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Course Sample:
I. Introduction
"It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases." (1)
As Dietitians, it is important to be sensitive to the cultural differences that our clients express as well as their personal preferences. For some, a vegetarian lifestyle is a religious issue. For example, Hindus do not eat meat. For others, a vegetarian lifestyle is chosen for health reasons or ethical reasons, as people may not want animals to be killed and then to be served as their food.
Health benefits of vegetarian diets include a reduced risk of heart disease and diabetes. Vegetarians tend to have lower blood pressure, lower cholesterol levels, and better controlled blood sugar levels. Increased soy consumption may be protective against osteoporosis.
The vegetarian diet is based mainly on fruits ,vegetables, grains and includes many nutrients that can protect against cancer and other diseases. These include dietary fiber, carotenoids, ascorbic acid, tocopherols, folic acid, indoles, thiocyanates, cumarins, phenols, flavonoids, terpenes, protease inhibitors, plant sterols, and other phytochemicals.
The main health risk of the vegetarian diet is marginal intake of certain essential nutrients including protein and calcium. However, the risk of animal based diets includes a high risk for cancer and cardiovascular disease due to excess energy and saturated fat, and insufficient phytochemical consumption.
Dietitians have the responsibility to respect the dietary convictions of their patients. If a chosen diet is not adequate in nutrients,it is the dietitians responsibility to help the client/patient adjust their diet using food preferences and possibly, supplementation. The correct choice in helping a client achieve an optimal diet is to objectively assess the nutrient intake and then to help the client identify plant sources that may make up for the missing nutrients. Occasionally, a supplement may be needed depending on the type of vegetarian diet and the patient?s food preferences.
Because of widespread misunderstandings regarding vegetarian diets, in this course are included a section on common vegetarian foods. A vegetarian dinner plate should not consist of only cooked carrots, potatoes, broccoli, and a roll, despite the ideas of some caterers.
II. Types of Vegetarian Diets
- Ovo-lacto-vegetarians
Most vegetarians are ovo-lacto-vegetarians. Ovo-lacto-vegetarians consume milk and dairy products and eggs in addition to plant based foods. They consume no animal flesh foods; therefore, they do not consume red meat, poultry, or fish. Those ovo-lacto-vegetarians who consume a variety of foods, including good sources of B vitamins and iron, rarely deal with nutrient deficiencies.
Those who follow an ovo-lacto-vegetarian diet should not rely very heavily on cheese, milk, and eggs. These items are generally high in saturated fat and cholesterol and may be eaten instead of healthier fiber-containing foods. The group of ovo-lacto-vegetarians who consume low-fat and nonfat dairy products was shown to have a lower rate of cancer, heart disease, obesity, diabetes, and hypertension than the average population.
- Lacto-Vegetarians
- Vegan
Fewer people choose to follow a strictly vegan diet. A vegan diet includes plant-based foods such as fruits, vegetables, nuts, legumes, and grains. Any animal-derived foods including milk, gelatin, and eggs are excluded, as well as any meat, poultry, or fish. This diet may be adopted due to health concerns, ethical reasons, or religious reasons. Ethnic foods are often consumed.
- Macrobiotic
The macrobiotic diet is linked to Buddhism and to the Chinese concept of yin and yang. The founder of macrobiotics, George Ohsawa, claims to have cured himself by eating a diet of rice and water only. (2, p. 12) Many people believe the macrobiotic diet can cure cancer. Although this is not supported by research, cancer patients on macrobiotic diets tend to live longer. (2, p. 13)
Modern macrobiotic diets consist mainly of grains, vegetables, sea vegetables (seaweed), soups, and beans. Also included are fruits and nuts as well as many Asian foods including tamari, miso, umeboshi plum, daikon, and lotus root. Fish may be consumed in small quantities. Foods excluded from the macrobiotic diet include red meat, poultry, vegetables in the nightshade family (potatoes, tomatoes, eggplant, and peppers), tropical fruits, and refined sugar. The diet focus is on balance and harmony. Foods should be eaten in season and locally produced foods are preferred.
People who follow a macrobiotic diet have an energy consumption below that of ovo-lacto vegetarians and ovo-vegetarians. (3)
- Pesce-vegetarians
Pesce-vegetarians consume fish in addition to plant-based foods, and may or may not also consume dairy products and eggs.
- Semi-vegetarian (also called Flexitarian)
Semi-vegetarians consume varying quantities of meat products in addition to primarily vegetarian food choices. These individuals usually include small amounts of poultry and fish in their diets. Depending on the individual, meats may be used as condiments or only eaten a few times per week. Also, individuals who avoid red meats but consume chicken and fish may feel they fit into this category.
- Fruitarian
A fruitarian diet is based mainly on fruits. Nuts, seeds, and vegetables that are botanically fruits including squash, tomatoes, eggplant, peppers, and avocado are eaten. It is extremely difficult to plan a fruitarian diet with adequate protein and calcium. This diet is not advised for adults and is definitely not advised for children.
- Raw Foods Diet
Those who follow a raw foods diet eat uncooked foods because the cooking process denatures the enzymes naturally found in the food. Those on this diet consume raw vegetables, fruits, nuts, seeds, and sprouted grains and seeds. Between fifty to one hundred percent of the foods are eaten raw. (2, p. 14) Although cooking can destroy the enzymes and deactivate some vitamins in the food, cooking also makes foods easier to digest as it loosens up the starch molecules. If an adequate amount of sprouted grains and sprouted beans are included, this diet can be nutritionally adequate. However, this diet is not advised for children as the very high fiber content and low calorie content does not meet the nutritional needs of growing children.
III. Important Nutrient Concerns
- Macronutrients
- Protein
In the United States, protein intake is associated with animal food consumption. However, many cultures have been consuming plant-based diets for centuries and obtaining adequate amounts of protein without eating any animal products. However, consumption of animal foods is culturally looked at as a sign of prestige and power. That is why animal-based protein intake, and total protein consumption tends to increase when people rise in social class. This phenomena is seen with recent immigrants who consume more meat in the United States because it is available and affordable.
Historically, the concern was that vegetarians would not obtain enough protein for proper health. However, although vegetarians consume less protein than meat eaters, on the average, a well-planned vegetarian diet is adequate in protein content. Meat eaters tend to consume 14-18% of their total calories from protein, whereas ovo-lacto vegetarians consume 12-14% of their calories from protein and vegans consume 10-12% of their calories from protein. (2, p. 18)
According to the US RDA, adults should consume 0.8 g/kg of their body weight as protein. (2, p. 83) Proteins do not have to be consumed in specific combinations at each meal, but a variety of protein sources should be used throughout the day to ensure that all twenty amino acids are consumed each day. The current average protein intake in the United States of 14-18% of calories derived from protein sources greatly exceeds the RDA recommendation. (2, p. 84-90)
Optimal levels of protein intake depend on the digestibility as well as the amino acid content. However, the majority of proteins are digested and absorbed quite well. Proteins from plant foods such as whole grains, beans, refined grains, and vegetables are about 85% digestible and the protein consumed by those consuming meats and refined grains is about 95% digestible. In countries where beans play a large part in the diet and refined grains are not available, digestibility could be down to 75%. Higher quality proteins would have more of a variety of amino acids in them. Cereals tend to be low in lysine and threonine and legumes tend to be low in methionine and cysteine. Complete proteins supply all essential amino acids. (2, p. 84-90)
Humans need twenty amino acids, but cannot produce nine of these, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Animal-based foods and soybeans contain complete proteins. Grains are high in some amino acids including the essential amino acid lysine and beans are low in lysine. To obtain the required amino acids, complementary proteins have to be eaten during the same day, but not necessarily at the same meal. Grains and beans contain complementary proteins, as do nuts and seeds, and corn and legumes. For example, a dish of beans and rice would contain all twenty amino acids as the beans and rice contain complementary proteins to each other.
- Carbohydrates and Fiber
The vegetarian diet has a higher percentage of calories from carbohydrate than the mixed diet containing meat products. The carbohydrate intakes for ovo-lacto vegetarians generally is between 50 to 55% of calories, and for vegans is 50 to 65 percent of calories, but only less than 50% for meat eaters. The dietary fiber intakes for ovo-lacto vegetarians is between 20 to 35 grams/day, and for vegans is 25 to 50 grams/day, but only 10 to 12 grams/day for meat eaters. (2, p. 18)
The recommended level of dietary fiber level is at least 25-30 grams/day for a healthy adult. (34)
Since vegetarians consume approximately double the fiber of non-vegetarians, they receive the benefits of reduced colon cancer rates.
- Fat and Cholesterol
At the end of an eight week study of increased fruit and vegetable consumption in a group of African hypertensive subjects in Nigeria, researchers found significant reductions (P < 0.05) in serum triglycerides (125.87 +/- 6.0 to 108.27 +/- 5.49 mg/dL); total serum cholesterol (226.60 +/- 6.15 to 179.20 +/- 5.78) and LDL cholesterol (135.69 +/- 5.56 to 93.07 +/- 7.18 mg/dL). However, no significant reductions were found for BMI or HDL cholesterol levels. The dietary fiber and high antioxidant of the vegetarian diet leads to a lower heart disease risk. (4)
A cross-over study of 35 healthy, premenopausal women showed that mean serum LDL, high-density lipoprotein (HDL), and total cholesterol concentrations decreased 16.9%, 16.5%, and 13.2%, respectively while the subjects followed the vegetarian diet for the length of two menstrual cycles. The LDL/HDL ratio did not change. This study again showed the vegetarian diet to benefit cholesterol levels, despite the undesirable decrease in the HDL levels along with the desirable decrease in LDL levels, thus reducing the risk for heart disease. (5)
- Calorie Level/ Amount of Food
In the United Kingdom, a study of 37,875 healthy men and women between 20 and 97 years old showed a significant difference in BMI between meat eaters and vegans. Age-adjusted BMI was highest in the group of meat eaters (24.41 kg/m2 in men, 23.52 kg/m2 in women), lowest for the vegans (22.49 kg/m2 in men, 21.98 kg/m2 in women), and intermediate for the fish eaters (23.29 kg/m2 in men, 22.60 kg/m2 in women) and the vegetarian group (23.28 kg/m2 in men, 22.51 kg/m2 in women). The same study reported calorie intakes of 9344 kJ in male and 8039 kJ in female meat eaters, intakes of 9011 kJ in male and 7782 kJ in female fish eaters, 8872 kJ in male and 7632 kJ in female vegetarians, and 8232 kJ in male and 7034 kJ in female vegans. This study adjusted for lifestyle factors, including smoking and exercise levels. Obesity rates were significantly lower in the vegan group. The vegan diet has an overall lower caloric density, so more food can be consumed without causing obesity. Also, low fiber intakes tend to be associated with obesity. Meat eaters have much lower fiber intakes than vegans. The authors suggest that increasing the levels of plant foods in the general diet could help prevent obesity. (6)
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