Diet and disease prevention
Research has shown that diet has a tremendous impact on short- and long-term health. Poor diet can lead to nutritional deficiencies and chronic diseases such as obesity, diabetes mellitus, and coronary heart disease. A good diet combined with exercise promotes a healthy weight, reduces many health risks, and increases both physical and mental well-being.
The concept of diet quality in relation to health has changed over time. In the early 1900s, lack of refrigeration, frozen food technology, and reliable transportation meant that people ate what grew locally and what was available seasonally. At that time, nutrition scientists focused on preventing specific nutrient and calorie deficiencies. Today, most people in developed countries have access to a large quantity and variety of foods. Nutrition researchers have shifted their focus to exploring the relationships among diet, chronic disease, longevity, and quality of life.
Well-nourished people have more energy, are more resistant to disease, and are better able to tolerate treatments and to recover from acute illnesses, surgery, and trauma. Consumption of a wide variety of foods, with appropriate amounts of protein, carbohydrate, fat, vitamins, and minerals, forms the basis of a healthy diet. However, many acute and chronic conditions are related to inadequate dietary intake. Obesity, a major public health concern, and many of the leading causes of death in the United States, including coronary heart disease, stroke, diabetes mellitus, and some cancers, are at least partially attributable to poor diet and alcohol consumption. Diet education has become a focus of public health outreach programs.
The position of the Academy of Nutrition and Dietetics (formerly the American Dietetic Association) on the role of nutrition and diet in health promotion and disease prevention programs includes steps for primary, secondary, and tertiary prevention.
These steps include the following guidelines:
1. Primary prevention (health promotion): Health promotion is a population-based approach that encourages behaviors for better health. For example, taking nutrition classes at a local adult education center would be considered a primary prevention
Prevention (risk appraisal and risk reduction): For people at risk of illness who are beginning to encounter health-related problems, secondary prevention encompasses risk appraisal and screening to detect preclinical disease and early intervention to promote health and well-being. Cholesterol screening for people with a family history of cardiovascular disease is an example of a secondary prevention measure.
2. Tertiary prevention (treatment and rehabilitation): For people experiencing illness, injury, or disability, tertiary prevention includes treatment and rehabilitation to promote maximum health and prevent further disability and secondary conditions resulting from the initial health problem. Examples of tertiary prevention include medical nutrition therapy or diabetes education for people diagnosed with type 2 diabetes mellitus.
The seventh edition of the Dietary Guidelines for Americans, published in 2010 by the U.S. Department of Agriculture (USDA) and Health and Human Services (HHS), provides an overall view of good nutrition along with specific recommendations for improved dietary habits. These dietary guidelines include:
1. Make half your plate fruits and vegetables.
2. Switch to fat-free or low-fat (1%) milk (for people over age 2).
3. Drink water instead of sugary drinks.
4. Compare sodium in foods like soup, bread, and frozen meals and choose the foods with lower numbers.
5. Avoid oversized portions.
6. Enjoy your food, but eat less.
For more information we recommend the book:
More than one hundred years ago, in 1894, the USDA published its first set of national nutrition guidelines. MyPlate, replacing the former MyPyramid, is the most recent set of guidelines. The MyPlate design was simplified from the food pyramid to help consumers visualize the actual breakdown of each meal. Half of the plate is devoted to vegetables and fruits; slightly less than
one-quarter is made up of protein (no longer meat and beans); and the remaining amount is dedicated to grains. Aside of dairy is also featured, and the previous ‘‘fats and oils’’ category is obsolete. The MyPlate ethos emphasizes lifestyle factors such as exercise in addition to nutrition.
GRAINS. Wheat, rice, oats, barley, and cornmeal are common grains in the American diet. Less familiar grains include buckwheat (also called kasha), amaranth, quinoa, sorghum, millet, rye, and triticale. Pasta, bread, oatmeal, breakfast cereals, grits, crackers, tortillas, and other foods made from grains are part of this group.
Grains are divided into two categories: whole grains and refined grains. MyPlate recommends that at least half of the grains an individual eats daily be whole grains. In whole grain, the whole kernel, including the bran and germ of the grain seed, is used or ground into flour. Examples of whole-grain products include whole-wheat flour; cracked wheat (bulgur); brown rice; wild rice; whole cornmeal; oatmeal; whole-wheat breads, pastas, and cereals; and popcorn.
In refined grains, the bran, or seed coating, and the germ, or center of the kernel, are removed during processing. This produces softer flour and removes oils from the grain. It also slows the spoilage process and increases the shelf life of refined-grain products. However, refining also removes dietary fiber, iron, and B-complex vitamins. Products made with refined grain often have B vitamins and iron added to replace some of what was lost by removing the germ and bran. Calcium is also added. These products are labeled as ‘‘enriched.’’ Examples of refined-grain products include white flour, degermed cornmeal, white rice, couscous, crackers, flour tortillas, grits, pasta, white bread, and corn flake cereal. Some products are made with a mixture of whole grain and refined grain flours to help improve texture and taste but still retain some nutrients.
VEGETABLES. Any vegetable or any 100% vegetable juice is considered part of the vegetable group. This group is subdivided into different types of vegetables, based on nutrient content.
The subgroups are:
1. dark green vegetables—bok choy, broccoli, collard greens, dark green leafy lettuce, kale, mesclun, mustard greens, romaine lettuce, spinach, turnip greens, watercress
2. red and orange vegetables—acorn squash, butternut squash, carrots, hubbard squash, pumpkin, red peppers, sweet potatoes, tomatoes, tomato juice
3. beans and peas—black beans, black-eyed peas, chickpeas, kidney beans, lentils, navy beans, pinto beans, soy beans, split peas, white beans
4. starchy vegetables—cassava, corn, green bananas, green or field peas, green lima beans, plantains, potatoes, taro, water chestnut
5. other vegetables—artichokes, asparagus, avocado, bean sprouts, beets, Brussels sprouts, cabbage, cauliflower, celery, cucumbers, eggplant, green beans, green peppers, lettuce, mushrooms, okra, onions, parsnips, turnips, wax beans, zucchini.
FRUITS. Fruits can be fresh, canned, frozen, or dried. One hundred percent fruit juice also counts as fruit. Virtually all fruit is included in this group, including citrus fruits, berries, melons, and common fruits such as apples, bananas, pears, and raisins (dried grapes).
DAIRY. Nonfat, low-fat, and whole milk all contain about the same amount of calcium, the most important mineral in milk. Nonfat and low-fat milk are the preferred choices in this group. Other foods in the milk group include yogurt, cheese, and desserts made with milk such as ice cream and pudding. When foods like ice cream, full-fat cheese, or sweetened yogurt are selected, the extra calories from fat and sugar should be subtracted from a person’s daily discretionary calories (calories allotted for treat foods such as desserts). People who are lactose intolerant can choose lactose-reduced and lactose-free products. Cream cheese and butter contain only small amounts of calcium and are not counted as dairy servings.
PROTEIN. The protein group includes meats, poultry, eggs, beans and peas (including soy products), nuts and seeds (including nut butters), and seafood. People who do not eat meat need to make sure they are getting adequate amounts of iron and other nutrients (e.g., vitamin B12). The meat group contains several subgroups, including lean cuts, game meats, ground meats, deli meats, and organ meats. People should try to eat less red meat and more fish, poultry, and dried beans. Meat should be trimmed of all visible fat and baked, broiled, or grilled. If fat is added in cooking, it should be counted as an oil or in the discretionary calories.
OILS. Oils are liquid at room temperature, compared to fats, which are solid at room temperature. Oils are preferred because they contain less saturated fat and trans fat. Diets high in saturated fat and trans fat are associated with an increased risk of cardiovascular disease. Oils come from plant sources and include olive oil, canola oil, corn oil, safflower oil, and oil blends. Fats come mainly from animal sources and include butter, lard (pork fat), tallow (beef fat), and chicken fat. Stick margarine and shortening are made of vegetable oils that are treated to make them solid. This process, called hydrogenation, increases the amount of saturated fat and trans fats they contain, making them less desirable sources of fat. Palm and coconut oils, although liquid at room temperature, are not recommended because they are unusually high in saturated fat and trans fat. Avocados, nuts, olives, and some fish, such as salmon, are high in oils, but they contain omega-3s, which are beneficial to health. Processed foods such as mayonnaise, salad dressings, and oil-packed tuna are also high in oil but do not have the same health benefits.
EMPTY CALORIES. Empty calories are calories derived from solid fats or added sugars that provide little-to-no nutritional value. Foods like desserts, soda pop, and fried foods may contain all or some empty calories. MyPlate acknowledges that occasional consumption of empty calories is okay, but these foods should be eaten in moderation and considered against daily caloric goals.
For more information we recommend the book:
PHYSICAL ACTIVITY. MyPlate recommends engaging in regular physical activity in addition to a person’s normal daily routine. Adults are advised to do at least 2 hours and 30 minutes of moderate physical activity every week, or 75 minutes of vigorous activity every week. Children (ages 6–17) are recommended to participate in 60 minutes of activity every day. There are no specific recommendations for younger children, as they are generally regularly active.
Examples of moderate activities include: brisk walking, hiking, yard work and gardening, dancing, golfing without a golf cart, easy bicycling, light weight training
Vigorous activities include: running or jogging, brisk or hard bicycling, lap swimming, aerobic exercising, power walking, many competitive sports (tennis, basketball, etc.), heavy yard work such as chopping wood, heavy weight training