The relationship between diet and health has been recognized throughout recorded history. Dietary habits are one of the major contributory factors for the genesis of cancer. Diet, physical inactivity, and obesity are related to approximately 30-35% of cancer deaths . Physical inactivity is believed to contribute to cancer risk not only through its effect on body weight but also through negative effects on the immune and endocrine systems. Diets that are low in vegetables, fruits, and whole grains and high in processed or red meats are linked with a number of cancers. A high salt diet is linked to gastric cancer, aflatoxin B₁, a frequent food contaminant, with liver cancer, and betel nut chewing with oral cancer [31].
Surveys conducted in the USA have shown that cancer incidence is above 300 cases per 100,000, whereas in Asian countries it is less than 100 cases per 100,000 (Garodia et al. . Also, although the incidence of cancer of the prostate, lung, breast, and colon is highest in Western countries, it is lowest in Eastern countries . The reason for this high incidence of cancer in the USA is unclear; however, lifestyle has been thought to be one of the major contributors to the incidence of cancer. The higher incidence of cancer among immigrants from the East to the West further emphasizes the role of lifestyle . Additionally, diet is considered an important aspect of lifestyle related to cancer development . While many dietary recommendations have been proposed to reduce the risk of cancer, few have signifi-cant supporting scientific evidence . The primary dietary factors that increase the risk of cancer are obesity and alcohol consumption, with a diet low in fruits and vegetables and high in red meat being implicated but not confirmed . Consumption of coffee is associated with a reduced risk of liver cancer . Studies have linked the consumption of red or processed meat to an increased risk of breast cancer, colon cancer, and pancreatic cancer, a phenomenon that could be due to the presence of carcinogens in foods cooked at high temperatures . Thus, dietary recommen-dations for cancer prevention typically include mainly vegetables, fruit, whole grains, and fish and a reduced intake of red meat, animal fat, and refined sugar .
Disease prevention through the healthy preparation of foods and eating habits has been discussed in religious and civil writings for thousands of years . Since the nineteenth century, Western scientific methodologies have been applied to the study of diet and disease with the intent of reducing the disease burden from noncommunicable diseases such as cancer, coronary heart disease, and other conditions endemic to societies after the advent of industrialization. Diet in India developed over thousands of years and is based on a mix of religious and secular beliefs. A large percentage of Indians, particularly Hindus, practice vegetarianism and avoid meat and fish products in their diet. Vegetarian diets have been associated with decreased risk of prostate cancer . An impressive body of data exists in support of the concept that Indian food ingredients can be used in preventive strate-gies aimed at reducing the incidence and mortality of different types of cancers because of their antioxidative, antimutagenic, and anticarcinogenic properties .Case-control studies comparing nonvegetarian and vegetarian diets and alcohol and tobacco use in India have reported that vegetarians have a reduced risk of oral,
esophageal, and breast cancers . Vegetarian diets rely on pulses (e.g., beans, chickpeas, and lentils) as a source of protein, and pulses have been significantly associated with reductions in cancer .
Our knowledge of the transformation of a normal cell into a cancer cell has greatly expanded over the past decade. The simplistic, stepwise concept of initia-tion, promotion, and progression has matured to a better understanding of the serial genotypic changes that ultimately lead to cancer . Chemoprevention inhibits the development of invasive cancer either by blocking the DNA damage that initiates carcinogenesis or by arresting or reversing the progression of premalignant cells in which such damage has already occurred . Many of the chemopreventive agents are antioxidants and might suppress carcinogenesis through (1) inhibiting Phase I enzymes, (2) inducing Phase II enzymes, (3) scavenging DNA reactive agents, (4) suppressing type-2 cell proliferation induced by carcinogens, or (5) inhibiting cer-tain properties of neoplastic cells . The Phase I detoxification system, composed mainly of the cytochrome P450 supergene family of enzymes, is generally the first enzymatic defense against foreign compounds. Most pharmaceuticals are metabo-lized through Phase I biotransformation. Phase II conjugation reactions generally follow Phase I activation, resulting in a xenobiotic that has been transformed into a water-soluble compound that can be excreted through urine or bile. Several types of conjugation reactions are present in the body, including glucuronidation, sulfation, and glutathione and amino acid conjugation. These reactions require cofactors that must be replenished through dietary sources. The human diet contains a variety of compounds that exhibit chemoprevention effects toward an array of xenobiotics . Epidemiology studies have suggested that some dietary constituents may act as naturally occurring cancer prevention agents and may explain some of the differ-ences in cancer incidence seen in populations with varying dietary intakes .
Oxidative stress is one of the main ways in which DNA is damaged from either an exogenous or an endogenous source (e.g., inflammation). Antioxidant micronu-trients have been reported to oppose this effect . Thus, food interacts in different ways with the initiation phase, and the protective effect of food is likely to be more important than food's contribution as a mutagen. The promotion step is the clonal proliferation of mutated cells that occurs as a result of genetic alteration and epigen-etic modulations and thus achieves tumor growth. Reactive oxygen species (ROSs) are necessary to intracell signaling for the synthesis of growth factor and antioxi-dants that may interfere in this pathway. Little is known about the effect of food at the invasion step. Food can interfere with genetic and epigenetic alterations in this phase; for example, some experimental work suggests that dietary phenolic com-pounds can modify angiogenesis .
Chemoprevention by natural products has been obtained in several hundred ani-mal studies . Chemopreventive agents can be grouped into three broad catego-ries . The first category is blocking agents. These compounds prevent carcinogenic agents from reaching or reacting with a critical target site; thus, they act by exerting a barrier function. The second category is composed of compounds that decrease the vulnerability of target tissue to carcinogenic stimuli. The third category is suppressing agents. These compounds prevent the evolution of neoplastic processes in tissue that otherwise would become malignant.
Preventing Cancer by Dietary Modulation: Ayurvedic Viewpoint
Ayurveda promotes health by enlivening the body's inner intelligence to create har-mony .Unlike modern nutritional theories, which tend to recommend "one size fits all" guidelines that change with each new wave of research, Ayurvedic physi-cians maintain there is no one single diet or food that is healthy for all individuals. Ayurveda identifies six major tastes we need in our diet every day sweet, sour, salty, pungent, bitter, and astringent. Each of these tastes has specific health-giving effects. By including all six, one can be most completely nourished. When we con-sistently eat only a few of the tastes, it not only causes health problems but also triggers cravings for unhealthy foods. For instance, fast food contains mostly sweet, sour, and salty tastes. If we eat a steady diet of fast food, we can develop a craving for sweets. Adding more pungent, bitter, and astringent tastes can help tame an out-of-control desire for fast foods.
Ayurvedic texts compare the process of digestion to cooking over a flame. Digestive "fires," collectively called agni, "cook" food so that nutrients can be opti-mally utilized. When agni is strong, our body fully assimilates nutrients and elimi-nates what it doesn't need. Ultimately a fully functioning digestive system uses the food we eat to produce a biochemical called ojas, a fluid substance that nourishes the body and maintains the balance of all bodily systems. If the digestive fire is weak, the incompletely digested portion of the meal forms a sticky, toxic substance called ama. The opposite of ojas, ama blocks the flow of the body's inner intelli-gence. It settles in areas of the body that are out of balance, taking on many forms, such as calcium deposits in the joints, plaque in the arteries, and cysts and tumors. A coated tongue, bad breath, dullness of the senses, depression, and unclear think-ing can indicate the presence of ama. To prevent ama from forming, plenty of warm water should be taken and eating late at night should be avoided. Eating freshly prepared meals and cooking with seasonal, organic fruits and vegetables are essen-
tial. Strengthen agni by "kindling" it with heating foods and spices, such as ginger and black pepper. Every food has its own taste (rasa), a heating or cooling energy (virya), and a postdigestive effect (vipaka). Some also possess prabhava, an unex-plained effect. So while it is true that an individual's agni largely determines how well or poorly food is digested, food combinations are also of great importance. Poor combinations can produce indigestion, fermentation, putrefaction, and gas formation and, if prolonged, can lead to toxemia and disease .
Ayurveda recommends strict dietary principles for maintaining healthy life. For example, Satvika ahara (fresh food composed of milk, fruits, and vegetables con-sumed in a congenial environment), as recommended in Gita, is considered whole-some compared to rajas food (spicy, hot, fast food, acidic food) and tamas food and habits (stale food, alcohol, smoking, nonvegetarian food). We can deduce that rajas and tamas foods may have a greater affinity for developing malignancy compared to satvika foods.
Ayurveda promotes health by enlivening the body's inner intelligence to create har-mony .Unlike modern nutritional theories, which tend to recommend "one size fits all" guidelines that change with each new wave of research, Ayurvedic physi-cians maintain there is no one single diet or food that is healthy for all individuals. Ayurveda identifies six major tastes we need in our diet every day sweet, sour, salty, pungent, bitter, and astringent. Each of these tastes has specific health-giving effects. By including all six, one can be most completely nourished. When we con-sistently eat only a few of the tastes, it not only causes health problems but also triggers cravings for unhealthy foods. For instance, fast food contains mostly sweet, sour, and salty tastes. If we eat a steady diet of fast food, we can develop a craving for sweets. Adding more pungent, bitter, and astringent tastes can help tame an out-of-control desire for fast foods.
Ayurvedic texts compare the process of digestion to cooking over a flame. Digestive "fires," collectively called agni, "cook" food so that nutrients can be opti-mally utilized. When agni is strong, our body fully assimilates nutrients and elimi-nates what it doesn't need. Ultimately a fully functioning digestive system uses the food we eat to produce a biochemical called ojas, a fluid substance that nourishes the body and maintains the balance of all bodily systems. If the digestive fire is weak, the incompletely digested portion of the meal forms a sticky, toxic substance called ama. The opposite of ojas, ama blocks the flow of the body's inner intelli-gence. It settles in areas of the body that are out of balance, taking on many forms, such as calcium deposits in the joints, plaque in the arteries, and cysts and tumors. A coated tongue, bad breath, dullness of the senses, depression, and unclear think-ing can indicate the presence of ama. To prevent ama from forming, plenty of warm water should be taken and eating late at night should be avoided. Eating freshly prepared meals and cooking with seasonal, organic fruits and vegetables are essen-
tial. Strengthen agni by "kindling" it with heating foods and spices, such as ginger and black pepper. Every food has its own taste (rasa), a heating or cooling energy (virya), and a postdigestive effect (vipaka). Some also possess prabhava, an unex-plained effect. So while it is true that an individual's agni largely determines how well or poorly food is digested, food combinations are also of great importance. Poor combinations can produce indigestion, fermentation, putrefaction, and gas formation and, if prolonged, can lead to toxemia and disease .
Ayurveda recommends strict dietary principles for maintaining healthy life. For example, Satvika ahara (fresh food composed of milk, fruits, and vegetables con-sumed in a congenial environment), as recommended in Gita, is considered whole-some compared to rajas food (spicy, hot, fast food, acidic food) and tamas food and habits (stale food, alcohol, smoking, nonvegetarian food). We can deduce that rajas and tamas foods may have a greater affinity for developing malignancy compared to satvika foods.
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