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Man to Man: The Metabolic Syndrome

By Harvey B. Simon
Content provided by the Faculty of the Harvard Medical School

Few men have heard of the metabolic syndrome, and fewer still understand it. But if present trends continue, that's likely to change, since the metabolic syndrome is a strong threat to America's health.

The Fearsome Fivesome

The metabolic syndrome is a cluster of five closely related cardiovascular risk factors. Each is dangerous in its own right, but when they occur together, the overall risk is greater than the sum of its parts.

Table 1 shows the metabolic syndrome's components. The presence of any three abnormalities is sufficient to establish the diagnosis, but the hazards are even greater when four or five abnormalities are present.

  1. Abdominal obesity (waist circumference 40 inches or more)*

  2. Fasting triglyceride levels of 150 mg/dL or higher

  3. HDL cholesterol levels below 40 mg/dL**

  4. Blood pressure of 130/85 mmHg or higher

  5. Fasting blood sugar of 110 mg/dL or higher

* 35-inch waist for women ** HDL below 50 for women

Here is a rundown on each component of the syndrome.

1. Obesity. It's the fundamental factor in the metabolic syndrome, and the rapid increase in America's girth accounts for the rapid emergence of the syndrome.

Excess body fat is always troublesome, but extra abdominal fat is particularly harmful. Unlike fat cells in the buttocks and thighs, fat around the abdominal organs resist the action of insulin, contributing to the risk of diabetes. It also releases free fatty acids that are deposited in the liver, pancreas, and heart, where they can produce organ damage.

If you're like most overweight guys, you've been dropping your belt towards your knees to accommodate the "beer belly" that's much more common in men than women. Instead of relying on your belt size to see if you quality for the metabolic syndrome, just measure your waist at the navel.

2. Triglycerides. Because they transport fatty acids through the bloodstream after they're absorbed from food, a fasting blood sample is required for an accurate measurement. Doctors still don't know whether a high triglyceride level increases the risk of heart disease if it's the only thing that's abnormal. But it's now clear that high triglyceride levels are risky indeed when they are part of the metabolic syndrome.

3. HDL cholesterol has been called the "good" cholesterol because high levels are associated with a reduced risk of heart attack and stroke. HDL is protective because it represents cholesterol molecules that are being carried away from arteries to the liver, which disposes of them by dumping them into the bile.

The higher your HDL, the better. Normal values for men begin at 35 mg/dL, but even a "normal" level of 40 will increase risk when it's part of the metabolic syndrome.

4. Blood pressure. Experts have been progressively lowering their goals for healthy blood pressure readings as they've learned more about blood pressure and the risk of stroke, heart disease, and kidney failure. Even with these changes, however, the diagnosis of hypertension still depends on readings of 140/90 or higher. But although a pressure of 130/85 is only in the range of "prehypertension," it's enough to contribute to a diagnosis of the metabolic syndrome.

5. Blood sugar. An elevated blood sugar level is the hallmark of diabetes. In type 1 diabetes, the problem is a lack of insulin. In contrast, most patients with the much more common type 2 form of the disease can produce insulin; the problem is that their tissues don't respond properly to the hormone — they have insulin resistance.

Is It Dangerous?

In a word, yes. In round numbers, the metabolic syndrome doubles a man's risk of having a stroke or dying from heart disease. And new research suggests the syndrome also contributes to cognitive decline, kidney disease, and liver disease. And if that's not bad enough, doctors in Finland report that the metabolic syndrome nearly doubles a man's risk of prostate cancer.

What to Do?

The only proven remedies for the metabolic syndrome are weight loss and exercise. Here are some guidelines:

Diet

  1. Calories. To lose weight, you must take in fewer calories than you burn up. That means smaller portions and fewer calorie-dense foods such as sugars and fats.

  2. Carbs. You don't have to shun carbs, but you should choose the right ones. Try to restrict simple sugars and other rapidly absorbed carbs such as white rice and potatoes. Instead, favor complex carbohydrates found in unrefined high- fiber foods such as bran cereals, whole grains products, and beans.

  3. Fats. At 9 calories per gram, all fats are calorie-dense. But saturated fats and trans fats raise the LDL ("bad") cholesterol, and trans fats also lower the HDL ("good") cholesterol. Substitute the monounsaturated and omega-3 fats found in olive oil, nuts, canola oil, and fish - - but don't overdose, since calories do count, even if they come from heart-healthy fats.

  4. Salt. To help lower your blood pressure, keep your sodium intake below 2,300 mg a day. In place of snack foods, processed meats and other salty foods, choose fruits, vegetables, and low-fat dairy products.

  5. Alcohol. People who drink have a lower risk of heart attack, stroke, and diabetes than teetotalers as long as they limit themselves to one or two drinks a day. But even in small amounts, alcohol has two important drawbacks for the metabolic syndrome: It raises triglycerides and adds calories. On the other hand, alcohol raises HDL cholesterol levels, a big benefit. So if high triglycerides and a stubborn inability to lose weight are features of your syndrome, avoid alcohol; but if low HDL is a major issue, consider one or two drinks a day as long as you can drink safely and responsibly. Alcohol is hardly a cure-all for the metabolic syndrome, but a 2004 study of 8,125 people found that those consuming modest amounts of wine or beer were less likely to develop the metabolic syndrome than teetotalers.

Exercise

It's the best way to prevent the metabolic syndrome, and it's also the mainstay of therapy once the problem has developed.

A study of 612 healthy men demonstrates the power of prevention. The subjects were between the ages of 42 and 60 when the study began, and none had the metabolic syndrome. Over the next four years, though, 107 men developed the problem. But the men who exercised regularly were only about half as likely to develop the syndrome as the inactive men. And it didn't take heroic amounts of exercise to produce protection; just three hours a week did the trick.

Exercise can also treat the metabolic syndrome. In fact, it can help correct each of the five abnormalities:

  1. Obesity. By burning calories, exercise promotes weight loss. Nearly all people who win at the losing game attribute their success to exercise as much as diet. In addition, exercise seems to have a specific ability to reduce abdominal obesity, a big plus for health.

  2. Triglycerides. Exercise reduces triglyceride levels, and the reduction is greater than one would expect from weight loss alone.

  3. HDL cholesterol. Regular exercise boosts HDL ("good") cholesterol. It takes a while for the effect to kick in, but it will be substantial as long as the exercise continues. As few as eight miles of walking or the equivalent exercise will help, but the more you do, the higher the HDL will be.

  4. Blood pressure. Exercise is one of the most important lifestyle treatments for hypertension, and it is just as helpful for the prehypertensive levels recorded by many men with the metabolic syndrome. Endurance exercise is best. Walking is an example; only 30 minutes a day can be expected to reduce systolic blood pressure by 4–9 mmHg.

  5. Blood sugar. Exercise makes muscles and other body tissues more sensitive to insulin, which means that less insulin is needed to keep the blood sugar down. Exercise is an important way to prevent and treat diabetes, and its dual benefits — lower blood sugar levels and lower insulin levels — are very helpful in the metabolic syndrome.

Lifestyle Therapy

Diet and exercise are the dynamic duo, but it's also important to shun tobacco. Smoking lowers HDL cholesterol levels. That's its only specific impact on the metabolic syndrome, but it has many other health effects, all harmful.

Lifestyle treatment works. A three-year study of 3,234 at-risk individuals found that it reduces the risk of developing the syndrome by 41%. And a 2004 study reported that the combination of a Mediterranean diet and moderate exercise corrected the metabolic syndrome in 55% of participants. Still, many patients with the syndrome need more.

Medication

If there's an illness, there should be a medication; if it's a common and serious illness, there should be a powerful medication. The logic is unassailable, but in the case of the metabolic syndrome the need has not yet been met. There is no medication for the syndrome, but many medications can help correct each of its components except obesity.

Drugs for blood pressure. For otherwise healthy people, the target for treatment is 140/90, but for diabetics it's 130/80. Since the metabolic syndrome has so many similarities to type 2 diabetes, the lower target may be wise. And if that's the case, patients might benefit most from an angiotensin converting enzyme inhibitor or, if cough prohibits its use, an angiotensin receptor blocker. Thiazide diuretics, which are generally the first drug for hypertension, and calcium channel blockers are close behind. Many other antihypertensive medications are available.

  • Drugs for blood lipids. Most treatment guidelines focus on the LDL cholesterol level, which is not among the five criteria for the metabolic syndrome. But because of its very high cardiovascular risk and similarities to diabetes and hypertension, it may be reasonable to set the same stringent LDL target of 70 that is used for other high-risk patients. Nearly all people need medication to bring their LDLs all the way down to 70. Usually, that means starting with a statin drug. Atorvastatin (Lipitor) and rosuvastatin (Crestor) are the only members of the class that lower triglycerides as well as LDL cholesterol. But none of the statins are very effective at boosting HDL cholesterol. When that's a priority, doctors might consider using niacin (alone or with a statin) or a fibrate such as gemfibrozil (Lopid) or fenofibrate (Tricor), alone or with niacin. Combination therapy requires extra care to detect and prevent muscle inflammation.

  • Drugs for blood sugar. If a patient with the metabolic syndrome has diabetes, he should be treated according to current guidelines. But it's not clear if medication would help the mild sugar elevations often seen in the metabolic syndrome. Doctors are evaluating medications that increase insulin sensitivity, such as pioglitazone (Actos) and rosiglitazone (Avandia) as well as metformin (Glucophage), a drug that reduces sugar production and release from the liver.

Combining forces

The metabolic syndrome won't show up on many death certificates, but it is an important cause of heart disease and stroke, the first and third leading killers in America. About 47 million Americans have the syndrome, though many don't know it. And if present trends continue, the number is sure to grow along with America's waistline.

The metabolic syndrome is a complex abnormality with five components. Medications are available for four of the five, but doctors are just now learning how to best use them for this disorder. But for prevention as well as therapy, a combined approach is crucial. Medications will be important for many patients, but all will benefit from the combination of regular exercise and a healthful diet. They are, after all, the hand and glove of prevention and good health.

Last Annual Review Date: 2006-08-14T00:00:00-06:00 Copyright: Copyright Harvard Health Publications

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