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Medicine LibreTexts

9.3: Popular Diets

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  • The concept of functional foods represents initiatives aimed at addressing health problems. Certain diet plans take this concept one step further, by striving to prevent or treat specific conditions. For example, it is widely understood that people with diabetes need to follow a particular diet. Although some of these diet plans may be nutritionally sound, use caution because some diets may be fads or be so extreme that they actually cause health problems. Before experimenting with a diet, discuss your plans with your doctor or a registered dietitian. Throughout this section, we will discuss some of the more popular diets. Some fall under the category of fad diets, while others are backed by scientific evidence. Those that fall into the latter category provide a good foundation to build a solid regimen for optimal health.

    The DASH Diet

    The Dietary Approaches to Stop Hypertension, or DASH diet, focuses on reducing sodium intake to either 2,300 milligrams per day (as recommended by the Dietary Guidelines for Americans) or 1,500 milligrams per day. The DASH diet is an evidence-based eating plan that can help reduce high blood pressure. This plan may also decrease the risk of heart attack, stroke, diabetes, osteoporosis, and certain cancers. DASH tips to lower sodium include:

    • Using spices instead of salt to add flavor
    • Reading sodium content on processed or canned food labels, and choosing low-sodium options
    • Removing some sodium from canned foods (such as beans) by rinsing the product before consumption
    • Avoiding salt when cooking

    DASH dieters eat lots of whole grains and high-fiber fruits and vegetables, and moderate amounts of low-fat dairy products, lean meats, and heart-healthy fish. In addition, DASH limits the use of saturated fats to less than 7 percent of total calories, and restricts the consumption of sweets and alcohol. The DASH diet also calls for consuming less added sugar and drinking fewer sugar-sweetened drinks. It replaces red meat with fish and legumes and calls for increased calcium, magnesium, potassium, and fiber. Also, even though some people on the DASH diet may find it lowers their HDL (good) cholesterol along with their LDL (bad) cholesterol, it still has a positive cumulative effect on heart health.

    The Gluten-Free Diet

    The gluten-free diet helps people whose bodies cannot tolerate gluten, a protein found in wheat, barley, and rye. One of the most important ways to treat this condition is to avoid the problematic foods, which is not easy. Although following a gluten-free diet is challenging, it is prescribed for patients with gluten intolerance and celiac disease, an autoimmune disorder with a genetic link. People who have celiac disease cannot consume gluten products without damaging their intestinal lining. Eating a gluten-free diet means finding replacements for bread, cereal, pasta, and more. It also means emphasizing fresh fruits, vegetables, and other foods without gluten. However, it is important to note that the gluten-free trend has become something of a fad even for those without a gluten intolerance. Celiac disease is a relatively rare condition found in only 1 percent of the population. Therefore, a gluten-free diet should be followed only with a physician’s recommendation.

    Low-Carb Diets

    Low-carb diets, which include the Atkins Diet and the South Beach Diet, focus on limiting carbohydrates—such as grains, fruit, and starchy vegetables—to promote weight loss. The theory behind the low-carb diet is that insulin prevents the breakdown of fat by allowing sugar in the form of blood glucose to be used for energy. Proponents of this approach believe that because limiting carbs generally lowers insulin levels, it would then cause the body to burn stored fat instead. They believe this method not only brings about weight loss, but also reduces the risk factors for a number of conditions. However, some studies have shown that people who followed certain low-carb diet plans for two years lost an average of nearly 9 pounds, which is similar to the amount of weight lost on higher carbohydrate diets.

    The benefits of this kind of diet include an emphasis on whole, unprocessed foods and a deemphasis of refined carbohydrates, such as white flour, white bread, and white sugar. However, there are a number of downsides. Typically, the first two weeks allow for only 20 grams of carbs per day, which can be dangerously low. In addition, dieters using the low-carb approach tend to consume twice as many saturated fats as people on a diet high in healthy carbohydrates. Low-carb diets are also associated with a higher energy intake, and the notion that “calories don’t count,” which is prevalent in this kind of diet, is not supported by scientific evidence.

    The Mediterranean Diet

    The traditional Mediterranean diet incorporates many elements of the dietary choices of people living in Greece and southern Italy. The Mediterranean diet focuses on small portions of nutritionally-sound food. This diet features food from plant sources, including vegetables, fruits, whole grains, beans, nuts, seeds, breads and potatoes, and olive oil. It also restricts the consumption of processed foods and recommends eating locally grown foods rich in micronutrients and antioxidants. Other aspects of this eating plan include consuming fish and poultry at least twice per week, eating red meat only a few times per month, having up to seven eggs per week, and drinking red wine in moderation and with meals. Unlike most diets, the Mediterranean diet does not cut fat consumption across the board. Instead, it incorporates low-fat cheese and dairy products, and it substitutes olive oil, canola oil, and other healthy oils for butter and margarine.

    More than fifty years of nutritional and epidemiological research has shown that people who follow the Mediterranean diet have some of the lowest rates of chronic disease and the highest rates of longevity among the populations of the world. Studies have shown that the Mediterranean diet also helps to decrease excess body weight, blood pressure, blood fats, and blood sugar and insulin levels significantly.

    The Raw Food Diet

    The raw food diet is followed by those who avoid cooking as much as possible in order to take advantage of the full nutrient content of foods. The principle behind raw foodism is that plant foods in their natural state are the most wholesome for the body. The raw food diet is not a weight-loss plan, it is a lifestyle choice. People who practice raw foodism eat only uncooked and non-processed foods, emphasizing whole fruits and vegetables. Staples of the raw food diet include whole grains, beans, dried fruits, seeds and nuts, seaweed, sprouts, and unprocessed produce. As a result, food preparation mostly involves peeling, chopping, blending, straining, and dehydrating fruits and vegetables.

    The positive aspects of this eating method include consuming foods that are high in fiber and nutrients, and low in calories and saturated fat. However, the raw food diet offers little in the way of protein, dairy, or fats, which can cause deficiencies of the vitamins A, D, E, and K. In addition, not all foods are healthier uncooked, such as spinach and tomatoes. Also, cooking eliminates potentially harmful microorganisms that can cause foodborne illnesses.

    Therefore, people who primarily eat raw foods should thoroughly clean all fruit and vegetables before eating them. Poultry and other meats should always be cooked before eating.

    Vegetarian and Vegan Diets

    Vegetarian and vegan diets have been followed for thousands of years for different reasons, including as part of a spiritual practice, to show respect for living things, for health reasons, or because of environmental concerns. For many people, being a vegetarian is a logical outgrowth of “thinking green.” When a food system is heavily focused on meat production there are deforestation issues, overgrazing of land and pasturage, and animal abuses. By avoiding animal flesh, vegetarians hope to look after their own health and that of the planet at the same time. Broadly speaking, vegetarians eat beans, grains, and fruits and vegetables, and do not eat red meat, poultry, seafood, or any other animal flesh. Some vegetarians, known as lactovegetarians, will eat dairy products. Others, known as lacto-ovo vegetarians, will eat dairy products and eggs. A vegan diet is the most restrictive vegetarian diet— vegans do not eat dairy, eggs, or other animal products, and some do not eat honey.

    Vegetarian diets have a number of benefits. Well-balanced eating plans can lower the risk of a number of chronic conditions, including heart disease, diabetes, and obesity. They also help to promote sustainable agriculture. However, if a vegetarian does not vary his or her food choices, the diet may be insufficient in calcium, iron, omega-3 fatty acids, zinc, and vitamin B12. Also, if people who follow these diets do not plan out their meals, they may gravitate toward foods high in fats.

    Table \(\PageIndex{1}\) The Pros and Cons of Seven Popular Diets

    Diet Pros Cons
    DASH Diet
    • Recommended by the National Heart, Lung, and Blood Institute, the American Heart Association, and many physicians
    • Helps to lower blood pressure and cholesterol
    • Reduces risk of heart disease and stroke
    • Reduces risk of certain cancers
    • Reduces diabetes risk
    • There are very few negative factors associated with the DASH diet
    Gluten-Free Diet
    • Reduces the symptoms of gluten intolerance, such as chronic diarrhea, cramping, constipation, and bloating
    • Promotes healing of the small intestines for people with celiac disease, preventing malnutrition
    • May support weight loss
    • May be beneficial for other autoimmune diseases, such as Parkinson’s disease, rheumatoid arthritis, and multiple sclerosis
    • May be helpful for Types 1 and 2 diabetes and anemia
    • Risk of folate and iron deficiencies
    • Special gluten-free products can be hard to find and expensive
    • Requires constant vigilance and careful food label reading, since gluten is found in many products
    Low-Carb Diet
    • Restricts refined carbohydrates, such as white flour and white sugar
    • May temporarily improve blood sugar or blood cholesterol levels
    • Not entirely evidence based
    • Results in higher fat and protein consumption
    Mediterranean Diet
    • A reduced risk of cardiovascular disease and mortality
    • A lower risk of cancer • De-emphasizes processed foods and emphasizes whole foods and healthy fats
    • Lower sodium intake, due to fewer processed foods
    • Emphasis on monosaturated fats leads to lower cholesterol
    • Highlighting fruits and vegetables raises consumption of antioxidants
    • Does not specify daily serving amounts
    • Potential for high fat and high calorie intake as nuts and oils are calorie-dense foods
    • Drinking one to two glasses of wine per day may not be healthy for those with certain conditions
    Raw Food Diet
    • Emphasizes whole foods
    • Focuses on nutritionally-rich foods
    • High in fiber
    • Not entirely evidence-based
    • Very restrictive and limits protein and healthy fat intake
    • Could encourage the development of foodborne illness
    • Extremely difficult to follow
    • Can cause deficiencies in essential vitamins
    Vegetarianism and Veganism
    • May reduce cancer risk
    • May reduce heart disease risk
    • May reduce obesity risk
    • May help prevent Type 2 diabetes
    • Helps with weight reduction and weight maintenance
    • Guidelines regarding fat and nutrient consumption must be followed
    • Requires vigilance to watch out for hidden animal products
    • Requires negotiating meals and holidays with meat-eating friends and family