After swallowing, food lakes approximately three seconds to travel from the mouth to the stomach. It takes one to five minutes for the first mouthful to enter the duodenum, and twenty minutes for half the consumed food to leave the stomach. In four and a half hours it travels from the duodenum to the end of the small intestine. After five and a half hours the first mouthful has reached the start of the large intestine, the caecum. The first mouthful of food takes nine and a half hours to reach the end of the large intestine, the sigmoid colon.
From start to finish, the complete process of digestion takes from twelve to twenty-four hours.
Next time you have a meal, try to increase your body awareness by following the progress of digestion in your body. Of course you will have to remember throughout the day that the process is going on, but this exercise will increase your awareness. Another interesting exercise is to visualize the tubes concerned with defecation, when you go to the toilet. Awareness can be expanded any time and anywhere. There should be no limitations to your awareness, and no psychic blocks or complexes concerning bodily functions.
Saliva is secreted at a rate of one to two litres per day. It breaks down starch and naturalizes acid in the stomach. It is important to chew your food properly and make use of saliva and the enzymes it contains. This is the first step to proper digestion and health. The food we eat cannot be directly absorbed into the body; it first requires a complex chemical transformation. Many people gulp down their food without chewing long enough to mix it thoroughly with their saliva. If people chewed their food more, they would need less bicarbonate of soda and pills for indigestion.
The mechanism of digestion is very delicate and intricate; a weak system is easily upset. That is why we recommend yoga to strengthen the digestive system as well as the rest of the body. This includes the nervous system which co-ordinates such activities as seeing the food and conscious appreciation of it, right down to the last stage where defecation occurs.
The sight and smell of food causes our digestive juices to flow, especially when it is something which we really enjoy eating. When we are hungry, we enjoy our food more. Hunger is determined by a drop in the blood sugar level. This produces contractions of the stomach wall which last about thirty seconds each. These ripples are called 'hunger pains'.
If we are tense, or the chewing is inadequate, the juices will not flow properly. So do not eat if you are tense or when you have been rushing around. Avoid excessive indulgence if you want to tread the path of yoga and good health.
The nutritive properties of food depend not only on the quality but also on the way in which it is prepared and the atmosphere in which it is eaten. Thus food prepared with the important ingredients of care and love contains a great deal of prana and energy, and gives life to the body. One's mental attitude to the food is also of great importance to good digestion.
The stomach is about the size of your hands cupped together. To fill the stomach we need eat no more than this quantity. However, the stomach can stretch to enormous proportions to accommodate the sometimes enormous amounts of food we deposit in it. For optimal digestion fill the stomach with one third solid, one third liquid and one third air.
Food stays in the stomach for two to six hours, depending on the type of food consumed. Fats and meat are harder to digest than other protein foods and carbohydrates. This is why a vegetarian meal gives one more energy and does not create a feeling of fullness or heaviness. When we eat a big meal, more blood is drained from the brain and other vital organs to the stomach for greater periods of time than a light, small meal. Thus we may feel sleepy after a large meal. This problem is corrected easily by such techniques as vyaghra kriya (described later in this issue).
The inside of the small intestine feels like velvet. The wall contains hundreds of thousands of villi (hair like projections), which contain blood vessels and lacteals to absorb food. These villi serve to increase the surface area of the absorption mechanism enormously, from 76,000 square centimetres to 4,500 square meters, the size of three tennis courts placed next to each other. Thus there is plenty of room to absorb nutrients from food, but we must be sure that the nutrients of the food are accessible to the process of absorption. This means that we must chew our food properly and with awareness in order to break down the components. We should also be relaxed to allow the correct concentration of acids, enzymes and hormones for optimum digestion.
The large intestine contains myriads of bacteria, most of which are useful and necessary to manufacture certain B-group vitamins which we cannot live without. Strong laxatives and antibiotics sweep out these bacteria, thus depriving the body of important products. We should use them only if it is absolutely necessary.
Many people are unnecessarily worried if they retain faeces for too long a time, and fear that poisons may re-enter the body. This is a fallacy, for no such mechanism exists to absorb anything other than water and salts. Faeces can safely remain in the colon for long periods of time. One person has gained the world record by retaining faeces for over a year and producing a massive amount at the end of this time, with no apparent ill effects. Of course, the best way is regular defecation, an average being between three times per day to once every three days.
There are five main categories of food: carbohydrates, fats, proteins, vitamins and minerals.
Carbohydrates and fats provide our body with energy. About seventy-five percent of our energy goes into maintaining body temperature by the fire of metabolism. We need less food in hot weather, but in winter our digestive fire burns like a volcano, and we need to eat more. The rest of the energy is used by the muscles, motor system, heart, brain and internal organs. Fats also form a protective layer, shielding organs from injury and allowing a storage of energy for future use. Over consumption of these foods, however, leads to overweight. Butter and oils are almost pure fat, while sugar is one hundred percent carbohydrate. Potato, rice, bread and grain contain mostly carbohydrate along with vitamins and minerals, and very little fat.
Proteins are the remarkable materials out of which the body tissues are built. Proteins repair worn out tissues, and this process goes on continually. They are also necessary for the production of essential special substances that help build up the body's resistance to disease, called immunoglobulins. Protein is found in meat, milk, cheese, fish, eggs, grains, beans, lentils, nuts etc. Mineral salts are essential elements present in minute quantities. Phosphorus and calcium are required in relatively large amounts for building bones, and activating muscles and the brain. Iron helps the blood to transport oxygen through the body and it is used by the blood cells. It is found in eggs, raisins, spinach, whole grain cereals, apricots, potatoes, meat and liver. Iodine is used by the thyroid gland to control the whole process of metabolism. It is found in iodized salt, sea foods and vegetables. Salt, in the form of sodium chloride, is essential for the maintenance of normal acid to base balance. Too much salt raises the blood pressure and causes swelling in the legs; only a moderate amount is recommended.
Vitamins are engaged in many different and diversified functions. Vitamin A is used in all the organs of the body, especially the respiratory, digestive and urinary tracts. It keeps the mucus membrane of the nose, throat and windpipe strong and healthy. In this way it helps to prevent colds and other infections. It keeps the skin smooth and clear. It is perhaps best known for its use in the maintenance of vision; a lack of it can cause night blindness. The best sources are carrots, fruits, vegetables, cream, butter, whole milk and egg yolk.
Vitamin B complex has more than a dozen different components. B1 or thiamine is important and is concerned with nerves and muscles. It is thought that a lack of thiamine causes alcoholics to suffer from nervous system degeneration. Without thiamine the body would be in a constant state of aches and pains. It is most prevalent in liver, brewers yeast, peanuts, whole grains, meat and eggs. Riboflavin, another important member is necessary for skin, eyes and digestion. Niacin is also important for digestion. All the elements are found in wholegrain cereals, milk, cheese, eggs and liver.
Vitamin C is the great healing vitamin, essential for the building of bones, small blood vessels, teeth and gums. A lack of this vitamin causes scurvy. It is found in fresh fruits (especially citrus), leafy vegetables, potatoes and tomatoes.
Vitamin D is necessary for the development of strong healthy bones. A deficiency causes rickets (softening of the bones) but this is rare as the body can manufacture its own supply from sunshine and fresh air interacting with oils in the skin. It can also be found in milk, eggs and vegetable oils.
Vitamin E is the mystery vitamin and its function is not fully known. However, it is believed to help the nucleus of the cells and reproductive functions. It is found in whole grain cereals, green leafy vegetables, coconut oil and other vegetable oils.
Vitamin K is important in blood clotting and is found in green leafy vegetables, soya beans, tomatoes and eggs.
Vitamins are found in a great variety of foods, so there is really no need to take extra vitamin supplements if you are eating well. At times of stress vitamin B and C may be required in greater numbers, and a supplement may be useful.
A healthy body has the capacity to transform one type of foodstuff into another as required. Many yogic practices such as surya namaskara and pranayama increase the efficiency of this transformation process and the whole process of digestion. Indeed, after a good morning workout of asanas, pranayama and meditation, the body should feel vital, alive and hungry, ready for the new day. With practice and mastery of the exercises one gains control over the body functions, and can influence them at will through the mind. Thus the yogi can live on a simple but pure diet and maintain complete health.
Until now we have been talking about the ideal digestive system, one that is strong enough to burn up the poisons that enter our systems in the fire of metabolism. A strong digestive system can digest anything.
Unfortunately this state of health is far from common, and poor eating habits are one of the reasons why.
Poor eating habits include the food that is eaten and the way in which it is eaten. Poor eating habits lead to poor digestion or indigestion, the disease of every man. Everyone has had indigestion at least once in his life, and many people suffer from chronic digestive ailments such as constipation, diarrhoea, wind, excess acidity etc. This is the reason that we are starting our series of articles on yoga therapy with the digestive system and hatha yoga shatkarmas (cleansing exercises) such as neti, kunjal and vyaghra kriya, which can play such a beneficial role in the removal of diseases of the digestive system, even though they are not limited to this role.
People with digestive upsets often suffer them until they become chronic. This allows other diseases to manifest more readily within them because of the lack of energy due to chronic disability. If these people knew about yoga practices such as neti and kunjal before their disease became chronic, they would escape the chronic disease state. However, even if illness has become chronic, it is still not too late. For by the application of yoga over a period of time, chronic disease can be removed and made a thing of the past.
We would like to awaken in you the idea that good eating habits and the regular practice of yoga can keep away disease and maintain a healthy body. When you are strong and fit you can enjoy life and work more efficiently. Being free from health worries, you will have energy to do things you had previously thought were beyond your capabilities. This is yoga in action.