Michael Greger

Michael Herschel Greger (born October 25, 1972) is an American physician, author, and speaker on public health issues best known for his advocacy of a whole-food, plant-based diet, and his opposition to animal-derived food products. He founded the website NutritionFacts.org which provides videos and studies around diet and nutrition. His books How Not to Die, How Not to Diet, and How Not to Age have been New York Times best sellers .

Early life and education Michael Greger was born on October 25, 1972, in Miami, Florida, United States. Greger has said that he was inspired to pursue a career in medicine at the age of nine after witnessing his grandmother's health improvement that she attributed to following dietary and lifestyle changes prescribed by American nutritionist Nathan Pritikin. He later graduated from the Cornell University School of Agriculture in 1995, where as a junior he wrote informally about the dangers of bovine spongiform encephalopathy on a website he published in 1994. In the same year, he was hired to work on mad cow issues for Farm Sanctuary, near Cornell, and became a vegan after touring a stockyard as part of his work with Farm Sanctuary. He later enrolled at Tufts University School of Medicine, originally for its MD/PhD program, but then withdrew from the dual-degree program to pursue only the medical degree. He received his MD in 1999 as a general practitioner specializing in clinical nutrition. 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. Greger (center) at the USDA Dietary Guidelines Advisory Committee, Washington, D.C., 2019. 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 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". He has been critical of the USDA, stating that "a conflict of interest right in their mission statement" protects the economic interests of food producers in lieu of clear dietary guidelines.

(with Gene Stone) (with Gene Stone & Robin Robertson)

(with Kristine Dennis)