A study, Metabolic Syndrome and Risk of Incident Cardiovascular Events and DeathA Systematic Review and Meta-Analysis of Longitudinal Studies, was recently published in the Journal of the American College of Cardiology. Researchers evaluated the findings of thirty-seven studies which evaluated associations between MetS and cardiovascular events or mortality and concluded "the best available evidence suggests that people with MetSyn are at increased risk of cardiovascular events. These results can help clinicians counsel patients to consider lifestyle interventions, and should fuel research of other preventive interventions."
Metabolic syndrome isn't a disease per se; rather it is a clustering of multiple metabolic abnormalities - abnormal cholesterol (elevated triglycerides, low HDL), central adiposity, high blood sugar, and high blood pressure - that when occuring together increase the risk of cardiovascular disease and death.
Some background first - in recent years the diagnosis of MetS has been under fire since two major health organizations - the American Diabetes Association (ADA) and the American Heart Association (AHA) - disagreed about the clinical utility of the diagnosis. The ADA issued a joint statement with the European Association for the Study of Diabetes (EASD) that the syndrome should not be considered a separate disease; the AHA followed up with a statement that it should.
As I wrote back in August 2005, the major sticking points addressed in the ADA statement included: there was no agreement for definition of the syndrome, a lack of understanding of the pathogenesis of MetS, no agreement about course of treatment for those diagnosed, no agreed upon standards of care for those diagnosed, and no agreed upon strategies to help prevent MetS. The AHA shot back with a statement in September 2005 to clarify and justify the diagnosis.
In June 2006, the two organizations seemed to harmonize their positions when they issued a joint statement that emphasized agreement between the organizations. It placed an emphasis on treating "a core set of risk factors (pre-diabetes, hypertension, dyslipidemia, and obesity)" as well as smoking. The statement sidestepped the genesis of the still-simmering disagreement—a dispute that neither group tried to hide—the definition of metabolic syndrome.
Why this background is important is because while the two organizations squabbled, a number of papers were published that shed light on preventing and reversing Metabolic Syndrome. The most important of these was in December 2005; when a study published in Nutrition and Metabolism, Carbohydrate restriction improves the features of Metabolic Syndrome. Metabolic Syndrome may be defined by the response to carbohydrate restriction, connected the dots between diet and development of Metabolic Syndrome.
As Jeff Volek, PhD, RD, lead researcher from the University of Connecticut, Storrs said, "Make a list of the features of metabolic syndrome, then, make a list of the things that carbohydrate restriction is good at fixing. They're the same list. Somehow, we never really noticed that. We know the cause of metabolic syndrome is often linked to disruption of insulin. Thus, the key to treating metabolic syndrome is to control insulin, and carbohydrates are the major stimulus for insulin."
So while HeartWire summed up the findings from the paper in the Journal of the American College of Cardiology, as "new meta-analysis show that the syndrome is more than the sum of its risk factors - and that it may pose a higher risk to women than to men...[m]etabolic syndrome...nearly doubled a person's risk of developing CVD...[t]he overall relative risk for cardiovascular events and death for people with the metabolic syndrome was 1.78 (95% CI 1.58-2.00), the study found. Cardiovascular events were about 33% higher for women than men;" and noted that the "findings are applicable to clinical practice: clinicians can use this evidence to motivate patients when counseling them to reduce risk factors;" we still find nothing but a big question mark when it comes to prevention and treatment!
Basically, the paper quantifies the risk of Metabolic Syndrome and the AHA notes that until its publication "clinicians were getting a mixed message about the utility of making the diagnosis."
So now we have jusification to diagnosis Metabolic Syndrome, but the question remains - what is a clinician to do with the data? The meta-analysis found a significant increase in risk - but what exactly are physicians to do with that knowledge when they have a real live patient standing before them and a diagnosis of metabolic syndrome?
Well if they look to the AHA for guidance they'll find the TLC (Therapeutic Lifestyle Changes) diet is recommended and is as follows:
TLC Diet in ATP III
Total Fat 25–35%
Saturated Less than 7%
Polyunsaturated Up to 10%
Monounsaturated Up to 20%
Carbohydrate 50–60% of total calories
Protein Approximately 15%
Cholesterol Less than 200 mg per day
Total Calories Balance energy intake and expenditure to maintain desirable body weight and prevent weight gain
These guidelines ignore Level 1 evidence that points to a more effective dietary approach and dismisses the importance of the paper Carbohydrate restriction improves the features of Metabolic Syndrome.
They also ignore, from the AHA journal Circulation, a paper published four years ago - Diets and Clinical Coronary Events: The Truth Is Out There
As the researchers noted in that paper, everything is "bad" according to the recommendations, "[f]ats are considered "bad" because they lead to cardiovascular events. However, one of the alternative energy sources, carbohydrates, is "bad" because it increases the risk of diabetes, and the other, protein, is "bad" because of increased burdens on the liver and kidneys."
So they asked, What, then, can be done to give patients a simple answer to their most frequent question: "What can I eat that will keep me from dying, having a heart attack, or having a stroke?"
After reviewing the evidence they concluded that "The time has come to apply to diet research the same level of evidence required for other interventions. We believe that indications or claims made for weight loss or health improvement via diet—whether made by authors, the government, or associations—must be supported by 3 types of evidence: proof that the diet provides essential nutrients in actual patients, efficacy studies, and randomized, controlled trials with clinical events as end points....Until then, the public will continue to be subject to speculation and potentially hazardous extrapolation from putative biological surrogates to clinical outcomes."
Remarkably, four years later, we still have a lack of convincing evidence to eat a low-fat, mostly plant-based diet; but that hasn't stopped the AHA from revising their recommendations late last year, nor stopped them from recommending the TLC diet for those at risk.
In an editorial I featured here, Dr. Gil Wilshire, MD, FACOG expressed his outrage over the lack of "gold standard" evidence to support the revisions in the AHA dietary recommendations. In part, his words parallel those of the researchers back in 2003:
Show me some high-quality data. Show me that someone has bothered to properly test the 50 year-old hypothesis.
In the absence of this information, I would like to make the following recommendation:
AN IMMEDIATE MORATORIUM ON ALL POPULATION-WIDE DIETARY RECOMMENDATIONS THAT LACK SUPPORT FROM WELL-PERFORMED, PROSPECTIVE, EVIDENCE-BASED HUMAN STUDIES.
Sanity in this field will only come out of a complete overhaul. We need to tear down the current edifice of confusion to its most basic foundations, and rebuild it from the bedrock up.
While today we now have a meta-analysis to point to that finds a significant increase in risk for cardiovascular disease and death in those with Metabolic Syndrome, thus a justification to utilize it as a diagnosis; we still do not have dietary recommendations based on evidence to help those at risk for or diagnosed with Metabolic Syndrome!
I consider this a national shame, especially when you consider that one-third of our population is believed to have or are developing features of Metabolic Syndrome.
The American Heart Association is failing us and it's time we speak up and hold them accountable for their continued dismissal of evidence that clearly points to carbohydrate restriction as a scientifically supported, valid dietary approach to treat those with Metabolic Syndrome!
If you've seen improvements from a controlled-carb diet or feel the AHA must review the data available for carbohydrate restricted diets - tell the AHA here!