Meat

I posted this on another forum, but thought I'd share my hard work here too...

For fifty years after William Banting publicized William Harvey's prescription for a carbohydrate restricted diet in 1863, the primary clinical disagreements were on the role of fat in the diet. Banting's original prescription was a high-fat diet, but then it was modified by Harvey himself and by the German clinicians Felix von Niemeyer and Max Oertel into lower-fat, higher protein versions, and by Wilhelm Ebstein into a version featuring still more fat. "The fat of ham, pork or lamb is not only harmless but useful," Ebstein wrote.

The notion of a carbohydrate-restricted diet based exclusively on fatty meat was publicized after World War I by the harvard anthropologist-turned-Artic-explorer, Vilhjalmur Stefansson, who was concerned with the overall healthfulness of the diet, rather than it's potential for weight loss. Stefansson has spent a decade eating nothing but meat among the Inuit of northern Canada and Alaska. The Inuit, he insisted, as well as the visiting explorers and traders who lived on this diet were among the healthiest if not the most vigorous populations imaginable.

Among the tribes with whom Stefansson lived and traveled, the diet was primarily caribou meat, "with perhaps 30 percent fish, 10 percent seal meat, and 5 or 10 percent made up of polar bear, rabbits, birds and eggs." The Inuit considered vegetables and fruit "not proper human food," Stefansson wrote, but they occasionally ate the roots of the knotweed plant in times of dire necessity.

The Inuit paid little attention to the plants in their environment "because they added nothing to their food supply,"noted in 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; fresh beefsteaks, three times a day...[in] perfect health, and without ailing 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 sill hold by the 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."

This philosophy, however, was based almost exclusively on studies of deficiency diseases, all of which were induced by diets high in refined carbohydrates and low in meat, fish, eggs and dairy products. When the Scottish naval surgeon James Lind demonstrated in 1753 that scurvy could be prevented and cured by the consumption of citrus juice, for example, he did so with British sailors who had been eating the typical naval fare "of water gruel sweetened with Sugar in the morning, fresh mutton broth, light puddings, boiled biscuit with sugar, barley and raisins, rice and currants." Pellagra was associated almost exclusively with corn-rich diets, and beriberi with the eating of white rice rather than brown. When beriberi broke out in the Japanese navy in the later 1870's, it was only after the naval fare had been switched from vegetables and fish to vegetables, fish and white polished rice. The outbreak was brought under control by replacing the white rice with barley and adding meat and evaporated milk. Pellagra too, could be cured or ameliorated, as Carl Voegtlin demonstrated in 1914, by adding fresh meat, milk, and eggs to a pellagra-causing diet, which in Voegtlin's experiments constituted primarily wheat, cabbage, corn-meal and corn syrup, turnips, potatoes, and sugar. Nutritionists working with lab animals also found that they could induce deficiency diseases by feeding diets rich in refined grains and sugar. Guinea pigs were given scurvy in a series of laboratory experiments in the 1940's when they were fed diets of mostly crushed barley and chickpea's.

This research informed the conventional wisdom of the era that fresh meat, milk, and eggs were what the Scottish Nutritionist Robert McCarrison called "protective foods" (which is how they were known before Ancel Keys and his contemporaries established them as the fat-rich agents of coronary disease), but it also bolstered the logic that a "balanced" diet, with copious vegetables, fruits, and grains, were necessary for health. Because diets of mostly grains and starches, or diets of refined grains, fish and vegetables, such as the Japanese sailors consumed, might be deficient in a vitamin or vitamins essential for health, nutritionists considered it a reasonable assumption that this might be true of any such "unbalanced" diets, including those that were made up exclusively of animal products.

What the nutritionists of the 1920s and 1930s didn't then know is that animal food contain all the essential amino acids (the basic structural building blocks of proteins), and they do so in the ratios that maximize their utility to humans. "They also contain twelve of the thirteen essential vitamins in large quantities. Meat is a particularity concentrated source of vitamins A, E and the entire complex of B vitamins. Vitamins D and B-12 are found ONLY in animal products (although we can usually get sufficient vitamin D from the effect of sunlight on our skin)"

The thirtieth vitamin, vitamin C, ascorbic acid, has long been the point of contention. It is contained in animal foods in such small quantities that nutritionists have considered it insufficient and the question is whether this quantity is indeed sufficient for good health. Once James Lind demonstrated that scurvy could be prevented and cured by eating fresh fruits and vegetables, nutritionists assumed that these foods are an absolutely essential dietary source of vitamin C. What had been demonstrated, they will say, is that scurvy is "a dietary deficiency resulting form lack of fresh fruit and vegetables". To be technically accurate, however, Lind and the nutritionists who followed him in the study of scurvy demonstrated only that that the disease is a dietary deficiency that can be cured by the addition of fresh fruits and vegetables. As a matter of logic, though, this doesn't necessarily imply that the lack of vitamin C is caused by the lack of fresh fruits and vegetables. Scurvy can be ameliorated by adding these to the diet, but the original lack of of vitamin C might be caused by other factors. In fact, given that the Inuit and those Westerners living on the vegetable and fruit-free diet never suffered from scurvy, as Stefansson observed, then other factors must be involved. This suggested another way of defining a balanced diet. It's possible that eating easily digestible carbohydrates and sugars increases our need for vitamins and we would otherwise derive from animal products in sufficient quantities.

This was the issue that Stefansson was raising in the early 1920s. If the Inuit thrived in the harshest of environments without eating carbohydrates and whatever nutrients exist in fruits and vegetables, they, by definition, were consuming a balanced, healthy diet. If they did so solely because they had become evolutionarily adapted to such a diet, which was a typical rejoinder to Stefannson's argument, then how can one explain those traders and explorers, like Stefansson himself and the members of the expeditions , who also lived happily and healthfully for years at a time on this diet?

Nutritionists of the era assumed that all-meat diets were unhealthy because (1) excessive meat consumption was alleged to raise blood pressure and cause gout; (2) the monotony of eating only meat - or any other single food - was said to induce a physical sense of revulsion; (3) the absence of fresh fruit and vegetables in these diets would cause scurvy and other deficiency diseases, and (4) protein-rich diets were thought to induce chronic kidney damage, a belief based largely on early research by Louis Newburgh.

None of these claims were based on compelling evidence. Newburgh, for instance, had based his conclusions largely on experiments in which he fed excessive quantities of soybean, egg whites, and beef protein to rabbits, which as critics would later observe, happen to be herbivores. Their natural diet is buds and bark, not their fellow animals, and so there was little scientific value in force-feeding them meat or animal protein. Nonetheless, the dangers of an all-meat diet were considered sufficiently likely that even Francis Benedict, as Stefansson told it, claimed that it was "easier to believe" that Stefansson and all the various members of his expeditions "were lying, than to concede that [they] had remained in good health for several years on an exclusive meat regimen."

In the winter of 1928, Stefansson and Karsten Anderson, a thirty-eight year old Danish explorer, becomes the subjects in a yearlong experiment that was intended to settle the meat-diet controversy. The experiment was planned and supervised by a committee of a dozen respected nutritionists, anthropologists, and physicians. Eugene Du Bois and ten of his colleagues from Cornell and the Russell Sage Institute of Pathology would oversee the day to day details of the experiment.

For three weeks, Stefansson and Anderson were fed a typical mixed diet of fruits, cereals, vegetables, and meat while being subjected to a battery of tests and examinations. Then they began living exclusively on meat, at which point they moved into Bellevue Hospital in New York and were put under twenty-four-hour observations. Stefansson remained at Bellevue for three weeks. Anderson for thirteen weeks. After they were released, they continued to eat only meat for the remained of one year. If they cheated on the diet, according to Du Bois, the experimenters would know it from regular examinations of Stefansson's and Anderson's urine. "In every individual specimen of urine which was tested during the intervals when they were living at home," Du Bois wrote, "acetone [ketone]bodies were present in amounts so constant that fluctuations in the carbohydrate intake were practically ruled out."

The experimental diet included many types of meat. To test the argument that the vitamins necessary in such a diet to avoid scurvy and remain healthy could be obtained only by eating raw meat, as was incorrectly assumed to be the practice of the Inuit, all the meat was cooked. (In fact, the Inuit only occasionally ate raw meat). Stefansson and Anderson each consumed an average of almost two pounds of meat per day, or twenty-six hundred calories: 79 percent from fat, 19 percent protein, and roughly 2 percent from carbohydrates (a maximum of fifty calories a day), which came from glycogen contained in the muscle meat. (Glycogen is the compound that stores glucose, a carbohydrate, in the liver and the muscle.)

"The only dramatic part of the study was the surprisingly undramatic nature of the findings," wrote Du Bois, when he later summarized the results. "Both men were in good physical condition at the end of the observation," he reported in 1930, in one of the nine articles he and his colleagues published on the study. "There was no subjective or objective evidence of any loss of physical or mental vigor." Stefansson lost six pounds over the course of the year, and Anderson three, even though "the men led somewhat sedentary lives." Anderson's blood pressure dropped from 140/80 to 120/80; Stefannson's remained low (105/70) throughout. The researchers detected no evidence of kidney damage or diminished function, and "vitamin deficiencies did not appear." Nor did mineral deficiencies, although the diet contained only a quarter of the calcium usually found in mixed diets, and the acidic nature of a meat-rich diet was supposed to increase calcium excretion and so deplete the body of calcium. Among the minor health issues reported by D Bois and his colleagues, was the observation that Stefansson began the experiment with mild gingivitis, but this "cleared up entirely, after the meat diet was taken."

When Stefansson published Not by Bread Alone, a popular treatise on fat-and-protein diets, in 1946, a New York Times reviewer wrote, "Mr. Stefansson makes the mixed-diet technicians and the nuts and fruits addicts look terribly silly." Du Bois, who supervised the experiments, wrote an introduction to Stefansson's book. After Stefansson and Anderson were living exclusively on meat, he said, "a great many dire predictions and brilliant theories faded into nothingness," A diet that should have left Stefannson and Anderson deathly ill from scurvy had left them as healthy or healthier than the balanced diet they had been eating in the years immediately preceding the study. "Quite evidently we must revise some of our text book statements" Du Bois concluded.

The textbook statements on vitamins would go unrevised, however, despite laboratory research that has confirmed Stefansson's speculations. Nutritionists would establish by the late 1930s that B vitamins are depleted from the body by the consumption of carbohydrates. "There is an increased need for these vitamins when more carbohydrate in th diet is consumed", as Theodore Van Itallie of columbia University testified to McGovern's Select Committee in 1973. A similar argument can now be made for vitamin C. Type 2 diabetics have roughly 30 percent lower levels of vitamin C in their circulation, than do nondiabetics. Metabolic syndrome is also associated with "significantly" reduced levels of circulating vitamin C, which suggests that vitamin-C deficiency might be another disorder of civilization. One explanation for these observations-described in 1997 by the nutritionists Julie Will and Tim Byers, of the Centers for Disease Control and the university of Colorado respectively, as both "biologically plausible and empirically evident" - is that high blood Sugar and/or high levels of insulin work to increase the body's requirements for vitamin C.

The vitamin-C molecule is similar in configuration to glucose and other sugars in the body. It is shuttled from the bloodstream into the cells by the same insulin-dependent transport system used by glucose. Glucose and vitamin C compete in this cellular-uptake process, like strangers trying to flag down the same taxicab simultaneously. Because glucose is greatly favored in the contest, the uptake of vitamin C by cells is "globally inhibited" when blood-sugar levels are elevated. In effect, glucose regulates how much vitamin C is taken up by the cells, according to the University of Massachusetts nutritionist John Cunningham. If we increase blood-sugar levels the cellular uptake of vitamin C will drop accordingly. Glucose also impairs the reabsorption of vitamin C by the kidney, and so, the higher the blood sugar, the more vitamin C will be lost in the urine. Infusing insulin into experimental subjects has been shown to cause a "marked fall" in vitamin-C levels in the circulation.

In other words, there is significant reason to believe that the key factor determining the level of vitamin C in our cells and tissues is not how much or little we happen to be consuming in our diet, but whether the starches and refined carbohydrates in our diet serve to flush vitamin C out of our systems, while simultaneously inhibiting the use of what vitamin C we do have. We might get scurvy because we don't faithfully eat out fruits and vegetables, but it's not the absence of fruits and vegetables that causes the scurvy; it's the presence of refined carbohydrates. This hypothesis has not been proven, but, as Will and Byers suggested, it is both biologically plausible and empirically evident.



From "Good Calories Bad Calories"
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