Juniper berry essential oil

Juniper berry essential oil is the essential oil distilled with steam from the ripe berries of common juniper, the berries that flavour gin. It smells fresh, warm, balsamic and sweet-woody and is used in perfumery and in flavourings, and also in aromatherapy. In the mid-20th century much of the oil sold under this name was not distilled from the berries themselves but was a by-product of juniper brandy making, or was mixed with cheaper materials.

Type

Essential oil

Botanical name

Juniperus communis

INCI name

Juniperus Communis Fruit Oil

Other names

juniper oil

The plant

Common juniper is a conifer of the cypress family. It probably comes from northern Europe and mountain regions and now grows wild across central and southern Europe, northern and south-western Asia, North Africa and North America. Male and female cones grow on separate plants, and the "berries" are in fact the fleshy seed cones of the female plant, which turn purple-black when ripe. They are up to 10 mm across, often with a bluish bloom, and usually hold three very hard seeds. They contain up to 3% essential oil.

How the oil is made

The best oil is distilled with steam from crushed ripe berries, dried or partly dried. The international standard for the oil (ISO 8897) also allows fresh and fermented berries. Oil for medicinal use, as defined by the European Pharmacopoeia, is distilled from ripe, non-fermented berries, without needles or wood from the tree.

Much commercial juniper berry oil comes from another process. In central Europe the sugary berries are fermented to make juniper brandy, and an oil is separated from the fermented mass as a by-product. This oil smells more of turpentine and pine, has little balsamic sweetness, fades sooner and is not suitable for flavouring. In the mid-20th century the best berries were collected in northern Italy, Austria, Czechoslovakia, Hungary, Yugoslavia and France.

Composition

The oil has about 105 known components and consists mostly of monoterpenes, light scent compounds. The main ones are alpha-pinene, myrcene, sabinene, limonene and beta-pinene; terpinen-4-ol is also present. Their shares vary with the source: in analysed oils alpha-pinene made up 24–55% and sabinene 1–29%. For medicinal oil the 2008 edition of the European Pharmacopoeia set limits, for example 20–50% alpha-pinene.

Scent and uses

The steam-distilled oil is colourless, pale yellow or pale green. It smells fresh and warm, rich-balsamic, sweet-woody and of pine needles, and is very close in scent to mountain pine oil. Its taste is warm and balsamic but clearly bitter. In aromatherapy it counts as a middle note of mild to medium strength, crisp, woody, sweet and earthy.

In perfumery the oil gives fresh-balsamic notes. It blends very well with pine needle oils, scents room sprays together with citrus oils, and is used in spicy perfumes, aftershaves and colognes.

The ripe cones are used as a flavouring and are an essential ingredient of gin; the name gin comes from the Dutch word for juniper. For drinks, makers prefer an oil with the terpenes removed, or a distillate of the berries, because the whole oil dissolves poorly in alcohol and tastes bitter. Such products flavour gin, Steinhäger and herbal liqueurs such as Bénédictine.

In aromatherapy the oil is used in room mists and diffusers and is described as calming without making people drowsy. Aromatherapy books also recommend it for colds, flu, acne and rheumatism; these effects are not medically established.

Herbal medicine

Juniper oil is traditionally used to increase the flow of urine and to ease digestive complaints. Only the first is backed by experiments as well as tradition, and there are no clinical trials of the oil. Health Canada's juniper monograph covers the dried berries, not the oil, traditionally taken by mouth as a diuretic and for mild urinary tract infections, digestion and appetite, but not in pregnancy or kidney disorders. A separate aromatherapy monograph lists the oil for use on the skin or by inhalation, for example for joint and muscle pain or calming.

Quality and adulteration

In the mid-20th century juniper berry oil was very often adulterated, and commercial oil was rarely the true distillate of the berries. The most common addition or substitute was the poorer oil from fermentation; others were pinene, camphene, fractions of turpentine oil and oils from juniper wood or twigs. At that time only careful judging by smell and taste revealed a poor or adulterated oil. For medicinal oil, the assessment by the European Medicines Agency (EMA) therefore asks that quality be proven.

Safety

Many older handbooks warn that juniper damages the kidneys. The EMA assessment found the reports of overdose and long use vague and of poor quality. It noted that the warning may have been copied from findings on turpentine oil. Oil contaminated with turpentine may also have caused the harm reported. It still advises against juniper in inflammation of the kidneys. The aromatherapy safety authors Robert Tisserand and Rodney Young consider the kidney and pregnancy warnings for the oil inaccurate and unnecessary.

The oil is generally not regarded as sensitising or as making the skin sensitive to light, but undiluted it can irritate. In a 24-hour patch test, full-strength oil irritated the skin of 2 of 20 people, while 5–8% in petroleum jelly caused no irritation. Among 86 patients with allergic reactions, it caused a reaction in 6. Oil that has oxidised should not be used.

Sources differ on pregnancy. Juniper berries should not be used during pregnancy and breastfeeding. For this reason the EMA assessment does not recommend the oil as a medicine at these times either. The National Association for Holistic Aromatherapy lists juniper among the oils that appear to be safe in pregnancy when properly diluted.

Products containing it

• Juniper Berry Essential Oil (E 106)