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Introduction

Bitter orange, also called citrus aurantium, is a fruit that is native to Africa and tropical Asia but is also now grown throughout the Mediterranean region.

This fruit should not be confused with a traditional orange, which is far less bitter and more palatable.

Bitter orange has long been a traditional part of Chinese medicine for the purpose of preventing and treating nausea and indigestion.

The main component within bitter orange that is linked to its health benefits is an alkaloid called synephrine, which can be endogenously produced in the human body but only in small amounts.

Interestingly, synephrine is very similar to the main chemical within the extremely powerful weight loss drug called Ephedra (banned by the U.S. Food and Drug Administration).

Unsurprisingly, bitter orange is now incorporated into over-the-counter weight loss supplements as a means to reduce hunger. It is also used in dietary supplements targeted towards treating heartburn, nasal congestion, and pain relief.

Bitter Orange Extract Health Benefits

May Increase Energy Expenditure

Current research on bitter orange and synephrine have contradictory findings regarding weight loss.

Research is available supporting the claim that synephrine may increase the numbers of calories burned each day, however this does not necessarily translate to improved weight loss [1].

However, a large review of over 20 studies found that 20-35mg of synephrine per day did increase metabolic rate and also have a measurable impact on weight loss [2].

Specifically, a single dose of 50mg synephrine has shown to increase caloric expenditure by 65 calories when measured over the next 75 minutes in healthy and rested individuals [3].

The mechanisms in which it might achieve this are through increasing the basal metabolic rate and lipolysis [4]. The upregulated lipolysis in fat cells is through beta-adrenergic stimulation [5].

In combination with this, synephrine alkaloids are well-documented to reduce food intake in animals [6]. This is likely due to antagonizing adrenergic receptors [7], which could increase the production of peptide hormones such as CCK that decrease gastric motility and food intake [8].

A major problem with studies on bitter orange extract and synephrine are that they use products with multiple ingredients so it is hard to know the isolated effects of the supplement.

How To Take Bitter Orange Extract?

There is no definitive dosage of bitter orange extract.

Based on the pool of evidence, we would recommend a supplemental dosage of 20-40mg a day, as this is likely effective and safe.

Some clinical trials have even gone as high as 240–360mg per day, but we would not recommend this at the current stage of research due to safety concerns [9].

Bitter Orange Extract Safety And Side Effects

The use of bitter orange extract and synephrine appears to be very safe, with no serious adverse events being directly attributable to this ingredient [10].

Rare but notable side effects of synephrine in high doses include:

  • Increased heart rate
  • Elevated blood pressure
  • Anxiety

In addition, despite no apparent safety concerns, this is based almost solely on short-term data and the long-term implications of consuming bitter orange extract are not yet known.

Much like all herbal and dietary supplements, consumers should also be aware that they are not regulated by Food and Drug Administrations. This means there is no product guarantee that it contains the listed ingredients, or that the supplement is free from contaminants.

More to this, a study analyzing 20 alkaloid supplements found that ~50% had clear differences in the actual contents versus what was stated on the label [11].

Conclusion

Bitter orange extract is part of a fruit that has an active component known as synephrine.

Some evidence shows that synephrine may be able to significantly increase ones energy expenditure, and therefore may be a tool for weight loss, which is why it’s an ingredient that’s commonly found within fat burner supplements and weight loss shakes.

The intensity of its effects may also be amplified when it’s combined with other stimulants such as caffeine.

While it does appear to be safe, those with high blood pressure or heart problems should likely speak to a healthcare professional prior to consuming high doses.

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This article has been reviewed and fact-checked by a certified nutritionist, and only uses information from credible academic sources.