THE SILENT KILLER

By Yew-Por Ng M.D.

Without any doubt, with the hustle and bustle of our society, hypertension has become one of the most prevalent disorders in the United States.

Hypertension is often considered the “silent killer” because it produces few, if any, symptoms but contributes to the death of 210,000 Americans a year.

The condition affects about 50 million Americans, and is a primary cause of stroke, heart disease, heart failure, kidney disease, and blindness. Fortunately, in most cases, the condition is easily detected and usually reversed with lifestyle changes such as diet, exercise, and stress management.

There are two types of hypertension --- primary and secondary.

Secondary hypertension accounts for less than 5%. A number of disorders such as kidney disease, adrenal tumors, coarctation of the aorta (narrowing of a portion of the aorta in the chest), as well as, drugs can cause this type of hypertension.

Primary or essential hypertension comprises 90-95% of affected individuals. We do not know of any specific cause. While hypertension is common in virtually all economically developing countries, it is uncommon in several isolated societies.

When individuals from those societies migrate to developed countries, they often develop hypertension. These observations suggest that environmental factors, such as eating habits, and the level of stress and physical activity play an important role in the development of hypertension.

CAUSES OF HYPERTENSION

The cause of most hypertension can be traced to one or more of these three factors.

PUMP (HEART): The heart acts as a pump. Any external pressure or demand such as stress, excitement and pain can increase the strength of the contraction and stroke volume resulting in an increase of blood pressure.

Like an internal alarm system, stress prepares the body to take action and is usually mediated through the hormonal influence. However, this response, if prolonged, can have a detrimental effect on the blood pressure. The effects of stress, excitement, and pain on our body clearly demonstrate the mind-body connection phenomena.

VOLUME: When blood volume increases, the blood pressure will usually increase correspondingly, except when increase through aerobic conditioning.

Sodium is one of the culprits that will increase blood volume. High sodium levels raise blood pressure in two ways.

First, sodium increases blood volume by causing the body to retain water, resulting in an increase in blood pressure. Also, sodium causes smooth muscle in the small blood vessels to constrict and thus produces a greater resistance to blood flow.

Restriction of sodium is particularly important for people age 65 and older, black people, and people with diabetes, all of whom are especially susceptible to the blood pressure-raising effect of a high sodium intake.

The recommended sodium intake is no more than 1,500 mg/day. New research indicates that hypertensive people who follow a diet containing 1,500 mg of sodium a day can lower their systolic blood pressure by 11.5 mm Hg. This reduction in blood pressure is similar to what can be achieved with a single antihypertensive medication.

Diet that is high in fruits and vegetables with lots of nutrients such as potassium, magnesium, and calcium can also lower blood pressure.

PERIPHERAL RESISTANCE: A diet that is high in saturated fat (as well as trans fat), cholesterol, and refined sugar can contribute to the formation of atherosclerotic plaques in the major blood vessels, causing hypertension through an increase in resistance of the blood flow.

Recently, attention has been directed to a common constellation of abnormalities ----- obesity, hypertension, high triglyceride level, low HDL cholesterol level and premature coronary heart disease known as Insulin Resistance Syndrome also called Metabolic Syndrome.

Obesity is a root cause of this syndrome, resulting in tissue resistance to the action of insulin. To overcome this resistance, the pancreas increases its production of insulin resulting in high insulin levels in the blood. Insulin promotes an increased accumulation of triglycerides --- blood lipids associated with plaque formation. Its high level will increase the risk of coronary heart disease (CHD).

Similarly, low levels of HDL (good cholesterol) in this syndrome will make the blood vessels more vulnerable to atherosclerotic plaques.

Insulin also heightens the activity of the sympathetic nervous system and causes sodium retention by the kidney, both of which will raise the blood pressure.

Taken together, the abnormalities associated with insulin resistance syndrome are a potential “time bomb” ready to explode at any time.

PREVENTION OF HYPERTENSION

The key to preventing hypertension is lifestyle modification. It consists of weight reduction, regular outdoor exercise, good stress management and a diet rich in fruits and vegetables and whole grains, and low in saturated fat and sodium (preferably plant-based). Abstinence from alcohol and cigarettes are needed since both of them have adverse effects on the blood vessels. Such relatively simple steps can have a considerable impact. The benefits of prevention are likely to be more substantial when several lifestyle changes are maintained for an extended period of time.