Bitter Orange - Citrus aurantium

Detailed Description

An old Chinese saying states: if you wish for immortality and happiness, choose the bitter orange.

Botanical Information

Bitter Orange, also known as Citrus aurantium, is an evergreen tree that can reach up to 10 meters in height, with regularly arranged branches and gray-brown bark. The leaves are leathery, oval, dark green, alternately arranged, and 7–10 centimeters long. White flowers with 5–8 leathery petals appear from May to June. The fruit is oval, darker, and firmer than the sweet orange, with a characteristically bitter and astringent peel.

Origin and Distribution

Believed to have originated in Southeast Asia, Citrus aurantium spread through Asia into Europe via trade routes. By the 10th and 11th centuries, it was introduced to the Mediterranean region, where it became widely cultivated. Today, it is grown commercially in tropical and subtropical zones, especially in Southern Europe (notably Spain and Portugal), as well as in the Caribbean and Israel. For trade purposes, the tree was likely introduced to South America in the 15th century.

Usage / Dosage

The earliest records of Bitter Orange come from Arabic written sources, and its exact earliest presence in Europe is uncertain, though estimated between the 10th and 11th centuries. Bitter orange is widely used in folk medicine as well as in the pharmaceutical and cosmetic industries—for example, it appears in the European Pharmacopoeia as aurantii dulce pericarpum.

As a flavoring agent, bitter orange is present in alcoholic and nonalcoholic beverages, frozen desserts, candies, baked goods, gelatin, meat products, and more. It is particularly popular in Iran, Turkey, and Iraq. In South India, it is incorporated into Tamil cuisine with yogurt rice (thayir sadam). In countries like Nicaragua, Cuba, Haiti, and the Dominican Republic, it is often used in meat marinades. Belgian Witbier, or white beer, is famous for its hint of bitter orange essence.

In the United States, rational indications for Bitter Orange include prevention of certain cancers such as skin, breast, and colon cancers. Several studies have focused on the activity of pectin, vitamin C, and flavonoids in preventing colon, lung, and pancreatic cancers, revealing a cancer-protective potential.

Topically, Bitter Orange is used for treating difficult-to-resolve fungal infections, while internally it is consumed for heartburn. In the USA, bitter orange is regarded as a milder, safer alternative to weight loss supplements. After ephedrine-containing supplements were banned in 2004, many products began containing Bitter Orange instead.

Synephrine, found in the peel of Bitter Orange, is chemically related to adrenaline and ephedrine. It assists in fat breakdown, clinically supports weight loss and provides an energy boost without undesirable cardiovascular effects. Synephrine increases energy expenditure, promotes thermogenesis, and adjusts metabolism toward calorie burning. Studies have confirmed its effect as an energy burner and the role of Bitter Orange peel in increasing heat production. N-methyltyramine, another compound present, boosts aerobic fatty acid metabolism and helps improve physical performance.

Oil or aqueous extracts of Bitter Orange peel are widely used in Asia for gastrointestinal complaints such as duodenal ulcers, constipation, diarrhea, presence of blood in stool, and bloating. In general, Bitter Orange is recommended for digestive issues, poor digestion, and dyspepsia. The bitters stimulate the production of bile acids, support stomach and intestinal motility, and help release appetite-regulating hormones. Some people use it for diabetes, to stimulate heart activity, and for blood purification. Traditional Chinese Medicine recognizes its use for strengthening the liver and dissolving kidney and gallbladder stones.

Aqueous Bitter Orange extracts have undergone several animal studies for their effects on the respiratory system and respiratory functions, showing promising results. Bitter Orange is generally recommended for respiratory tract disorders. Two animal studies also indicate potential antiviral effects, particularly from constituents like hesperidin, neohesperidin, naringin, and rutin, which may help relieve upper respiratory tract infections.

Smaller clinical studies have described positive effects of Bitter Orange extracts for local use in fungal infections, shingles, and athlete's foot. In aromatherapy, the essential oil is used for topical application or inhalation to relieve pain, migraines, stress, and sleeping difficulties.

For cardiovascular health, studies have shown an increase in HDL (good cholesterol) and a reduction in LDL (bad cholesterol) after regular intake of hesperidin and vitamin C, possibly also aided by fiber and pectin content.

In vivo studies have investigated the anxiolytic (anti-anxiety) and relaxing effects of Bitter Orange peel extract with favorable results. In animal models, it reduced anxiety and enhanced the hypnotic effects of pentobarbital. Synephrine also demonstrated an antidepressant effect in animals, suggesting that Bitter Orange can help induce sleep and calm the nervous system.

Folk Medicine

In Traditional Chinese Medicine, Bitter Orange is used as a tonic and carminative for dyspepsia, and was historically used for abdominal fullness, diarrhea, and blood in stools. In Haiti, its bark is a traditional antiseptic and laxative. Folk medicine employs it both to increase appetite and promote the opposite—weight loss and fat burning. Additional uses include relief from stomach sickness, nasal congestion, and chronic fatigue syndrome. In Turkey, it is traditionally valued as a sedative, a sleep aid, and a source of vitamin C.

In European folk practice, Bitter Orange has been used as a sedative for nervous disorders and insomnia, as a prophylactic for gastrointestinal issues, and to address anaphylaxis, cardiac problems, heart failure, and cancer. Brazilian folk medicine takes advantage of the anticonvulsant properties of Citrus aurantium as well as its use for anxiety and insomnia.

Precautions

There is no information about Bitter Orange safety during pregnancy and breastfeeding; therefore, it is not recommended for use in these cases. Furthermore, Bitter Orange compounds interact with the metabolism of many medications (antivirals, some antihypertensives, and others), so it is advisable to consult a physician or pharmacist before use.

Active Compounds

The rind of Bitter Orange contains alkaloids (synephrine, also known as symphatol/oxedrine, tyramine, octopamine, hordenine, n-methyltyramine), volatile oils (composed 90% of monoterpenes—limonene, citral, citronellal), polysaccharides (glucopyranosides), alcohols, bitter flavonoid glycosides (hesperidin, isohesperidin, aurantiamarin), glycosylated flavanones (naringin, neohesperidin), nobiletin, naringenin, rhoifolin, beta-sitosterol, beta-daucosterol, ergostanol, aldehydes, esters, coumarins and furanocoumarins, tetranotriterpenoids (limonin), amino acids (asparagine, tyrosine, valine, alanine, isoleucine), minerals, pectin, vitamins (A, B1, C), carotenoids, organic acids, and many others.

Traditional Dosage

Healthcare professionals recommend steeping 1–2 g of dried bark in about 200 ml of water for 10–15 minutes. A daily dose for adults is typically 3 cups. For certain indications, 12–20 ml of aqueous extract or a similar amount of tea (infusion) is used. Other dosage guidelines for the peel are not currently available.