Chapter 8  Science of the Carbohydrate Hypothesis

The Tokelau Island Migration Study - the most comprehensive migration study ever carried out in the history of nutrition and chronic disease research. Tokelau is in the Polynesian atolls and under the administration of New Zealand in the mid-1920s, but it remained isolated. As a result, Tokelau lingered on the fringes of Western influence. The staples of the diet remained coconuts, fish, and a starchy melon known as breadfruit well into the 1970s. More than 70 percent of the calories in the Tokelau diet came from coconut; more than 50 percent came from fat, and 90 percent of that was saturated. 

In the mid 1960s, the population had grown and the NZ government, concerned about overpopulation, initiated a voluntary migration program during which more than half the Tokelauans moved to the mainland. From 1968 to 1982, anthropologists, physicians and epidemiologists studied the health and diet of the emigrants as they resettled, as well as those who remained behind on the islands as their diets were progressively Westerized. 

 Coconut consumption decreased, offset by a sevenfold increase in sugar consumption and sixfold increase in flour consumed. Previously, the only noteworthy health problems had been skin diseases, asthma, and infectious diseases. In the decades that followed, as the diet changed, the new diseases appeared: diabetes, hypertension, heart disease, gout and cancer. This coincided with a decrease in cholesterol levels. 

As for the migrants, it was even worse. Once again, fat and saturated-fat consumption dropped, to be replaced by carbohydrates, especially a big increase in sugar consumption. This coincided with an almost immediate increase in weight and blood pressure, and a decrease in cholesterol levels - all more pronounced than the increases witnessed on Tokelau. To make it even more confusing, the emigrants to the mainland smoked less than the islanders, so tobacco was unlikely to explain this pattern - and the migrants tended to be younger, and had a more rigorous lifestyle! 

The dominant approach has been that diseases are coincidentally related. 

Less common is that the diseases of civilization all manifest one underlying disorder. 

The simplest explanation - Occam's razor. 

Cleave's saccharine disease hypothesis was one, later, in the 1980s, Syndrome X was used to describe the metabolic abnormalities common to obesity, diabetes, and heart disease. This was gradually accepted and has many names, including metabolic syndrome. It wasn't until the late 1990s that the evolving science of metabolic syndrome began to have any significant influence outside the field of diabetes. The potential implications of metabolic syndrome for heart disease and other chronic diseases have only just begun to be appreciated by the research community. 

Hormones control reproduction, regulate growth and development, maintain the internal environment (homeostasis) and regulate energy production, utilization, and storage. All other hormones are secondary to the role of insulin in energy production, utilization, and storage. Historically, physicians have viewed insulin as though it has a single primary function: to remove and store away sugar from the blood after a meal. This is the most conspicuous function impaired in diabetes. But the roles of insulin are many and diverse. It is the primary regulator of fat, carbohydrate, and protein metabolism; it regulates the synthesis of a molecule called glycogen, the form in which glucose is stored in muscle tissue and the liver; it stimulates the synthesis and storage of fats in fat depots and in the liver, and it inhibits the release of that fat. Insulin also stimulates the synthesis of proteins and of molecules involved in the function, repair, and growth of cells, and even of RNA and DNA molecules, as well. 

Insulin, in short, is the one hormone that serves to coordinate and regulate everything having to do with the storage and use of nutrients and thus the maintenance of homeostasis and, in a word, life. 

Eventually, insulin's effects on disease have come to be accepted. But authorities interpret the evidence while ignoring the unique ability of refined carbohydrates to elevate insulin! 

Hypertension - Textbooks recommend salt reduction as the best way to reduce or prevent hypertension. But that's just the hypothesis, and in fact it has always been remarkably difficult to generate any reasonably unambiguous evidence that it's correct. Our belief in the dangers of salt in the diet is based once again on a philosophy of preventive medicine. Guess what? Hypertension is also a disease of Western civilization. In native populations eating traditional diets, hypertension was never seen, and blood pressure, if anything, dropped lower with age, which is the opposite of what happens in developed nations. Carbohydrates cause the body to retain water. The laboratory evidence that carbohydrate-rich diets can cause the body to retain water and so raise blood pressure dates back well over a century. Insulin, it turns out, causes the kidneys to reabsorb sodium, with chronically elevated levels of insulin kicking off hypertension. (Explanaton page 149) And yet, when the carb-induced water retention and hypertensive effect of insulin were discussed in textbooks, they always appear solely in the technical context of water and electrolyte balance, whereas the discussion of hypertension prevention would focus exclusively on the salt hypothesis.