This powerful statement is among the most important findings made by research doctors Weindruch and Walford, based on the hundreds of animal experiments which they have conducted involving dietary modification and restriction (see Chapter 5). And, what is more, they believe that what they have found is available to all of us by simply applying the principles they have established from their studies.

As well as this, they point to another phenomenon, and that is that animals already ill with chronic disease at the start of the dietary restriction experiment frequently recovered full health, with the illness significantly improving or vanishing completely. They explain that a number of diseases arise 'spontaneously' (it might be more accurate to say they commonly arise, since they do not appear in everyone there is obviously a cause, and this cannot therefore be considered spontaneous) in humans as they age, including cardiovascular disease, cerebrovascular disease, cancer, diabetes, arthritis, osteoporosis, dementia, cataracts etc. Some of these are clearly life-threatening, adding markedly to the likelihood of a reduced life span, while others increase the chances of accidents as well as reducing the quality of life.

The animal studies that the two researchers conducted showed that not only are these diseases far less likely to occur when diet is modified, but that if they do occur it will be at a far later stage in the life of the animal. Thus 'spontaneous' diseases of old age are reduced in animals that live on a diet which contains a full complement of nutrients (vitamins, protein etc.) but which has a lower than usual level of calorie content.

A longer life, less chance of developing serious disease and even recovery from such disease if it already exists. These are quite astounding and revolutionary claims.

Different patterns of dietary restriction
The ways in which animals are induced to achieve a restricted diet varies. In some instances they are allowed to eat whatever they wish of a fully balanced diet for a restricted amount of time; often this is for 12 hours every other day. In other instances they are fed a known amount of food which represents between 40 and 70 per cent of what similar animals would eat when offered the chance to feed whenever they wish. In some experiments these restricted amounts are boosted by supplements of nutrients to ensure that no deficiencies occur. Diets which contain an identical amount of nutrients (apart from calories) to those given to non-restricted animals are called isonutrient diets.

The animals were started on a restricted diet both very early in life, and later in life to compare the effects brought about by early and late changes. In each case the diet, when used experimentally, produced similar results in increased life span and reduction of disease, but it was found that when the diet restriction was started early in life it could have particularly harmful side effects through changes in the development of the animal, unless nutrient intake was kept at levels of absolute excellence.

These two research pioneers say that they decided to introduce adult animals to dietary restriction with the express purpose of learning more about the improvements in the disease patterns commonly seen in human ageing. Such eating patterns, they believe, can plausibly be usable in humans. But, in responding to the two searching questions which they had posed-'Can adult dietary restriction slow down the onset of late-life disease in humans? and 'Can human adult dietary restriction forestall the progression of, or aid in curing, ongoing diseases?' - their answer included what can only be a mistaken assumption because they said: 'Although human data are unavailable, results of adult dietary restriction studies in rodents, although much less extensive than early life dietary restriction studies, also show favourable effects on late-life disease patterns.'

The assumption that no data exists to support human results following dietary restriction ignores much research into therapeutic fasting and naturopathic treatment methods which include dietary restriction. I will outline these methods later in this chapter and in other chapters.

Fasting patterns
On Mondays, Wednesdays and Fridays Weindruch and Walford had fed their experimental animals an isonutrient diet (that is, all the nutrients that a free feeding animal would receive but with calorie restriction), and they reported equal success in terms of life extension and disease reduction with animals fed every day but in reduced quantities. Whichever regimen, their overriding rule was that the animals were never malaourished and always received their total requirement of protein, vitamins and minerals whilst calories were restricted. The pattern of feeding, therefore, was one of 'undernutrition without malnutrition'.

If you or I were eating on alternate days only, we would be fasting on the others, and even if we ate just once daily, we could be said to be fasting for the rest of the day. It is in the variations of patterns of eating and fasting that we should look to find our personal strategies, for it is the effects of periodic fasting which might hold the key to the door to life extension and disease reduction. The benefits seem always to be the same whatever variation in pattern used, as long as the basic principle of calorie restriction is kept to.

Reduction in disease levels
From strains of rats and mice specially bred for experimental it is possible to select types which are more than commonly prone to particular diseases. These may involve different types of tumour (lung, breast, leukaemia etc.) or a variety of other chronic degenerative diseases. When such prone types were used in the dietary restriction experiments of Weindruch and Walford the development of a wide array of diseases was seen to be delayed and the overall incidence was dramatically reduced. As the dietary restriction programme was intensified the disease prevention effects became greater and this was most marked in the case of cancers of many types. On top of this, research also shows that despite the dietary restriction normal physiological function is maintained and in many instances improved.

Weindruch and Walford's experimental work is recent and ongoing. Another man's efforts in researching the nutrition health link dates back to earlier this century, but it is no less valid and important today than it was when he carried it out.

McCarrison's Indian observations
During his many yeas in India, the famed medical researcher into nutrition, Sir Robert McCarrison, observed the varying patterns of health current amongst different groups on the subcontinent. He was fascinated by the different levels of health and physical efficiency, and found that the single factor that had the most profound influence on these characteristics was not the climate, endemic disease or race, but food. His first observations were of the decline in stature, body weight, stamina and efficiency of the people as he traveled from the north to the south of India. He compared this with the local diets and found a direct and constant correlation in that there was a fall in nutritive value of the commonly eaten food, from north to south. He makes the following statement in his book Nutrition and Health (McCarrison Society, London, 1982):

This is not to say that in these parts [the south] there are not people of good physique nor that in the north of India there are not many whose physique is poor. But speaking of the generality of the people, it is true that the physique of northern races of India is strikingly superior to that of southern, eastern and western races. This difference depends almost entirely on the diminishing value of the food . . . with respect to the amount and quality of proteins, the quality of the cereal grains forming the staple article of the diet, the quality and quantity of the fats, the minerals and vitamin contents, and the balance of the food as a whole.

What were the diets?
In northern India at that time grains such as wheat were eaten, usually as whole grains. Whole wheat has a high protein content,

McCarrison observed, especially when eaten freshly ground, with the grain retaining much of its high levels of minerals and vitamins. Also, in the north, the diet included milk products such as clarified butter (ghee), buttermilk and curds, as well as pulses (lentils mainly, eaten as dhal) and fresh vegetables and fruit. Meat was eaten sparingly if at all, although some groups such as the Pathans ate it in abundance.

By comparison the southern diet was based on white rice (mainly milled, polished or parboiled [often all threel, following which it was washed in many changes of water and finally boiled, reducing its nutritional value to virtually nil). Little milk protein was consumed in the south and meat was largely proscribed for religious reasons, and there was only a poor intake of vegetables and fruit.

McCarrison's experiments
Just as and longevity research is based on animals because human experiments are impossible, having made his observations amongst humans, set out to prove his thesis by applying to laboratory rats - all of which started from the same level of well-being - the various patterns of diet he had seen. Rats mature about 30 times faster than humans, making an experiment lasting 140 days equivalent to roughly 12 years in human terms.

In his first major experiment in this series he took seven different groups of the same strain of rat, with each group containing 20 rats, each having an even number of males and females, matched for body weight. They were kept in large cages under precisely the same conditions, each group being fed on a different pattern of diet, containing exactly the normal ingredients of either the Sikhs, the Pathans, Ghurkas, Mahrattas, Kanarese, Bengalis or the Madrasis. After 80 days and 140 days the animals were weighed and photographed, and their health was monitored throughout. The results proved precisely what McCarrison had anticipated, that the best diet of all was the Sikh (abundant in all nutrients) and the poorest the Madrasi (high in poor quality carbohydrate and deficient in protein and other nutrients).

This initial experiment so impressed McCarrison that he decided in future to keep his stock of rats (used for other experiments) on the Sikh diet. He had roughly 1,000 such animals to which he subsequently fed whole grain chappatis, fresh butter, sprouted pulses, raw fresh vegetables (cabbage, carrots) plus milk and water. Dry crusts were provided to keep their teeth healthy. Once a week a small amount of meat and bone was given. The rats were kept in these conditions for an average of two years - about 50 to 60 years in human terms, with young rats being taken periodically for experimental purposes and the older 1,000 being kept on the diet for breeding purposes.

Over a five year period McCarrison noted no case of illness, no death from natural causes, no maternal mortality and no infantile mortality amongst this group of rats. They were of course kept clean and had exposure to the sun daily and were generally well cared for, but the same conditions and care were given during these years to thousands of other rats fed deficiently on southern Indian diets, amongst which a wide variety of illness was observed. It was the altered diet which provided a disease-free environment for the rats, and this corresponded with a sturdier physique, just as McCarrison had observed amongst humans following these different dietary patterns.

He concluded that if attention is paid to three things cleanliness, comfort and food - it is possible to exclude disease from a colony of cloistered rats, and that it is possible greatly to reduce disease by the same means in human beings.

McCarrison's final experiments
Having found that the Sikh diet provided an ideal for good health and long life, McCarrison then took two groups of 20 matched rats and fed one on a Sikh diet and the other on a typical British diet (white bread, margarine, sweetened tea, a little milk, boiled potatoes and cabbage, tinned meat and tinned jam). The differences between the two groups of rats were dramatic and rapidly observable. The Sikh-diet fed rats were, as in previous studies, contented and healthy. The British-diet fed rats did not flourish: