of pregnancy and lactation (L).
Source: Reprinted from Baroni et al. (2018).
A well‐planned vegetarian diet, containing a variety of foods and food groups such as vegetables, fruits, whole grains, legumes, nuts, and seeds, can provide adequate nutrition. In 2009, the American Dietetic Association (ADA) published a position statement regarding the nutrient adequacy and safety of a vegetarian diet:
It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well‐planned vegetarian diets are appropriate for individuals during all stages of the lifecycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes.
However, more recent data support the notion that the risk of specific nutrient deficiencies is real, especially in those following a vegan diet. Therefore, vegans must regularly consume sources of vitamin B12 and D, omega‐3 fatty acids, Ca, iodine, iron, and zinc, such as fortified foods or supplements – otherwise they may become deficient in these nutrients. Recent data support that not only vegans but also lacto‐ovo‐vegetarians are at risk of developing B12 deficiency, and thus all vegetarians could benefit from B12 supplementation.
Key Point
Vegans must regularly consume sources of vitamin B12 and D, omega-3 fatty acids, Ca, iodine, iron, and zinc.
Many people consider vegetarian diets to be superior to nonvegetarian diets, in terms of quality. This is because the vegetarian food choices are high in dietary fibers, magnesium (Mg), potassium (K), vitamins C and E, folate, carotenoids, and other phytochemical substances, and they are low in saturated fat, cholesterol, and sodium content. Vegetarian dietary patterns have been shown to reduce cardiometabolic risk, including the risk of developing T2DM and hypertension. Results from large clinical trials suggest that vegetarian dietary patterns can improve ΗbA1c, fasting glucose levels, and other established cardiometabolic risk factors, such as high LDL‐C and high systolic and diastolic BP compared to nonvegetarian dietary patterns.
Results from large cohort studies, with a follow‐up period ranging from 4 to 21 years, show that the vegetarian dietary pattern is associated with reduced overall incidence of cancer, compared to nonvegetarians. The mechanism(s) mediating the effect of vegetarian diets on cancer risk is not known. It has been suggested that vegetarians have lower levels of hs‐CRP compared to people who eat meat; the high antioxidant and anti‐inflammatory effects of the food groups included in this pattern may also result in lower inflammation in the long term.
Adopting a vegetarian diet results in significantly lower CVD risk. The protective effect of vegetarian diets on cardiovascular risk seems to be mediated by the reduction of meat consumption and the increased consumption of fruits and vegetables. For each additional serving of fruits and vegetables consumed, the likelihood of all‐cause mortality decreases by 5%, while eating more than five servings/day does not appear to further mitigate the risk. Regarding CVD deaths, for each daily serving of fruits and vegetables per day, CVD mortality is reduced by 4%.
Key Point
Adopting a vegetarian diet results in significantly lower CVD risk.
A detailed description of the vegeterian dietary model and a sample menu plan can be found in Appendix B.3.
Take‐Home Messages
A vegetarian diet is a dietary pattern based predominantly on plant‐origin products. Vegetarians exclude most meat (including fowl) and products containing meat.
Vegan diets are devoid of all flesh foods (such as meat, poultry, seafood, and their products). Other types of vegeterian diets are devoid of all flesh foods but may include egg (ovo‐vegetarain), fish (pesce‐vegetarian), dairy (lacto‐vegetarian), or combinations.
A well‐planned vegetarian diet, containing a variety of foods and food groups such as vegetables, fruits, whole grains, legumes, nuts, and seeds, can provide adequate nutrition.
However, the risk of specific nutrient deficiencies is real, especially in those who follow a vegan diet. The most common nutrient deficiencies are vitamins B12 and D, omega‐3 fatty acids, calcium, iodine, iron, and zinc, as these micronutrients are derived mainly from animal products.
Vegetarian diets are considered by some to be of higher diet quality compared to nonvegetarian diets due to their high content in dietary fibers, Mg, K, vitamin C and E, folate, carotenoids, and other phytochemical substances, and their low content in saturated fat, cholesterol, and sodium.
Vegetarian dietary patterns have been shown to reduce cardiometabolic risk, including the risk of developing T2DM, hypertension, and obesity, as well as cancer incidence and mortality from CVD.
Self‐Assessment Questions
1 What are the most common vegetarian diets?
2 Are there any risks of specific nutrient deficiencies when a person follows a vegan diet?
3 Why do people following a vegetarian diet have a lower risk of developing cancer?
4 How can a vegetarian diet contribute to sustainability?
The Religious/Fasting Diets
Disease prevalence and mortality rates differ between populations. Differences in genetic makeup, lifestyle habits, and other characteristics may explain these disparities. Religion is an important factor in shaping some people's beliefs; their lifestyle and dietary habits are often influenced by their religious traditions and practices. Many religious doctrines exist, each one having followers with varying degrees of devotion. It is common for these religious creeds to be related to specific religious food practices or customs; dietary restrictions may include the types of foods that are allowed in the diet, the foods that are allowed to be consumed on specific days of the week/month/year, the timing of food consumption, methods to prepare food, and when and how long to fast.
Fasting is common in most religions. It is considered a call to purification, holiness, and spirituality. The practice of fasting is acknowledged as the means by which the pious believers expiate for their sins, so as to be accepted by God, as well as to identify themselves with the anguish of the destitute. Fasting signifies resistance to temptation, as a deed of expiation for committed sins but also as a means to prevent excessive eating and drinking. The duration of fasting may vary from a few hours during the day (e.g., from sunrise to sunset for Jews), to a fixed number of hours (e.g., 12‐24 hours or more for Catholics, Greek Orthodox, and Mormons whose fasting is practiced on specific days), but also for several successive days, as happens during the Ramadan month for Muslims.
Detailed descriptions of the following religion‐based dietary models and their corresponding sample menu plans can be found in Appendices B.4.‐B.8.
Buddhism
“Do not kill or harm living things” is the first of five basic precepts of Buddhism. Thus, the majority of Buddhists abstain from meat consumption, and all of them exclude beef products from their diet. The major religious events for Buddhism are the birth, the enlightenment, and the death of Buddha; on these days devotees do not work but spend their time celebrating and fasting. Buddhist monks undergo complete fast depending on the moon phase, and they refrain from solid food intake after noon.
The life of a Buddhist encompasses many other lifestyle factors that have been shown to improve health. For example, Buddhists practice meditation and yoga, activities that have been shown to cause favorable health effects. Meditation has positive effects on reducing stress and increasing mindfulness,