October 2024 Issue
Herbs & Spices: Juniper Berries
By Carrie Dennett, MPH, RDN
Today’s Dietitian
Vol. 26 No. 8 P. 18
What modern science says about this traditional culinary and medicinal herb.
Juniper berries are more than just a key ingredient in gin—they’re a traditional spice and medicine in many parts of the world, including among Indigenous peoples across the United States. In modern times, they’re a popular ingredient in marinades, spice rubs, and specialty cocktails due to their aromatic flavor. In addition, juniper berry supplements carrying various health claims are widely available.
Junipers are coniferous trees and shrubs in the genus Juniperus, with between 50 and 67 species distributed throughout the cold and temperate parts of the Northern Hemisphere, growing in many parts of North America, Europe, and Asia. While various juniper species are widely grown as ornamental plants in home landscapes and public parks and gardens, not all juniper berries are edible—the berries of some species, such as J. sabina, are toxic, but it’s unclear at what dose. In this article, Today’s Dietitian takes a closer look at juniper berries’ culinary uses and health benefits, as well as some things to keep in mind when including them in one’s diet.
Culinary Applications
The primary species used for edible purposes is J. communis (common juniper) because it’s the most aromatic. However, J. virginiana (eastern red cedar), J. californica (California juniper), J. occidentalis (western juniper), J. drupacea (Syrian juniper), and J. phoenicea (Phoenician juniper) are also edible. Because the astringent blue-black berries—technically female seed cones with three to six fleshy scales that fuse together to form a berry-like structure called a galbulus—are too bitter to eat raw, they’re usually sold dried, then crushed or roughly ground to release their flavor before use in a dish.1 While they’re the hallmark flavor of gin, they’re also used as a culinary spice and are the only spice that comes from a conifer.2
Juniper berries, primarily from J. communis, are an important spice in many European cuisines, especially in areas where junipers are abundant.2 According to The Flavor Bible, juniper berries are classic to German, Scandinavian, Alsatian, and Mediterranean cuisines; they pair especially well with beef, lamb, pork, wild game, cabbage, sauerkraut, and red wine. They also make a good flavor pairing with poultry, salmon, and other fish and in combination with fennel, garlic, onions, marjoram, oregano, parsley, rosemary, sage, and thyme.3
An infusion of fully grown but unripe juniper berries is used to flavor gin, a liquor developed in the 17th century in the Netherlands as a medicinal spirit due to the diuretic properties of juniper berries. The name gin is derived from either the French genièvre or the Dutch jenever, both of which mean “juniper.”2 Most gin is made in the United Kingdom, using berries from J. communis, which is highly aromatic with a piney flavor that’s more savory than sweet. However, some US distilleries are making gin from other edible species, including the berries of J. occidentalis, which is native to the Western United States from British Columbia to Southern California.
Health Benefits
Juniper berries have been used as an herbal medicine for thousands of years, reportedly having anti-inflammatory, antifungal, analgesic, hepatoprotective, antidiabetic, antihyperlipidemic, antimicrobial, antioxidant, and antibacterial activity. Most modern research on the health benefits of juniper berries has focused on Juniperus communis.
Analysis of compounds in the berries has found they contain a number of phytochemicals, including bioflavonoids such as flavones and flavonols, as well as vitamin C.4,5 In vitro and animal studies have found that juniper berry essential oil extract has a variety of pharmacological activities,5,6 including antioxidant and anti-inflammatory properties. However, human clinical data substantiating health benefits is lacking. Despite that, juniper berry dietary supplements carry claims ranging from improved digestive function—one even claims their product supports a “squeaky clean inside”—and urinary tract health to reduction of inflammation and oxidative damage and even enhanced immune health.
Anti-Inflammatory and Antioxidant Effects
Juniper berry extracts potentially have strong antioxidant activity, as established by studies using antioxidant assays to evaluate free-radical scavenging ability and metal chelating potential. One in vitro study detected more than 70 compounds in the oil—with the majority being the monoterpenes alpha-pinene, beta-pinene, myrcene, limonene, and sabinene—and found that the oil reduced cellular damage in yeast cells by increasing the activity of the enzymes glutathione peroxidase, superoxide dismutase, and catalase, each of which has a primary role of protecting cells from free radical damage.6 Another in vitro study found that juniper berry essential oil significantly reduced inflammation in human skin cells, an effect researchers attributed to the oil’s high concentration of monoterpenes.7 However, in vitro studies are not an ideal indicator of the effects of antioxidants or other bioactive compounds in living bodies, so more research is needed.
Antimicrobial Effects
In vitro and animal studies show that juniper berry essential oil has antimicrobial properties, attributed primarily to the monoterpenes in the oil. In one in vitro study, juniper berry essential oil demonstrated antibacterial and antifungal effects against 16 bacterial species, seven yeastlike fungi, three yeasts, and four strains of dermatophytes, a type of fungus that typically causes skin infections.8 Another study found that the oil significantly inhibited the activity of three species of Mycobacterium—M. gordonae, M. avium, and M. intracellulare, each of which can cause opportunistic infections in immunocompromised people—in freshwater.9
Research also suggests that both essential oil and crude extract from juniper berries may inhibit Campylobacter jejuni, a common cause of foodborne illness, by preventing adhesion to nutrient-rich media and the formation of biofilms. C. jenuni’s ability to form biofilms on stainless steel and other surfaces can make it a persistent problem in food processing environments.10 The essential oil may similarly interfere with both biofilm formation and mature biofilms of Staphylococcus aureus and Pseudomonas aeruginosa, bacteria that are particular concerns in health care settings.11
Cardiometabolic Effects
For centuries, many plants have been a source of antidiabetic drugs, especially in developing countries. Juniper berries were used in traditional medicine practices to treat diabetes, and while there’s a lack of human research, animal studies suggest they may indeed have antidiabetic properties. In addition, they may also promote heart health by improving HDL (good) cholesterol levels.
One study observed that supplementing with juniper berry extract significantly reduced blood glucose and increased levels of HDL cholesterol in diabetic rats.12 Another study in diabetic rats demonstrated that treatment with an ethanol-based extract of Chinese juniper berry (J. chinensis) significantly reduced blood glucose, while a water-based extract reduced total cholesterol and triglyceride levels by 57% and 37%, respectively, compared with a control group.13 However, more human research is needed.
Anticancer Effects
The active compounds in many medicinal plants are a potential source of anticancer medications with minimal side effects.14,15 Lab studies of J. procera, native to mountainous areas in Africa and the Arabian Peninsula, have found that its phytochemicals may have anticancer effects. For example, one 2024 study, using in vitro and computer simulation analyses, found that extracts of the leaf and berry were cytotoxic against two human ovarian cancer cell lines, demonstrating a potency that’s in line with US National Cancer Institute guidelines for in vitro cytotoxicity.14 A 2023 in vitro study found that essential oil from the berries of J. phoenicia, found in North Africa, showed potential cytotoxic effects on a colon cancer cell line.16 With no human research in this area, it remains unclear if the compounds in juniper berries can reach cancer cells and have the same effects observed in vitro.
Cautions
Juniper berry oil from J. communis has GRAS (generally recognized as safe) status,17 but berries from J. communis and many other species—along with a number of other plants, including wormwood, Thuja (arborvitae), mugwort, and common sage—contain the monoterpene thujone, a GABA antagonist that causes muscle spasms and convulsions.18 For this reason, it’s recommended that women avoid juniper berries during pregnancy, as they’re considered uterine stimulants and could cause complications in high doses. Large amounts may also cause diarrhea.
High doses of juniper berry, such as through use in a dietary supplement form, may also interact with certain medications, including diuretics and diabetes drugs. In addition, many online sources state that concentrated juniper berry supplements may harm your kidneys—and many supplement manufacturers caution against use in individuals with renal disorders—although there’s no clear evidence to support these claims.
It’s worth restating that there’s a lack of human research on which to base the safety and effectiveness of taking juniper berry supplements. Dietitians should counsel patients and clients to talk with their physician before use, as with any new dietary supplement.
— Carrie Dennett, MPH, RDN, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Non-Diet Approach to Optimal Well-Being.
References
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7. Han X, Parker TL, Benavente C. Anti-inflammatory activity of Juniper (Juniperus communis) berry essential oil in human dermal fibroblasts. Cogent Medicine. 2017;4(1).
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9. Peruč D, Gobin I, Abram M, et al. Antimycobacterial potential of the juniper berry essential oil in tap water. Arh Hig Rada Toksikol. 2018;69(1):46-54.
10. Klančnik A, Zorko Š, Toplak N, et al. Antiadhesion activity of juniper (Juniperus communis L.) preparations against Campylobacter jejuni evaluated with PCR-based methods. Phytother Res. 2018;32(3):542-550.
11. Camporese A. In vitro activity of Eucalyptus smithii and Juniperus communis essential oils against bacterial biofilms and efficacy perspectives of complementary inhalation therapy in chronic and recurrent upper respiratory tract infections]. Infez Med. 2013;21(2):117-124.
12. Banerjee S, Singh H, Chatterjee TK. Evaluation of anti-diabetic and anti-hyperlipidemic potential of methanolic extract of Juniperus Communis (L.) in streptozotocinnicotinamide induced diabetic rats. Int J Pharma Bio Sci. 2013;4(3):P10–P17.
13. Ju JB, Kim JS, Choi CW, Lee HK, Oh TK, Kim SC. Comparison between ethanolic and aqueous extracts from Chinese juniper berries for hypoglycaemic and hypolipidemic effects in alloxan-induced diabetic rats. J Ethnopharmacol. 2008;115(1):110-115.
14. Al-Zahrani AA. The potential role of phytochemicals of Juniperus procera in the treatment of ovarian cancer and the inhibition of human topoisomerase II alpha activity. Bioinform Biol Insights. 2024;18:11779322241248904.
15. Alhayyani S, Akhdhar A, Asseri AH, et al. Potential anticancer activity of Juniperus procera and molecular docking models of active proteins in cancer cells. Molecules. 2023;28(5):2041.
16. Mansour RB, Wasli H, Bourgou S, et al. Insights on Juniperus phoenicea essential oil as potential anti-proliferative, qnti-tyrosinase, and qntioxidant candidate. Molecules. 2023;28(22):7547.
17. Molecule of the Week Archive: a-Thujone. American Chemical Society website. https://www.acs.org/molecule-of-the-week/archive/t/a-thujone.html. Published June 17, 2008.
18. Title 21, Chapter I, Subchapter B, Part 182—Substances Generally Recognized as Safe; section §182.20 Essential oils, oleoresins (solvent-free), and natural extractives (including distillates). Code of Federal Regulations website. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-182. Updated August 2, 2024.