Silver birch (bark, tar, sap)

What is Silver birch (bark, tar, sap)?

Silver birch is a slim tree with white, papery bark. It grows across Scandinavia and northern Europe. Nordic names for it include björk, bjørk and koivu.

Three parts are used. The sap is a thin spring drink. The inner bark goes into skin creams and teas, and bark can be heated to make a thick black tar.

Birch tar is the björktjära or tökötti of old Nordic life. It sealed boats and roofs, and people chewed it or rubbed it on skin. Long use like this is not proof that a remedy works, and it is not proof that it is safe.

Here is the short verdict. One refined birch bark gel is a real prescription medicine with trial evidence for wound healing. Home-made sap, bark and tar remedies are barely tested in people.

How does Silver birch (bark, tar, sap) work?

Most of the proposed actions come from lab work, not from people.

Birch bark is rich in betulin. In cell studies, betulin extracts appear to speed up the skin cells that close a wound. A refined bark gel built on this idea has now been tested in patients.

Inner bark also holds salicylates, the aspirin-like family. These may ease pain and swelling. Birch bark itself has not been shown to do that in human trials.

Birch tar is full of phenols. In test tubes these slow some bacteria and fungi. Tar also softens thick, scaly skin, which is why wood tars were used on rashes.

Whether birch tar helps a skin problem on the body is poorly tested. Most tar research used coal tar, which is a different material.

Birch sap is mostly water, simple sugars and traces of minerals. Claims that it cleanses the body or acts as a water pill (diuretic) come from tradition, not from trials.

What forms does Silver birch (bark, tar, sap) come in?

Fresh sap is the best known form. It is tapped in early spring and drunk cold. Bottled and lightly flavoured versions are sold as soft drinks.

Bark extracts appear in creams, balms and one prescription wound gel. That gel, sold in Europe as Episalvan or Filsuvez, is a refined betulin product. It is not something you can make at home.

Birch tar is sold as a thick black liquid for treating wood and leather. A distilled form, birch tar oil, turns up in some soaps and shampoos.

Tiny amounts of birch tar oil are also used as a smoky food flavouring. Food use is tightly limited by law.

Dried inner bark is sold loose for tea in some Nordic shops. Birch leaf tea is far more common and is a different product.

Chewing tar, the old tökötti, is still sold in Finland as a novelty gum and sweet flavour.

Where it comes from:

Birch was one of the most useful trees in the Nordic world. Nearly every part had a job.

Tar was made in earth kilns and tar pits from at least the Iron Age. Sweden and Finland exported huge barrels of it for ships' ropes and hulls. Birch tar glue is far older still, and has been found on Stone Age tools.

On the farm, tar was painted on wooden walls and on animals' sores. People rubbed it on itchy skin and chewed hardened tar for the teeth. Folk sayings placed tar beside spirits and the sauna as a last resort.

Sap was drunk in spring as a fresh tonic after a long winter. It was also boiled down to syrup or fermented into a light beer.

Inner bark was ground into famine bread flour in hungry years. Bark was also used for shoes, baskets and roofing. None of this tells us whether birch helps a health problem today.

What does Silver birch (bark, tar, sap) help with?

• Wound healing and grazes: This is the one area with solid human evidence, and it applies to a specific medicine. A refined birch bark gel speeds the closing of partial-thickness wounds and graft sites in trials. It is approved in Europe for wounds in a rare blistering skin disease. A home bark salve has not been shown to do the same thing.
• Eczema and dry, scaly patches: Wood tar was a standard Nordic answer for itchy, scaly skin. Tar does soften thick scale, and coal tar has trial support in psoriasis. Birch tar itself has very little human testing. It can also irritate skin and stain it.
• Aching joints and muscles: Bark and buds were rubbed on sore joints, and the salicylates give a loose link to aspirin. No good human trials back birch bark for pain. Treat this as tradition only.
• Spring tonic drink: Birch sap was drunk to 'clean the blood' after winter. It is a pleasant, low-sugar drink with some minerals. There is no trial evidence that it detoxifies anything or treats a disease.
• Mouth and gum care: Chewing tar was said to clean teeth and firm the gums. Lab work shows tar phenols slow some bacteria. No human studies show a benefit for gum disease, and the tar chemicals argue for keeping this occasional at most.
• Flushing the urinary tract: Birch is a traditional water pill in northern Europe, mostly in leaf form rather than bark or sap. European registration for birch leaf rests on long use, not on trials. It is not a treatment for a urine infection.

Which foods are rich in Silver birch (bark, tar, sap)?

Birch sap is sold as a drink, and birch syrup is used like a thin, tangy maple syrup. Tiny amounts of birch tar oil are allowed as a smoky flavouring in some foods. Xylitol, the tooth-friendly sweetener, was first made from birch wood, but most on sale now comes from corn.

What are the side effects of Silver birch (bark, tar, sap)?

• Itchy mouth, lips or throat in people with birch pollen allergy
• Hives, swelling or breathing trouble in a true allergic reaction
• Skin redness, burning or stinging from tar
• Contact rash from tar or bark creams
• Small spots around hair follicles after tar use
• Skin that burns more easily in sunlight after tar use
• Brown staining of skin, nails, clothes and bedding
• Stomach upset from bark tea
• Stomach upset or fizzy, sour taste from sap that has started to ferment

Good to know:

Most problems are skin problems, and they are mild and reversible.

Allergy is the main real risk. Birch pollen allergy is common in northern Europe, and birch products can trigger it.

Tar deserves more respect than the others. It irritates skin, stains everything, and contains chemicals linked to cancer with heavy or repeated exposure.

How much Silver birch (bark, tar, sap) should you take?

• Recommended daily: No medical dose is set for birch bark, sap or tar. Bottled sap is a drink. Labels usually point to a glass, around 200 to 250 ml, in the same way as any juice. Bark tea packets commonly list one to two grams of dried bark per cup. That is a label figure, not advice for you. This page gives no amount or method for birch tar. Tar strength varies hugely between batches, it is meant for outside use only, and swallowing it is not safe. The prescription birch bark gel is used only as a doctor or pharmacist directs.
• Best time of day: Time of day does not matter much. Sap is usually drunk in the morning or with a meal, simply out of habit. Tar-based skin products are often used at night. They stain skin, clothes and bedding, so old towels and dark sheets help.
• With or without food: Sap is a drink, so food does not matter. Bark tea can upset a sensitive stomach because of its salicylates. Taking it with food may help. Skin and tar products are used on the skin, so this does not apply.
• Time to effect: Be ready for it to do nothing. Sap tastes fresh straight away, but no health effect has been proven, at any point. If a bark or tar cream suits your skin, people usually notice less itch or scale within one to two weeks. Many notice nothing at all. The prescription bark gel worked over weeks, not days, in its trials.
• How long to take it: Sap drinking is naturally short. The season lasts a few weeks in early spring. Skin products are a different matter. If a bark cream has done nothing in two weeks, there is little reason to keep going. Tar preparations are not for long or repeated use on skin. The tar chemicals and the risk of irritation both argue against it. For the prescription gel, your doctor sets how long you use it.