Citrus Aurantium

Nutritional Compound



Citrus aurantium, commonly referred to as bitter orange, has been used for thousands of years in Traditional Chinese Medicine to improve and maintain overall health. That is, until recently, when science discovered compounds (the most well-known being synephrine) from these little orange fruits demonstrated equally powerful thermogenic (“fat-burning”) activity. In fact, synephrine is referred to as ephedra’s “calmer chemical cousin” because it increases the body’s metabolic rate or ability to burn calories, without producing negative side effects on the central nervous system and the cardiovascular system.

Other names for Citrus Aurantium

synephrine, bitter orange, naranja agria, zhi shi

Where to find Citrus Aurantium

Citrus aurantium is also called bitter orange because it tastes bitter and is orange. Like other orange trees, this is a big, fruit-bearing evergreen tree that orginated in Asia but is now found all over the world, including places like the Mediterranean. The fruits are small, about the size of a cherry.

Citrus aurantium contains around 0.2 to 0.5% essential oil, which is distilled from the unripe, green fruit and its peel. The oils contain compounds called limonoids, monoterpenes, and flavonoids. The peel contains the alkaloid synephrine and carotene pigments.

Synephrine is also found naturally in humans, though in very small amounts, primarily in the adrenal glands.


Why athletes use Citrus Aurantium

If you use ephedra and are feeling a little too amped up, or if you have considered using ephedra and are concerned about potential (unwanted) side effects, Citrus aurantium might be just what you’ve been waiting for. Science has discovered this little orange fruit, sometimes called bitter orange, may still give your body a quick “boost” of energy as well as rev up your metabolism to assist your fat-fighting efforts without the undesirable effects of ephedra-based supplements.

Ways that Citrus Aurantium can enhance Fat Loss:
  • Increase the body’s metabolic rate, using calories for energy to help burn fat
  • Potentially promote weight loss by suppressing appetite
Ways that Citrus Aurantium can enhance Energy & Endurance:
  • Mildly “stimulate” the body, thus supplying greater amounts of energy


Signs of Citrus Aurantium deficiency

No deficiency conditions are known to exist.

Potential uses for Citrus Aurantium

Research indicates that Citrus Aurantium may be useful in the treatment of:

  • Obesity
  • Fatigue/Weakness
  • Gastrointestinal disorders
  • Anxiety
  • Insomnia/sleep disorders
  • Anorexia
  • Dermatitis


More about Citrus Aurantium

Looking for a natural energy “boost” or increased fat-burning effects, but scared of using ephedra? Look no further than Citrus aurantium. While much milder than ephedra, recent research has shown Citrus aurantium revs up the metabolism, increases energy output, plus offers the additional benefit of improved digestion of foods, which may supply the body with even greater amounts of energy.

While the jury’s still out on some other claims, like appetite control, it may be an even more effective thermogenic “fat burner” than ephedra. For this reason alone, this one’s got us interested. Here’s the lowdown…

Stimulant and thermogenic effects

Citrus aurantium appears to work by way of its active compound called synephrine, which is a bit like ephedra (a caffeine-like chemical found in a lot of weight loss and performance products). Like ephedra, this chemical also appears to reduce appetite and boost metabolism — the rate our bodies burn calories — thus stimulating fat loss. Unlike ephedra, though, you’re likely to experience very little, if any, side effects with Citrus aurantium. This is because synephrine doesn’t seem to cross the blood/brain barrier as easily as ephedra, which means reduced central nervous stimulation and cardiovascular effects. Ultimately, this could mean no nervous energy, shakes, or insomnia.

According to recent research at McGill University, another reason Citrus aurantium gives you a smooth flow of energy without the jitters is because it stimulates certain receptors (called beta-3 adrenergic receptors) that help break down fat. Simultaneously, this stimulation causes an increase in the metabolic rate. Therefore, you burn fat without bothering other receptors (namely, beta-1, beta-2, or alpha-1) that over-stimulate your heart rate and blood pressure. In contrast, ephedra stimulates all beta-adrenergic receptors, thus causing unwanted side effects.

Synephrine is now being used as a replacement for ephedra in many thermogenic formulas to reduce unwanted side effects.

Improved digestion of foods

Citrus aurantium is useful for digestive ailments as well. In fact, bitter orange has been used for thousands of years in Traditional Chinese Medicine for maintaining stomach and gastrointestinal health, improving circulation, and supporting liver health — with no reported adverse reactions.

Research suggests it works by helping the muscles of the digestive tract relax and increasing gastric juice secretion. By providing an environment for better food absoroption, this could supply the body with even greater amounts of energy, facilitating improved physical performance.

Appetite suppressant

Another application of Citrus aurantium is appetite control, but this one is a little fruity. While some sources claim it helps control appetite, the German Commission E, THE encyclopedia for herbal supplements, tells us the herb actually stimulates appetite! So, which is it?

Well, Citrus aurantium extract contains chemicals called tyramine and octopamine, and the latter is possibly the key to the appetite control. In the real world, when bugs try and eat this fruit, it disgusts them. Interestingly, in real live humans, octopamine seems to work like a fake neurotransmitter, which fools the pituitary into producing two distinct actions: first, it secretes chemical messages to the brain that give the sensation of “fullness,” and second, it secretes growth hormone, which could theoretically help you build muscle. But before you plant your own bitter orange tree, honestly, much more research is needed to confirm this theory.

Soothing skin and “other” solutions

Topically applied, Citrus aurantium oil is also useful for treating skin fungi like athlete’s foot and ring worm. But watch out if you’re fair skinned. As mentioned above, the peel of the raw fruit can make you more sensitive to sunlight due to the toxic effect of “furocoumarins.”

In conclusion

Whoever thought that nice little mini-orange tree growing in your backyard could be such a powerhouse of health and performance? Now, it’s not really your typical orange tree, but once again, Traditional Chinese Medicine has led us to an important discovery: this little orange has the potential to ward of unwanted bodyfat and ramp up energy levels. As an ephedra substitute, Citrus aurantium certainly bodes well… very well. We’ll be sure to keep you posted on more factual findings on this powerful supplement in the future.



Research indicates that 4 to 20 mg of synephrine per day, which usually is provided by supplementing with 200 to 600 mg of a standardized Citrus aurantium extract (3 to 6% synephrine), may be effective.

If you’re brave, you can stick the crushed peel in some hot water and “savor” a really bitter tea. Use 4 to 6 grams per day of cut peel for teas or 2 grams in 150 ml or boiled water 3 times a day. Alcohol solutions (tinctures) and liquid extracts are another (more enjoyable) way to take it.

Important Note

According to recent data, it appears that using the whole fruit extract is the best way to take Citrus aurantium since there are many additional chemicals in the plant besides synephrine that are used for increasing the metabolism, and we’re only beginning to understand their total, combined effects.


For weight loss, use in evenly divided doses throughout the day, preferably on an empty stomach. For stimulant effects, use 30 to 45 minutes before exercise, again, without food.

Synergists of Citrus Aurantium

Citrus aurantium is often included in formulas with kola nut and guarana (which are caffeine sources) to synergistically assist in thermogenesis.

Citrus aurantium is sometimes combined with Garcinia cambogia (HCA) to increase thermogenic effects.

Safety of Citrus Aurantium

Both isolated synephrine and Citrus aurantium extract can crank up your blood pressure, so if you’ve got heart problems or high blood pressure, it may be best to avoid it. Synephrine causes a rise in blood pressure by triggering vasoconstriction (tightening of your vascular system or blood carrying network). Like many natural supplements, avoid use during pregnancy or lactation.

Drugs that interact with Citrus Aurantium

Do not combine with heart or blood pressure medications.

Toxicity of Citrus Aurantium

Like most bitter herbs, there is stuff in here you don’t want to be messing with. Try to avoid rubbing raw Citrus aurantium (the fruit) all over your body since the peel can irritate the skin and even make you more sensitive to sunlight due to the phototoxic effect of furocoumarins.

Bans and restrictions

Some experts have theorized that synephrine may show traces of alkaloids in the body similar to ephedra, but more research is needed to verify if this is, in fact, the case. At present, synephrine is not on any banned list. Still, if you are an elite athlete who is regularly drug tested, it is recommended that you discuss supplementation with your physician before use.


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