Monday, 31 December 2012

CLASSIFICATION OF FOODS




CLASSIFICATION OF FOODs

This chapter is, I think, the only one, which may seem a little complicated to take in and assimilate. Bear with me if it seems rather technical; the remainder of the book, I promise you, will prove very easy to read.

Throughout the rest of the book, though, I shall be mentioning different categories of foods. If you are not familiar with these categories, you will find the Method in general hard to understand.

I have tried to reduce this chapter to its simplest, including only the information that is essential to understand what follows.

But if, despite this, you catch yourself yawning over it and are feeling drowsy by line ten or so, skip to the summary at the end of the chapter. Before you start actually trying to apply the method, though, it will be essential to return to the main part of the chapter, or you may not understand what you are doing.

Foods are edible substances containing a number of organic elements, such as proteins, lipids, carbohydrates, minerals and vitamins. They also contain water and non-digestible matter, such as fibre.

PROTEINS


Proteins are the organic cells that make up living matter: muscle, the various organs, including the liver and the brain, the skeletal structure, and so on. They are themselves composed of simpler elements called amino acids. The body manufactures some of these, while most of the others are introduced into the body in a variety of foods. Food protein comes from two sources:

Animal sources: proteins are found in large quantities in meat, fish, cheese, eggs, milk.

Vegetable sources: soya, almonds, hazelnuts, whole cereals and certain pulses also contain protein.

Ideally, we should consume as much vegetable protein as animal. Protein is essential to the body:

For building cells as a potential source of energy, once it has been converted into glucose (via the Krebs cycle).
For making certain hormones and neurotransmitters.
For the production of nucleic acids (essential for reproduction).

A diet deficient in protein can have serious consequences for the body; these include muscle deterioration and wrinkling of the skin.

A child should consume about 60g of protein per day, while an adolescent needs 90g. The adult daily intake should be 1g per kilogram of body weight, subject to a minimum of 55g for women and 70g for men.

In addition, an adult's protein consumption should represent at least 20 % of the daily energy intake. If substantially too much protein is consumed, however, and physical activity is low, the excess protein will remain in the body and is converted into uric acid, which is the basic cause of gout.

With the exception of eggs, neither animal proteins nor vegetable proteins alone can achieve the necessary balance of amino acids.

The absence of one amino acid can constitute an impediment to the assimilation of others. The diet should therefore include both animal and vegetable proteins.

A vegan diet, based solely on vegetable protein, will be unbalanced, in that it will be lacking in cystine, which will result in problems with nail and hair growth. A vegetarian diet, which includes eggs and dairy produce, on the other hand, can be perfectly well balanced.

CARBOHYDRATES


Carbohydrates are molecules composed of carbon, oxygen and hydrogen.

Blood glucose level (glycaemia)


Glucose is the body's principal”fuel". It is stored in the form of glycogen in the muscles and liver. The blood glucose level (or blood sugar level, or glycaemia) is simply the level of glucose in the bloodstream. On an empty stomach, this is normally one gram per litre of blood.

When carbohydrates (bread, honey, starchy foods, cereals, sweets, etc.) are ingested on an empty stomach, the effect on the blood sugar level is found to be as follows :

The first stage is that blood glucose rises (to a greater or lesser extent, according to the nature of the carbohydrate).
The second stage is that, after insulin has been secreted by the pancreas, the blood glucose level falls and the glucose is released into the body's tissues.
So, thirdly, the blood sugar level reverts to normal (see graph on the following page).

Traditionally, it was usual to place carbohydrates in one of two distinct categories,”quick sugars”and”slow sugars", the terms referring to the body's rate of absorbing them.

"Quick sugars”were simple sugars (such as glucose) and disaccharides, such as the sucrose found in refined sugars (both cane and beet), honey and fruit. The term”quick sugar”owed its existence to the belief that, because of the simple nature of the molecule, the body rapidly absorbed these sugars after ingestion.

Conversely,”slow sugars”referred to all carbohydrates whose more complex molecule had first to be chemically converted into simple sugar (glucose) in the course of digestion. This applied notably to starches, from which, it was thought, glucose was released into the body slowly and progressively.



This way of classifying carbohydrates is today completely outdated, and is based on a misconceived theory.

Recent studies show that the complexity of the carbohydrate molecule does not actually determine the speed with which glucose is released and absorbed into the body.

It is now accepted that the glycaemic peak (that is, the point of maximum absorption) is reached at the same rate for any carbohydrate eaten in isolation and on an empty stomach, and occurs about half an hour after ingestion. Therefore, instead of talking about their speed of absorption, it is more to the point to consider different carbohydrates in terms of their potential to induce a greater or lesser rise in blood glucose, that is, in terms of the sheer quantity of glucose they produce.

Disaccharides (white sugar, maltose in beer, lactose in milk)
Polysaccharides (cereals, flours, potatoes, pulses)
Monosaccharides (glucose and fructose found in fruit and honey)

So scientists and others now agree in the field of nutrition (see bibliography) that carbohydrates should be classified according to what is called their hyperglycaemic potential, as defined by the glycaemic index.

The glycaemic index


The potential of each carbohydrate to induce a rise in blood glucose (glycaemia) is defined by the glycaemic index, first used in 1976. This index derives from the area below the curve (shaded on the graph) of the hyperglycaemia induced by ingestion of the particular carbohydrate.

Glucose is arbitrarily given an index of 100, standing for the area below its own hyperglycaemic curve. The glycaemic index of other carbohydrates can then be arrived at using the following formula:



The greater the hyperglycaemia induced by the carbohydrate in question, the higher will be its glycaemic index.



HIGH GLYCAEMIC          INDEX LOW GLYCAEMIC INDEX
It should be noted that chemical processing of carbohydrates raises their glycaemic index. For example, cornflakes have a glycaemic index of 85, while corn (maize) in its natural state has an index of 70; instant potato has a glycaemic index of 95, whereas the index of boiled potatoes is 70.

We also know that it is both the quantity and the quality of the fibre in a carbohydrate which determines whether it has a high or low index; soft white baps have an index of 95, white baguette an index of 70, wholemeal bread 50, 100% stoneground wholemeal bread 35, white rice 70 and wholegrain rice 50.

Bad Carbohydrates


These are all the carbohydrates whose absorption leads to a large rise in blood glucose. This applies to table sugar in whatever form (on its own or combined with other food stuffs, as in cakes). The classification also covers all processed carbohydrates, such as white flour and white rice, and also alcohol (particularly spirits), as well as potatoes and corn (maize).

Good Carbohydrates


Unlike the carbohydrates mentioned above, “good carbohydrates” are those which are only partly absorbed by the body, and which therefore produce a much smaller rise in blood glucose level. They include whole cereals (unrefined flour, for example), wholegrain rice and some starchy foods, such as lentils and broad beans. Most importantly, they also include most fruits, and all the vegetables which are classified as fibre (leeks, turnips, lettuce, green beans, etc.) and which all contain a small quantity of glucose.

LIPIDS (or FATS)


Lipids, or fats, have complex molecules. They are divided into two broad categories, according to their origin:

Lipids of animal origin : these are found in meats, fish, butter, cheese, cream, etc.

Lipids of vegetable origin: these include peanut oil, margarine, etc.

Lipids can also be divided into two categories of fatty acids :

Saturated fatty acids, found in meat, cooked meats and pates, eggs and dairy products (milk, butter, cheese, cream).
Monounsaturated and polyunsaturated fatty acids; these are the fats that remain liquid at room temperature (sunflower oil, rapeseed oil, olive oil), though some can be solidified by hydrogenation (as in margarine manufacture). Also included in this category are all fish oils.

Lipids are necessary in the diet. They contain a number of vitamins (A,D,E,K), as well as essential fatty acids (linoleic acid and linolenic acid), and are needed for the synthesis of various hormones. Only cold pressed virgin oils can be guaranteed to retain their essential fatty acids.

When lipids are mixed with bad carbohydrates, their absorption by the body is interfered with and, as a result, a high proportion of the energy the lipids provide is stored as body fat.

As a general rule, we eat too much fat. Fried foods, doughnuts, unnecessary sauces and the use of too much fat in cooking have crept into our eating habits; a lighter diet, avoiding excessive use of fats, need be no less delicious.

Some of the lipids are the villains in the cholesterol story, but here again, there are two types of cholesterol,”good”and”bad". The aim should be to keep the total cholesterol level as low as possible, with “good” cholesterol accounting for as much as possible of the total.  What needs to be understood is that not all lipids lead to an increase in”bad”cholesterol. In fact, some of them even tend to lower the"bad”cholesterol level significantly. To give a complete picture, it is necessary to divide fats into three further categories :

Fats which raise cholesterol These are the saturated fats found in meat, butter, cooked meats, cheese, lard and milk products.
Fats which have very little effect on cholesterol These are the ones found in shellfish, eggs and skinless poultry.
Fats which lower cholesterol

These are the vegetable oils : olive oil, rapeseed oil, sunflower oil, corn oil, etc.

As for fish oils, they play no real part in cholesterol metabolism, but help prevent cardiovascular disease by bringing down the level of triglycerides and helping avoid thromboses. We ought therefore to consume oily fish (salmon, tuna, mackerel, herrings, sardines). The weight-loss Method that I am suggesting depends in part on choosing between “good” and “bad” carbohydrates. In the same way, choices have to be made between “good” and  “bad” lipids, especially if you tend to have a high cholesterol level or simply want to protect yourself permanently from the risk of it, with a view to avoiding cardiovascular disease. Avoiding excessive consumption of saturated fats is an essential part of the Method.

DIETARY FIBRE

Dietary fibre is a substance found mainly in vegetables, pulses, fruit and whole cereals.

Although it is true that it has no actual energy value, it nevertheless plays an extremely important role in the digestive process. The cellulose, lignin, pectin and gums that it contains ensure good intestinal function, and lack of dietary fibre is the cause of most cases of constipation. Moreover, fibre is very rich in vitamins, major minerals and trace elements, without which serious deficiencies can occur.

It also blocks the absorption of fats, so reducing the risk of atherosclerosis.

Fibre has yet another advantage. It limits the toxic effects of certain chemical substances, such as additives and colourings. And gastro-enterologists believe that some forms of fibre have the property of protecting the colon from a number of risks, particularly that of cancer.

Over recent decades, the rise in the standard of living seen in industrialised countries has brought with it a reduction in the amout of fibre consumed.

In France, for example, the current average daily consumption of fibre is 20g, whereas the recommended daily intake is 40g. In 1925, consumption of pulses, which are particularly rich in fibre, was running at 7.3kg per person per year. Now it is down to 1.3kg. In Italy the staple diet has always been pasta. But 30 years ago, the major part of Italians' diet consisted of vegetables (high in fibre) and wholewheat pasta that is, pasta made with whole flour containing the wheat fibres .

SOURCES OF FIBRE with fibre content per 100 g of food

Cereal Products
Dried Vegetables
Oily dried fuit
Bran
Wholemeal Bread
Wholemeal Flour
Wholegrain Rice
White Rice
White Bread
40g
13g
9g
5g
1g
1g
Dried Beans
Split peas
Lentils
Chickpeas
25g
23g
12g
2g
Dessicated coconut
Dried figs
Almonds
Raisins
Dates
Peanuts
24g
18g
14g
7g
9g
8g
Green Vegetables

Fresh Fruit
Cooked peas
Parsley
Cooked spinach
Lamb’s lettuce
Artichokes
Leeks
12g
9g
7g
5g
4g
4g

Cabbage
Radishes
Mushrooms
Carrots
Lettuce
4g
3g
2.5g
2g
2g
Raspberries
Pears with skin
Apples with skin
Peaches
8g
3g
3g
2g
2g


With today's higher standard of living, meat has more often than not replaced vegetables, while pasta is manufactured with refined, white flour, from which the fibre has been removed. This is the explanation given by Italian doctors for a higher incidence of obesity and also for the alarming increase in cancers of the digestive tract.

Furthermore, it has been shown that fibre has a beneficial effect on obesity. Introducing it into the diet has the effect of reducing both the blood glucose level and the level of insulin in the blood; as we shall see in the following chapter, it is these two factors that are responsible for the laying down of body fat.

Of the four main groups of nutrients, proteins are absolutely essential to our bodies, as they contain vital amino acids which we cannot make ourselves. Equally important are certain lipids, which contain vitamins and essential fatty acids (linoleic acid and linolenic acid) that our cells are incapable of producing independently. Only carbohydrates can be considered more expendable, since the human body is able to make its own glucose from stored fat.


It has to be understood, though, that lipids and proteins are often found in combination in the same foods; meat is an example.

On the other hand, only carbohydrates and lipids have high energy potential. That is why, for simplicity's sake, we will largely ignore the question of protein.

So whenever we mention a particular food, we will simply put it in one of the following three categories:

carbohydrates (specifying whether they are ”good” or ”bad")
lipids
dietary fibre

When a food contains both carbohydrate and lipids, as in the case of peanuts, we will refer to it as a carbohydrate-lipid .


SUMMARY

Proteins are substances contained in a number of foods of animal or vegetable origin. They are found in meat, fish, eggs, diary produce and pulses. Proteins are indispensable to the human body and do not make us fat. Carbohydrates are substances that are metabolised into glucose. They occur in foods which originally contain either sugar (fruit, honey) or starch (flour, cereals, starchy foods) All carbohydrates ingested on an empty stomach are absorbed at the same rate. They are classified according to their potential for raising blood glucose; this potential is measured by the glycaemic index. It is therefore possible to draw a distinction between ”good” and ”bad carbohydrates” with a high index. Lipids are substances that may be of either animal or vegetable origin. They are fats (meats, cooked meats, fish, butter, oil, cheeses etc...) Some have the potential to raise blood cholesterol (meat, dairy products) while others actually help to lower it (olive oil etc ) Dietary fibre : in this category come all green vegetables (lettuce, chicory, leeks, spinach, French beans, etc) Some dried vegetables, fruit and whole grains also contain a significant amount of fibre. It should be consumed frequently; failure to do so can lead to serious deficiencies.

LIST OF FOODS CLASSIFIED AS LIPIDS,   CARBOHYDRATES,

CARBOHYDRATE-LIPIDS OR DIETARY FIBRE


(1)     All the foodstuffs in this column (except butter, oils and margarine) contain protein.
(2)     Some carbohydrate foods, such as pulses, also contain protein.
(3)     Containing a very small amount of carbohydrate .


LIPIDS (1)
CARBOHYDRATES (2)
CARBOHYDRATE-LIPIDS
DIETRY FIBRE (3)
MEATS
FLOUR
UNSKIMMED MILK
ASPARAGUS
- LAMB
BREAD
WALNUTS
GREEN SALADS
- BEEF
RUSKS
HAZELNUTS
SPINACH
- VENISON
POTATOES
ALMONDS
TOMATOES
- VEAL
RICE
PEANUTS
AUBERGINES
- PORK
PASTA
BRAINS
COURGETTES
COOKED MEATS
SEMOLINA
LIVER
CELERY
POULTRY
TAPIOCA
SOYA FLOUR
CABBAGE
RABBIT
DRIED BEANS
WHEATGERM
CAULIFLOWER
FISH
PEAS
EGG PAST
SAUERKRAUT
CRAB
LENTILS
CASHEWS
FRENCH BEANS
SHRIMPS
CHICKPEAS
COCONUT
LEEKS
SCAMPI
CARROTS
CHOCOLATE
ARTICHOKES
LOBSTER
SUGAR
OLIVES
PEPPERS
EGGS
HONEY
CHESTNUTS
CHICORY
BUTTER
MAOZE
SWEET CHESTNUTS
MUSHROOMS
CHEESES
FRUIT
SCALLOPS
TURNIPS
OILS
DRIED FRUIT
OYSTERS
SALFISH
MARGARINES

AVACADO







No comments:

Post a Comment