. 2000. Principles and Practice of Phytotherapy. Churchill Livingstone. Elselvier Health.
    3. M. J. R Howes, P. J Houghton 2017. Neurobiology of Chinese Herbal Medicine. International Review of Neurobiology.
    4. Y. Y Tian et al. 2006. Catalpol protects dopaminergic neurons from LPS-induced neurotoxicity in mesencephalic neuron-glia cultures. Life Sciences. Volume 80. Issue 3.
    5. H. H Yu et al. 2006. Protective effect of Rehmannia glutinosa on the cisplatin-induced damage of HEI-OC1 auditory cells through scavenging free radicals. Journal of Ethnopharmacology. Volume 107. Issue 3.
    6. L.B. Gui Ying. 2018 Rehmannia glutinosa exhibits anti-aging effect through maintaining the quiescence and decreasing the senescence of hematopoietic stem cells. Animal Models and Experimental Medicine. Volume 1. Issue 3.
    7. Liu, Y.-F et al. 2014. Ionone glycosides from the roots of Rehmannia glutinosa. Journal of Asian Natural Products Research, Issue 16. Volume 1.
    8. Huang Y. 2016. Rehmannia glutinosa polysaccharide liposome as a novel strategy for stimulating an efficient immune response and their effects on dendritic cells. International Journal of Nanomedicine, Volume 11.
    9. Liu, Y.-L et al. 2022. Renoprotective activity of a new amide and a new hydroxycinnamic acid derivative from the fresh roots of Rehmannia glutinosa. Journal of Asian Natural Products Research,  Volume 24. Issue 2.
    10. Zhang X teal. 2021. Therapeutic potential of catalpol and geniposide in Alzheimer’s and Parkinson’s diseases: A snapshot of their underlying mechanisms. Brain Research Bulletin. Issue 174.
    11. 11. Ren, L. et al. 2017. Effects of water extracts of Rehmannia glutinosa on antioxidant system of Nrf2 in paraquat-induced insulin resistance diabetic rat model. Experimental and Therapeutic Medicine. Issue 14. Volume 6.
Aromatic
An ‘aromatic’ remedy, high in volatile essential oils, was most often associated with calming and sometimes ‘warming’ the digestion. Most kitchen spices and herbs have this quality: they were used both as flavouring and to ease the digestion of sometimes challenging pre-industrial foods. Many aromatics are classed as ‘carminatives’ and are used to reduce colic, bloating and agitated digestion. They also often feature in respiratory remedies for colds, chest and other airway infections. They are also classic calming inhalants and massage oils, and are the basis of aromatherapy for their mental benefits.
Astringent taste
The puckering taste you get with many plants (the most familiar is black tea after being stewed too long, or some red wines) is produced by complex polyphenols such as tannins. Tannins are used in concentrated form (eg from oak bark) to make leather from animal skins. The process of ‘tanning’ involves the coagulation of relatively fluid proteins in living tissues into tight clotted fibres (similar to the process of boiling an egg). Tannins in effect turn exposed surfaces on the body into leather. In the case of the lining of mouth and upper digestive tract this is only temporary as new mucosa are replenished, but in the meantime can calm inflamed or irritated surfaces. In the case of open wounds tannins can be a life-saver – when strong (as in the bark of broadleaved trees) they can seal a damaged surface. One group of tannins, the reddish-brown ‘condensed tannins’ are procyanidins, which can reduce inflammation and oxidative damage.
Bitter
Bitters are a very complex group of phytochemicals that stimulate the bitter receptors in the mouth. They were some of the most valuable remedies in ancient medicine. They were experienced as stimulating appetite and switching on a wide range of key digestive functions, including increasing bile clearance from the liver (as bile is a key factor in bowel health this can be translated into improving bowel functions and the microbiome). Many of these reputations are being supported by new research on the role of bitter receptors in the mouth and elsewhere round the body. Bitters were also seen as ‘cooling’ reducing the intensity of some fevers and inflammatory diseases.
Blue-purple colouring
Any fruits with a blue-purple colouring contain high levels of the polyphenols known as anthocyanins. These work 1) on the walls of small blood vessels, helping to maintain capillary structure to reduce a key stage in inflammation, and improving the microcirculation to the tissues; 2) to improve retinal function and vision; 3) to support connective tissue repair around the body.
Cooling
Traditional ‘cold’ or cooling’ remedies often contain bitter phytonutrients such a iridoids (gentian), sesiquterpenes (chamomile), anthraquinones (rhubarb root), mucilages (marshmallow), some alkaloids and flavonoids. They tend to influence the digestive system, liver and kidneys. Cooling herbs do just that; they diffuse, drain and clear heat from areas of inflammation, redness and irritation. Sweet, bitter and astringent herbs tend to be cooling.
Hot
Traditional ‘hot’ or ‘heating’ remedies, often containing spice ingredients like capsaicin, the gingerols (ginger), piperine (black or long pepper), curcumin (turmeric) or the sulfurous isothiocyanates from mustard, horseradich or wasabi, generate warmth when taken. In modern times this might translate as thermogenic and circulatory stimulant effects. There is evidence of improved tissue blood flow with such remedies: this would lead to a reduction in build-up of metabolites and tissue damage. Heating remedies were used to counter the impact of cold, reducing any symptoms made worse in the cold. .
Mucilaginous
Mucilages are complex carbohydrate based plant constituents with a slimy or ‘unctuous’ feel especially when chewed or macerated in water. Their effect is due simply to their physical coating exposed surfaces. From prehistory they were most often used as wound remedies for their soothing and healing effects on damaged tissues. Nowadays they are used more for these effects on the digestive lining, from the throat to the stomach, where they can relieve irritation and inflammation such as pharyngitis and gastritis. Some of the prominent mucilaginous remedies like slippery elm, aloe vera and the seaweeds can be used as physical buffers to reduce the harm and pain caused by reflux of excess stomach acid. Mucilages are also widely used to reduce dry coughing. Here the effect seems to be by reflex through embryonic nerve connections: reduced signals from the upper digestive wall appear to translate as reduced activity of airway muscles and increased activity of airway mucus cells. Some seed mucilages, such as in psyllium seed, flaxseed (linseed) or guar bean survive digestion to provide bulking laxative effects in the bowel. These can also reduce rate of absorption of sugar and cholesterol. .
New-mown hay aroma
The familiar country odour of haymaking, of drying grass and other plants, is largely produced by coumarins (originally isolated from tonka beans – in French coumarou) and widely used in perfumery. They are chemically categorised as benzopyrone lactones and are important phytochemicals, with strong antioxidant activity in the laboratory and likely effects in modulating inflammation. They were most often associated with the calming effect linked to their use in stuffing mattresses and pillows and plants, high In coumarins were commonly used for these properties.
Resinous
Resins are most familiar as tacky discharges from pine trees (and as the substance in amber, and rosin for violin bows). They were most valued however as the basis of ancient commodities like frankincense and myrrh (two of the three gifts of the Three Wise Men to the baby Jesus) and getting access to their source was one benefit to Solomon for marrying the Queen of Sheba (now Ethiopia). Resins were the original antiseptic remedies, ground and applied as powders or pastes to wounds or inflamed tissues, and were also used for mummification. With alcohol distillation it was found that they could be dissolved in 90% alcohol and in this form they remain a most powerful mouthwash and gargle, for infected sore throats and gum disease. They never attracted much early research interest because they permanently coat expensive glassware! For use in the mouth, gums and throat hey are best combined with concentrated licorice extracts to keep the resins in suspension and add extra soothing properties. It appears that they work both as local antiseptics and by stimulating white blood cell activity under the mucosal surface. They feel extremely effective!
Salty
The salty flavour is immediately distinctive. A grain dropped onto the tongue is instantly moistening and a sprinkle on food enkindles digestion. This easily recognisable flavour has its receptors right at the front of the tongue. The salty flavor creates moisture and heat, a sinking and heavy effect which is very grounding for the nervous system and encourages stability. People who are solid and reliable become known as ‘the salt of the earth'.
Sharpness
The sharp taste of some fruits, and almost all unripe fruits, as well as vinegar and fermented foods, is produced by weak acids (the taste is generated by H+ ions from acids stimulating the sour taste buds). Sour taste buds are hard-wired to generate immediate reflex responses elsewhere in the body. Anyone who likes the refreshing taste of lemon or other citrus in the morning will know that one reflex effect is increased saliva production. Other effects are subjective rather than confirmed by research but there is a consistent view that they include increased digestive activity and contraction of the gallbladder.
Sweet
In the days when most people never tasted sugar, ‘sweetness’ was associated with the taste of basic foods: that of cooked vegetables, cereals and meat. In other words sweet was the quality of nourishment, and ‘tonic’ remedies. Describing a remedy as sweet generally led to that remedy being used in convalescence or recovery from illness. Interestingly, the plant constituents most often found in classic tonics like licorice, ginseng are plant steroids including saponins, which also have a sweet taste.

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