Hypertension

What Is Hypertension?

Hypertension, or high blood pressure, is a chronic condition in which the force exerted by blood against arterial walls is persistently elevated. Blood pressure is expressed as two values: systolic pressure (the peak force when the heart contracts) over diastolic pressure (the resting force between beats), measured in millimeters of mercury (mmHg). Current guidelines from the American College of Cardiology define hypertension as a sustained blood pressure at or above 130/80 mmHg.

Hypertension affects approximately 1.28 billion adults worldwide and is responsible for approximately 10.4 million deaths per year, primarily through stroke, coronary artery disease, heart failure, and chronic kidney disease. It is often called a "silent killer" because the large majority of people with hypertension experience no symptoms until a serious complication occurs.

Causes and Risk Factors

Primary (essential) hypertension, which accounts for 90–95% of cases, has no single identifiable cause but arises from the interaction of genetic predisposition with multiple environmental factors. Secondary hypertension results from an identifiable condition such as renal artery stenosis, primary aldosteronism, or sleep apnea. Key modifiable risk factors for primary hypertension include:

• Excess sodium intake: the global average is approximately 4,000 mg per day; reducing to less than 2,300 mg per day lowers systolic blood pressure by 3–8 mmHg on average
• Obesity: each 1 kg of weight loss is associated with approximately 1 mmHg reduction in blood pressure
• Alcohol: more than 2 standard drinks per day is a dose-dependent contributor
• Physical inactivity, chronic stress, and smoking each contribute independently to elevated blood pressure

The DASH Diet and Nutritional Interventions

The Dietary Approaches to Stop Hypertension (DASH) diet is the most evidence-based dietary pattern for blood pressure reduction, supported by multiple randomized controlled trials. In the original DASH trial, adopting the diet reduced systolic blood pressure by 11.4 mmHg and diastolic pressure by 5.5 mmHg in people with hypertension — a magnitude comparable to many antihypertensive medications. The DASH diet emphasizes:

• 8–10 servings of fruits and vegetables per day (providing approximately 4,700 mg of potassium daily)
• 2–3 servings of low-fat dairy per day (providing approximately 1,250 mg of calcium daily)
• Nuts, seeds, and legumes 4–5 servings per week
• Whole grains rather than refined grains
• Limited red meat, sweets, and sodium-containing processed foods

Potassium counteracts sodium's blood pressure-raising effect by promoting urinary sodium excretion and relaxing arterial walls. Magnesium and calcium also contribute to vascular tone regulation. Combining the DASH diet with sodium restriction below 1,500 mg per day produces the largest blood pressure reductions observed in dietary trials.