Monday, January 28, 2013

Metabolic Syndrome: Part 1

(a.k.a. insulin resistance, pre-diabetes, hyperinsulinemia, Syndrome X)

I mentioned in the last blog the surprising statistic that 50% of all heart attacks occur in people with low LDL cholesterol, and that accumulating evidence indicates that cardiovascular disease is a multi-factorial disease which at its root is a problem of inflammation.  Among those “multi” factors are low HDL (“good”) cholesterol, high triglycerides, hyperinsulinemia, high blood pressure, the metabolic syndrome, C-reactive protein, homocysteine, lack of exercise, stress, and lack of a varied diet.  A good place to start discussing each risk factor individually is with the metabolic syndrome.

The metabolic syndrome is a constellation of risk factors which occur in response to “hyperinsulinemia” (a condition in which the pancreas pumps ever-increasing amounts of insulin in an effort to overcome the “insulin resistance” of the cells).  The symptoms that result in response to high insulin are high triglycerides, abdominal obesity, low HDL cholesterol, high blood pressure, and "high normal" blood glucose (fasting plasma glucose above 110 mg/dL, while the cutoff for diabetes is 126 mg/dL).  Having the symptoms of the metabolic syndrome significantly increases your chance of developing cardiovascular disease and/or diabetes, and the numbers of Americans afflicted is quickly rising.  The CDC recently estimated that 1 out of 3 American adults fits the criteria for the metabolic syndrome. . .

The gold standard report in cholesterol management issued by the National Cholesterol Education Program in 2001 (Adult Treatment Panel III) concluded that “The metabolic syndrome and its associated risk factors have emerged as a coequal partner to cigarette smoking as contributors to premature CHD. In addition, the insulin resistance accompanying the metabolic syndrome is one of the underlying causes of type 2 diabetes.  For these reasons, ATP III places increased emphasis on the metabolic syndrome as a risk enhancer.” (p. II-26)

From the ATP III Executive Summary, pp. 15-16: “Evidence is accumulating that risk for CHD can be reduced beyond LDL-lowering therapy by modification of other risk factors.  One potential secondary target of therapy is the metabolic syndrome, which represents a constellation of lipid and nonlipid risk factors of metabolic origin.  This syndrome is closely linked to a generalized metabolic disorder called insulin resistance in which the normal actions of insulin are impaired.”

Diagnosis of the metabolic syndrome is made if just three of the symptoms in the table below are present:

Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III), p. II-27

The ATP III panel further identified six components of the metabolic syndrome that relate to cardiovascular disease:

Abdominal obesity
Atherogenic dyslipidemia (elevated triglyceride, small LDL particles, low HDL cholesterol)
Raised blood pressure
Insulin resistance (with or without glucose intolerance)
Proinflammatory state
Prothrombotic state (formation of blood clots)

Note that it is generally recognized in the research that it is a particular sub-fraction of LDL cholesterol--small (dense) LDL particles--that is problematic (recall previous blog entitled “LDL Cholesterol is Not a Good Indicator of Heart Attack Risk”).  Also note the presence of inflammation.  More and more the evidence seems to indicate that cardiovascular disease is an inflammatory condition, perhaps the reason why many doctors recommend “a baby aspirin a day” for its well-documented effect of preventing heart attacks, and even colon cancer and dementia.  (I do not recommend you indiscriminately take aspirin daily because the level of stomach protection is decreased increasing the likelihood of bleeding.  People who take aspirin regularly have roughly double the likelihood of having a perforated ulcer or bleeding in the GI tract, so the benefit of taking aspirin needs to be carefully weighed by a medical professional against the potential for serious complications.)

More on the metabolic syndrome, and what you should know to prevent it, in the next blog.

Assisting in a healthy lifestyle,
Diane Preves, M.S., R.D.

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1 comment:

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