The Inuit paid little attention to the plants in their environment “because they added nothing to their food supply,” noted the Canadian anthropologist Diamond Jenness, who spent the years 1914–16 living in the Coronation Gulf region of Canada’s Arctic coast. Jenness described their typical diet during one three-month stretch as “no fruit, no vegetables; morning and night nothing but seal meat washed down with ice-cold water or hot broth.” (The ability to thrive on such a vegetable-and fruit-free diet was also noted by the lawyer and abolitionist Richard Henry Dana, Jr., in his 1840 memoirs of life on a sailing ship, Two Years Before the Mast. For sixteen months, Dana wrote, “we lived upon almost nothing but fresh beef; fried beefsteaks, three times a day…[in] perfect health, and without ailings and failings.”

None of Stefansson’s observations would have been controversial had not the conventional wisdom at the time been—as it is still—that a varied diet is essential for good health. A healthy diet, it is said, must contain protein, fats, and carbohydrates, the latter because of the misconception that the brain and central nervous system require dietary glucose to function, and the debatable assumption that fresh vegetables and fruit, which contain carbohydrates, are essential to prevent deficiency diseases.

Because it is still common to assume that a meat-rich, plant-poor diet will result in nutritional deficiencies, it’s worth pausing to investigate this issue. The assumption dates to the early decades of the twentieth century, the golden era of research on vitamins and vitamin-deficiency diseases, as one disease after another—scurvy, pellagra, beriberi, rickets, anemia—was found to be caused by a lack of essential vitamins and minerals. This was The Newer Knowledge of Nutrition, as it was called by the Johns Hopkins nutritionist Elmer McCollum; it dictated that the only way to ensure all the essential elements for health was to eat as many types of foods as possible, and nutritionists still hold by this logic today. “A safe rule of thumb,” as it was recently described, “is that the more components there are in a dietary, the greater the probability of balanced intake.”