Posted by: Chris Maloney | August 23, 2012

Thoughts on Dr. Oz and Green Coffee Extract’s Effect On Weight Loss.

English: Typical Brazilian coffee at 75° F, un...

English: Typical Brazilian coffee at 75° F, unroasted coffee. (Photo credit: Wikipedia)

If the marketers are to be believed, we are entering a green coffee revolution.  I have received multiple calls and offers to send samples out to my patients.  Dr. Oz has come up several times as an enthusiastic promoter of green coffee for weight loss.

I’ve already addressed the studies on green coffee in an earlier post.  I’ve also noted that Dr. Oz does not endorse products and anyone who says he has endorsed their product may get a legal letter from him.

So now I’d like to look at the whole raw vs. cooked nature of green and brown coffees.

Anyone familiar with the debate about raw vs. cooked knows that raw food contains more enzymes while cooked food is more digestible.  We have whole schools of thought, with raw foodists competing directly with Chinese Medicine‘s admonition to eat nothing cold lest you deplete yourself.

Do we have any information about green coffee vs. brown coffee in the same vein?  Yes.  It turns out that slightly cooking the coffee beans makes the helpful compounds more bioavailable.  Cooking them too long degrades the same compounds.

Anyone who has ever cooked an egg and then burned an egg knows all about this situation.

Looking ahead, I’m going to predict lightly roasted coffee as a new fad.  Maximized absorption of compounds, without overcooking.  Maybe they’ll even start grading coffee like olive oil.  “First mildly heated batch” vs. regular.  (BTW, olive oil is a whole other topic.)

Here’s the study on the changes caused by roasting coffee.

J Agric Food Chem. 2012 May 2;60(17):4265-75. Epub  2012 Apr 19.

Influence of coffee roasting on the incorporation of phenolic compounds into melanoidins and their relationship with antioxidant activity of the brew.


Laboratório de Bioquímica Nutricional e de Alimentos, Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Brazil.


In the present study, the influence of coffee roasting on free and melanoidin-bound phenolic compounds and their relationship with the brews’ antioxidant activity (AA), evaluated by TRAP, TEAC, and TRAP, were investigated. Changes in the relative content of free chlorogenic acids (CGA), free lactones, and melanoidin-bound phenolic acids during roasting indicate that phenolic compounds were incorporated into melanoidins mainly at early stages of the process, being thereafter partly oxidized to dihydrocaffeic acid, and degraded. Although less than 1% of CGA in green coffee was incorporated into melanoidins during roasting, the relative content of melanoidin-bound phenolic acids increased significantly during this process, reaching up to 29% of total phenolic compounds in brews from dark roasted coffees. Regardless of the AA assay used and considering all roasting degrees, the overall contribution of CGA to the AA of the whole brews was higher than that of melanoidin-bound phenolic compounds. It was estimated that the latter compounds contributed to 25-47% of the AA, depending on the assay used.




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