,
Washington, D.C., 2019. In 2001, Greger joined the
Organic Consumers Association to work on mad cow issues, on which he spoke widely as cases of the disease appeared in the US and Canada. Previously in 1994, in a
Cornell University animal rights publication, Greger highlighted the results of a survey in Britain that appeared to support the view of a microbiologist at the
University of Leeds that mad cow disease was "much more serious than
AIDS". A decade later, in early 2004, the
Daily Bruin, the student newspaper of the
University of California, Los Angeles, reported that Greger had called mad cow disease the "plague of the 21st century". However, Greger later denied ever making such a statement, clarifying that he had merely posed it as a question during a speech. That same year, Greger cited a study and said that "thousands of Americans may already be dying because of Mad Cow disease every year". In 2004, he launched a website and published a book critical of the
Atkins Diet and other
low-carbohydrate diets. and Greger was a founding member, and fellow. In 2005, Michael Greger joined the farm animal welfare division of the
Humane Society of the United States as director of public health and animal agriculture. Three years later, he testified before the
United States Congress after the Humane Society released its
undercover video of the Westland Meat Packing Company, which revealed
downer animals entering the meat supply. This led the USDA to mandate the recall of 143 million pounds of beef, some of which had been routed into the nation's school lunch program.
NutritionFacts Greger founded the website
NutritionFacts.org, with funding from the Jesse & Julie Rasch Foundation. It was founded in August 2011 to provide information on nutrition and health. Jesse & Julie Rasch Foundation provided the initial seed funding. Greger, then known for
public-health lectures and his work with the
Humane Society of the United States, aimed to "cut through the hype" by summarizing findings from
peer-reviewed studies in an accessible format. From its inception, the site released a new video every weekday, drawing on Greger's
Latest in Clinical Nutrition lecture series, to make complex research digestible for the general public. In 2017, Greger received the ACLM Trailblazer Award in
lifestyle medicine, with NutritionFacts.org cited as a model of freely available, evidence-based education. In 2024, Greger stated that the four things that he would recommend to increase longevity are to live a diet focused around plants, use a
treadmill desk, exercise daily, and eat calories earlier in the day. In 2025, its
podcast Nutrition Facts with Dr. Greger was voted "Best Podcast" in the
VegNews Veggie Awards.
Eric Adams, then
Borough President of
Brooklyn and later
Mayor of New York City, cited Greger's research as a catalyst for adopting a plant-based diet to reverse his
type 2 diabetes. Greger also serves in the
U.S. News & World Report expert panel that ranks the "Best Diets".
Reception Greger's books have appeared on
The New York Times Best Seller list multiple times, including
How Not to Die three times, and
How Not to Diet, and
How Not to Age once each. Greger's third book,
Bird Flu: A Virus of Our Own Hatching, received a favorable review which said it was "interesting and informative to both scientists and lay persons". Public health expert
David Sencer was critical of the book, writing that it "focuses heavily on doomsday scenarios and offers little in terms of practical advice to the public" and that "a professional audience would quickly put [the book] aside for more factually correct sources of information". In 2024, Morgan Pfiffner of
Red Pen Reviews gave his sixth book,
How Not to Diet a score of 50% for its scientific accuracy and a score of 75% for its healthfulness. Pfiffner commented that "While much of the book is well supported by research, there are a significant number of fairly questionable claims, leading to a handful of dietary recommendations that seem unnecessary, too restrictive, or potentially counterproductive". He also argues that Greger's claim that a whole food plant-based diet can reverse heart disease is questionable. According to Pfiffner this has not been demonstrated as the randomized controlled trial that he cited from
Dean Ornish did not show regression of atherosclerotic plaque.
Harriet Hall argues that, while it is well-accepted that it is more healthy to eat a plant-based diet than a typical Western diet, Greger often overstates the known benefits of such a diet as well as the harm caused by eating animal products (for example, in a talk, he claimed that a single meal rich in animal products can "cripple" one's arteries), and he sometimes does not discuss evidence that contradicts his strong claims.
Joseph A. Schwarcz of
McGill University argues that although Greger takes his information from respected science journals and produces impressive videos, he has a vegan agenda and cherry picks his data. He adds, "Of course that doesn't mean the cherries he picks are rotten; they're fine."
Jonathan Jarry in a 2026 article "Dr. Michael Greger’s Bias Is Food for Thought" commented that "while some of the information he puts forward is backed up by good scientific evidence, he regularly demonizes synthetic compounds, exaggerates the danger posed by eating or handling meat, and is uncritical of inadequate studies alleging all sorts of benefits for plant-based compounds". ==Publications==