Birch sap

Extraction of birch sap

Birch sap or birch water is the sap directly tapped from birch trees, Betula alba (white birch), Betula pendula (silver birch), Betula lenta, Betula papyrifera, and Betula fontinalis.

Birch sap may be consumed both fresh and naturally fermented. When fresh, it is a clear and uncoloured liquid, often slightly sweet with a slightly silky texture. After two to three days, the sap starts fermenting and the taste becomes more acidic.

Birch sap is a traditional beverage in boreal and hemiboreal regions of the northern hemisphere^[1] as well as parts of northern China.

Harvest

Birch sap is collected only at the break of winter and spring when the sap moves intensively. Birch sap collection is done by drilling a hole into its trunk and leading the sap into a container via some conduit: a tube or simply a thin twig: the sap will flow along it because of the surface tension.

Birch sap has to be collected in early spring before any green leaves have appeared, as in late spring it becomes bitter. The collection period is only about a month per year. Tapping a tree does not harm the health of the tree.^[2]

Traditional regions

Birch sap was a traditional beverage in Russia (Russian: берёзовый сок / byeryozovyi sok), Latvia (Latvian: bērzu sula), Estonia (Estonian: kasemahl), Finland (Finnish: mahla), Lithuania (Lithuanian: Beržų Sula), Belarus (Belarusian: Бярозавы сок / biarozavy sok, Byarozavik), Poland (Polish: sok z brzozy, oskoła), Ukraine (Ukrainian: Березовий сік / berezovyi sik), France, Scotland and elsewhere in Northern Europe^[1] as well as parts of Northern China.

Composition

Sap, birch water^[3]

Nutritional value per 100 g (3.5 oz)
Energy	4.6 kcal (19 kJ)
Carbohydrates	1.1 g
Sugars	1.1 g
Dietary fiber	0 g
Fat	less than 0.1 g
Minerals
Calcium	(6%) 60 mg
Iron	(1%) 0.1 mg
Magnesium	(3%) 11 mg
Manganese	(52%) 1.1 mg
Phosphorus	(1%) 6.4 mg
Potassium	(3%) 120 mg
Units μg = micrograms • mg = milligrams IU = International units
Percentages are roughly approximated using US recommendations for adults.

Birch sap contains heterosides (betuloside and monotropitoside),^[4][5][6] 17 amino acids including glutamic acid,^[7] as well as minerals, enzymes, proteins, betulinic acid and betulin,^[8][9][10] antioxidants,^[11] sugar (xylitol, fructose and glucose) and vitamins (C and B(group)).^[11]

Nutritional and medicinal uses

Birch sap is commonly known for its detoxifying, diuretic, cleansing and purifying properties. Heterosides present in birch sap release methyl salicylate by enzymatic hydrolysis which is analgesic, antiinflammatory and diuretic.^[12][13] The activation of diuresis helps eliminating organic wastes such as uric acid and cholesterol. Birch sap is also known for helping with joint and bone health, loss of hair, arthritis, and weight loss.^{[14][15][16][17]}

Birch sap can be used in case of hyperuricemia and hypercholesterolemia^[18] and to treat kidney stones.^[14]

Folk uses

Folk uses vary from medicinal use, supplementary nutrition (minerals and vitamins) and cosmetic applications for skin and hair.^[1]

Region	Medicinal use	Cosmetic use
Belarus	lung diseases, gout
Bulgaria		hair growth
Czech Republic	poor health, infertility	against freckles
Estonia	(prevention of) eye diseases, skin diseases, source for vitamins	washing hair, against freckles and to bleach the skin
Hungary	stomach and lung diseases	against freckles
Latvia	“revitalization”	washing hair
Poland	“revitalization”, kidney stones	washing hair in order to strengthen it
Romania	kidney stones, jaundice, as milk-rennet, scab, diuretic	hair colouring, to remove sunspots and moles
Russia	externally against sores, to help children during teething	washing face
Sweden	scurvy, cholera
Ukraine	treating skin diseases, source of vitamins, diuretic	against freckles
England and Scotland	tonic, rheumatism, first nourishment for new-born children	prevention of baldness

Commercial birch sap and derivative products

Bottle of Russian commercial birch sap

Birch sap may be consumed both fresh and naturally fermented. Fresh birch sap is highly perishable; even if refrigerated, it is stable for only up to 2–5 days. Shelf life can be prolonged by freezing or preservation techniques. Existing preservation techniques:^[19]

1. Nothing i.e. bottled fresh sap (shelf life: 2-5 days refrigerated)
2. Filtered with a 0,22μ net (shelf life: 3 weeks refrigerated)
3. Collected under anaerobic conditions (shelf life: 1 year ambient)
4. Added sugar (3g per 100ml)^[1]
5. Heat pasteurized; pasteurization should be conducted under specific temperature levels and time spans (shelf life: 1 year ambient). Although level of Vitamin C is lower than fresh saps', all benefits are preserved
6. Frozen at -25C (shelflife: 2 years)

Birch sap can also be used as an ingredient in food or drinks, such as birch beer or wintergreen flavored candy.

Concentrated birch sap is used to make birch syrup, a very expensive type of syrup mainly made from paper birch in Alaska^[20] and Canada, and from several species in Russia, Belarus and Ukraine.

References

1. Svanberg, Ingvar; et al. (2012). Uses of tree saps in northern and eastern parts of Europe. Acta Soc Bot Po. doi:10.5586/asbp.2012.036.
2. http://www.tapmytrees.com/faq.html#q4
3. Kūka, Māra (2013). Determination of Bioactive Compounds and Mineral Substances in Latvian Birch and Maple Saps. Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. doi:10.2478/prolas-2013-0069.
4. Sosa, A (1935). "Un glucoside nouveau de Betula Alba L. Le bétuloside et son aglycone, le bétuligénol". Paris Masson Ed.
5. Thieme, H; Winkler, H.J. (1969). "Chemotaxonomic significance of the presence of rhododendrin in family Rhododendron". Pharmazie. 24: 703.
6. Kim, M.H.; Nugroho, A; Choi, J; Park, J.H. (2011). "Rhododendron, an analgesic/anti-inflammatory arylbutanoid glycoside, from the leaves of Rhododendron aureum". Arc. Pharm. Res. 34 (6): 971–978. doi:10.1007/s12272-011-0614-1. PMID 21725818.
7. Ahtonen, S; Kallio, H (1989). "Identification and seasonal variation of amino acids in birch sap used for syrup production". Food Chemistry. 33 (2): 125–132. doi:10.1016/0308-8146(89)90115-5.
8. http://www2.publicationsduquebec.gouv.qc.ca/essences/arbre.php?id=98
9. Bouchet, Jérome (2007). "Les Stratégies en Thérapeutique Antivirale": 24.
10. http://www.santenatureinnovation.com/la-seve-de-bouleau-est-deja-la/
11. Demirci, B; Demirci, F; Hüsnü Can Baser, K; Franz, G (2004). "Essential oil of Betula pendula Roth. Buds". Evid. Based Complement. 1 (3): 301–303. doi:10.1093/ecam/neh041. PMID 15841263.
12. Zhang, B; Li, JB; Zhang, DM; Ding, Y; Du, GH (2007). "Analgesic and anti- inflammatory activities of a fraction rich in gaultherin isolated from Gaultheria yunnanensis (Franch.)". Rehder. Biol Pharm Bull. 30 (10): 465–469. doi:10.4103/0973-7847.91102.
13. Tétau, M (1987). "Nouvelles cliniques de gemmothérapie". Ed. Similia, Paris.
14. http://www.botanical-online.com/english/birchsap.htm
15. http://www.webmd.com/vitamins-supplements/ingredientmono-352 birch.aspx?activeingredientid=352&activeingredientname=birch
16. Jean Valnet, La Phytothérapie – Se soigner par les plantes
17. Tomoko, S (2005). "Birch sap: survey on traditional uses and their impacts on future uses. In : TERAZAWA, M. editors. Tree Sap, Proceedings of 3rd International Symposium on Sap Utilization (ISSU)". Hokkaido University Press: 53–59.
18. Henri Leclerc, Précis de phytothérapie. Essai de Thérapeutique par les plantes françaises
19. Nicole & Olivier Lhomme, NICOLL-Nature, « Le Bio Logis », https://www.lebiologis.fr/medias/files/seve-de-bouleau.pdf[]
20. Alaska Birch syrupmakers association Petition to US Food and Drug Administration for establishment of Standard of Identity for birch syrup, including the Alaska Birch Syrupmakers' Association Best Practices. July 18, 2005.