As for vitamin C, the source in the Eskimo diet was long a mystery. Most animals can synthesize their own vitamin C, or ascorbic acid, in their livers, but humans are among the exceptions, along with other primates and oddballs like guinea pigs and bats. If we don’t ingest enough of it, we fall apart from scurvy, a gruesome connective-tissue disease. In the United States today we can get ample supplies from orange juice, citrus fruits, and fresh vegetables. But vitamin C oxidizes with time; getting enough from a ship’s provisions was tricky for early 18th- and 19th-century voyagers to the polar regions. Scurvy—joint pain, rotting gums, leaky blood vessels, physical and mental degeneration—plagued European and U.S. expeditions even in the 20th century. However, Arctic peoples living on fresh fish and meat were free of the disease.

HERRING

Impressed, the explorer Vilhjalmur Stefansson adopted an Eskimo-style diet for five years during the two Arctic expeditions he led between 1908 and 1918. “The thing to do is to find your antiscorbutics where you are,” he wrote. “Pick them up as you go.” In 1928, to convince skeptics, he and a young colleague spent a year on an Americanized version of the diet under medical supervision at Bellevue Hospital in New York City. The pair ate steaks, chops, organ meats like brain and liver, poultry, fish, and fat with gusto. “If you have some fresh meat in your diet every day and don’t overcook it,” Stefansson declared triumphantly, “there will be enough C from that source alone to prevent scurvy.”


In fact, all it takes to ward off scurvy is a daily dose of 10 milligrams, says Karen Fediuk, a consulting dietitian and former graduate student of Harriet Kuhnlein’s who did her master’s thesis on vitamin C. (That’s far less than the U.S. recommended daily allowance of 75 to 90 milligrams—75 for women, 90 for men.) Native foods easily supply those 10 milligrams of scurvy prevention, especially when organ meats—preferably raw—are on the menu. For a study published with Kuhnlein in 2002, Fediuk compared the vitamin C content of 100-gram (3.55-ounce) samples of foods eaten by Inuit women living in the Canadian Arctic: Raw caribou liver supplied almost 24 milligrams, seal brain close to 15 milligrams, and raw kelp more than 28 milligrams. Still higher levels were found in whale skin and muktuk.

As you might guess from its antiscorbutic role, vitamin C is crucial for the synthesis of connective tissue, including the matrix of skin. “Wherever collagen’s made, you can expect vitamin C,” says Kuhnlein. Thick skinned, chewy, and collagen rich, raw muktuk can serve up an impressive 36 milligrams in a 100-gram piece, according to Fediuk’s analyses. “Weight for weight, it’s as good as orange juice,” she says. Traditional Inuit practices like freezing meat and fish and frequently eating them raw, she notes, conserve vitamin C, which is easily cooked off and lost in food processing.

Hunter-gatherer diets like those eaten by these northern groups and other traditional diets based on nomadic herding or subsistence farming are among the older approaches to human eating. Some of these eating plans might seem strange to us—diets centered around milk, meat, and blood among the East African pastoralists, enthusiastic tuber eating by the Quechua living in the High Andes, the staple use of the mongongo nut in the southern African !Kung—but all proved resourceful adaptations to particular eco-niches. No people, though, may have been forced to push the nutritional envelope further than those living at Earth’s frozen extremes. The unusual makeup of the far-northern diet led Loren Cordain, a professor of evolutionary nutrition at Colorado State University at Fort Collins, to make an intriguing observation.

Four years ago, Cordain reviewed the macronutrient content (protein, carbohydrates, fat) in the diets of 229 hunter-gatherer groups listed in a series of journal articles collectively known as the Ethnographic Atlas. These are some of the oldest surviving human diets. In general, hunter-gatherers tend to eat more animal protein than we do in our standard Western diet, with its reliance on agriculture and carbohydrates derived from grains and starchy plants. Lowest of all in carbohydrate, and highest in combined fat and protein, are the diets of peoples living in the Far North, where they make up for fewer plant foods with extra fish. What’s equally striking, though, says Cordain, is that these meat-and-fish diets also exhibit a natural “protein ceiling.” Protein accounts for no more than 35 to 40 percent of their total calories, which suggests to him that’s all the protein humans can comfortably handle.

This ceiling, Cordain thinks, could be imposed by the way we process protein for energy. The simplest, fastest way to make energy is to convert carbohydrates into glucose, our body’s primary fuel. But if the body is out of carbs, it can burn fat, or if necessary, break down protein. The name given to the convoluted business of making glucose from protein is gluconeogenesis. It takes place in the liver, uses a dizzying slew of enzymes, and creates nitrogen waste that has to be converted into urea and disposed of through the kidneys. On a truly traditional diet, says Draper, recalling his studies in the 1970s, Arctic people had plenty of protein but little carbohydrate, so they often relied on gluconeogenesis. Not only did they have bigger livers to handle the additional work but their urine volumes were also typically larger to get rid of the extra urea. Nonetheless, there appears to be a limit on how much protein the human liver can safely cope with: Too much overwhelms the liver’s waste-disposal system, leading to protein poisoning—nausea, diarrhea, wasting, and death.