What Is Metabolic Syndrome? Symptoms, Causes, Diet and Treatment

What Is Metabolic Syndrome?

Metabolic syndrome names a group of risk factors increasing heart disease, type 2 diabetes and stroke risk. Officially first defined in medical textbooks in 1998, “metabolic” refers to biochemical processes in normal bodily function. It is not a disease alone, but a cluster of metabolic disorders.

It affects approximately 23 percent of adults in industrialized countries. The American Heart Association reports 47 million Americans with metabolic syndrome, meaning one in every 6 people.

Metabolic syndrome is closely linked to weight gain and is becoming more common as insulin resistance and obesity increase.

What Is a Syndrome?

A syndromeis a collection of signs and symptoms seemingly unrelated but appearing together as one phenomenon. Syndromes can be inherited or acquired.

What Are the Dangers of Metabolic Syndrome? 

Associated health risks emerge over the long term and are often serious.

• Type 2 Diabetes: In metabolic syndrome, type 2 diabetes risk increases 9 to 30-fold over the general population. Once diabetes develops, risks of eye damage (retinopathy) and nerve damage (neuropathy) also increase
• Cardiovascular disease (heart attack or stroke): Atherosclerosis develops, increasing heart attack and stroke risk 2 to 4-fold.
• Fatty liver: Fat and inflammation accumulate independently of alcohol, increasing cirrhosis potential.
• Kidney damage: Metabolic syndrome causes kidney damage associated with microalbuminuria (urinary protein leakage).
• Disordered sleep breathing, including sleep apnea (stopped breathing during sleep), develops
• Polycystic ovary syndrome (ovarian cystic disease with hormonal disturbance) may occur
• It may reduce cognition in older adults and increase age-related dementia risk.
• Hyperuricemia and gout may occur.

Metabolic syndrome particularly causes atherosclerosis (fat, cholesterol and other substances adhering to inner arterial walls), or arterial hardening. Damage from causes such as hypertension promotes clots, potentially causing heart attack or stroke.

Cardiovascular and all-cause mortality risks are high. This appears related more to combined risk factors and insulin resistance than obesity alone. In Framingham, obese people without metabolic syndrome did not have increased diabetes or CVD risk.

However, obese individuals with metabolic syndrome, compared with normal-weight people without it, had a 10-fold diabetes risk and twofold CVD risk association. Normal-weight people with metabolic syndrome had 4-fold diabetes risk and 3-fold CVD risk in the findings.

Metabolic syndrome appears likely to overtake smoking as the leading cardiovascular risk factor.

What Causes Metabolic Syndrome?

It is closely linked to obesity, high blood lipids and hypertension developing through unhealthy diets and inactivity.

Excess Weight

Increased weight is a major risk factor. Prevalence is only 5 percent in normal-weight people, 22 percent in overweight people and 60 percent in obesity.

Framingham found that in people aged 16 or older, weight gain of 2,25 kg or more increased risk by 21 to 45 percent. A large waist alone may raise five-year risk by up to %46.

Some normal-weight individuals also risk hypertension, cardiovascular disease and diabetes. Whether they represent a different phenotype, “normal-weight, metabolically obese”, is unknown. A genome study evaluating 19 common insulin-resistance variants identified 11 relevant variants associated with increased metabolic risk, liver markers, type 2 diabetes and coronary artery disease. Despite increased visceral and subcutaneous fat, these people had lower BMI, unlike obesity.

Other Factors

Genetics (ethnicity, family history) is associated with metabolic syndrome. A parental history increases risk. Genetics may explain up to 50 percent of variation in children’s syndrome features.

Advancing age is also a risk factor: risk in the 40s is % 20, rising in the 50s to % 35 and in the 60s and later to % 45.

Other factors include postmenopause, hormonal imbalances such as polycystic ovary syndrome, smoking, low income, high-carbohydrate diets (bread, pastries, etc.) and inactivity. Framingham linked soft drinks and sugar-sweetened drinks to increased risk. Certain drugs, particularly psychiatric medicines clozapine and olanzapine and steroids, substantially increase risk.

What Are the Symptoms?

Most metabolic risk factors have no specific symptoms, but a large waist (abdominal obesity) may be visible.

Patients with diabetes, particularly type 2, may have high blood sugar symptoms: increased thirst, frequent urination especially at night, fatigue and blurred vision.

Hypertension is usually symptomless but may cause headache, dizziness or rarely nosebleeds.

High insulin resistance may cause sleepiness after eating, daytime sweet cravings and constant fatigue.

Metabolic Syndrome Diagnostic Criteria 2020

WHO first defined criteria in 1998. Many organizations have updated them. One of the most commonly used is the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III), updated in 2005. 

The NCEP ATP III definition is easiest to apply. Doctors and interested patients can score five criteria using simple, readily measured values to decide whether metabolic syndrome exists.

Those with of the following 5 criteria, those with at least 3 are considered to have metabolic syndrome.

1. High Blood Sugar: Fasting glucose above 100 mg/dL or medication use (insulin or diabetes tablets)
2. Large Waist Circumference: Waist circumference;
   1. 102 cm or greater for men;
   2. 88 cm or greater for women
3. High Blood Pressure (Hypertension): Blood pressure 130/85 mmHg or higher, or antihypertensive medication
4. Low HDL (Good) Cholesterol: HDL, known as good cholesterol,
   1. for men: below 40 mg/dL;
   2. for women: below 50 mg/dL, or
   3. cholesterol medication use
5. High Triglycerides: This blood fat at 150 mg/dL or higher, or triglyceride-lowering medication 

Any one risk factor is undesirable, but together they create much more serious health problems than alone.

The good news is that even with many risk factors, lifestyle changes can largely control the condition.

How Does Metabolic Syndrome Develop? Cellular Mechanisms

Proinflammatory cytokines released from fat contribute to atherosclerosis and coronary artery disease, reducing adiponectin, causing insulin resistance and inflammation. Metabolic syndrome can also trigger liver damage progressing through nonalcoholic fatty liver, fibrosis, cirrhosis and liver cancer. The precise mechanism of nonalcoholic fatty liver is unknown, but metabolic syndrome, especially insulin resistance, is associated with a proinflammatory state.

Insulin regulates blood sugar, helping transport elevated glucose into cells for energy. Excess unused sugar is stored as fat under insulin’s influence. Persistently high glucose makes this transport difficult and insulin resistance develops. High glucose and fat storage continue, increasing fat cells in the body and organs, causing overweight and then obesity.

Insulin resistance also causes microvascular damage, predisposing to endothelial dysfunction, vascular resistance, hypertension and vessel-wall inflammation. Increased plasminogen activator type 1 and adipokines can cause endothelial dysfunction and blood clotting tendency. Damage disrupts homeostasis and promotes atherosclerosis and hypertension, further risking ischemic heart disease and renal failure.

Metabolic Syndrome Screening (Identifying High-Risk People)   

Endocrine Society guidelines recommend assessment every three years for adults with risk factors. Screening includes blood pressure, waist circumference, fasting lipid profile and glucose to identify cardiovascular and type 2 diabetes risk. Prediabetes (impaired glucose tolerance or fasting glucose) should be screened using fasting glucose or a 2-hour glucose tolerance test every 1-2 years.

High-risk people should undergo assessment using Framingham Risk Score or Systematic Coronary Risk Evaluation (SCORE). Estimating 10-year CVD risk helps identify who needs blood pressure or cholesterol medicines.

Other markers include elevated C-reactive protein (CRP), interleukin (IL)-6 and plasminogen activator inhibitor (PAI)-1, indicating proinflammatory and prothrombotic states. Their value for measurement and monitoring in metabolic syndrome is unclear. They are more appropriate for CVD risk assessment and monitoring reduction. AHA and CDC guidelines do not recommend routine CRP testing in metabolic syndrome.

How Is Metabolic Syndrome Treated?

This risk-factor cluster includes abdominal fat, hypertension, high glucose and unhealthy cholesterol. Treatment should prevent each risk worsening, reducing additional health risks.

Lifestyle Changes

The best treatment usually depends on your actions. Substantial lifestyle changes focused on weight loss and increased activity are the most fundamental treatment.

• Exercise: At least 30 minutes of moderate-to-vigorous exercise five to seven days weekly is important.
• Follow a Diet: Healthy eating can improve cholesterol, insulin resistance and blood pressure even without weight loss. Most patients are overweight, but improving insulin sensitivity is a major dietary goal beyond weight loss. Various approaches are advocated. Heart disease or diabetes requires appropriate nutrition. Generally, a high-fiber (30 gr/day) diet low in saturated and trans fats, cholesterol and salt and rich in vegetables, lean protein, beans, low-fat dairy and whole grains helps. Mediterranean and DASH diets are ideal.
• Lose Weight: Exercise and healthy eating naturally promote weight loss, which should be a primary goal in overweight or obesity. It can improve every aspect of metabolic syndrome. Losing 7 to 10 percent of current weight is an important start toward improving all parameters.
• Quit Smoking If You Smoke: Smoking or tobacco avoidance is not a diagnostic criterion, but smoking worsens commonly affected blood vessels and increases cardiovascular risk.

Medication

Your doctor may prescribe medicines lowering blood pressure, cholesterol and / or glucose, and low-dose aspirin to reduce stroke and heart attack risk.

Medicines Used in Metabolic Syndrome

Metformin, generally used for type 2 diabetes, may prevent or delay diabetes in nondiabetic people with impaired glucose tolerance. In one study, metformin with appropriate diet and exercise reduced diabetes risk by 31 percent versus placebo. However, intensive lifestyle changes prevented diabetes more effectively than metformin.

No established guideline supports metformin for metabolic syndrome without known diabetes.

The latest JNC (Joint National Committee) guideline recommends blood pressure below 140/90mmHg generally and below 130/80mmHg in diabetes. JNC-8 recommends, for those aged 65 or above, 150/90 or less. Antihypertensive treatment is recommended above these levels. Data conflict on whether ACE inhibitors or angiotensin II receptor blockers (ARBs), used for hypertension in type 2 diabetes, also reduce insulin resistance.

Lipid treatment should increase HDL as well as lower triglycerides and LDL. First support smoking cessation, weight loss, diet and exercise. Medication is considered when triglycerides exceed 500 mg/dl, also considering elevated LDL because both increase atherosclerosis and cardiovascular risk. Moderate- or high-intensity statins are used initially. Fibrates, niacin and omega acids treat high triglycerides. Particularly with 10-year ASCVD risk above % 7.5, high-intensity statins should aim to lower LDL by % 50.

Severe obesity may benefit from bariatric surgery, recommended at BMI ≥ 40 kg / m2 or BMI 35 kg / m2 with life-threatening comorbidities. Long-term follow-up is advised to avoid surgical, nutritional and psychiatric adverse effects. Abdominal liposuction, however, does not improve insulin sensitivity or heart attack risk factors.

Can Metabolic Syndrome Be Prevented?

Prevention is certainly possible. Adopt heart-healthy lifestyle changes, maintain ideal waist circumference and healthy blood pressure and cholesterol through appropriate diet, exercise, ideal weight and reduced insulin resistance.

Maintaining ideal weight should be the key preventive step. Eat a healthy diet of fruit, vegetables and whole grains. Exercise to prevent gain or lose unwanted weight. Regular activity lowers blood pressure, glucose and cholesterol. Discuss vigorous exercise or major dietary changes with your doctor beforehand.

Regular medical visits are also important. Your doctor can examine you, measure waist circumference, blood pressure and blood tests suggesting early metabolic syndrome. Early diagnosis and treatment reduce long-term complications.

Metabolic Syndrome Diet 

The diet should improve insulin sensitivity, lower blood pressure, regulate lipids and promote weight loss. The Mediterranean diet more than satisfies all these criteria.

Its main foods include fruit, vegetables, nuts, whole grains and olive oil. Compared with another low-fat diet, it produced greater weight loss, lower blood pressure, improved lipids and insulin sensitivity, and lower inflammation and endothelial dysfunction markers.

DASH resembles the Mediterranean diet, limiting daily salt to 1500-2300mg and encouraging more low-fat dairy. Compared with a weight-reducing diet emphasizing healthy choices, it produced greater weight loss and improvements in diastolic pressure, triglycerides and fasting glucose.

A high-fiber diet (30mg/day), compared with an American Heart Association diet, produced similar weight loss and systolic and diastolic pressure changes.

Low-glycemic-index foods may improve glucose and lipids. A diet low in glycemic index/load, replacing refined grains with whole grains, fruit and vegetables and excluding high-sugar carbonated drinks, may benefit patients.