How Not to Die

Michael Greger is an American doctor who decided, instead of seeing patients only in an office, to devote a good part of his career to combing through thousands of scientific studies on food and summarizing what he found for the lay public. "How Not to Die" grew out of that project, a book that tries to answer why certain populations live longer and get sick less often from common chronic diseases.

The book is split into two very different parts. The first goes disease by disease, covering the deadliest ones in the Western world and showing what research associates with preventing each. The second becomes a list of foods and a daily routine that the author recommends, which he calls the Daily Dozen.

This summary treats both parts with the same care. It is not medical advice or a diet prescription. It is an analysis of the book's ideas and claims, including how much scientific evidence supports each one. Any real change in eating, especially for people who already have a disease or take daily medication, needs medical or nutritional supervision, not a book summary.

Greger's central thesis is that a good share of the diseases that kill the most people in the Western world, heart disease, type 2 diabetes, some kinds of cancer, are strongly tied to the dominant eating pattern, rich in processed meat, sugar and ultraprocessed food.

This is not the author's isolated opinion. The link between eating patterns and chronic disease is recognized by practically all of preventive medicine, with evidence considered strong in long-term population studies conducted in many different countries.

Where the discussion gets heated is the intensity of the recommendation. Greger argues, with openly stated personal conviction, for a diet built almost entirely on plants as the best possible prevention, a position that part of the scientific community considers correct in general but exaggerated in some specific details that the book presents as settled certainty.

It is worth separating, right now, two different levels of claim that show up mixed together throughout the book: saying that eating more plants and less ultraprocessed food helps prevent disease is an idea with broad backing, while saying that this specific pattern is the only correct path to health is a stronger claim than most of the data can support on its own.

The chapter on heart disease is the longest and most quoted in the book. Greger gathers studies that associate a diet rich in vegetables, whole grains and legumes with lower rates of clogged arteries, including research that followed patients for decades.

The evidence here is considered moderate to strong by the medical literature, especially for primary prevention, stopping the problem before it starts. The book's boldest claim, that a radical diet change can reverse arterial blockage already in place in some patients, comes from smaller studies and is still seen as moderate evidence, not definitive.

It bears repeating: this kind of decision, reversing or treating an already diagnosed heart condition, should never be attempted on your own based on a book. That is a cardiologist's territory, with tests and follow-up, not a DIY change of menu.