If you made a list of the most famous doctors in America, Dr. Oz would surely be at the top. A surgeon who rose to fame after appearances on the Oprah Winfrey Show, Dr. Oz now hosts his own television show focused on health and well-being. Never one to confine himself to traditional medical practices, Dr. Oz is fond of touting the latest vitamins and nutritional supplements, even when they haven’t been fully scientifically vetted. Recently, this has landed him in some hot water with Congress.
At congressional hearings in 2014, lawmakers pointedly questioned Dr. Oz about claims he’s made about a variety of health and weight-loss supplements (1). Politicians like Senator Claire McCaskill of Missouri pointed out the wide gap between the claims Dr. Oz has made on his show about a variety of supplements, ( see: forskolin) and the actual scientific evidence that backs them.
What does the scientific literature say about some of the supplements that Dr. Oz has promoted on his show over the years?
Green Coffee Bean Extract
One of the supplements that featured prominently in the congressional hearings is green coffee bean extract. As reported in The Atlantic (2), Dr. Oz called green coffee bean extract a “miracle pill” which can “burn fat fast for anyone who wants to lose weight.”
There is indeed some science on green coffee bean extract—a 2006 study found that the supplement, when provided in high doses, reduced body fat slightly in lab mice (3), and a 2012 experiment by researchers at the University of Scranton found that humans taking green coffee bean extract dropped their body fat percentage by an impressive four points (4).
However, the study in mice was conducted and funded by employees of a company in Japan that sells green coffee bean extract, and the University of Scranton researchers retracted their own paper after the Federal Trade Commission filed a complaint saying the study’s design was “hopelessly flawed.” A retraction in the scientific community essentially invalidates the study. It doesn’t mean the study found the wrong answer to the question of whether green coffee bean extract promotes weight loss, but it does mean that the study’s design was so poor as to render its results useless