Juniper berries (actually fleshy cones) are a popular wild harvested spice. They are often used to flavour meats and are used to flavour gin. Medicinal usage centres around their aromatic and antimicrobial properties. Juniper berries are useful in treating digestive complaints, respiratory illness, and urinary tract infection.
In this article I would like to draw your attention towards a commonly planted ornamental species of juniper called Savin Juniper (Juniperus sabina). In the Calgary area it is so popular there is a cultivated variety called “Calgary carpet”. Savin Juniper is known to be toxic and potentially deadly poisonous if taken in large enough quantities. It can be difficult to accurately distinguish between different species of cultivated junipers because they have been bred to have unique features not present in their wild forms. I find the best way to identify Savin Juniper is to observe the ascending growth habit of the branches, however, I don’t recommend consuming any cultivated juniper species that have scale-like leaves unless you are very confident in your identification.
I have met folks who have made juniper syrup using Savin Juniper without realizing the potential toxicity. The only species I recommend people using confidently in Common Juniper (Juniperus communis) because this species is the most easy to identify, the leaves are awl-shaped, or to put more simply more needle-like, and there is long record of safe usage.
The rest of this article is concerned with looking at the history and use of Savin Juniper to get a better picture of how toxic the plant really is, and how likely an accidental poisoning could be.
The title of an article by Papavassiliou published in the French journal Société de Médecine Légale in 1937 indicates that in two cases of poisoning, oil of Savin was able to cross the placental barrier. I could not find any online access to the article, but according to Jacobs and Madari (2004) the toxicity was caused by large doses of the branches being taken orally resulting in abortion and serious poisoning. The oil of Savin (also know as Sabine) was found in the viscera of the foetus demonstrating the ability of the oil to cross the placental barrier.
The essential oil of Common Juniper berries is used in the making of gin. In Spain where Common Juniper and Savin Juniper grow in the same habitat there is a concern for potential contamination of harvested juniper berries with toxic Savin Juniper berries. Casares (1964) writes that any juniper harvest that was believes to be contaminated with Savin Juniper was destroyed. He further writes that Savin oil contains sabinene, sabinyl acetate and sabinol, compounds that are structurally related to thujane, thujol, and thujone. The latter are well known for their toxic effects and are found in infamous plants such as Tansy (Tanacetum vulgare) and Wormwood (Artemisia absinthium). According to Casares, Savin oil can cause irritation of the mucus lining of the intestines, congestion of abdominal organs, congestion of the kidneys leading to haematuria (blood in the urine), menorrhagia (heavy menstrual bleeding) and abortion.
Other studies have looked at the effect of Savin oil on pregnant mice. An essential oil containing 50% sabinyl acetate was injected in mice at doses of 45 and 135 mg/kg. On days 0 to 4 of pregnancy 50% of placental implantation was prevented, but on days 8 to 11 pregnancy was not prevented and the incidence of malformations in the fetuses was not increased relative to control mice (Pages et al., 1996). In a similar study the same doses injected in mice on days 6 to 15 of gestation caused significant toxicity to the mouse embryo but not the mouse fetus (Pages et al., 1989). Animal studies cannot be directly applied to humans, but they can indicate potential toxicity. To put the doses used in these studies in perspective, for a person of 60 kg (132 lbs) the amount of injected essential oil would be 2.7 g and 8.1 g. Such high doses of essential oils, even for essential oils considered safe for human consumption, would never be recommended internally in humans.
Some studies have also looked at the cytotoxic (cell-killing) properties of compounds found in Savin Juniper. Cytotoxic compounds are potential candidates for anti-cancer drugs. Savin Juniper contains a compound called podophyllotoxin, which has been shown to inhibit mitosis through the inhibition of microtubule assembly (Jacobs and Madari, 2004). In simple terms this means that podophyllotoxin prevents cells from dividing. Compounds that prevent cell division are frequently used as chemotherapy drugs to stop cancerous tumours from growing. A study by Shokrzadeh et al. (2010) found that a water and alcohol extract of Savin Juniper berries had cytotoxic effects against some cancer cell lines comparable to extracts from Yew (Taxus baccata). The Yew tree is well known to be a very poisonous plant when ingested. The chemotherapy drug Paclitaxel is derived from Yew. However, it does not follow that plants that contain cytotoxic compounds are poisonous. Common food plants such as coriander (Coriandrum sativum), celery (Apium graveolens) and oregano (Origanum vulgare) have also been shown to have cytotoxic properties (Jacobs and Madari, 2004).
Various reports exist of Savin Juniper being used as a traditional medicine in different cultures. The berries were used internally as a decoction in Bosnia and Herzegovina for venereal disease (Redzic, 2007). In Iran the berries were used as for their antifertility, antioxidant, and anti-inflammatory properties (Jazayeri et al., 2014). In Uzbekistan and Kyrgyzstan a decoction (boiled tea) of the roots was used for kidney stones (Ahmed et al., 2016). In Uyghur folk medicine in China the leaves and branches were used in the treatment of rheumatoid arthritis. The flavonoid content of Savin Juniper was extracted and orally fed to mice at doses of 124 to 500 mg/kg in a rheumatoid arthritis mouse model. The results showed the flavonoid content was anti-inflammatory (Zhao et al., 2016). Animal models are experiments that attempt to create an imitation of a disease, for example injecting irritating chemicals into a joint creates a model for arthritis. It should also be noted that the flavonoid content would not contain the above-mentioned toxic chemicals.
Historical publications also report various uses of Savin
Juniper. An article from La Lancette
Française (1843) wrote that a Dr. Pitechaft found from his experience with
patients that the leaves of “sabine” could be used to prevent miscarriage and
premature labour due to their ability to prevent the excessive filling of uterine
blood vessels. The preparation method suggested was 8 g in 100 mL of boiling
water followed by adding 30 g of cinnamon syrup. The dose was 1 spoonful every hour for up to
8 days. In some cases 8 g of sage (Salvia
officinalis) leaves were added, particularly where there had been excessive
sweating. The sage was added to activate the circulation and nervous system. It
is interesting to note that sage essential oil contains thujone, mentioned
above as being structurally similar to toxic compounds in Savin essential oil.
Thujone in large doses can be toxic to the central nervous system.
The King’s American Dispensatory (1898) written by Dr. Harvey Wickes Felter and
pharmacist John Uri Lloyd provides an incredible repository of experience-based
evidence for plant medicines. Savin Juniper is described as having the ability
to induce abortions, but reinforces the publication in La Lancette Française that very small doses may be used to prevent
miscarriage. Other uses mentioned are the treatment of worms, ulcers, menstrual
irregularities, urinary tract diseases, and venereal warts. They write that
great caution should be used in administering Savin Juniper as fatalities have
occurred and there is a significant side effect of severe inflammation of the
stomach and bowels. The toxicity of the essential oil is described as causing
severe gastro-intestinal inflammation, inability to urinate, congestion of the
pelvic organs, fever, mental intoxication, coma and death. The recommended dose
of essential oil to induce abortion accompanied by severe side effects was 10
to 15 drops (1 drop is roughly equivalent to 0.05 mg) on a cube of sugar three
times a day. Various low doses are described for safe internal use of the
leaves. For syrup 325 mg to 975 mg of powdered leaves should be used, I presume
for a litre of syrup based on other writings in the text. The dose is 3 times
per day; again I presume the dose would be between 3-7 mL.
From the research presented it is apparent that Savin Juniper is toxic, but that the toxicity is dose dependent. Moreover, clearly it is the essential oil that is the most toxic. A safe dose to ingest of the leaves and berries is not entirely clear from the literature. Although some indication is given from older texts there are discrepancies in dose. Further sub-lethal toxic doses in humans and animals vary widely. Tasting a single berry seems unlikely to cause any toxic effects, however, without a doubt caution must be taken to not ingest significant amounts of unidentified juniper leaves or berries.
It is worth noting that it is likely safety concerns for Savin Juniper that have been indiscriminately extrapolated to other species of juniper including Common Juniper. It is frequently noted in books and online that care should be taken when ingesting juniper due to potential kidney toxicity. However, incredibly high doses, as high as 1000 mg/kg, of the essential oil of Common Juniper were fed to rats for 28 days without causing any toxicity to the kidneys (Schilcher and Leuschner, 1997). Small doses of the essential oil were even shown to have kidney protective effects in rats (Butani et al. 2003). Further, Common Juniper was traditionally used in Bosnia and Herzegovina for kidney and urinary system disorders (Redzic, 2007). I was pleased to find that the Finish herbalist Henriette Kress (2010) shares the same observation with regards to Common Juniper on her website.
References:
Ahmed, S., Hasan, M.H.
& Mahmood, Z.A. 2016, “Antiurolithiatic plants in different countries
and cultures”, Journal of Pharmacognosy and Phytochemistry, vol. 5,
no. 1, pp. 102-115.
Butani, L., Afshinnik, A., Johnson, J., Javaheri, D., Peck, S., German, J. B., & Perez, R. V.
2003, “Amelioration of tacrolimus-induced nephrotoxicity in rats using juniper oil”, Transplantation, vol. 76, no. 2, pp. 306‑311.
Casares, R. 1964, Juniperus sabina. Food, Cosmetics and Toxicology, vol. 2, 680-681.
Felter, H.W., Lloyd, J.U. 1898, King’s American Dispensatory. Available at : http://www.henriettes-herb.com/eclectic/kings/index.html [Accessed 01 Dec. 2016]
Jazayeri,
S.B.e.a. 2014, “A preliminary investigation of anticholinesterase activity
of some Iranian medicinal plants commonly used in traditional medicine”, DARU
Journal of Pharmaceutical Sciences, vol. 22, no. 17.
Kress, K. 2010, Juniper Berry Toxicity, Available at: http://www.henriettes-herb.com/blog/juniper-toxicity.html [Accessed 01 Dec. 2016]
Madari, H. & Jacobs, R.S. 2004, “An Analysis of Cytotoxic Botanical Formulations Used in the Traditional Medicine of Ancient Persia as Abortifacients”, Journal of Natural Products, vol. 67, pp. 1204-1210.
Pages, N., Fournier, G., Baduel, C., Tur, N. & Rusnac, M. 1996, “Sabinyl Acetate, the Main Component of Juniperus sabina L’Hérit. Essential Oil, is Responsible for Antiimplantation Effect”, Phytotherapy Research, vol. 10, no. 5, pp. 438-448.
Pages, N., Fournier, G., Chamorro, G., Salazar, M., Paris, M. & Boudene, C. 1989, “Teratological evaluation of Juniperus sabina essential oil in mice”, Planta Medica, vol. 55, no. 2, pp. 144-146.
Papavassiliou M.J. 1937, “Sur deux cas d’intoxication par la sabine la permèabilité placentaire a l’essence de sabine”, Société de Médecine Légale, vol. 15, pp. 778-81.
Redziz, S.S. 2007, “The Ecological Aspect of Ethnobotany and Ethnopharmacology of Population in Bosnia and Herzegovina”, Collegium Antropologicum, vol. 31, no. 3, pp. 869-890.
Revue Therapeutique. 1843, La Lancette Francaise Gazette des Hopitaux Civils et Militaires, book 5, vol. 2, pp. 588.
Schilcher H, Leuschner F. 1997. “The potential nephrotoxic effects of essential juniper oil”, Arzneimittelforschung, vol. 47, no. 7, pp. 855-8.
Shokrzade, M., Azadbakht, M., Ahangar, N., Naderi, H. & Saeedi Saravi, S.S. 2010, “Comparison of the cytotoxic effects of Juniperus sabina and Zataria multiflora extracts with Taxus baccata extract and Cisplatin on normal and cancer cell lines”, Pharmacognosy Magazine, vol. 6, no. 22, pp. 102-105.
Zhao, J., Liu, T., Xu, F., You, S., Xu, F., Li, C. & Gu, Z. 2016, “Anti-arthritic Effects of Total Flavonoids from Juniperus sabina on Complete Freund’s Adjuvant Induced Arthritis in Rats”, Pharmacognosy Magazine, vol. 12, no. 47, pp. 178-183.