From your earliest embryonic days, long before your body had developed a recognisably human form, you had two quite different sorts of skin: one to keep the world out, the other to select in from outside what you require to live. The first became your principle frontier and defence. The second asserts your needs, identity and right to be alive: from it evolve your thymus gland to direct your immune system, and your catering arrangements — intestine and digestive glands.
The digestive passage forms a continuous tube from mouth to anus down which you let pass a selection of material from your surroundings that seems good to eat and satisfies your hunger. To draw nourishment from this material you must first digest it into a form that you can assimilate into your own substance. Digestion takes place entirely within the passage, where the food is still strictly speaking outside your body. Assimilation is when you really let it in, as if clearing it through customs. At its best digestion prepares your food into the ideal physical and chemical condition for you to assimilate selectively from it what you need, feeling under no pressure to accept what you have no use for.
What kind of food you eat and how you organise your meals largely determine your success. In Pamphlet F1 we explain how human history has given us three separate levels of digestion, each with its own location. All these levels work best on food fresh and whole, as found in nature; still alive and able to contribute actively to its own digestion. If you fill each digestive compartment in succession with appropriate food well chewed, all of it can be properly treated without danger or wasted effort. Then assimilation is straightforward, and self-reinforcing because your intestine gets perfectly nourished along with the rest of you.
Neglect these principles and things go wrong. White bread becomes a watery slop instead of a doughy jell, calling up far too much acid and swamping your blood with sugar it cannot handle well. Meat in the sandwich goes wrong, mistakenly digested into irritant chemicals that can damage your delicate intestinal skin making it less selective and efficient. Your needs are not satisfied, yet substances you would normally reject get in by mistake — a double bind. You meet your next meal less well prepared, easier prey for even worse trouble.
Good food wisely eaten satisfies your appetite, balances your nourishment, keeps your blood and tissues clean and helps you excrete wastes efficiently. Any departure from this has compound effects that last for several meals. Look after your eating habits, and the technical details of your digestion and assimilation will look after themselves.
What to do
1. Only eat when you are in the mood. If you are angry, flustered or in a hurry you will digest food badly and add to your problems.
2. Eat only when you are hungry, and only the kind of food you have an appetite for.
3. Try, even so, to make mealtimes special (particularly with children). Beware of living on snacks.
4. Chew all food well to taste it properly and give digestion a flying start. That way you get more satisfaction out of less food.
5. Try always to choose food that has itself been nourished as you intend to be. Garden vegetables grown on compost and naturally resistant to pests always satisfy better than fragile plants grown on impoverished soil with chemical fertilizers and pesticides. Use tinned or chemically processed food as little as you can.
6. You rely on the fibre in vegetables, fruit and wholemeal cereals to thicken your digestive juices, keep things moving and wrap up irritants for excretion. Get plenty of it.
7. These four courses take best advantage of your three levels of digestion:
8. Meat requires a lot of digestive work anyway, and will distract effort for some hours after the meal. Do not eat it more than a few times weekly, and keep it well separate from starchy food — a meat sandwich in white bread is highly indigestible. Avoid meat at lunchtime if you have hard work to do in the afternoon.
9. Beware of sugar in any form. Even unrefined sugar is stressful to your digestion, but you can use its stronger flavour to cut down on the amount you use. Do not eat lots of honey or malt to compensate — get used to things being less sweet.