Synephrine (oxedrine, Sympatol) - How oranges might help you lose weight

  • so synephrine actually comes in three slightly different flavours: ortho, meta, and para
    • when people (including this blogger) talk about synephrine, they are usually referring to the para isomer (p-synephrine)
    • meta-synephrine is better known as phenylephrine or neosynephrine, a decongestant that is currently making a comeback thanks to restrictions on the sale of pseudoephedrine, another decongestant, since it can be used to make sweet, sweet crystal meth
  • has been used as a drug since 1927, usually formulated as eye drops for the treatment of glaucoma, but has also been employed to treat circulatory failure, asthma, and nasal congestion
    • pharmacologically speaking, it's a sympathetic alpha-adrenergic agonist with some beta2-adenergic activity, which essentially means that it causes blood vessels to constrict (thus increasing blood pressure, reducing blood flow to the extremities, etc.) and is able to widen the airways (thus helping to relieve asthma)
  • produced by several species of Citrus (it's an actual genus) plants, including Citrus aurantium (bitter/sour/Seville orange)
    • C. aurantium is used primarily as a dietary supplement intended to promote weight loss
    • is also produced in small amounts by the human body, where it may function as a neurotransmitter
  • theorized to produce weight loss by: (a) increasing the number of calories you burn while you laze about the house (i.e. your resting energy expenditure), and (b) reducing your food intake (possibly by decreasing the rate at which food passes throughout your stomach and intestines, making you feel full for a longer period of time)
  • similar in structure and action to ephedrine, a CNS stimulant that has been used to promote weight loss, although such use is currently banned by the FDA
    • unsurprisingly, synephrine can be found in some diet pills, even though it has not yet been shown conclusively that it makes people less fat
    • C. aurantium fruit extracts containing synephrine have been shown to reduce food intake, and ultimately body weight, in rodents
    • eating a bunch of oranges might help you lose weight, but it will probably be due to all that wonderful diarrhea all that fresh fruit will cause and not due to the effects of synephrine
- Haaz S et al. Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: an update. Obes Rev. 2006 Feb;7(1):79-88. Review.
- http://www.itmonline.org/arts/syneph.htm

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