Is There Evidence to Support the Idea of Life Extension?

In one word - YES - abundantly so - at least in animals.
The evidence is now overwhelming that the same calorie restriction strategies which allow animals to live 30% to 40% longer than their mates, will produce human life extension and also better health.^1,2
The evidence is so compelling that many scientists and technicians working in this area of research have enthusiastically adopted calorie restriction methods for themselves and their families.
In order to understand the evidence we need to swiftly establish how long we are 'supposed' to live, and what happens as we age.³

How Long Should We Live?

An accepted formula for calculating life expectancy in mammals is based on the multiplication by five of the time it takes the skeleton to mature.
This leads to a 15 year average lifespan for dogs (which take three years for skeletal maturity) and in humans, who stop growing at around 25 years of age, to the stunning thought that we should live in good health to around 125 years of age.
What happens when we age is clear enough but the question 'how?' and 'why?'we age have many different theories to explain them.

Aging Theories

Some researchers have concluded that the changes which take place in cells leading to damaged genetic material (DNA) are the main causes of aging. Others suggest that a decline in the efficiency of our organs, accompanied by lowered hormonal and immune function are the underlying cause of aging. There are also those who disagree, arguing that these changes are effects rather than causes of the process.
Many scientists blame a combination of accumulated toxins, free radical activity, declining efficiency of our protective anti-oxidant enzymes along with radiation damage and nutritional deficiencies as the causes, perhaps assisted by built in coding in our genes which 'switches us off' when a certain level of wear and tear becomes apparent.
The signs of aging include increasingly poor protein manufacture by the cells, accompanied by cross-linking of tissues (making it less elastic, hard and wrinkled) plus accumulating levels of age-pigments called lipofuscin (liver-spots) in the cells and tissues which prevents them from normal function. As this happens there is a dramatic drop in efficient defensive enzyme activity as well as lower levels of hormone production, such as the Growth Hormone (GH) from the pituitary (GH is associated with rebuilding and repairing tissues).⁴

Anti-Aging is Not the Same as Life Extension

If free radical activity, toxic accumulation, lack of nutrients (especially the anti-oxidants) were the cause of aging then a health-enhancing diet would be adequate as an anti-aging strategy.
We could simply ensure anti-oxidant nutrients, including enzymes, in our food or as supplements, avoid exposure to toxic factors such as radiation and pollution and take adequate exercise and rest.
While this approach will certainly lead to better health and a slowing of the features of aging (wrinkles, tight tissues, loss of energy etc) it does not lead to life extension...the adding of years to the current norms of life expectancy.

Research Evidence

Research has shown that it is however possible, using one specific strategy, to not only produce life extension, but as a by-product to have the remarkable spin-off of reducing the chances of degenerative diseases such as cancer, arthritis and heart disease, and what is more to often see the normalisation of such conditions when they already exist.
This strategy is called Calorie Restriction and we will examine it in greater detail below. Before examining it though we should briefly examine other life extension approaches.

1. Growth Hormone Stimulation:

This hormone is produced in the pituitary gland and is vital for growth and repair. It is possible to artificially stimulate growth hormone secretion by taking the amino acids (building blocks of protein) ornithine and arginine. This approach was advocated by Durk Pearson and Sandy Shaw and has led to a mini-industry in Life Extension products.⁵
While G.H. stimulation produces a definite 'youth enhancing' result there is no evidence at all that it increases life span.
A 1990 research study at the Medical College of Wisconsin⁶ showed that when synthetic growth hormone was injected into elderly men for a period of six months they built lean body mass (muscle) and lost fatty tissue; increased their bone density; had improved skin quality and thickness, and appeared 10 to 20 years younger than their chronological age. They also felt fitter, more energetic and had enhanced libido.
But neither the stimulation of growth hormone using amino acids, nor the injection of synthetic growth hormone produces an extension of life beyond the current norms.
Calorie Restriction boosts G.H.: Interestingly though levels of Growth Hormone are increased when Calorie Restriction methods are used, and also when we perform aerobic exercise.

2. Antioxidant Approach:

Oxygen is a cellular poison and its free radicals can cause major tissue damage connected with the aging process. Free radicals are thought to be major elements in production of cancer, arthritis, nerve degeneration and atherosclerosis.⁷
All the evidence points to major health benefits and protection against such chronic disease when free radicals are efficiently quenched by anti-oxidant nutrition (vitamins A,C,E and the minerals selenium and enzymes such as Super Oxide Dismutase and Catalase for example) ...but there is very slim evidence of this health enhancing leading to actual life extension.⁸
There is though, perhaps surprisingly, some evidence for life extension in some animals when synthetic anti-oxidants such as the food preservative BHT is added to their feed.⁹
Calorie Restriction boosts anti-oxidants: As we saw in the example of the influence of Calorie Restriction on Growth Hormone, so it is interesting to discover that there is massive 50% increase in the presence of the powerful anti-oxidant enzyme, catalase, when Calorie Restriction methods are used, most noticeably in the liver and kidneys where its presence usually declines as we age.¹⁰
The conclusion is that anti-oxidant nutrition is a sensible addition to any Life Extension programme.

Lowering Core Temperature

The higher the normal core-body temperature of a species the longer is the average life span of its members; but the lower the individual core body temperature of a member of that species (compared with the average) the greater will its own life expectancy be as compared with its fellows. Temperature represents your metabolic rate, how fast fuel is burned per unit of body weight.
When insects are kept in a cold environment their core temperature drops and they can live extraordinarily long lives. It has been suggested that if we could respond in the same way to cold we would live to 200 years of age. Unfortunately though our core temperature goes up when we are cold, rather than down as it does in fruit flies!
If we could find a way of reducing our metabolic activity (as animals do when they hibernate) we could increase the potential for life extension. One proven way of achieving this is via deep meditation methods which have been shown to have precisely this effect.¹¹

Calorie Restriction Lowers Core Temperature

And once again we see how the one proven method of life extension influences this area as well since Calorie Restriction methods effectively reduce metabolic activity as part of their effect.
It is therefore logical that as part of a life extension programme we should add meditation methods to the use of antioxidants, but that our prime aim should be towards balanced nutrition combined with calorie restriction.

Calorie Restriction

A large range of animals including large mammals have been shown to enjoy improved health, greater vitality, relative freedom from chronic disease as well as life extension of up to 40% (which would take the human life span to around 120) when careful calorie restriction methods are used.Is there human evidence for its efficacy?

Human Evidence

There is a great deal of evidence to support the value of Calorie Restriction, none more compelling than concerning the population of Okinawa where the population comes very close to living according to the guidelines set by Walford, Weindruch and Chaitow.^12,13
There are accurate records of births and deaths in this part of Japan dating to 1872 and there are also extensive records kept by the Japanese Ministry of Welfare and Health which periodically evaluates and records dietary habits throughout the country.
Okinawa produces 40 times as many centenarians as the rest of Japan which as a country has a reputation for longevity.
Cancer, strokes, heart disease and other chronic killers are around half to two thirds the level of the rest of Japan, in Okinawa. So what do they eat in Okinawa?
Okinawa intake compared with Japan as a whole of Sugar is 25%, cereals 75%, Green and yellow vegetables 300%, Fish 200%, total protein intake 100% and ENERGY IN CALORIES 80%.
This is the Life Extension Diet in action, as recommended by Weindruch, Walford and Chaitow in their books, based on years of research.
Naturopaths have long used therapeutic fasting as a means of improving health and this is also a valid means of calorie restriction.¹⁴

The Plan

It has been shown by years of experimentation that there is a right and a wrong way of using Calorie Restriction when moving from a standard western diet.

• It must be introduced slowly.
  
• It must not be too severe in the degree of restriction or the weight loss that accompanies it (see below).
  Note: Weight loss is not the aim of Calorie Restriction, but is a usual by-product of it.
  
• It must incorporate FULL nutritional content of ALL nutrients except calories.
  
• Calorie restriction for children is completely contraindicated and ideally no-one under the age of 20 should attempt these methods.
  
• It is never too late to start, but the older you are when you start the slower must be the introduction of calorie Restriction.
  
• Calorie restriction methods are inappropriate for diabetics, people with eating disorders or chronic disease, or who are suffering mental disease requiring regular medication, unless supervised by a suitably qualified adviser.

• First it is necessary to find your 'set point'. This represents the weight you were (or are) between ages 20 and 30 whether your weight has remained stable since then or not.
  
• Based on this set point you must ensure that as you adopt calorie restriction methods (full nutrition with calorie restriction) which does not allow your weight to fall more than 25% from that set point weight, or less than 10% below it, in the first year.
  
• An intake of between 1800 and 2000 Calories per day will satisfy the requirements of Calorie Restriction for most people.
  
• One well formulated multimineral and multivitamin supplement is suggested daily to ensure no that deficiency is triggered by the programme.
  
• The programme should be started slowly (especially important in the elderly) and weight loss should not be rapid.
  
• The selection of foods is based on what are called Exchange Units.

Exchange Units

This is a method commonly used by Diabetics, in which each category of food (Fat, Grain/starch, High Protein, Fruit, Vegetable and Dairy) is assigned a fixed unit of measurement (cupful, tablespoonful etc) which represents a particular number of calories (and in the case of fats and proteins a set number of grams of each of these).
Exchange Units give you the chance to select foods according to personal taste while staying within a framework which guarantees balance and full supply of essential nutrients.¹⁶
Lists are provided which tell you how many Exchange Units each measure of a particular food group carries, and whether it contains protein or fat and if so how many grams of each.
You are also told how many Exchange units of each category, and how many grams of protein and fat you need (based on your current bodyweight) to consume daily in order to ensure good health.¹⁷
Using these guidelines you construct your own choice of foods making sure of the required number of Exchange Units, grams of protein and fat, and in so doing the calorie intake will take care of itself. You do not need to count calories!¹⁸

Other Methods?

A long list of life extension methods have been promoted over the years.
Some might show results when further research is carried out but so far only Calorie Restriction (possibly aided by Anti-oxidant nutrition and lowering of core temperature) has a proven track record of increased longevity and reduced chronic disease.

References