Metabolic syndrome, syndrome X: syndrome X, Y, Z …?

Townsend Letter for Doctors and Patients, May, 2007 by Stephen Holt

Introduction

Metabolic syndrome, or "Syndrome X," as it is often called, is the variable combination of obesity, hypercholesterolemia, and hypertension linked by an underlying resistance to insulin. This condition is often associated with excess insulin secretion. The syndrome was first described by Reaven in 1998, (1) but its principal component of obesity was not initially emphasized. Retrospective data from the National Health Nutritional Survey for the period 1988 to 1994 implied that 47 million Americans had metabolic syndrome. (2) The current prevalence of the syndrome may now be approximately one in every four adults in the United States population, or about 70 million individuals. So common and so pernicious are the negative health outcomes of metabolic syndrome X that it qualifies as the number one public health problem facing several Western societies.

Although the metabolic syndrome X is identified as a major cause of cardiovascular disease, it is less apparent that it increases deaths and disabilities from all causes and underlies female reproductive disorders, polycystic ovary syndrome (PCOS), nonalcoholic fatty-liver disease, non-alcoholic steatohepatitis, gestational diabetes mellitus, significant changes in body eicosanoid status, inflammatory disease, poor cognitive function, Alzheimer's Disease, and certain cancers, (3) to name a few diseases.

Rethinking the Management of Metabolic Syndrome

Excessive dietary intake of refined sugar, lack of exercise, poorly defined genetic tendencies, environmental toxins, and adverse lifestyles contribute variably to the pathogenesis of the metabolic syndrome. (3) Current pharmaceutical and surgical approaches to management of the syndrome have many obvious disadvantages and limitations. It has been suggested by Federal government researchers that focused treatments of the individual components of the syndrome (hypercholestemia, obesity, and hypertension) are unlikely to provide a better outcome than are "integrated" management strategies. (2) This suggestion is consistent with dietary attempts to restrict refined, carbohydrate intake, and it helps to explain the short-term success of some low carbohydrate diets for weight control. (3) The notion of "integrative" management strategies as first-line options for syndrome X opens the door for "alternative" management with dietary supplements.

First-Line Management Options for Metabolic Syndrome

Metabolic syndrome has variable clinical manifestations, which I have attempted to incorporate in a new, unifying concept of disease. (3) This concept extends far beyond the existing definition of syndrome X as obesity, hypertension, and hypercholesterolemia, linked by underlying insulin resistance. (3) In order to take account of this unifying concept, I have coined the term Syndrome X, Y, and Z ... to incorporate many other diseases linked to insulin resistance (Figure 1).

Effective prevention and treatment of metabolic syndrome involves a multifaceted approach directed at all its cardinal components. (3) Current allopathic treatments (drugs) for syndrome X have been too specifically focused on the individual components of metabolic syndrome (e.g., anti-hypertensive therapy, cholesterol-lowering drugs, etc.) While pharmaceutical interventions should be applied where necessary, they most often form a "back-up plan" for its management. In contrast, the natural techniques of lifestyle modification and nutritional or nutraceutical interventions, or both, may provide versatile and potent first-line options for the management of syndrome X. (3)

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In many cases, treating obesity must involve the management of syndrome X, but syndrome X may occur infrequently in an individual of normal body weight, and not all overweight people have syndrome X (Table 1). Failing to diagnose or manage syndrome X in the obese individual is negligent, medical practice. There is no doubt that syndrome X is both underdiagnosed and undertreated in both conventional and alternative medical practices.

Clear Benefits of Dietary Fiber in Syndrome X

Many types of soluble fiber may benefit individuals with metabolic syndrome, through their effects on appetite or satiety regulation, body weight, and blood cholesterol levels. (3) Evolution of research into soluble components of dietary fiber has led to the discovery of fractions of oat soluble fiber (beta-glucans) that have been shown to effectively lower blood cholesterol, reduce postprandial blood glucose, induce satiety, and suppress appetite. (4-7) Although the glucocolloids that contain these beta-glucan fractions of oat fiber have physicochemical properties that modulate upper gastrointestinal motility by delaying gastric emptying, (8) or by retarding or impeding the absorption of specific (macronutrients such as glucose and fats), they also have intrinsic metabolic effects (IMEF). These IMEF occur, in part, as a consequence of the prebiotic actions of fiber and fermentation of soluble fiber in the colon to yield short-chain fatty acids, including propionic, acetoacetic, and butyric acids. Of these, propionic acid can enter the portal circulation of the liver and may interfere with cholesterol synthesis by blocking the activity of hydroxymethyl-glutaryl coenzyme A (HMG CoA) reductase, a key enzyme in the synthetic pathway of cholesterol. (3,6) Other types of soluble fiber are of value in blunting postprandial blood glucose responses, e.g., soy fiber, pectin, and guar gu. (9,10)