Food and Diet

Abstract

Diet is a primordial strategy for disease prevention and health protection. This chapter offers an interesting history of food, and the evolution of modern and Ayurvedic concepts of nutrition. The chapter highlights the importance of digestion as part of nutrition, in addition to concepts like calories, and proximate principles. Varying diet according to season and the nature of the individual are practiced by many communities. The authors discuss the physiological effects of fasting, calorie restriction, and special diets prescribed during various stages of the life cycle. Emerging data supports the importance of gut microflora, pre- and probiotics, and diet and immunity. Ayurveda prescribes dos and don'ts regarding diet, which are based on principles to maintain, or regain homeostasis. Ayurveda considers diet and nutrition specific to the individual constitution, which is similar to the nutrigenomics approach. Ayurveda concepts of Prakriti and Agni as regulators of metabolism are also discussed. The chapter provides case studies in order to indicate potential areas of research, which are important in health care.

Keywords

Calorie restriction; Dietary advice; Dietetics; Digestion; Fasting; Food; History; Lifestyle modifications; Nutrigenomics; Nutrition

Let food be thy medicine, and medicine be thy food.

Hippocrates

Historical Account

Every living form requires food for survival and growth. Interestingly, all species have interdependence in terms of food—whether it is obtained from vegetable or animal sources. In this chapter we will deal with historical perspectives, current status, and future trends related to food, nutrition, and diet for human beings.

Food is an essential part of life needed to produce energy, metabolism, sustenance, and growth. Food contains essential nutrients known as proximate principles including carbohydrates, fats, proteins, vitamins, and minerals. The Encyclopedia Britannica defines food as “any substance consumed to provide nutrition for the body.” However, in many traditions and holistic systems, the purpose of food is not only for nourishment of the body, but also to nourish mind and spirit. Probably, the expression “food for thought” is the result of such thinking. A detailed discussion on the philosophy of food is given by Harvard neurobiologist, Dr David Kaplan [1].

The history of food goes back to the history of mankind. Primitive populations were reliant on food mainly from water bodies, and forests. People secured food mainly through hunting and agriculture. Probably, sometime around 7000 BC, neolithic man acquired fire and cooking techniques. Dr Lynne Olver, famous food historian, started an interesting Web site The Food Timeline, which gives a very comprehensive account of the evolution of food, nutrition, diet, and culinary sciences. It describes use of various food items on a timescale that covers the use of salt, rice, and millet from ancient times (around 17,000 BC) until modern times with the example of cultured beef in the laboratory [2]. In earlier times, with the abundance of water, ice, salt, and forests primitive food consisted of different types of fish, squid, oysters, eggs, meat, insects, mushrooms, vegetables, and fruits. Rice seems to be the most ancient food grain, followed by millet—a generic name for cereals other than those of the genera of wheat, barley, rye, and oats [3].

Scientists estimate that nearly 10,000 years ago, rice cultivation was practiced in India and China. In around 1609, in the United States, rice cultivation began in Virginia, followed by South Carolina, and other parts of the country. Wheat emerged some time around 8000 BC, followed by many other foods like cereals, pulses, nuts, honey, ginger, chili peppers, maize, and dates. It took almost two millennia for milk, yogurt, and potatoes to emerge on the scene. The oldest known record of animals being kept in groups, and milked is found in cave paintings of 5000 BC in the Libyan Sahara. The Sumerians, around 3500 BC, and the Egyptians a few centuries later, used milk, and curdled milk products. At around 3000 BC chicken domestication, butter, palm oil, olive oil, onions, garlic, spices, and soybeans probably emerged. The beginning of processed food was also during this period, starting with popcorns. At around 2000 BC, many more meats, like ham and duck, and fruits and vegetables, like peaches, apples, and radishes, came into use. Recipes for pasta and noodles were originated. Around 1000 BC, chocolate, vanilla, sugar, mangoes, oats, tomatoes, celery, pickles made way. Probably from 4000 BC food processing and recipe science started developing with yeast fermented bread, pita bread, and ice cream was introduced some time in 3000 BC.

Ancient Egyptian and Mesopotamian recipes and customs dominated until the first century BC when ancient Romans introduced Italian cuisine, soups, puddings, omelets, fried chicken, and cheese cake. This was followed by Anglo-Saxon foods from the fifth to ninth centuries AD, and medieval foods from the tenth to fifteenth centuries. The sandwich was introduced by John Montagu in 1762, followed by a wide range of European, English, and Scottish foods such as pastries, muffins, and preserves.

An era of great American foods consisting of a large variety of irresistible and addictive junk foods began in the late nineteenth century. In 1853, the potato chip was developed as a new food product in New York. Pemberton developed and launched Coca-Cola in Atlanta, Georgia in 1886. The hamburger was first created by Louis Lassen in 1900. Junk food chains including McDonalds, Kentucky Fried Chicken, Burger King, Pizza Hut and others spread like wildfire in the United States. During the past two decades, the junk food industry has come on to the radar of public activists and scientists. The many health hazards from the consumption of junk food were noticeable, which led to increased awareness, and reduced consumption, especially in the United States. As a result, the junk food industry came under pressure to infiltrate new markets in developing countries. Today in India, chilled Coke and chips are available in remote areas where safe drinking water, and lifesaving drugs are scarce.

The lifestyle and dietary changes of the twentieth century had a deep impact on the social fabric in the United States. During this period, the United States witnessed substantial increase in automation, and an automobile-based way of life. A new culture of fast food consumption, and consumerism emerged. Mass entertainment, starting with radio and television, followed by social networking, and the IT revolution had additional impact [4].

As a result, the family structure was disturbed, food habits were changed and social interactions now take place in a virtual mode. Physical activity and personal interactions have been greatly reduced. Home theaters have brought cinema into the living room, and the habit of eating out has supplanted the home kitchen. This double burden of food and lifestyle change has silently affected the American population, resulting in an epidemic of obesity—a greater than 75% rise in obesity prevalence has been reported between the years 1890 and 2000 [5]. The United States’ National Health and Nutrition Examination Survey showed that more than one-third of children, and more than two-thirds of adults in the United States are overweight, or obese [6]. All agencies, including the National Institutes of Health (NIH), Centers for Disease Control and Prevention (CDC), and United States Department of Agriculture (USDA) emphasize the importance of improved nutrition, reducing calorie consumption, and increasing physical activity. Junk foods, red meat, sodas, and sugary drinks are going out of fashion. Healthy, organic, and nutritious food is gaining popularity. The rich world has just completed a full cycle. Nutrition is back to center stage.

Food and Nutrition

Food has two main functions. The first is to provide the nutrition to build every cell and tissue for body growth. The second function of food is to provide the necessary energy, in terms of calories, to keep the body functions running. Food consists of five proximate principles, including proteins, carbohydrates, fats, salts, and vitamins. Water is also an essential component of food, but has no caloric value. Proteins, carbohydrates, and fats are known as macronutrients, because they are required in large quantities. Vitamins and minerals are considered as the micronutrients, because they are needed in small quantities.

Carbohydrates are the main source of energy for our body. They constitute grain-based products, sugars or simple carbohydrates, starches or complex carbohydrates, and dietary fiber. The main sources of carbohydrates are cereals. Proteins are the building blocks vital for the structures and functions of the body. They are required for muscles mass, cell membranes, and for every tissue. All enzymes are proteins. The sources of proteins are legumes, pulses, milk, meat, poultry, and fish. Fats serve as the major storage of energy in the body. Excess fat is stored in the body in adipose tissues. The main sources of fats are butter, oils, nuts, and fish.

Vitamins regulate many functions in the body. They are essential for various metabolic processes, and building body tissues. They help in digesting carbohydrates, proteins, and fats. They prevent several deficiency diseases, promote healing, and good health. All fruits and vegetables, milk and milk products, nonvegetarian food, and cereals are good sources of vitamins. Minerals are also essential because they are required to build muscles, tissues, and bones; they are important components of hormones, and enzyme systems. There are two types of minerals: macro-minerals, which are required in large quantities, include calcium, phosphorus, magnesium, sodium, potassium, sulfur, and chloride; trace or micro-minerals, which are required in smaller quantities, include zinc, iodine, copper, manganese, fluoride, chromium, and selenium. The sources of minerals are all fruits, vegetables, milk and milk products, cereals, and nuts, and non-vegetarian food.

Science of Nutrition and Diet

The process of food assimilation, and its use for sustenance, growth, and tissue regeneration is called nutrition. Nutrients are substances essential to life, which are available in food. Food is part of the ecosystem, and is required by all living, interdependent species. Thus, changes in the environment, and ecosystem have a direct impact on food, and hence, on nutrition. Hippocrates, in year 400 BC, said “Let thy food be thy medicine, and thy medicine be thy food.” In those days foods were often used as cosmetics, or as medicine. Far-Eastern, and biblical writings make references to food and health. The famous philosopher and artist, Leonardo da Vinci, compared the process of metabolism in the body to the burning of a candle. This has a striking similarity to the concept of Agni in Ayurveda, which is elaborated in the primer, and discussed in later sections. In 1747, James Lind, a physician in the British navy, performed the first clinical trial as a scientific experiment. Lind gave six groups of sailors different supplements, along with the same diet. The six groups received cider, elixir of vitriol, vinegar, seawater, barley water, and oranges with lemon. He noticed that those receiving oranges and lemons were cured of the disease, scurvy. Vitamin C was discovered in the 1930s, and the nutritional value of lime was understood. Antoine Lavoisier, who is considered the father of nutrition, discovered the process of metabolism in 1770. He demonstrated that body heat is generated from the oxidation of food. In the early 1800s, it was discovered that food contains four elements, carbon, nitrogen, hydrogen, and oxygen. In 1840, Justus Liebig of Germany, showed that sugars are made up of carbohydrates, fats makeup fatty acids, and proteins are made up of amino acids.

In 1897, Christiaan Eijkman from Holland, observed that some of the natives in Java suffered from heart problems, and paralysis due to the disease, beriberi. He observed that when chickens were fed the native diet of white rice, they developed the symptoms of beriberi, but when they were fed unprocessed brown rice with the outer bran intact, there were no symptoms of the disease. When Eijkman fed brown rice to beriberi patients, they were cured. Later, it was discovered that the outer rice bran contains thiamine, or vitamin B1, and its deficiency leads to beriberi. This was the beginning of functional foods. Frederick Hopkins, an English biochemist discovered tryptophan, an important amino acid, which can’t be synthesized by our body, and has to be supplied through proper diet. In 1912, he published the findings of his animal experiments. He demonstrated that the growth of rats is impeded when they were fed artificial mixtures of isolated casein, fat, carbohydrate, and salts. He demonstrated that the rats who were given additional fresh milk were able to maintain normal growth [7].

Sir Frederick concluded that, “no animal can live upon a mixture of pure protein, fat, and carbohydrate. Even necessary inorganic material like salt supplementation is not enough for any animal to grow and sustain.” There are certain other ingredients, and minor factors that are vital for growth and sustenance. Later, some of these were categorized as vitamins. The requirement of these ingredients may be very small, but their presence in diet is vital to produce enzymes, hormones, and other substances, which are essential for growth, development, and survival. These are now known as micronutrients, and consist of several vitamins, minerals, and other growth factors. The consequences of micronutrient deficiency are severe. Eijkman and Hopkins were awarded the Nobel Prize for their discovery of vitamins.

In 1912, Dr Elmer McCollum, from the University of Wisconsin, discovered the first fat soluble vitamin, vitamin A. He demonstrated that rats fed on butter were healthier than those fed on lard. He showed that it was because of the vitamin A present in butter. That same year Dr Casimir Funk, a Polish biochemist coined the term vitamins—vital amines in the diet. Later, in 1930s, Dr William Rose, a professor of physiology from the University of Illinois discovered the essential amino acids as the building blocks of protein. In the 1940s, American chemist Russell Marker synthesized progesterone from diosgenin in wild yams. Subsequently, work on essential nutrients, and the role of vitamins and minerals as cofactors of enzymes and hormones, was advanced.

German physiologist, Carl von Voit is the father of modern dietetics. He demonstrated that protein turnover can be measured in the form of excreted urea. Another German physiologist, Max Rubner, proposed the isodynamic law of calories. This law stated that based on their caloric values, different foodstuffs can replace one another. This notion originated the much debated phase in modern nutrition “a calorie is a calorie.” These two scientists helped in shaping modern dietetics. Rubner also stated the inverse relation between metabolic rate and longevity, based on his observations: “Larger animals have slow metabolic rate, hence they live longer than smaller animals.” This theory was also debated in due course, however, and formed the relation between metabolic rate and longevity. Nobel laureate, Dr Linus Pauling, suggested that mega doses of vitamin C given intravenously can improve the quality of life of cancer patients. This was the beginning of nutraceuticals, and dietary supplements. Necessary regulations begun to be enforced from this time by FDA.

As discussed in Chapter 3, nutrition is one of the most important determinants of health. Both under-nutrition, and overnutrition may result in ill-health. This has led to concept of the balanced diet, which provides macro- and micronutrients in required quantities. Diet also provides energy in terms of calories which are required for running our systems. Foods rich in calories, but poor in nutrition are often termed junk foods. A good diet needs a balance of nutrients and calories. Of course, there is nothing like a universal balanced diet. The components and proportions may change depending on geo-cultural environments. Therefore, we need scientific evidence to know, and design healthy diets from available foods so that optimal nutritional needs are met. This is addressed in a discipline known as dietetics, and the job is done by dietitians.

The science and art of applying food and nutrition knowledge to design diets is known as dietetics. Dietitians are expert professionals who are able to advice the right diet for people in order to promote, and prevent disease. Food, nutrition, diet, and different cuisines have evolved over thousands of years. They have gone through individual’s and communities’ experimentation in relation to type of foods, processes, nutritive value, health benefits, taste, appearance, and many more considerations. This interdisciplinary science is known as gastronomy, which involves researching, discovering, understanding, tasting, experiencing, and documenting food preparations. It also studies the sensory qualities of human nutrition, and interfaces with broad sociocultural practices. A new branch, known as molecular gastronomy, deals with applying the knowledge of biology and chemistry to cooking, and the culinary arts.

Digestion and Gut Health

A review of the physiological mechanisms controlling energy balance is interesting, and an understanding of these mechanisms is propelling modern dietetics to become a holistic and interdisciplinary discipline. Modern nutrition and dietetics—that was previously confined to the approach, “a calorie is a calorie”—is adopting a comprehensive view based on the advancing understanding of physiology. Advancing physiology is adding to our understanding of the complex processes of hunger, food intake, digestion, and elimination of wastes.

The desire for food is hunger. This feeling is a basic instinct of every animal. Appetite is the word used for a feeling of craving the consumption of something. The delay between the swallowing of food, and its digestion may lead to overeating; hence the mechanism for the short-term control to prevent overeating is the sensation of satiety. Satiety is the feeling of satisfaction that limits further intake. These signals are triggered by centers in the hypothalamus, and regulate food intake. Hunger and satiety maintenance requires a balance of energy, and depend on several psychological, social, and environmental factors, such as nutrients and metabolic processes, gastric and intestinal contractions, blood levels of nutrients, and temperature.

The sensation of hunger is a complex phenomenon regulated by mechanical and hormonal stimuli. Ghrelin, a hormone produced by the empty stomach, sends signals to the brain that stimulates the hunger center. Orexin, another hormone secreted by the hypothalamus, also stimulates the hunger center. The amount of food intake is controlled by other hormones, and nervous controls. The distension of the walls of the stomach and duodenum causes vagus nerve stimulation that sends inhibitory signals to the feeding center. Cholecystokinin released mainly in response to the presence of fat and proteins, contributes to satiety, and prevents overeating. Neuropeptide Y, and insulin suppress appetite. Apart from these short-term controls of feeding, leptin is another hormone important for the long-term regulation of food intake, and body fat. Adipose tissue is not just energy storage, it is now considered to be an endocrine organ, as it produces the resistance hormones, leptin, adiponectin, and resistin.

Leptin and ghrelin are satiety hormones, and regulates energy storage. Leptin decreases the feeling of hunger while ghrelin increases appetite. Leptin levels are lowered during starvation, which, facilitates the stimulation of the hunger center. In the case of sufficient fat storage, it suppresses hunger. Adiponectin is an anti-inflammatory adipokine that regulates insulin sensitivity, and suppresses apoptosis and reduces oxidative stress. Its preventive role in atherosclerosis, obesity, diabetes, liver diseases, kidney diseases, and neurocognitive disorders is suggested in recent studies [8]. Like hormonal control, nervous mechanisms of energy balance are also interlinked. The vagus nerve is a cranial nerve that constitutes the sympathetic component of the autonomic nervous system. The vagus nerve lowers heart rate and sweating; and controls muscle movements of larynx for speech and breathing. It carries axons that increase secretions of the mucous glands of the pharynx, larynx, and other organs in the thorax, and abdomen. The vagus nerve also has sensory functions, and carries sensations from the epiglottis region, thoracic and abdominal viscera, auditory meatus and tympanic membrane, and aorta. The hormones regulating energy storage are involved in many other functions. The orexin system, apart from controlling energy homeostasis and feeding, regulates sleep/wake states, and the maintenance of wakefulness. The orexin system also affects behavior and emotions [9]. The role of ghrelin in promoting growth, and in regeneration mechanisms has been studied. The experiments demonstrate the enhancement of the regenerative potential of the GI epithelium by modulating cell proliferation. Ghrelin hormone also accelerates the regeneration process when hyperthermia is induced suggesting its regenerative potential [10]. Hormones, and nervous controls of energy balance regulate other vital functions. These coordinated functions suggest interlinks between various vital organs, with nutritional status as the common trigger [11].

The complex and interconnected functions of the gut constitutes the enteric nervous system (ENS). This brain in the gut has several added features. The ENS can operate autonomously to regulate motility, and secretions of the gut [12]. Another typical attribute of ENS is the modulation of the response, based on the nutrient composition of the food. The neurotransmitter, serotonin (5-hydroxytryptamine) is found in the central nervous system, platelets, and gut. The enterochromaffin cells of the gut secrete serotonin, which is taken up by platelets. The activities of serotonin in vasoconstriction, depression, memory, sleep, appetite, and temperature control have been known for years. The recent understanding of serotonin explains more functions like gastrointestinal motility, enteric neurogenesis, mucosal growth and maintenance, intestinal inflammation, osteoblast proliferation, and promotion of hepatic regeneration [13]. Serotonin is an important growth factor of ENS that elaborates the gut–brain relationship.

Many research publications in recent years discuss gut microbiota. In the human body, microorganisms constitute an ecosystem consisting of around 100 trillion bacteria and other microorganisms—almost 10 times the number of the cells of the body. The gut microbiota or intestinal flora has many functions, and is considered to function like an organ. It synthesizes vitamins B and K, provides protection from pathogens, maintains the intestinal barrier, absorbs lipids and polysaccharides, and modulates intestinal motility. The gut microbiota and brain interaction maintains gastrointestinal homeostasis [14]. Microbiota can affect several nervous and cognitive functions. The alteration of healthy flora can lead to a range of disorders like inflammatory gastrointestinal disorders, and obesity [15].

The concept of gut health is becoming a point of discussion. More than 6000 papers discuss the various aspects of gut health. More than 6500 papers published so far focus on the association of gut health, and metabolism. The concept is important as a determinant of diseases, as well as its possible role in preventive and therapeutic strategies. The characteristic of microbiota is an important indicator of overall, physiological functions. The detailed study of gut health-related gastrointestinal (GI) functions is now considered important in preventive medicine.

Various components define gut health. Gut health is now considered a new objective in medicine. A healthy gut can ensure good digestion, and absorption of food, prevent GI illness, has normal intestinal microbiota and effective immune status, and can provide a status of wellbeing [16]. Various intestinal, and extra-intestinal diseases are associated with the GI barrier and microbiota. For example, diarrhea, inflammatory bowel disease, celiac disease, allergic diseases, arthritis, obesity, and many autoimmune diseases have a strong relation to gut health.

Diet Therapy

Different regions and cultures have different dietary practices. Traditionally, people have used local food resources as part of their everyday diet. It is believed that for regular consumption, foods available in neighboring regions are more compatible with people’s systems than exotic foods. However, in the process of human development, coupled with migration, travel, tourism, and in general, due to process of globalization, foods, and diets from one region have moved from one country, to other continents. Thus, Chinese and Indian food are popular in the West; Italian cuisine is popular worldwide; the Mediterranean diet is considered to be healthy; and Western fast food is considered to be junk food. Based on traditional experiences and scientific evidence, it is possible to propose a wide range of diets for health promotion, disease prevention, and treatment. Scientists and dieticians have prepared several types of diets for special purposes, or for treating, and preventing specific diseases. A short review of a few of these special diets will be interesting.

The Western dietary pattern is criticized mostly because it contains refined food, its high caloric content, low vegetable content, the excessive use of saturated fatty acids and sugars, and low fiber. The effect of maternal Western diet on neonates was studied in a mice model, in order to understand its mechanism. The milk of such mice was found to contain long chain, and saturated fatty acids in large proportions. This “toxic” milk can trigger inflammation in the mice neonates [17].

Ten trials with a whole grain component, like oats, have reported the lowering of low density lipoproteins (LDL) cholesterol, compared to the control foods. However, experts suggest that the positive findings about whole grain oats should be cautiously studied. A systematic review has indicated that most of the trials on whole grain oats were funded by companies with commercial interests in whole grain. Experts are emphasizing the need for randomized controlled trials on whole grain foods other than oats [18].

A diet rich in fruits, vegetables, low-fat dairy products, low cholesterol, and less sugary products can help to lower blood pressure in individuals with prehypertension. The health benefits of this diet were studied in a trial known as the Dietary Approaches to Stop Hypertension (DASH). The DASH diet is introduced by the National Heart, Lung, and Blood Institute of the United States. The diet plan suggests plenty of fruits, vegetables, whole grains; limited use of fat, dairy items, meat, fish, poultry, sugar-sweet foods and beverages, and red meat. The DASH diet plan also aims at providing a balanced diet for general prevention of diseases, apart from its therapeutic effects on hypertension.

A more comprehensive lifestyle modification program that includes exercise and weight loss, together with the DASH diet can significantly improve insulin sensitivity [19]. Another review has concluded that the DASH diet alone can lower blood pressure in overweight individuals. It has shown that a DASH-like diet can significantly protect against Cardiovascular diseases (CVDs), stroke, and cut heart failure (HF) risk by 20–30%. The DASH diet may play an important role in glycemic control in long-term interventions [20].

The Mediterranean diet primarily consists of plant foods, such as fruits and vegetables, whole grains, legumes and nuts. It uses healthy fats, such as olive oil instead of butter, and uses herbs and spices, instead of salt to flavor foods. It restricts the use of red meat to not more than few times a month, and uses fish and poultry at least twice a week. It also recommends moderate drinking of red wine. Several studies have been done in recent years to assess the benefits of the Mediterranean diet [21]. A meta-analysis of 12 studies involving 140,001 individuals was published recently in the Journal of the American College of Cardiology has reported a greater than 21% reduced risk for diabetes, and consequent prevention of cardiovascular disease [22]. A randomized trial involving 7447 persons at high cardiovascular risk was undertaken to study the role of the Mediterranean diet in the prevention of cardiovascular disease. Results of this well-controlled trial indicate that the Mediterranean diet, supplemented with extra virgin olive oil, or nuts can reduce the incidence of many cardiovascular events [23]. Eleven relevant, randomized controlled trials involving 402 participants have reported improved glycemic control, and a significant decrease in the glycated-hemoglobin (HbA1c), in subjects on a low-glycemic index [24].

A diet plan suggested by the General Motors Corporation for their employees to shed weight, has now become one of the most talked-about diet regimens on the Internet, and television [25]. However, scientific evidence on this diet plan is lacking. The plan is considered the fastest way to reduce weight, through intensive modifications in a week-long crash course. The plan is also criticized for the associated side effects.

We feel that several regions and cultures across the globe have unique food and dietary practices. Most of them are based on locally available food materials. The environmental compatibility between the food and people must be kept in mind before propagating, or generalizing particular practices to other regions or communities. What is important is the basic principle behind that practice, and not necessarily the actual food materials, which can vary depending on availability in respective geoclimatic regions.

There is little doubt that Mediterranean diet patterns are healthy. Many scientific studies have established their usefulness in preventing cardiovascular diseases. Extra virgin oil may add to their protective effects. However, these studies have been conducted on European, Caucasian communities for whom it is a traditional, natural diet. We cannot assume that similar benefits can be achieved if these dietary practices are embraced by Asian, or African communities. However, every region will have their own fruits and vegetables, and consuming these foods when they are fresh, may give similar benefits. In tropical regions, local fruits like banana, green leafy vegetables, local varieties of berries, and the use of sesame or coconut oil, may be more compatible with the people’s systems, affordable, and more beneficial than exotic blueberries, or extra virgin olive oil. Ayurveda advocates a principle that nature does provide all the necessary foods and nutrients in all surroundings, and local foods are the best, and most compatible to people. Therefore, for a change, one can taste different foods, and cuisines from different parts of the world; but for health protection, it is best to use locally available, natural food resources.

Dietary Advice

The routine dietary advice from dieticians, clinicians, and health professionals is very general. Eat fresh fruits and vegetables. Avoiding salt, sugar, sodas, refined flour, saturated fats, butter, oily, fried, spicy, and food stuffs seem to be general mantra. But in moderation everything is needed. Moreover, the environmental and socioeconomic conditions, coupled with cultural practices need to be taken into consideration when offering any dietary advice. Honest scientific advice can be beneficial in the prevention, and control of several diseases. Many professional bodies, associations and councils offer evidence-based, dietary advice. As the scientific knowledge advances, the nature of dietary advice keeps on changing. However, many other forces, and vested interests also play an influential role in making, and revising dietary guidelines. In the process, the situation becomes very confusing for people, and even for professionals.

Recent controversy about the role of fats in diet is a classic case. The American Heart Association’s (AHA) diet and lifestyle recommendations advise reducing foods containing partially hydrogenated vegetable oils, and saturated fats. This includes foods like butter. The general advice here is for people to reduce their intake of foodstuffs like butter. There have been good studies supporting this advice. For example, a meta-analysis of 44 trials, involving 18,175 healthy adults, with and without dietary advice related to reduction of salt and fat intake, and with an increase in the intake of fruit, vegetables, and fiber showed improvements in cardiovascular risk factors. Two trials followed people for 10–15 years, and showed a reduced incidence of heart disease, stroke, and heart attack [26]. Based on the guidelines from reputed professional organizations like the AHA, generally it has been accepted that eating saturated fats and butter is to be avoided.

In March 2014, a new meta-analysis was published by scientists from University of Cambridge in the Annals of Internal Medicine, which concluded: “Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids, and low consumption of total saturated fats” [27]. This came as a big comfort to the butter industry. Several articles were published in the media, with the message that butter is not bad. On June 12, 2014, Time Magazine published very provocative cover story “Eat Butter,” with article title “Ending the War on Fat.” The first paragraph stated: “For decades, it has been the most vilified nutrient in the American diet. But new science reveals fat isn’t what’s hurting our health.” Interestingly, Time Magazine had carried a cover story in March 1984, giving exactly the opposite message—butter was bad. This case is quite representative where one can sense the undercurrents—vested business interests, and the nexus between scientists, media, and industry. Finally, in the process, it is the gullible public that suffers.

Of course, there are well-meaning scientists, media, and business people as well. Following the publication of Time’s provocative article giving the clean bill of health to butter, the reputable journal, Science published a policy-analysis article, where many experts demanded a retraction, and press promotion as damage control. Many scientists pointed out the errors in this study, which compelled the authors of the original article in Time to amend their conclusions. Many skeptics believe that this was an attempt to check the growing popularity of olive oil, and an industry attempt to regain markets for butter. This is another case where scientists from reputable institutions have played dubious roles, and seem to have worked in a fashion that is beneficial to certain industries.

In India, cow’s milk is traditionally consumed. Ayurveda also recommends fresh milk from naturally grazing cows. Environmentalists and veterinarian scientists are showing concerns about the quality of milk and milk products obtained from hybrid varieties and also use of synthetic hormones and antibiotics just to increase the milk output. The quality of milk from such cows is different than artificially fed cows.

For Indian people, milk from local breeds may be healthier than western breeds like Jersey. Buffalo milk will have different properties as well as the hybrid varieties. Camel milk may be suited for tribal in the desert, goat milk may be suitable for shepherds or yak milk may be suitable for people staying in high altitudes. It is difficult to standardize milk that can be healthy and beneficial to the general global population. The geographical, regional, and cultural practices must be considered seriously while we are globalizing.

Milk is a whole food with numerous nutritive components; especially for infants. However, milk is not as simple as it may appear. Many infants may be immunologically sensitive to milk protein casein. Many individuals may have milk sugar lactose intolerance. Quality and composition of cow’s milk is different than buffalo. Several variants of beta-casein like A1, A2, A3, B, C, etc. are known. Of these A2 from bovine milk is similar to other beta-casein in mammals. The A1 and A2 caseins have different secondary structures, enzymatic hydrolysis products are different. This leads to different physiological properties and impact on digestive, immune, and brain development processes. Anecdotal evidence suggests symptomatic relief in patients with neurological, gastric, and immunological problems, after consuming A2 beta-casein containing milk. Hence, consuming milk containing A2 beta-casein is considered beneficial especially for infants’ growth and development [28].

Thus, even a simple thing like milk has region specific physiological effects. Milk from local breeds of cattle may be more beneficial and healthy. Such incidences actually strengthen our hypothesis that traditional knowledge and practices can be the best advisors, even in modern times. This is more valid in the area of food, nutrition, and dietetics. Traditional practices that have stood the test of the time may provide signposts, such as in the case of the Mediterranean diet. However, we feel that it might be better to offer dietary advice in the context of geoclimatic regions, cultures, and traditions.

Nutrigenomics and Personalized Diet

Diet is known to have a direct impact on the body. A good diet provides good nutrition, and promotes growth, and maintenance of various cells, tissues, and organs of the body. Several traditions believe that food has impact on behavior. According to yoga philosophy, certain types of meat are known as rajasik. They may cause “fight” type response with aggression, anger, annoyance, and irritation. Some foods like milk are known as satvik. They cause “flight” type response and can be very soothing, peaceful, and relaxing. Some types of foods, such as butter cause “freeze” type response and are known as tamasik. They can be lethargic, sluggish, and sleep inducing (Figure 7.1). Thus since ancient times different types of food was accepted to influence living behavior.

It is generally accepted that “we are what we eat.” However, it is now known that diet-related changes go beyond the body and the mind of an individual in this life, but can also affect following generations. These changes are not necessarily limited to, or dependent on, our genome—but go beyond genetics. These are known as diet-induced, epigenetic changes, which are not limited to one generation, but can be inherited by the descendants. Recent research on the effect of diet in the control of gene expression is showing how a pregnant woman’s eating behavior influences the long-term health of her children [29]. Several gut hormones are known to enter the brain. Some such hormones, which can influence cognitive ability, are also produced in the brain. Brain-derived neurotrophic factor is known to respond to specific food intake. Molecular mechanisms of interactions between food and cognitive functions need to be studied more, so that specific diets can be advised to increase neural resistance, and improved mental fitness [30].

Everybody has a different genetic makeup, hence every individual may respond to the same diet differently. Diet is also known to affect the expression of genes. A particular diet for one individual can be pathogenic, but may protect another individual by increasing resistance to certain diseases. Nutritional genomics, or nutrigenomics, is a branch of genomic research that studies the association between diet and genes. It can suggest dietary intervention considering nutritional status, nutritional requirement, and genotype of an individual. The personalized approach to diet can be helpful for preventing, and treating many diseases.

An interesting study by Canadian researchers indicates possible mechanisms of diet-induced, gene expression. Healthy volunteers were given a prudent diet consisting of fruits, vegetables, whole grain products, and lesser amounts of refined products. Another group was given a typical Western diet consisting of a high intake of processed meats, refined products, desserts, and sweets. The gene expression relevant to immune and inflammatory responses were different in both the diet patterns. The finding suggested that volunteers on the Western diet had a proclivity to cancer, and cardiovascular diseases [31]. It is known that specific nutrients can affect cognitive processes, and emotions. These studies actually support the notion of the three broad categories of diet in Indian culture discussed earlier: satvik, rajasik, and tamasik types.

Advancing research is completing the circle to move again toward natural products. The rising incidence of diseases produced by the action of free radicals, and inflammatory processes can be prevented with the help of a proper diet that utilizes the rich treasure of natural products. Italian researchers have suggested a strategy for neurodegenerative diseases that is based on an increased use of natural substances to augment neuroprotective pathways [32]. The researchers suggest that the use of natural substances for augmenting health-promoting genes, and for the reduction of the expression of disease-promoting genes.

Ayurveda Concepts of Nutrition

Vedic literature describes various dietary recipes, and their effects on health. The Veda and Upanishads describe food consumption practices, and culture. Food is often praised as the supreme spirit, a “vital force,” and divine gift from nature. The Veda and Upanishands describe various food items, including cereals, pulses, milk and milk products, vegetables, fruits, oils, salt and spices. The Vedas prescribe a code of conduct for food acquisition, cooking, and serving. Various patterns of meals are elaborated in detail. Consumption of food is considered sacred worship. The Bhagvad Gita describes properties of healthy food. It suggests that any food should be consumed within 3 h of preparation. A tasteless recipe, decomposed, putrid food, and remnants and unwholesome ingredients should not be consumed. Food during the Vedic period included barley, rice, green gram, black gram, lentils, ghee, and milk as staples. Contrary to the current belief, nonvegetarian food seems to have been prevalent in ancient India. Most of the Ayurveda classics have a special section on nonvegetarian diet.

Ayurveda texts refer to food as the source of energy and vitality. Good food nourishes Dhatu, and maintains Dosha in a balanced state. Ayurveda describes properties and activities of different foods. Good food should maintain health, should not vitiate Dosha, should nourish Dhatu, and strengthen the body. Diet is an important aspect of therapeutics. Food can be an etiological factor in disease pathogenesis, and its role in health and disease treatment is vital. Generally, wheat, barley, green-gram, milk, fruits, and green vegetables are examples of “health promoting” food. However, there cannot be an easy or universal definition of good food. The choice of appropriate food may differ according to a person’s prakriti. Food has temporal, and spatial influences, and the choice of food may vary greatly, depending on chronological cycles, and seasons. Ayurveda has made this easier by offering detailed “dos” and “don’ts,” called pathya and apathya, respectively. The “path” toward health is known as pathya (dos) in Sanskrit, and its antonym is apathya (don’ts). The success of the treatment largely depends on the patient’s adherence to pathya, and apathya, diet guidance. The emphasis and importance of pathya and apathya is clear in this quote from an Ayurveda text: “Those who follow proper diet, require no medicine, and those who do not follow a proper diet will not benefit from medicine.”

“Proper” diet is a relative, and contextual term. Good food for one person may not be “proper” or useful food for another. An Ayurvedic physician or Vaidya examines patients, and tries to establish the link between causative agents, and the manifested disease. The disease process, and pathogenesis is interpreted in terms of Dosha, Dhatu, Agni, and other relevant components. Upon considering the nature of pathogenesis, the diet is advised. Every disease has a set of defined dos and don’ts. For example, for an asthmatic patient, consuming curd is contraindicated, however, it can be consumed with asafetida as an additive spice. Thus the food can cater to the specific needs of a particular person. This is one of the important approaches of Ayurveda, which differs from present practices of nutrition, where all individuals are treated in the same manner. Good diet taken at the wrong time, or improper diet, can be responsible for the causation of diseases. For example, drinking excess water during bedtime can make an individual prone to upper-respiratory complaints, such as runny nose, sneezing, coughing, and dyspnea.

The process of digestion plays a key role in health and disease. Agni, in a normal state, can digest food, and convert it into an easily absorbable form that can circulate through microchannels, known as Srotas, to provide nourishment, or Dhatu, to various cells and tissues. Abnormal Agni can lead to disease. Powerful Agni accelerates the metabolic rate, while weak Agni is considered to be a cause of many diseases. Agni regulates the immune system by balancing Dosha, and strengthening Dhatu. In various autoimmune diseases, Ayurveda advocates improving digestion, and metabolic status through the maintenance of good health of the gut. According to Ayurveda, the gut is considered as Maha Srotas, meaning “the large channel.” It is not merely the GI tract, or the portion known as the gut, but is considered to be an intelligent system. Thousands of Srotas, or microchannels, are connected with Maha Srotas, hence, the health of the gut is given substantial importance.

Gut health also depends on microbiota, which can change during various conditions, such as constipation and indigestion. Dietary restriction, avoidance of food, and fasting are considered to be useful in improving digestion, which leads to improved gut health. Recent studies on dietary restriction therapies have highlighted the role of gut health in autoimmune, metabolic, and degenerative diseases. Some studies have shown that obesity can be prevented just by restricting food consumption. However, food restriction alone cannot control major risk factors such as insulin resistance. These results support the emerging view that gut microbiota plays an important role in the etiology, and pathogenesis of metabolic disease. It also suggests that immune system malfunction may lead to metabolic syndrome [34].

The role of Agni is pivotal in regulating the body’s internal environment. Disturbed Agni can lead to Dosha vitiation—despite proper diet. Improper digestion can lead to the buildup of toxic substances, known as Ama. This is another important concept in Ayurveda. Ama literally means “immature” or “undigested” material, which is an undesirable byproduct of digestion. Ama is described as a substance with heavy, unctuous, and sticky properties. Ama is thought of as a toxic material, which is responsible for pathologies. The role of Ama in various molecular, and biochemical processes resulting in metabolic, and inflammatory diseases is important [35] (Figure 7.2).

Ayurveda emphasizes the removal, or digestion of Ama, and improving Agni functions for the maintenance of health. Ayurveda suggests improving Agni as treatment of inflammatory diseases. Panchakarma therapies aim at improving the gut environment. The treatment of gastrointestinal diseases like diarrhea, irritable bowel syndrome, and amebiasis is done primarily by correction of Agni. Scientific exploration of Agni and Ama, and studying their role in pathogenesis can provide valuable leads in the understanding of metabolic diseases [36].

The concept of gut health is deeply rooted in Ayurveda [37], and has become a new research objective in modern health care [16]. The Agni concept can provide important inputs for research into metabolic functions, and bioenergetics. Normal Agni maintains a healthy gut environment by ensuring proper digestion, and elimination of excretory products like sweat, urine, and stool as Mala. A weaker Agni makes the gut environment sluggish—leading to improper digestion, and instead of normal Mala, toxic Ama is produced. Ama is a sticky, heavy substance, which may block the Srotas, and trigger inflammatory processes. Agni, in its normal state, maintains homeostasis, ensures nourishment, and results in a healthy, long life.

Many substances can be interchangeably used either as drugs, or as food. Many herbs used as spices improve digestion, and the absorption of food—not just its palatability. The use of spices is a specialty of Indian cuisine. Those having potent activity are generally regarded as drugs, while those with nourishing effects are used as food. For example, black pepper is a drug, while barley is a food. But black pepper can be used as spice in diet, and barley water can be used as a medicine. There are six tastes according to Ayurveda. These tastes are not merely those recognized by tongue—the concept of Rasa has a deeper meaning. The six Rasa include sweet, sour, salty, pungent, bitter, and astringent. Each taste has specific effects on Dosha and Dhatu (Figure 7.3).

Modern dietetics considers six main types of nutrients as proximate principles. Those are carbohydrates, fats, minerals, protein, micronutrients (vitamin, minerals), and water. A balanced diet is the one which provide required quantities of proximate principles. Similarly, the ideal or balanced diet according to Ayurveda, is the one which provides an appropriate combination of the six tastes or Rasa. A balanced diet with all six tastes maintains Dosha in a balanced state, leading to good immunity, and a healthy, long life.

Diet, Prakriti, and Chronobiology

The concept of personalized diet in Ayurveda is based on Prakriti, which gives specific diet advice for health promotion, and disease prevention. A Prakriti-specific diet is meant to maintain the balance of Dosha.

Kapha Prakriti persons are slow metabolizers; they can tolerate hunger and thirst. They require small amounts of food. They take a long time to digest. They may show weight gain, in spite of small quantity of meals. Their propensity for obesity is high, hence they are advised to fast or consume small meals. They may eat pungent, bitter, and astringent spices with their food, drink hot beverages, and consume dry, and light food.

Pitta Prakriti persons are fast metabolizers, and can digest heavy food. They are prone to ulcers in stomach, and acid peptic diseases; hence, they should control acidity in their food. They prefer frequent munching, also require large amounts of food. They cannot tolerate hunger or thirst. They should avoid spices, and foods with pungent, salty, and sour taste. They should preferably consume food and beverages with cooling properties.

Vata Prakriti persons are generally lean and thin, with dry skin. Their metabolic pattern can be variable, even due to a small change in diet and lifestyle. They may eat ghee, edible oils, and hot food with sweet and sour taste. They eat fast, and consume small amounts. They will not gain much weight, even if they consume a large amount of food. They should consume more oils, and ghee to prevent degenerative diseases, of which they are prone.

What time should meals be taken? The timing of meals is another important aspect of metabolic health. Researchers have studied how the timing of the first meal, breakfast, can have certain effects on the physiological function. The findings suggest that the first meal determines circadian phasing in the liver; the last meal relates to lipid metabolism. This experiment suggests that meal timing can have different physiological effects [38]. Thus, meal timing is an important consideration, especially in the treatment of metabolic diseases. Obese patients are advised to take early meals.

Ayurveda, and many other traditions, advise against eating late night dinners. Jains do not consume any food after sunset. The Ayurvedic concept of microchannels, or Srotas is important to understand as the basis of this practice. Srotas in the body are believed to open during sunrise, and start closing during sunset. The microchannels function optimally during daytime, and not during late night. After sunset, the Srotas are constricted, and their activity is reduced. If constricted Srotas are loaded with food, the balance of Dosha is disturbed, and Ama is produced. The short-term effects of Ama are indigestion, hyperacidity, headache, giddiness, lethargy, and constipation. The long-term effects of Ama are autoimmune, respiratory, and cardiac disease. There are studies on timing of food consumption, and the presentation of acute coronary events. Those who fasted had symptoms mostly in the afternoon [39].

Food and sleep share an important connection. Sleep is an anabolic activity that helps digestion. The parasympathetic system dominates sleep, and metabolic activities. Daytime sleep however, can cause digestion problems, and is considered a risk factor for diabetes. The relationship between the timing of sleep and meals is addressed by Ayurveda. Daytime, post-meal sleep is thought to increase Kapha. Therefore, those individuals whose Kapha is depleted may benefit from moderate sleep after the daytime meal. However, this kind of advice cannot be generalized. A study in healthy volunteers reports that those who slept during the day had a higher risk for diabetes [40]. Another study suggests that food intake before sleep, or late-night snacks can adversely affect sleep quality [41]. Thus, the timing of food intake and sleep are related, but vary depending on the individual Prakriti.

Calorie Restriction

Yoga therapy and Ayurveda advise fasting to clean the system, and improve its tone and vitality. In the absence of food, Agni digests vitiated Dosha; this is a basic principle of dietary restriction therapies. These therapies are called Langhana, and involve dietary restriction, along with monitoring symptoms of vitiated Dosha, Agni, and Dhatu. The endpoint of Langhana is feeling light, increased appetite, proper elimination of wastes, and improved cognitive functions.

The results of clinical trials on fasting support the contention that fasting has protective effects in cases of obesity, hypertension, asthma, rheumatoid arthritis, and that fasting can delay the aging process [42]. The mechanisms of fasting have shown its effects through lipolysis, and the upregulation of gluconeogenesis by the liver in mice. Fasting stimulates gut-derived serotonin upregulation, and prevents glucose uptake by hepatocytes [43]. The neuroprotective effects of fasting are thought to be linked to the activation of sirtuins [44]. Sirtuins are a family of proteins that regulate important, biological pathways such as those of aging, transcription, apoptosis, inflammation, stress resistance, and maintain alertness during calorie restriction. They also control circadian clocks, and mitochondrial biogenesis.

The physiological effects of fasting are receiving much attention against the background of the epidemic of non-communicable diseases such as diabetes, cancer, and autoimmune diseases. It is important to know when not to eat, so as to avoid burdening the digestive system. Intermittent fasting improves the lipid profile, and decreases inflammatory responses. Gene expression related to inflammatory response is reported to be altered with intermittent fasting [45].

Ayurveda advocates fasting as the first, and most important step in the management of any type of fever. Therapeutic fasting is also suggested as a treatment for many diseases, such as rheumatoid arthritis, diabetes, and obesity. The logic of therapeutic fasting is to regain homeostasis, and prevent generation of Ama. Therapeutic fasting helps in the digestion of Ama, and expedites the excretion of toxins, which relieve the fever.

Many types of fevers are caused by microbial infections. These pathogens produce enzymes known as neuraminidase, which unmasks host’s cellular lectins. These lectins can trigger the expression of human leukocyte antigen type II (HLA II). HLA II can then bind to food lectins, and may induce antibody response. Some of these antibodies can attack healthy tissues leading to disease. In this process, if food lectins are not available, further complications can be avoided. Therapeutic fasting is a way to avoid the production of food lectins. It works as a neuraminidase inhibitor, helping to prevent the genesis of autoimmunity during infection, thus removing a root cause of fever [46].

Dietary restriction (DR), or calorie restriction (CR) involve reduced food intake without causing malnutrition. Both CR and DR are often connected with delayed aging, and with the extension of life span, or longevity. Long-term DR, and short-term fasting is known to provide protection against many types of neuronal damage, surgical and ischemia-reperfusion injury, and Parkinson’s disease. DR and fasting have been shown to conserve energy, and increase mature B and T-cell numbers in bone marrow [47]. Recent research on monkeys has shown that long-term restriction of the diet significantly improve the survival and longevity [48]. Findings of other studies suggest that CR, or drugs such as rapamycin which mimic the mechanism of CR, may lead to the extension of lifespan [49]. Dietary restriction may improve stress resistance, and metabolic fitness, providing beneficial effects in conditions like surgical stress, inflammation, chemotherapy, and insulin resistance [50].

Fasting and Spirituality

In many cultures fasting has been advocated for health promotion, disease prevention, and therapeutic purposes. Fasting is also part of spiritual practices. Buddhist, Jains, Muslims, Hindus, and many other traditions engage in fasting as a ritual. Different traditions have different ways of fasting, in different seasons, and in differing durations. Jains follow Paryushanparva. Muslims observe the month of Ramadan. Hindus fast during the month of Shravan. In many traditional, and spiritual practices fasting is not limited to restrictive or selective intake, or avoidance of food to emphasis that fasting is a way to pursue spiritual goals. In these traditions, fasting is considered to facilitate meditation, awakening, and enlightenment.

A story about the Buddha is interesting. Even after intense fasting and meditation for years, the Buddha was not able to attain his goal of enlightenment. Finally, he gave up a long-duration fast by eating rice pudding, followed by meditation—he then attained enlightenment. Based on this story, an interesting hypothesis has been proposed:

Intense fasting may have inhibited the Buddha’s monoamine oxidase (MAO) activity. Eating rice pudding provided dietary tryptophan from carbohydrates. The carbohydrates triggered insulin release, which increased unbound tryptophan, while reducing the levels of competing amino acids at the blood–brain barrier. These effects may have led to a significant influx of tryptophan into the brain, where it was converted to serotonin. In the absence of MAO, serotonin does not degrade, and methyl-transferases convert excess tryptophan, and serotonin into endogenous, psychoactive tryptamines. The endogenous serotonin, and tryptamines are very important neurotransmitters, and many of the psychotropic, and hallucinogenic drugs act through their modulation. The absence of psychoactive substances, and the prolonged fasting may have given the experience its perceived spiritual power [51].

This hypothesis indicates that fasting and meditation techniques may have the ability to alter mental states.

In short, diet is the primary strategy for disease prevention, and health protection. Diet can affect personality, and behavior. Dietary requirements vary from person to person. The interactions between food and microbiota have become an important area of study. The consumption of natural foods, fresh vegetables, and fruits; the restriction of calories; and the mental state of the person positively influences health, and longevity. Guidance from Ayurveda and yoga can play an important role in health care.

If a proper diet is followed, what is the need for medicine? If the diet if not proper, what is the use of medicine?

An ancient Indian proverb