The term "Syndrome X" was coined in 1988 by Gerald Reaven, MD, a researcher at Stanford University School of Medicine. Millions of people could have Syndrome X, but are unaware of this "silent killer." A medical check-up including blood work is required for diagnosis.
Health risks: According to Jackie Berning, PhD, RD, assoc. prof. of nutrition at Univ. of Colorado-Colorado Springs, metabolic syndrome increases the risk for diabetes (type 2 adult-onset), heart disease, stroke and maybe even cancer (e.g., pancreas, breast, colon). These diseases are America's leading killers. About one-third to one-half of people with metabolic syndrome will develop diabetes.
"Many characteristics of metabolic syndrome are also risk factors for heart disease and/or type 2 diabetes," Berning notes. "Metabolic syndrome is defined by a cluster of clinical conditions including: hyperinsulinemia (high blood insulin levels), insulin resistance ('pre-diabetes'), glucose intolerance (blood sugar slightly above normal, but not as high as in diabetes), hypertension, overweight (especially around the stomach), high triglycerides and low 'good' HDL-cholesterol (protective against heart disease) in the blood."
Clinical diagnosis: Clinical diagnosis of metabolic syndrome is made if you have three or more risk factors, adds Wahida Karmally, MS, RD, dir. of nutrition at Irving Center for Clinical Research at Columbia Univ., New York (see chart).
"Although genetics can play a role in metabolic syndrome, lifestyle factors are just as important," she says. "Weight gain (especially around the abdomen) and inactivity are two warning signs. So weight loss (even 10%-15% of body weight) and exercise are two keys to reducing your risk."
Insulin resistance: "Insulin is the hormone we make to remove sugar from the blood and absorb it into body cells for energy," Berning points out. "In metabolic syndrome, the body has trouble using insulin (called 'insulin resistance'). In response to food, blood sugar rises and extra insulin has to be produced to absorb all of the sugar. The body is still able to make enough insulin to keep blood sugar in the normal range, but usually at the upper end of that range (impaired fasting blood glucose equals 110-126)."
Diabetes (fasting blood glucose above 126) does not occur, she continues, but high insulin levels are linked to risk factors for heart disease such as high blood triglycerides, "bad" LDL-cholesterol and blood pressure and low HDL-cholesterol.
"Contrary to popular belief, insulin resistance does not cause obesity," Karmally adds. "But, the opposite is true. Obesity results in insulin resistance. Smoking and inactivity make insulin resistance worse. Weight loss and exercise (aerobic and strength training) reduce insulin resistance and help improve blood lipids and glucose and blood pressure."
Dietary recommendations: No single weight loss diet works for everyone with metabolic syndrome, Berning notes. "Diets have to be individualized (see a registered dietitian), since degree of insulin resistance and specific risk factors vary with each person.
"Lose weight and exercise every day," she advises. "Also limit alcohol (raises triglycerides) and don't smoke (risk factor for heart disease). Sometimes medications to reduce hyperlipidemia (high blood lipids) and high blood pressure are needed, too." (See Nov. 15, 2001, FSD, p. 56 for dietary recommendations of the National Cholesterol Education Program to reduce risk of heart disease.)
Fat vs. carbohydrate: The ideal amount of dietary fat and carbohydrate for weight loss in people with metabolic syndrome is still debatable. "High carbohydrate, low-fat diets may not be beneficial," Berning says, "since carbohydrates can raise blood insulin levels and triglycerides and reduce HDL-cholesterol. Less carbohydrates (mostly complex) and more fat (mostly unsaturated) may be better for improving insulin sensitivity and blood lipids (e.g., decreasing triglycerides and increasing HDL-cholesterol).
"But, high-fat, low-carbohydrate diets like Atkins are not advised, since saturated fat (e.g., meat, cheese, butter) raises triglycerides and LDL-cholesterol (increases risk for heart disease)."
Reaven recommends a diet consisting of about 45% carbohydrate 15% protein, 40% fat (5-10% saturated, 30-35% monounsaturated and polyunsaturated) and less than 300 mg./day of dietary cholesterol. A daily calcium supplement is advised.
Diets moderate (not low) in fat may be more satisfying and easier to follow long-term to keep the weight off. Foods containing unsaturated fats like salad dressing, trans fat-free margarine, nuts, peanut butter and olive or canola oil should be included in moderation. "For weight loss, limit total fat and calories. Eat small portions," Karmally advises.
Include fatty fish like salmon (rich in omega-3 polyunsaturated fats) two or three times weekly. Add ground flaxseed (high in fiber and omega-3 fat) to cereals, breads, yogurt, muffins, pancakes, casseroles, salads, rice, or cooked vegetables. Limit foods containing simple sugar, but few nutrients, such as candy, baked goods and soda. Instead eat high fiber fruits, vegetables, beans and whole grains."
Recent studies at Harvard University show high fiber and low-fat dairy foods (three servings daily) both reduced the incidence of metabolic syndrome. These foods may help reduce high insulin levels and blood pressure.
Nutrition education: Metabolic syndrome has not been identified in children. But, Sheah Rarback, MS, RD, asst. prof. in the Univ. of Miami School of Medicine, works with obese children who exhibit hyperinsulinemia and hyperlipidemia which could lead to type 2 diabetes in childhood. She teaches a nutrition and exercise program for children to improve their food habits, increase exercise and lose weight.
Nutrition classes for families include recipe modification (e.g., more fiber, less fat and sugar) and healthy menus (e.g., "fast foods"). Children enjoy games, videos and food demonstrations (e.g., proper portion sizes).