How does it feel?
Anyone who has ever bitten into a raw acorn will have experienced the drying, constricting feeling of astringency, similar to having drunk a cup of strong black tea or a glass of red wine. This sensation experienced with these and many other plants is produced by the high tannin levels they contain. Many hours of soaking to remove the tannins and then cooking of acorns is required before they acquire a slightly sweet and nutty taste that some people enjoy as a coffee substitute or to use as flour.
What can I use it for?
Oak (Quercus robur) As a decoction the high tannin content makes oak a primary remedy for acute diarrhoea. The bark should be boiled for 10—15 minutes, strained and small sips taken frequently (1,3,6,7).
It is also vital to maintain hydration levels during episodes of acute diarrhoea. If symptoms do not resolve then medical attention should be sought.
A decoction made this way may also be used as a mouthwash for bleeding gums, gum disease and mouth ulcers. As a gargle it is indicated for sore throats associated with conditions such as tonsillitis, pharyngitis and laryngitis. It may also be used as a douche for leucorrhoea (1,6,7,8).
Externally, along with herbs such as witch hazel (Hammamelis virginiana), horse chestnut (Aesculus hippocastanum), marigold (Calendula officinalis), chamomile (Matricaria chamomilla) or rose (Rosa spp.), oak can be used in a cream or lotion for varicose veins and haemorrhoids (9).
Relief from the discomfort of haemorrhoids may be gained from the use of a sitz bath of oak bark decoction.
As a powder, it has been used as a snuff to stop nosebleeds and for “foul smelling ulcers and septic wounds” (10, 11). The powder may also be used to brush the teeth as part of a treatment for bleeding or inflamed gums (1,8).
A compress may be prepared for bruises, varicose veins, acute eye conditions or to stop bleeding from a wound by soaking a piece of gauze in a decoction of oak bark and applying it to the affected area (11).
Home herbal treatment is intended to relieve the symptoms of minor illnesses or injuries. If your symptoms do not resolve, it is advised that you seek further professional medical guidance from either your GP, a qualified medical herbalist or other healthcare provider. Our find a herbalist resource can help you find a herbal practitioner in your area.
Into the heart of oak
Oak leaves with fruit (Quercus robur) Energetically oak has long been associated with qualities such as strength, courage, protection and longevity. The strong enduring nature of the wood has led to it being chosen for the construction of dwelling places, ships and cathedrals, including Salisbury Cathedral in the UK where it can be seen to be structurally sound over 800 years after its construction (12).
It has been said that an oak tree is the ideal place to sit to calm your nerves and unravel problems that are affecting your well-being. In the Ogham, an ancient British and Irish language also known as the ‘Celtic tree alphabet’, oak represents the word Duir which is derived from the Gaelic word for ‘door’. Oak energy is associated with accessing the doorway to our inner strength and peace when we need it most (13).
Oak flower essence is indicated for individuals who have steadfastly remained strong against adversity but who are reaching the limit of their endurance (14). These individuals may also benefit from adaptogenic herbs.
Oak has been multiply immortalised in prose and verse including by John Keats (15).
“Those green-robed senators of mighty woods,
Tall oaks, branch-charmed by earnest stars,
Dream, and so dream all night without a stir…”(John Keats, from Hyperion, Book 1)
Traditional uses
Green oak leaves (Quercus robur) Oak has been used as medicine since the times of Hippocrates, Galen and Dioscorides. Records indicate it was considered effective for the treatment of diarrhoea, excessive uterine bleeding and the spitting of blood (5).
Culpeper (1653) advised that the inner bark of the oak tree along with the thin skin covering the acorn be used to “stay the spitting of blood, and the bloody flux. A decoction of the bark and powdered cups was given “to stay vomiting, bleeding at the mouth or other fluxes of blood in men or women” (16).
Other traditional herbalists claim the skin of the acorn to be effective against the spitting of blood and finely powdered oak bark is said to have been proven beneficial in the early stages of consumption after it was noted that working tanners appeared to be exempt from contracting this disease (17).
Homeopathically oak is indicated for chronic alcoholism and drunkenness; it is considered to be an antidote for alcohol intoxication and may be given to control cravings for alcoholic beverages (1,5,11, 18).
Traditional actions
Herbal actions describe therapeutic changes that occur in the body in response to taking a herb. These actions are used to express how a herb physiologically influences cells, tissues, organs or systems. Clinical observations are traditionally what have defined these actions: an increase in urine output, diuretic; improved wound healing, vulnerary; or a reduction in fever, antipyretic. These descriptors too have become a means to group herbs by their effects on the body — herbs with a nervine action have become the nervines, herbs with a bitter action are the bitters. Recognising herbs as members of these groups provides a preliminary familiarity with their mechanisms from which to then develop an understanding of their affinities and nuance and discern their clinical significance.
Traditional energetic actions
Herbal energetics are the descriptions Herbalists have given to plants, mushrooms, lichens, foods, and some minerals based on the direct experience of how they taste, feel, and work in the body. All traditional health systems use these principles to explain how the environment we live in and absorb, impacts our health. Find out more about traditional energetic actions in our article “An introduction to herbal energetics“.
What practitioners say
Old oak tree (Quercus robur) The high tannin content of oak is the reason it is primarily indicated in conditions that involve an excess of fluids, blood loss or tissues that are damaged or lack tone. The astringency that results from the action of these constituents creates a barrier protecting the underlying tissue from infection.
Digestive system
Within the digestive system oak is considered to be specific in the primary treatment of cases of acute diarrhoea including dysentery (7,19), where it clearly demonstrates its ability to reduce excess fluids. Adequate fluid intake is essential to maintain during episodes of acute diarrhoea and supplementary electrolytes may also be recommended in some situations.
Its benefits for this system are also evidenced in the treatment of disorders affecting the mouth such as inflammation or bleeding of the gums (8,10,19) where, as a mouthwash, it tightens tissues that lack tone whilst reducing the risk of potential infection.
Respiratory system
Oak could be included in a prescription for conditions of the upper respiratory system where there is seen to be an excess of fluid such as catarrh or congested sinuses (10).
Conditions affecting the throat including tonsillitis, pharyngitis and laryngitis, particularly when tissues are inflamed, appear boggy and infection is present, may benefit from the inclusion of oak bark in gargle for its astringent and microbial effects (6,11,20).
Its styptic action has been demonstrated through its ability to stop nosebleeds when administered topically as a snuff (10) and it may show benefits in reducing the size of nasal polyps when administered similarly or, alternatively, as a nasal spray alongside other anti-inflammatory, astringent or mucous membrane restorative herbs specific to the tissues of the nasal passages and sinuses.
Cardiovascular system
As a remedy for the cardiovascular system, the benefits of oak are most evident where there is venous insufficiency resulting in conditions such as varicose veins and haemorrhoids. Here the ability of oak to tighten and tone tissues is clearly demonstrated when applied topically to the affected area as a lotion (6,10) or, in the case of haemorrhoids a decoction may instead be used as an enema (11,20).
Oak tree leaves (Quercus robur) Gynaecological system
Oak is indicated in cases of both menorrhagia (heavy menstrual loss) and leucorrhoea (non-infective white vaginal discharge). However, there are many other herbs that a modern herbal practitioner may alternatively turn to when treating these conditions such as yarrow (Achillea millefolium), lady’s mantle (Alchemilla vulgaris), shepherd’s purse (Capsella bursa-pastoris), raspberry leaf (Rubus idaeus) and white dead nettle (Lamium alba). Additional herbs may also be added to a prescription to alleviate the cramping and pain that often accompanies heavy periods.
Heavy menstrual bleeding is often associated with the perimenopausal stage of an individual’s life or with conditions such as endometriosis, fibroids and uterine polyps for which investigations may be recommended in order that the underlying dysfunction or disease process can be addressed rather than merely palliating the symptoms.
Use of any herbs rich in tannins should be used selectively and for restricted amounts of time due to their effect of gut absorption of nutrients and minerals including iron, particularly given that any condition featuring regular blood loss as a symptom is associated with an increased risk of iron-deficiency anaemia.
Should any acute condition not resolved within acceptable time parameters or symptoms become chronic then seeking further professional medical advice is strongly recommended. This might include an appointment with a GP, practice nurse or other healthcare provider. The Find a herbalist feature on this website can be used to find a medical herbalist within your area.
Research
Tall oak tree (Quercus robur) Robuvit, a registered product containing 300 mg of standardised Q. robur extract was seen to significantly improve levels of fatigue during convalescence from acute illness when compared to the control group (21). Other clinical trials have shown beneficial effects in cases of chronic fatigue syndrome, liver failure and in the treatment of lymphoedema (6,21,22). These effects may be potentially attributed to the rejuvenation of mitochondrial function that has been evidenced following Robuvit supplementation (6,23).
Research into the anti-inflammatory action of ellagitannins found in herbs including oak bark, meadowsweet (Filipendula ulmaria), raspberry leaf (Rubus idaeus) and herb Robert (Geranium robertianum) has indicated they may have a key role to play as a source of bioavailable gut microbiota metabolites shown to demonstrate anti-inflammatory activity (24).
A 2016 study concluded there is sufficient evidence to suggest that oak bark may have a role to play in the mediation of allergic reactions. An oak bark decoction was demonstrated to inhibit degranulation and the release of cytokines from basophilic and mast cells in in vitro trials. Further research is required, however, this could potentially indicate a role for the topical use of oak in the management of allergic reaction (25).
An earlier study in 2013 investigated the potential benefits of Quercus acutissima, commonly known as saw-tooth oak which is native to China, Tibet, Korea and Japan, in the prevention of allergic asthma using an ethanol extract of the acorn rather than the bark as is most commonly seen. As foods derived from acorns are commonly available in the parts of the world this species of oak is native to, the study was intended to explore whether the consumption of acorns could be promoted as an anti-inflammatory health-food. The results of this work suggested that the acorn of Q. acutissima may have anti-inflammatory effects that are beneficial in the prevention of allergic asthma (26).
Another study utilising a part of oak other than the bark investigated the therapeutic efficacy of oak gall in a double-blind randomised controlled trial into its effectiveness and safety for treating bacterial vaginosis when compared to the standard treatment of metronidazole vaginal gel. The results of these trials indicate that a vaginal cream made from oak gall was equally effective as treatment with metronidazole gel based on symptom score after one week of treatment. Furthermore, none of the oak gall group experienced any adverse effects whereas 7.7% of the women using metronidazole gel reported vaginal burning (27).
As antibiotics are increasingly seen to reduce in efficiency as resistant bacterial strains continue to develop, there has arisen a need to identify alternative sources of antimicrobials including those that are plant-derived (28). Studies involving an aqueous (water-based) extraction of oak indicate that it has an effective antimicrobial action and may have a part to play in the solution to antibiotic resistance (29).
Did you know?
The etymology of the Latin name for the oak species ‘Quercus’ is said to be derived from the Celtic words quer and cuez which translates as ‘fine tree’(17).
Alongside its other traditional uses, oak has been synonymous with the process of tanning leather and the making of barrels for the storage of wines and spirits (30).
Until around a hundred years ago, oak galls were used to produce ink (30).
Additional information
Botanical description
The oak is a large, spreading deciduous tree demonstrating extreme longevity of 800 years or more which may grow to over 30–40 metres in its lifetime (35,36).
It has rugged bark but hairless twigs and leaves, initially a pale yet almost luminous green but darkening as the year progresses. They are described as oblong and pinnate lobed with four to five rounded side lobes and attached by a very short stalk. The pendulous male catkins may be seen in Spring along with the female flowers which develop on the ends of the new growth (36,37).
Acorns, each containing a single seed, develop in cups, often 2 or 3 together on a common stalk . They may be from 1.8–3cm long and fall to the ground around October time (36,37).
Common names
- English oak
- Pedunculate oak
- Common oak
- Eiche (Ger)
Although this monograph focuses mainly on Quercus robur, other species of oak such as Quercus alba, commonly known as white oak, which has been more frequently used in American herbalism, have a similar history of use in herbal medicine to that of Q. robur. Some herbalists have found that many other species of oak can be used similarly and globally the inclusion of a significantly wider diversity of oak species is seen to have been explored for their therapeutic effects both in practice and in research studies (1,2,3,4,5).
Safety
At this time, many sources consider that there is insufficient evidence to determine whether oak is safe to use internally during pregnancy and breast-feeding. However, there are no cautions regarding its topical use for conditions that may be associated with pregnancy including varicose veins or haemorrhoids.
Cautions
Although useful for acute, short-term conditions, oak should not be used internally at high doses longer term (6).
Externally the Commission E monographs cautions against using it for more than 2–3 weeks or topically on large areas of extensive skin damage (19).
Interactions
There are no reported interactions with prescribed or over-the-counter medicines and supplements. However the high tannin content of oak may result in a reduced absorption of nutrients and some prescribed drugs therefore it is advised that any remedies containing oak are administered apart from meals and other medicines (6,32).
Contraindications
Herbs that are high in tannins such as oak should be avoided in cases involving constipation and iron-deficient anaemia (6,7,8,32).
Preparations
- Decoction
- Powder
- Tincture
- Cream or lotion
- Suppository
Dosage
Tincture: A typical dosage would be 20–40 ml per week or 1–2 ml three times daily (6,7).
Decoction: 1 g of dried herb per cupful of water is suggested three times daily, unless otherwise prescribed (19).
Plant parts used
It is generally the bark that is specified when oak is indicated for medicinal use. However, many sources, both traditionally and within modern herbal medicine practice, mention the use of other parts of the tree including leaves, acorns and galls as also being beneficial (1,5,6,7,11,17).
Constituents
The predominant constituents in oak are the tannins, which may be up to 20% of the active compounds contained within the bark. These polyphenolic compounds include grandin and ellagitannins, such as gallic acid, ellagic acid, vescalagin and castalagin (6).
When compared it was found that Q. alba has lower ellagitannins whereas higher levels of gallic acid and total phenolics were to be seen in Q. robur (33).
Gallotannins and ellagitannins are to be found in many astringent herbs such as oak (Quercus spp.), witch hazel (Hammamelis virginiana) and raspberry leaf (Rubus idaeus). Their actions also include antimicrobial, anti-inflammatory and antioxidant (34).
Oak also contains flavonoid glycosides, including rutin and quercetin. and proanthocyanadins. Rutin and quercetin (a glycoside of rutin) have been shown to have anti-oxidant, anti-inflammatory and anti-allergic effects (6,34).
It is the mechanism of these constituents that results in the effects that can be seen whenever oak is either taken internally or applied topically.
Habitat
As a genus, when measured by diversity and distribution, it has been said that oaks are considered to be an evolutionary success. They are estimated to have appeared around 56 million years ago with a subsequent expansion throughout the Northern hemisphere (38).
Q. robur is native throughout Britain, Europe, the Caucasus, East Russia, North Africa and Asia minor and can be found within woodland, parks and hedgerows (35,36).
Sustainability
Although oaks are deemed to be of Least Concern (LC) according to IUCN Red List criteria there are seen to be potential threats in regards to its sustainability. In the UK, native woodlands, including oak have been diminishing significantly for several hundreds of years which has now resulted in the recent promotion of native woodland planting by the Forestry commission (36).
Another threat to the native oak population is that of disease. ‘Sudden oak death’, a fungal disease, has recently been identified in Britain but as yet does not appear to be affecting the native oaks. However ‘Acute oak decline’, the causes of which are currently not known, has also been reported in the UK which the native oaks, including Quercus robur, are susceptible to (36).
The conservation of oak trees, along which many other of our native species of woodlands, is of vital importance not just to ensure the ongoing survival of a tree so intertwined with our own history but so they may continue to provide the environment that supports the biodiversity of life that depends on it from the birds and mammals that feed on its acorns, the insects that live on and within it to the moulds, fungi, mosses and lichens occupying its roots, trunk and branches (36).
Quality control
Herbal Medicines are often extremely safe to take, however it is important to supply herbal medicines from a reputed supplier. Sometimes herbs bought from unreputable sources are contaminated, adulterated or substituted with incorrect plant matter.
Some important markers for quality to look for would be to look for certified organic labelling, ensuring that the correct scientific / botanical name is used and that suppliers states clearly the source of ingredients used in the product.
A supplier should also be able to tell you where the herbs have come from. There is more space for contamination and adulteration where supply chain is unknown.
How to grow
As it has been frequently quoted, often attributed to Geoffrey Chaucer (1374), “Mighty oaks from tiny acorns grow”.
Acorns can be collected and sown whilst green, either directly outside or into small pots in the green house in order to germinate the following spring. A threat over winter may result from the foraging of squirrels or mice so protection from this is advised (36).
They prefer fertile and well drained soil in full sun. If transplanting oak saplings they should be less than a year old as they don’t transplant well after this age. If buying in oak saplings they should appear healthy and be sourced from a reputable plant nursery (36,39).
Recipe
Oak tincture and oak bark (Quercus robur) Oak leaf wine*
Ingredients
- 4 ½ litres young, fresh oak leaves
- 4 ½ litres water
- 1kg sugar
- 3 oranges
- Yeast
- Pectinol
Method
Boil the water and pour over the oak leaves and leave to stand overnight.
Strain out the leaves and boil the remaining liquid for 20 minutes before adding the sugar, juice and grated rind of the oranges. Leave to cool to blood temperature before adding the yeast.
This should be left to ferment in an open bucket for five days before transferring to a fermentation jar with an airlock. This should be left until all signs of fermentation have ceased and any sediment has settled. Transfer into a clean vessel and add Pectinol to remove haze if desired. Leave for 24 hours before filtering the wine off into sterilised bottles and seal with corks that have been boiled for ten minutes.
* taken from Roger Phillips book Wild Food (31)
Tooth powder
Combine oak bark with other herbs such fennel seed, cinnamon or black walnut and grind finely, either with a pestle and mortar or in a coffee bean grinder, to create a powder that can be used to clean the teeth and relieve the symptoms of inflamed or bleeding gums. This should be stored in a clean, dry glass jar (1,8).
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