THE FOOD-HEALTH CONNECTION

Knowing what nutrients comprise a well-balanced diet, in what foods to find them, and in what quantities to eat them are some of the first steps to good health. Applying this knowledge by eating nutrient-rich foods and incorporating physical activity into your schedule at any stage of life are the greatest investments you can make in sustaining good health.

Although healthful eating may lower your risk for certain diseases, there are no guarantees that adhering to the tenets of good nutrition will prevent an illness from developing. Science has shown that not all diseases or disorders are associated with what you eat. However, statistics do show that lifelong food selections may influence the risk for some diseases.

Research continues to evaluate and clarify the role that diet and nutrition play in the promotion of health and in the development of obesity, high blood pressure, diabetes mellitus, coronary artery disease, osteoporosis, cancer, and other illnesses. The nutritional recommendations for prevention of many diseases are similar.

OBESITY

If obesity were merely a matter of aesthetics, it would be of less concern. But obesity is a health issue. It is associated with an increased risk of diabetes, lipid abnormalities, coronary artery disease, high blood pressure, certain cancers (such as breast, colon, and gallbladder in women and colon and prostate in men), stroke, degenerative arthritis, respiratory problems, sleep disturbances, and gallbladder disease.

Obesity places a huge burden on society in terms of lost lives, ongoing illnesses, emotional pain, discrimination, and economic cost (nearly $100 billion annually). The most ominous burdens posed by being overweight are reduction of the quality of life and shortening of life span. The likelihood of dying early (compared with the average age at death of all people in the population) progressively increases the more overweight you are. Diseases caused by obesity are the second leading cause of preventable deaths in the United States.

The Battle of the Bulge

With countless diet programs and products promising to help you shed pounds, losing weight should be easy. Simply eating too much and not being active enough are the causes of most overweight problems. But you also know it is hard to lose weight and even harder to keep it off. The cause of overweight and obesity is a chronic imbalance of calories ingested and calories burned. Genetic and environmental factors also contribute to obesity.

Americans spend more than $33 billion a year on weight-loss products and services, but they are losing the “battle of the bulge.” Despite the great desire of Americans to be thinner, they have become more obese. Some have even declared that the United States has an “obesity epidemic.” It is estimated that more than 50 percent of adult Americans are overweight. The prevalence of obesity also is increasing in several other countries.

Get the Terms Straight

“Overweight” and “obesity” are terms that often are used interchangeably, but they have different meanings. “Overweight” refers to having excess body weight compared with the norm for a person’s height, but the term does not account for what tissue is making up the weight. For example, athletes are often overweight according to weight-for-height tables because they have increased muscle mass. However, for most people, overweight means having too much fat.

“Obesity” refers to body fat in excess of what is healthful for an individual. In healthy women, an acceptable level of body fat ranges from 25 to 35 percent. In contrast, an acceptable range of body fat in men is from 10 to 23 percent.

How Your Body Uses Food

The number of calories used by an individual is determined by three factors: basal metabolic rate, the thermic effect of the food eaten, and the calories used during physical activity. The basal metabolic rate is the amount of energy needed to maintain bodily functions when an individual is at rest. This component accounts for 60 to 75 percent of the daily calorie requirement in sedentary adults. The major determinant of the basal metabolic rate is the amount of fat-free mass in the body. Muscle is one example of fat-free mass. Resistance (strength) training can increase the amount of muscle and therefore increase the basal metabolic rate. Resistance training also can help prevent the loss of lean mass that normally occurs with aging. Men tend to have more muscle than women and therefore burn more calories.

The thermic effect of food is the energy required to digest, metabolize, and store nutrients. The thermic effect of food accounts for about 10 percent of the total daily calorie use. The number of calories burned during exercise can vary tremendously depending on the amount of exercise performed. For most so-called sedentary persons, the activities of daily living (such as walking, talking, and sitting) account for 15 to 20 percent of the daily calorie use.

Should You Lose Weight?

How do you determine whether you are overweight or obese? Scientists can use sophisticated tests to measure body composition. However, these are not necessary for most individuals. You can measure your change in weight over time. Alternatively, you can calculate your body mass index (BMI) and determine its relationship to health risks.

Pinpointing Your Risk

There are risk factors that indicate a predisposition for obesity. Among these risk factors are the following:

Body mass index (BMI)—BMI is defined as your weight (in kilograms) divided by the square of your height (in meters). The advantage of BMI over bathroom scales and weight-for-height tables is that it normalizes weight for height and helps determine whether you have a healthful or unhealthful percentage of total body fat.

People who should not use the BMI for determining health risks include competitive athletes and body builders. Their BMI will be high because they have a larger amount of muscle. BMI is also not predictive of health risks for growing children, women who are pregnant or lactating, and frail, sedentary older adults.

A BMI from 19 to 24.9 is associated with a minimal to low health risk. A BMI from 25 to 29.9 is considered overweight and is associated with moderate health risks. A BMI of 30 or higher is considered obese and is associated with a substantially greater risk for development of various diseases. Extreme obesity is a BMI of more than 40.

Body shape—Increasing attention has been focused on the distribution of body fat as a potential indicator of health risk. Specifically, excess fat in the abdomen is associated with an increased risk for development of various metabolic illnesses, including diabetes mellitus, increased blood lipid levels, and high blood pressure. In contrast, people whose excess fat is located in their lower body (hips, buttocks, and thighs) seem to have minimal or no increased risk of these diseases. Upper-body obesity also is associated with an increased risk for coronary artery disease, stroke, and certain cancers.

Therefore, it can be helpful to assess your health risk by measuring your waist circumference. A measurement of more than 35 inches in women and 40 inches in men is associated with increased health risks, especially if you have a BMI of 25 or more.

What Is There to Lose? To Gain?

Although no one is without health risk—even the fittest person can have a heart attack, diabetes, or cancer—health and well-being are apt to be in less jeopardy if BMI, body shape, and family health history do not indicate problems. However, if your BMI is 25 or more, if your fat is primarily located in your upper body, and if you have a personal or family history of diabetes, heart disease, high blood pressure, or sleep apnea, losing weight can greatly improve your health.

Keep in mind that BMI and waist circumference are just starting points. Other factors also are important. When in doubt, seek a medical evaluation by your physician. A thorough history, examination, and blood studies can clarify whether your weight is having adverse effects on your health. The appropriate plan of action then can be tailored to meet your individual needs.

Getting Started

Losing body fat and keeping it off are not easy. Losing weight and then maintaining a healthful weight require collaboration with knowledgeable health care professionals. Obesity is not only a medical issue but also is a lifestyle issue. Your habits can help you maintain a desirable body weight or they can hamper your efforts to lose weight or even cause you to gain further weight. The types and amounts of food you eat and the exercise you perform will determine whether you gain, lose, or maintain your weight. Therefore, experts recommend that any weight loss program should consist of three main components: nutrition, exercise (or activity), and behavior modification.

Nutrition

Liquid meals, over-the-counter diet pills, and special combinations of foods promising to “burn” fat are not the answers to long-term weight control and better health. Learning to eat differently—to enjoy a well-balanced diet of fewer calories— is the best strategy to achieve health and weight goals. You should begin by substituting the words “healthful nutrition program” for “diet.”

Most people try to lose weight by eating 1,000 to 1,500 calories a day. In many instances, eating fewer than 1,400 calories makes it difficult to eat a balanced diet containing the recommended levels of nutrients. Therefore, nutrition programs that are too low in calories may be hazardous to  your health.

You can lose weight by eating fewer calories or by increasing exercise. A caloric deficit of 3,500 calories is required to lose 1 pound of fat. Over 7 days, this can be achieved by cutting 500 calories each day from your usual food intake or by cutting 250 calories each day (such as one or two fewer cookies) and burning an additional 250 calories with exercise (such as by walking briskly for 30 minutes). The good news is that a relatively small loss of weight can make a big difference in reducing the risk of health complications from obesity. Even a 10 percent weight loss can lead to improvement in your blood sugar level, lipid values, and blood pressure. Once this degree of weight loss has been achieved, further weight loss goals can then be set, if needed. Rather than aiming for an “ideal” weight, which may not be achievable or desirable, focus on achieving and maintaining a healthful weight.

A healthful diet for controlling weight includes foods from all food groups in the Food Guide Pyramid—ensuring balance and variety—in sensible amounts Food Guide Pyramid. It is helpful to review the energy density of the food consumed. Fat contains 9 calories/gram, protein 4 calories/gram, and carbohydrates 4 calories/gram. Alcohol contributes 7 calories/gram. For most people, the volume of food consumed determines how full you feel. Therefore, eating a small amount of an energy-dense food (such as fat) is usually not filling, whereas eating a large enough amount to fill you up results in a very large calorie intake. To lose weight, decrease your total calories by cutting back on the fat while filling up on low-calorie high-nutrient foods such as vegetables, fruits, and grains. You also can eat lower-fat versions of foods. However, be careful, because low-fat is not always low-calorie.

Healthful eating habits also avoid the feast or famine phenomenon. Distributing food selections throughout the day provides nourishment to support daily activities and can help to eliminate energy highs and lows. Three meals and occasional snacks also keep one’s appetite in check.

It is also important to avoid the hazards of repeatedly losing and gaining weight. Although repeated dieting is still a matter of debate, some studies suggest that it may lower the rate at which calories are burned. When a person is off the diet and more food is eaten, the body stores fat faster and more efficiently. This effect causes regain of the lost weight. In this circumstance, the amount of weight regained often is more than that lost in the first place.

Physical Activity

Improved eating habits in combination with decreased calorie intake and calorie-burning exercise is the best way to lose weight and maintain the results. In addition to enhancing weight loss efforts, physical activity promotes loss of body fat, increases muscle mass, and increases cardiovascular fitness. Regular exercise not only helps you lose weight by increasing the number of calories you burn but also makes it easier to keep off the weight that you have already lost.

Walking is a good choice for getting started on an exercise plan. A daily 2-mile walk burns approximately 1,000 to 1,200 calories per week. In addition, do not discount the physical activity that is part of ordinary activities of daily living—housework, climbing stairs, gardening— all important forms of exercise that can contribute to weight loss. It may be easier to maintain a schedule if you exercise with a friend.

Many experts recommend that you also participate in resistance (or strength) training. Resistance training can increase your muscle mass (which, as discussed previously, increases your basal metabolic rate), your bone density (which can help protect against osteoporosis), and your balance and coordination (which can lower the risk of injury), and it can help improve your posture.

People who are overweight, have been inactive, or have medical problems should check with their physician before starting an exercise program. An exercise stress test may be helpful because it can measure the response of the heart to exercise and help establish a safe starting level.

Behavior Modification

Behavior modification programs help identify triggers and treatments for unhealthful eating habits—such as uncontrolled snacking or late night eating. Such programs often explore the reasons behind an inactive lifestyle. Food diaries and activity logs frequently are used to heighten your awareness of what and how much is eaten and the type and amount of exercise done daily. These journals often provide insight into what triggers undesirable eating and what can be done to avoid or change this behavior.

Other key behavioral elements needed for success include:

Commitment—There must be personal motivation to change—to eat healthfully and to get regular physical

Priorities—It takes significant mental and physical energy to change deeply ingrained habits. If other major issues or life stresses are present, it is important to seek help for dealing with them. When balance in life is regained, you can focus on healthful nutrition more effectively.

Realistic goals—The best goals are those that can be achieved. Set daily or weekly goals that allow progress to be measured and rewarded. Aim to lose about 1 to 2 pounds weekly. It is important to know that small losses of weight—or improvements in physical activity—can improve health. Measurements of blood pressure, blood sugar level, and blood cholesterol and triglyceride values are more important in terms of health than the number on the scale. Accept the fact that there will be setbacks. Instead of becoming frustrated or angry, resume your health program once again.

Group support—Joining with people facing the same challenges can promote sharing of ideas and facilitate commitment.

HIGH BLOOD PRESSURE

High blood pressure, or hypertension, is the most common major health condition in the United States. It is one of the leading causes of heart attack, heart failure, stroke, kidney failure, and premature death. It also can damage parts of the circulatory system—including blood vessels in the heart, brain, eyes, and kidneys.

Sometimes called the “silent killer,” high blood pressure is a disease that can go undetected for years. The higher the blood pressure or the longer it goes undiagnosed, the worse the outlook. More than 50 million Americans have high blood pressure. Of that number, an estimated one-third do not know they have the disease.

There has been remarkable progress in detecting, treating, and controlling high blood pressure. Recently, there has been a substantial increase in the number of individuals who are aware of their high blood pressure and who are being treated for it. At the same time, the incidences of coronary artery disease and stroke have significantly decreased, partially as a result of progress in the detection, treatment, and control of high blood pressure. Despite these efforts, most people with high blood pressure do not have adequately controlled blood pressure. Unfortunately, high blood pressure remains a serious medical problem.

Approximately 5 percent of cases of high blood pressure can be traced to underlying diseases, such as kidney disorders or conditions that cause narrowing of the arteries. This is called “secondary hypertension.” But most cases have no known cause. This type is called “primary” or “essential” hypertension.

Risk Factors for High Blood Pressure

There are risk factors that indicate a predisposition for the development of high blood pressure. Among these risk factors are the following:

Family history—A family history of high blood pressure is a risk for hypertension.

Age—High blood pressure becomes more common among all people as they grow older. After all, nearly two-thirds of Americans aged 70 or older have the disease.

Sex—Although men and women are typically equally affected, women who use birth control pills and smoke cigarettes have a greater chance of having high blood pressure.

Race—As an example, high blood pressure is more common among blacks than whites.

You either have or don’t have the above risk factors. There are also other factors that increase your risk for high blood pressure which you can do something about:
• obesity—control your weight
• lack of exercise—get moving
• alcohol consumption—take control or abstain
• excessive salt (sodium) intake—cut down

Measuring Blood Pressure

Blood pressure is the force that the blood exerts on the artery walls as the heart pumps it through the body. The amount of force depends on various factors, including how hard the heart pumps and the volume of blood it pumps. Another factor is the amount of resistance blood encounters in the arteries—the thicker or more clogged the blood vessels, the greater the resistance. The elasticity of arteries also plays a role in blood pressure. The less elastic arteries are, the less they expand under the force of a heartbeat and the higher the resistance.

The standard way to measure blood pressure is in millimeters of mercury (mm Hg). This unit of measurement refers to how high the pressure inside the arteries is able to raise a column of mercury. Each blood pressure measurement has two numbers. The top number is the systolic blood pressure, or the highest pressure within the arteries that occurs during “systole,” when the heart is contracting. The bottom number is the diastolic blood pressure, or the lowest pressure within the arteries that occurs during “diastole,” when the heart is relaxed and filling with blood.

For most people, a blood pressure of 120/80 mm Hg or lower is considered healthy.

Effects of High Blood Pressure

Repeated blood pressure measurements that are more than 130/85 mm Hg indicate a potential for problems, a greater risk of progressing to definite high blood pressure, and the need to have regular blood pressure checks. A measurement of 140 systolic or more, 90 diastolic or more, or both indicates high blood pressure, which requires treatment. Recent guidelines stress the importance of treating to achieve a pressure less than 130/85. Indeed, treating to these lower levels of blood pressure further reduces the incidence of stroke, heart and kidney damage, and other vascular problems.

When high blood pressure occurs, it means that the force of the blood in the arteries is excessive and many health complications can occur.

Heart

High blood pressure forces the heart to work harder than it should to pump blood to distant tissues and organs. Another way to understand blood pressure is to think of it as a weight or a load that the heart muscle must “push” against. Like any muscle, the heart gets larger with pushing heavy weights. Eventually, the heart’s pumping efficiency decreases when the muscle can no longer adapt to the excessive workload that the high blood pressure demands. When this occurs, the heart muscle may weaken and the heart can fail.

Arteries

High blood pressure can also accelerate the development of plaque within the arteries, a condition known as atherosclerosis. With the narrowing of the artery walls, the risk of heart attack is increased. High blood pressure also can lead to bulges (aneurysms) in the arteries. If an aneurysm in a major artery ruptures, the results can be catastrophic and possibly fatal.

Brain

High blood pressure increases the risk of having a stroke, which occurs when a blood vessel within the brain either ruptures or is blocked.

Kidneys

The kidneys filter waste products from the blood and maintain proper blood minerals and blood volume. When these functions are impaired or compromised, so is their role in helping to maintain blood pressure. These effects can produce a destructive cycle that results in increasing blood pressure and a gradual failure of the kidneys to remove impurities from the blood.

Eyes

High blood pressure often causes problems with the eyes. Examination of the retina can reveal narrowing of the arteries, small hemorrhages, and accumulations of protein that have leaked from affected blood vessels (exudates). Although it is unusual for high blood pressure to impair vision, it can occur as a result of severe constriction of the retinal arteries and swelling (edema) of the retina during episodes of increased blood pressure. Treating the high blood pressure is the only way to reverse this vision loss.

Treating High Blood Pressure

Fortunately for many people, high blood pressure is preventable. Even those who already have high blood pressure or are at increased risk may be able to reduce the number and doses of medications needed to control it and minimize other health complications by the following lifestyle modifications.

Lose weight—If you are overweight, losing weight is the most effective non-drug method for lowering blood pressure. A weight loss of as little as 10 pounds can significantly reduce blood pressure in many overweight people with high blood pressure. In some people, weight loss alone is sufficient to avoid the need for blood pressure medication.

Exercise—When compared with more active and fit peers, sedentary individuals with normal blood pressure have a 20 to 50 percent increased risk for development of high blood pressure. Regular aerobic exercise such as walking or biking for 30 to 45 minutes most days of the week is a very effective means of lowering blood pressure.

Limit alcohol—Excessive alcohol intake is a risk factor for high blood pressure and stroke. It also can interfere with the effects of blood pressure medications. Men who drink should limit their intake to no more than 2 drinks a day; women should have no more than 1 drink daily.

Do not smoke—Smoking a cigarette temporarily increases blood pressure for up to 30 minutes. Smoking is also a major risk factor for cardiovascular disease. Everyone, especially people with high blood pressure, needs to quit smoking or never start.

Limit or avoid high-sodium foods—A high intake of sodium in the diet increases blood pressure in some people. The average American consumes about 4,000 milligrams or more of sodium a day. People with high blood pressure should limit their sodium intake to less than 2,400 milligrams a day, and many experts recommend the same limit for everyone.

Follow a balanced nutrition program—A low-fat, high-fruit and vegetable diet can lower blood pressure impressively, all by itself. A large percentage of people with high blood pressure may be able to decrease their need for blood pressure medication if they follow the recommendations of the Food Guide Pyramid. A diet following this plan promotes weight loss and is high in minerals such as calcium, potassium, and magnesium, which have been associated with lower blood pressure.

The National Heart, Lung and Blood Institute recently sponsored a study testing the effects of different diets on blood pressure, called the “DASH” (Dietary Approaches to Stop Hypertension) study. Participants in the study ate one of three diets: an average American diet, a diet rich in fruits and vegetables, or a “combination” diet that emphasized fruits, vegetables, and low-fat dairy products and was low in fat and saturated fat. Sodium consumption was the same in all three diets. Participants were asked to limit obviously salty food, to rinse canned vegetables, and to not add extra salt to food. Both the fruit-and-vegetable diet and the “combination” diet lowered blood pressure. However, the combination diet was the most effective. Within that group, people with above-normal blood pressure (more than 129/80 mm Hg) and those with high blood pressure (more than 140/90 mm Hg) experienced reductions of their blood pressure similar to those achieved with some blood pressure medications.

Researchers believe that people following the combination diet fared better because of the low saturated fat and high fruit and vegetable mixture that provided adequate potassium, magnesium, and calcium. For people with normal blood pressure, the combination diet may help to avoid blood pressure problems. If blood pressure is only slightly increased, following this diet may actually eliminate the need for medication. For people with severe high blood pressure, the diet may allow reduction in blood pressure medication.

When Medications Are Needed

When lifestyle changes alone are not effective for lowering high blood pressure, medications may be required. Medications vary in the way they control blood pressure. Some types help the kidneys to eliminate sodium and water, some make the heart beat more slowly and less forcefully, and others enable the blood vessels to relax and decrease the resistance to blood flow. Your physician will determine which drug or combination of drugs is best suited for you.

Persistent hyperglycemia causes almost all the symptoms that may alert an individual to the development of diabetes. These symptoms can include frequent urination, extreme thirst, blurred vision, fatigue, unexplained weight loss, recurrent infection, tingling or loss of feeling in the hands or feet, and hunger.

With diabetes, the excess glucose spills into the urine, and the urine output increases. Consequently, the person with diabetes becomes dehydrated and thirsty. Fatigue results when the supply of glucose to cells is not available, causing energy levels to decline. To compensate for the lost fuel, the body burns stored fat, and weight loss and hunger may occur. Left untreated, persistent hyperglycemia is also responsible for most of the long-term complications of diabetes.

Written by medical and nitrition experts from Mayo Clinic, University of California, USA, Academic Press, USA, 2002, excerps pp.47-58. Digitized, adapted and illustrated to be posted by Leopoldo Costa.