What Is Bitter Orange, and Does It Aid Weight Loss?
Medically reviewed by Adrienne Seitz, MS, RD, LDN, Nutrition — By Amber Charles Alexis, MSPH, RDN on March 17, 2021
Compounds & nutrients
Bitter orange (Citrus aurantium), also known as sour orange and Seville orange, is a citrus fruit with a multitude of uses. It’s commonly used in complementary medicine, herbal weight loss supplements, and certain foods and toppings like marmalade (1Trusted Source, 2, 3Trusted Source).
Thought to have originated in Southeast Asia, it’s now found throughout Latin America and the Caribbean, the South Sea Islands, Europe, and Western and Southern Africa (2).
This article covers all you need to know about bitter orange, including its role in weight loss and skin health, as well as its overall safety as a supplement.
bitter orange and slivers of peel for making marmalade
The fruit and its extracts
The bitter orange plant thrives in subtropical regions but can withstand adverse environmental conditions like frost for short periods (2).
Oval or oblong in shape, the fruit is red-orange when ripe and has a distinctively thick, dimpled skin. True to its name, it’s very bitter (2).
There are 23 cultivars of the fruit, the most prominent of which is Bergamot. You can expect some varieties to be more bitter than others.
Bitter orange contains several potent plant compounds that are sometimes extracted from the dried peel to make dietary supplements. The patented extract of bitter orange, p-synephrine, is sold in capsule form as the herbal weight loss supplements Advantra Z and Kinetiq (4Trusted Source).
Essential oils and powdered and liquid supplement forms are available as well.
Bitter orange is a citrus fruit with dimpled skin and potent plant compounds that are extracted and used in a variety of supplements.
Compounds and nutrients
The plant compounds in bitter orange, which are called protoalkaloids, have been used for over 20 years in supplements for weight loss, athletic performance, skin care, appetite control, and brain health, as well as perfumery (1Trusted Source, 2, 3Trusted Source, 5Trusted Source, 6Trusted Source, 7Trusted Source, 8Trusted Source).
P-synephrine, the main extract from bitter orange, has a similar structure to ephedrine, the main component of the herbal weight loss supplement ephedra (8Trusted Source).
This supplement was banned by the U.S. Food and Drug Administration (FDA) because it raised blood pressure, increased heart rate, and caused heart attacks and stroke among some consumers (1Trusted Source, 3Trusted Source, 7Trusted Source).
In addition, p-synephrine is structurally similar to your flight-or-fight hormones, epinephrine and norepinephrine, which also increase your heart rate (1Trusted Source, 4Trusted Source).
As such, the safety of bitter orange extract has been called into question.
However, several studies have shown that bitter orange extracts and the plant’s natural uses neither harm your heart and nervous system nor excite nervous system activity, as some stimulants do (3Trusted Source, 4Trusted Source, 5Trusted Source, 6Trusted Source, 7Trusted Source, 9Trusted Source).
Furthermore, at least one study has claimed that p-synephrine shouldn’t be classified as a stimulant (4Trusted Source).
P-synephrine is also found in other citrus fruits and their juices, such as mandarins and clementines (4Trusted Source, 7Trusted Source).
Like other citrus fruits, bitter orange provides limonene — a compound shown to have anti-inflammatory and antiviral properties (10Trusted Source, 11Trusted Source, 12Trusted Source).
Population studies suggest that limonene may prevent certain cancers, namely colon cancer. However, more rigorous human research is needed (13Trusted Source).
An ongoing study is also exploring the use of limonene as a treatment for COVID-19. However, the results are not yet known. Bear in mind that limonene cannot prevent or cure COVID-19 (12Trusted Source).
Another protoalkaloid found in bitter orange is p-octopamine. However, little to no p-octopamine exists in bitter orange extracts. Moreover, it’s thought to be metabolized very rapidly in your liver when consumed from the whole fruit (3Trusted Source, 5Trusted Source).
Likewise, it doesn’t appear to exert any beneficial or adverse effects on your body.
The leaves of the bitter orange plant are rich in vitamin C, which acts as an antioxidant. What’s more, its peel has a high content of flavonoids, which are potent antioxidants with high medicinal value (2, 14Trusted Source).
Antioxidants are substances that may protect your body from disease by preventing cell damage. They work by deactivating free radicals, which are unstable compounds that damage your cells, increasing inflammation and your disease risk (15Trusted Source, 16).
Protoalkaloids are plant compounds found in bitter orange that have anti-inflammatory and antiviral properties. They have been shown to be safe for consumption.
Does bitter orange aid weight loss?
Bitter orange and other citrus varieties show potential for weight loss, but there’s limited evidence on their effectiveness (1Trusted Source, 5Trusted Source, 6Trusted Source, 8Trusted Source, 17Trusted Source, 18Trusted Source).
Many weight loss supplements use bitter orange extracts in combination with other ingredients. However, scientific studies have not thoroughly examined the composition of these supplements to determine which ingredient, if any, supports weight loss.
Notably, p-synephrine has been shown to increase fat breakdown, raise energy expenditure, and mildly suppress appetite, all of which may contribute to reduced weight.
Yet, these effects occur at high doses that are discouraged due to the lack of safety information (4Trusted Source, 8Trusted Source, 18Trusted Source).
Thus, more studies on bitter orange’s weight loss properties are needed.
Although bitter orange extracts are often included in weight loss supplements, there’s limited evidence to support their effectiveness.
Health benefits of bitter orange
Bitter orange and its extracts are used in Traditional Chinese Medicine (TCM) to treat indigestion, diarrhea, dysentery, and constipation. In other regions, the fruit is used to treat anxiety and epilepsy (3Trusted Source).
Nonetheless, there’s limited evidence to support these uses.
There’s also insufficient evidence to support any uses for symptoms of premenstrual syndrome (PMS) (1Trusted Source).
Although a study in older rats suggested that flavanone compounds in citrus fruits and juices may improve thyroid function, it cannot be assumed that they’ll exert the same effects in humans (19Trusted Source).
All the same, given the high vitamin C content of bitter orange, it’s presumed that this fruit may improve skin health. Vitamin C’s role in wound healing and collagen formation is well established (16).
Another study noted that the bitter orange compound p-synephrine may improve athletic performance though by increasing total reps and volume load, or your ability to train harder (20Trusted Source).
There’s insufficient evidence to support the effectiveness of bitter orange and its extracts for its numerous medicinal uses.
Downsides and side effects of bitter orange
There’s conflicting information about whether synephrine, one of bitter orange’s natural compounds, should be considered a stimulant. A stimulant is a substance that increases your heart rate and blood pressure (1Trusted Source).
Several sports organizations, such as the National Collegiate Athletic Association (NCAA), list synephrine as a stimulant. Thus, it’s regarded as a banned substance in athletics (1Trusted Source, 21).
Furthermore, one study determined that bitter orange juice contains furanocoumarin, a compound that may cause the same medication interactions as grapefruit juice (22Trusted Source).
Therefore, people taking decongestants or those who have high blood pressure, an irregular heartbeat, or glaucoma should avoid the juice and fruit of bitter oranges. It’s unclear whether bitter orange supplements pose this risk (5Trusted Source).
Despite numerous studies showing that bitter orange extracts are not stimulants, widespread controversy exists, and the NCAA has listed it as a banned substance. Bitter orange may also interact with certain medications.
Dosage and safety information
Generally, bitter orange extracts in dietary supplements are safe to consume in doses of 50–98 mg per day (1Trusted Source, 23Trusted Source).
One study showed that 40 mg of synephrine combined with 320 mg of caffeine is a safe dose of these combined ingredients (3Trusted Source).
In another study, eating a whole bitter orange containing 30.6 mg of p-synephrine revealed no interactions with medications (24Trusted Source).
Still, people who are pregnant or breastfeeding should avoid bitter orange due to a lack of safety information (1Trusted Source).
Bitter orange is likely safe in doses ranging from 30.6 mg of synephrine in the fruit itself to 98 mg in dietary supplements, although additional research is required.
Culinary uses of bitter orange
Bitter orange is quite tart and unlikely to be eaten raw.
Naturally high in pectin, a gelling agent, the fruit’s primary culinary application is for making marmalade (2, 25Trusted Source).
Bitter orange oil is also used as a flavoring or additive for the following:
candy (chewing gum, hard candy, and candied fruit)
desserts (ice cream, pies)
sauces and chutneys
The juice of the bitter orange can be used as a marinade to flavor fish and meat. In some regions, it’s used similarly to vinegar (2).
What’s more, the extracted oils give a distinctive flavor to liqueurs like Grand Marnier (2).
In China, bitter orange is used to make herbal teas and medicines.
Bitter orange has several other household uses outside of the kitchen. These include (2):
essential oils (including neroli and petitgrain)
traditional medicine (such as antiseptics and hemostatics)
Bitter orange is a citrus fruit with several household and industrial uses, ranging from food additives to perfumery. It’s primarily used to make marmalades and jellies due to its high pectin content.
The bottom line
Bitter orange is a citrus fruit that’s often processed into an extract. It has several culinary uses as well, though it’s rarely eaten whole.
Although bitter orange supplements are widely considered safe at common doses, there’s inconclusive evidence for their efficacy for weight loss, thyroid health, and skin care.
You may want to avoid this fruit and its extracts if you have high blood pressure, an irregular heartbeat, or glaucoma. Likewise, bitter orange supplements are banned for NCAA athletes.
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