An effective slimming supplement doesn’t have to be packed full with potentially hazardous stimulants. A carefully balanced combination of Citrus aurantium and Rhodiola rosea reduces appetite and fat reserves, according to an animal study carried out at the State University of New Jersey.
Synephrine, the active ingredient in Citrus aurantium, reduces appetite, but can also narrow the arteries and thus cause high blood pressure. In-vitro studies have shown that Rhodiola rosea also has a couple of properties that are of interest to people who want to lose weight, and animal studies have also shown that Rhodiola protects the heart muscle. That’s why the researchers wondered whether it would be possible to make an effective slimming supplement by combining the two extracts.
The researchers set out to answer the question by doing an animal study.
They gave rats Citrus aurantium, Rhodiola or a combination of the two extracts daily for ten days via a tube. One control group was given just a small amount of fluid without active ingredients [Placebo]. Another control group was given exactly the same amount of food as the rats in the Citrus aurantium + Rhodiola rosea group ate [Control].
The Citrus aurantium extract consisted of 6 percent synephrine, a stimulatory compound similar to raspberry ketone, and ephedrine.
The Rhodiola extract consisted of 3 percent rosavins [structural formula above right] and 1 percent salidroside [structural formula below right].
A dose of 3.2-5.6 mg Citrus aurantium per kg bodyweight per day combined with 20 mg Rhodiola rosea per kg bodyweight per day reduced the rats’ daily calorie intake. If the Citrus aurantium dose is too high, the effect strangely disappears.
The human equivalent of these doses is about 45-75 mg Citrus aurantium and 260 mg Rhodiola rosea per day.
The amount of abdominal fat was significantly lower in the rats that had been given both Rhodiola rosea and Citrus aurantium than in the other groups.
The researchers don’t know quite how the combination of Citrus aurantium and Rhodiola rosea works, but they suspect it has an effect in the brain. They did discover that the combination boosted the concentration of appetite-suppressing neurotransmitters in the part of the brain that regulates eating behaviour. In the hypothalamus for example the combination had this effect on noradrenalin.
In the prefrontal cortex, another part of the brain that is involved in the regulation of appetite, the combination of Rhodiola and Citrus aurantium boosted the concentration of dopamine by a significant amount.
The researchers observed no cardiovascular side effects.
“Combinational doses of Citrus aurantium and Rhodiola rosea promote improvements in the alterations caused by high-fat feeding and obesity”, the researchers conclude. “Notably, these effects appear to result from an interaction between the two botanicals and their bioactive constituents, representing a novel mechanism that requires further examination.”
The study was funded by the American government, in the form of the National Center for Complementary and Alternative Medicine and the Office of Dietary Supplements.
Citrus aurantium and Rhodiola rosea in combination reduce visceral white adipose tissue and increase hypothalamic norepinephrine in a rat model of diet-induced obesity.
Extracts from the immature fruit of Citrus aurantium are often used for weight loss but are reported to produce adverse cardiovascular effects. Root extracts of Rhodiola rosea have notable antistress properties. The hypothesis of these studies was that C aurantium (6% synephrine) and R rosea (3% rosavins, 1% salidroside) in combination would improve diet-induced obesity alterations in adult male Sprague-Dawley rats. In normal-weight animals fed standard chow, acute administration of C aurantium (1-10 mg/kg) or R rosea (2-20 mg/kg) alone did not reduce deprivation-induced food intake, but C aurantium (5.6 mg/kg) + R rosea (20 mg/kg) produced a 10.5% feeding suppression. Animals maintained (13 weeks) on a high-fat diet (60% fat) were exposed to 10-day treatments of C aurantium (5.6 mg/kg) or R rosea (20 mg/kg) alone or in combination. Additional groups received vehicle (2% ethanol) or were pair fed to the C aurantium + R rosea group. Although high-fat diet intake and weight loss were not influenced, C aurantium + R rosea had a 30% decrease in visceral fat weight compared with the other treatments. Only the C aurantium group had an increased heart rate (+7%) compared with vehicle. In addition, C aurantium + R rosea administration resulted in an elevation (+15%) in hypothalamic norepinephrine and an elevation (+150%) in frontal cortex dopamine compared with the pair-fed group. These initial findings suggest that treatments of C aurantium + R rosea have actions on central monoamine pathways and have the potential to be beneficial for the treatment of obesity.
PMID: 23746567 [PubMed – indexed for MEDLINE] PMCID: PMC3808124