A prudent dietary pattern is characterized by high intakes of vegetables, fruits, legumes, whole grains, fish, and poultry. It carries a lower risk than the Western dietary pattern, which is characterized by high intakes of red meat, processed meat, refined grains, sweets and desserts, fried foods, and high-fat dairy products. ¹¹ A prudent diet is also a balanced diet. It involves eating a variety of foods and includes foods from each of the five major food groups. Dairy products are an important source of calcium, riboflavin, and protein. Animal products (meat, poultry) provide protein, iron, and B₁₂. Grains and cereals provide carbohydrates, proteins, thiamin, and potentially niacin. Fruits and vegetables are important sources of antioxidants, vitamins, and minerals, whereas fats are a major source of energy and vitamin A. Astute food selection enables vegetarians to eat a healthy diet. Lacto-ovo-vegetarians, by including milk and eggs in their diet, avoid most nutrient deficiencies. but they need to be aware of iron deficiency. Vegans who exclude all animal products need to exercise even greater care and are also at risk of zinc, calcium, and vitamin B₁₂ deficiencies. Dietary combinations of legumes and grains can obviate any risk of protein deficiency.

A good diet is preferable to nutritional supplements because the ratios of nutrients in whole foods are likely to be more consistent with metabolic needs. Furthermore, both nutrient and nonnutrient components in foods have important physiologic effects. Only relatively recently has the potential of lycopene (the red carotenoid pigment in tomatoes, various berries, and other fruits) to reduce the risk of certain cancers been identified¹² or the immunologic influence of phytosterols. ¹³ Dietary supplements may inadvertently omit important food constituents and may under supply or over supply various nutrients.

Although dietary fats, particularly saturated fats, should be limited, an adequate intake of unsaturated fat (e.g., linoleic and linolenic acids), the essential unsaturated fatty acids, is necessary. Essential unsaturated fatty acids serve as dietary precursors for the formation of eicosanoids, which are powerful regulators of cell and tissue functions. They are the precursors of various prostaglandins and leukotrienes that enhance thrombocyte aggregation, vascular constriction and dilation, and bronchial and uterine contraction.

Vegetable oils and fish are important dietary sources of polyunsaturated fats. In fact, to prevent cardiovascular and other chronic disease, it has been suggested that fish should be eaten two to three times a week. ¹⁴ For vegetarians and vegans, alternative sources of omega-3 fatty acids are spinach, flaxseeds, rapeseeds (rapeseed oil is also known as canola), walnuts, and navy or baked beans. Nonetheless, no more than 25% of dietary energy should be derived from fat. At low intakes of fat, the type of fat appears to be less significant, ¹⁵ but the total daily cholesterol intake should be restricted to less than 300 mg, and saturated fat should be reduced to less than 10% of the total calories.

A diet rich in whole-grain products, vegetables, and fruits is highly recommended. Although the benefits of fruit and vegetable intake may become evident with the consumption of as few as three servings per day, ¹⁶ a daily intake of at least five servings of fruits and vegetables and at least six servings of breads, cereals, or legumes are recommended. ¹⁷ A serving is one slice of bread, one-half cup of cereal or pasta, a medium piece of fruit, or one-half cup of legumes. Eating fresh whole foods is another important dietary principle. Although processing may occasionally enhance the bioavailablity of nutrients, it usually reduces the nutrient value of foods. Eating whole foods, including whole grains, is necessary to approximate the recommended intake of 25 grams of fiber per day.

Refined sugars should be limited, as should salt and sodium. A sodium intake of less than 2.5 grams or 100 micromolars per day requires that no salt be added during or after food preparation and that heavily or visibly salted items be excluded.

Alcoholic beverages should be consumed in moderation or not at all. ¹⁷ One-half pint of beer, one measure of spirits, or one glass of sherry or wine is considered one unit. The consumption of alcohol by men should not exceed 4 units or 40 grams of absolute alcohol per day on a regular basis or 28 units per week. Drinking is considered hazardous when 4 to 6 units are consumed per day or 28 to 42 units are consumed per week. Women should consume no more than 2 units of alcohol per day on a regular basis or 14 units per week. Drinking is harmful to women when 4 or more units per day or 28 or more units per week are consumed. Abstinence during pregnancy is highly recommended.

Fig. 20-1 provides a template for helping patients acquire good dietary habits. ¹⁰ Although a good diet can promote general health, specific dietary changes can target particular conditions. Prevention of cardiovascular disorders, osteoporosis, and even cancer may be facilitated by careful dietary choices. Fig. 20-2 demonstrates how this basic diet may be altered to reduce specifically the risk of cancer. ¹⁰ A prevalent theme is to limit energy consumption.

Excess calorie consumption has emerged as the major dietary health hazard of modern industrialized society. Maintaining a normal body weight and keeping the body mass index (BMI) between 20 and 25 is advocated.

(Body mass index is the weight in kilograms divided by the height in meters squared.)

All foods are a source of energy, but gram-for-gram fat is twice as energy-dense as carbohydrates and proteins. It is, however, not only energy intake that influences body weight. In fact, the trend toward an increasingly sedentary lifestyle in the United States is believed to explain the growing prevalence of obesity, despite a shift toward consumers purchasing reduced fat and low-calorie food products. ¹⁸

Exercise promotes wellness. Physical activity has even been found to lengthen life. ¹⁹ Compared with active persons, sedentary men are over two and one-half times more likely to die from any cause and over three and one-half times more likely to die from cardiovascular disease. ²⁰ A prospective study of over 12,000 American men found that 10 to 36 minutes each day of leisure-time physical activity of moderate intensity significantly reduced premature mortality. ²¹ A significantly lower death rate was also reported in individuals who performed an average of 47 minutes versus 15 minutes of activity per day. ²²

Epidemiologic studies indicate that a physically inactive lifestyle is associated with twice the risk of developing coronary artery disease. ²³ The scientific evidence from 75 trials implies a strongly positive protective relationship between cardiovascular fitness and coronary heart disease. ²⁴ Regular exercise modifies a number of the major modifiable risk factors for heart disease, ²³ including the blood lipid profile, ²⁵ blood pressure levels, ²⁶ and fibrinogen levels. ²⁷

Musculoskeletal health also requires adequate physical activity. Physical activity, aerobic fitness, and muscle strength all influence bone density. A lifestyle that combines a moderate level of physical activity with an adequate calcium intake promotes a competent skeleton. ²⁸ Older people with osteoporosis can benefit from moderate weight-bearing exercises. ²⁹ Exercise not only protects against bone loss but also prevents fractures by reducing the risk of falls through improved strength, flexibility, balance, and reaction time.^{3031 and 32} Appropriate physical activity in older osteoporotic individuals decreases pain and improves fitness and the overall quality of life. ³⁰

Evidence is accumulating that suggests that physical activity may help reduce the risk of cancer. ^32,33 Physically active people have been shown to have a decreased rate of all-cancer mortality, and the incidence of colon, breast, and perhaps prostate cancer is lower in active individuals when compared with sedentary persons. Mental health and standard body weight are also more likely in groups who regularly exercise. ³⁴ Exercise is a recognized strategy for stress reduction and is also a form of relaxation.