In the early 1980s Durk Pearson and Sandy Shaw’s book Life Extension was published, and it rapidly became an international bestseller, spawning a minor industry in production and sales of nutritional supplements such as antioxidants and enzymes. One of the approaches outlined in their book was the taking of such substances as the amino acids arginine and ornithine in order to stimulate the pituitary gland to produce greater amounts of growth hormone.
This hormone plays a vital part in all aspects of growth (especially in the young) and repair (which calls for enhanced protein synthesis), as well as having a beneficial influence on immune function. It is produced in the anterior pituitary gland (at the base of the brain) and the efficiency of its production is known to decline with age, so that by 60 years old almost a third of us have no growth hormone production at all. Not surprisingly, this is seen to be a key factor in the speed with which we age.
Among the stimulants which encourage production of growth hormone are peak level exercise (not just any exercise, only that which pushes you to the limit, such as aerobic), trauma (peak level exercise has a minor traumatizing effect on muscle, and this might be the trigger for growth hormone), fasting, sleep (but more so in young people) as well as the specific amino acids mentioned above.
In 1990 a remarkable research study, carried out by Dr Daniel Rudman, of the Medical College of Wisconsin, was reported in the New England Journal of Medicine. A group of 21 elderly men (age 61 to 81) were tested over a six month period, 12 of them receiving injections of synthetic growth hormone three times weekly, the other nine receiving no treatment (for comparison of results of those treated and those untreated). The diets of all 21 were kept much the same (protein 15 per cent of intake, carbohydrate 50 per cent and fats 35 per cent) with no change at all recommended in smoking and other habits. Those who received the hormone showed marked benefits at the end of the study:
- Increase in growth hormone levels in the blood to that of 40 year olds.
- Decrease of fatty tissue by 15 per cent
- Increase in lean body mass (mainly muscle) by 9 per cent
- Increase in density of bone (vertebrae) by 1.6 per cent
- Increase in skin thickness by 7 per cent
In many respects it was found that the men who received growth hormone appeared physiologically to be 10 to 20 years younger than when they started just six months previously. Subjectively the men felt trimmer, more energetic and healthier, noting firmer skin, less fat and more muscle. Not surprisingly none of the improvements or subjective feelings were seen or reported in the nine who received no treatment.
Caution is called for, warn the researchers running this test, for
the following reasons:
- Growth hormone replacement can cause diabetes, arthritis and high blood pressure. Although none of these occurred during the trial, long-term problems could arise if use continued indefinitely.
- The cost is over £8,000 for a year’s supply of growth hormone.
- There was no improvement in brain or eye cells, nor in elastic tissue.
This means that it almost certainly has no effect on free radical damage or DNA repair, although the results in terms of improved lean body mass shows that it does enhance protein synthesis. So, if the use of synthetic growth hormone does not reverse the ageing process totally, merely selectively, and if it has no proven effects on life-extension, would ‘natural’ growth hormone be different?
Evidence from animal studies
Weindruch and Walford have shown that dietary restriction produces strong effects on the endocrine (hormonal) system. They have also reviewed the work of many scientists who hold to a view different from that which sees ageing as the result of what happens in cells. The contrary view suggests that ageing has more to do with signals delivered by hormones, probably working in collaboration with the nervous system. Hormones are powerful chemical messengers and evidence exists of regeneration of tissues which have aged (possibly due to a decline in hormone levels) once hormone levels are topped up.
An example of this is provided by what happens in rats when growth hormone is implanted into them. Another important hormonal centre, the thymus gland, which often shrinks with age, is found to regenerate when growth hormone is implanted into elderly rats, resulting also in a marked improvement in immune function (with which the thymus is intimately involved). Similar regeneration is seen, but this time in nerve and brain tissue, when nerve growth hormone is infused into the brains of elderly rodents. Aspects of their memory are seen to improve as a result.
This shows that growth hormone might have a profound effect on complex organizational systems (such as hormonal, nervous, and immune systems) which together might be the elements which decide on the speed and sites of ageing. But how can humans improve their growth hormone levels? And what about ‘natural’ stimulation of growth hormone?
This brings us back to Pearson and Shaw, and their promotion of arginine and/or ornithine. These two amino acids are present in your diet every time you eat a complete protein such as eggs,
cheese or fish. When you take them as supplements they arrive in your body to join a pool of free amino acids derived from your food, where they wait for distribution and use in new protein synthesis or, in the case of ornithine, for use in body processes such as detoxification, transportation and metabolism.
When amino acids (the building blocks of protein) are used on their own in this way they act in a pharmacological manner, rather than as they would were they to be eaten as part of a food. It is in this way that they stimulate growth hormone production by the pituitary gland. Leslie Kenton, writing in Ageless Ageing (Century Arrow, 1988) extols their virtues but settles for ornithine as the most useful:
Ornithine is an excellent growth-hormone stimulator thanks to its action on the central nervous system. In fact it is twice as active as arginine. And it has an ability which arginine doesn’t have – it can actually be transported to the mitochondria, the cell’s energy factories. Many physicians and nutritionists who use growth hormone stimulants recommend taking ornithine alone instead of both.
A suggested supplement dosage of ornithine is 4 grams daily (good health food stores and most pharmacies stock it) taken with water, say 2 grams in the morning and 2 grams in the evening, away from meal times. A few months on such a regime should show results in terms of less fatty tissue and firmer skin and body generally, although whether this on its own can in any way translate into life extension seems doubtful. Were arginine used in preference to ornithine, approximately twice the dosage would be suggested, as long as the cautions given below are adhered to.
Whether either ornithine or arginine are used to stimulate growth hormone beware of possible side-effects of excessive growth hormone stimulation:
- Growth hormone should never be stimulated in people who have not completed their growing phase (unless under medical supervision).
- If excessive growth hormone is released skin may become coarse. This will be reversed and normalized when such stimulation ceases.
- Joint enlargement is possible if growth hormone stimulation continues for an excessive amount of time, and so a programme of several months use followed by several months non-use is suggested.
- It is suggested that any use of amino acids in this way be accompanied by a dietary strategy which increases antioxidant levels (see Chapter 8).
Is there a ‘death’ hormone?
I have shown the power on health and ‘youth’ of growth hormone produced by the pituitary gland, and I have suggested that it does not seem to influence life expectancy. But some researchers take the view that with ageing the pituitary may start to produce a ‘death hormone’. The evidence for this lies in unpleasant experiments in which rats and other animals have their pituitary gland removed so that effects can be observed. This is known as a hypophysectomy, and it is an operation performed on some people with cancer in order to slow down progression of their disease. When this operation is done experimentally the ageing process is seen to slow down. There is less cross-linking of tissues such as collagen, less chronic disease of ageing and a long list of ‘improvements’, all suggesting that ageing is being slowed.
However, as Weindruch and Walford report: ‘Although these animals show features of greater youthfulness, they do not enjoy an extended species-specific maximum life span.’ It may be that rather than production of a ‘death hormone’ being prevented by removal of the pituitary, what is actually being prevented is the circulation of ‘faulty’ hormones, such as a large molecule growth hormone which is often noted in elderly animals. It is believed that these have their harmful effect by blocking receptor sites, thus preventing ‘real’ growth hormone from being able to act.
In effect, whether the pituitary produces death hormones or faulty hormones which act like death hormones, the fact remains that it can be seen to be involved in the ageing process in a direct
way. What is of particular importance to us is the fact that dietary restriction has influences on the pituitary similar to those in hypophysectomy. Dietary restriction, it is suggested, may therefore act in much the same way as an hypophysectomy.
However, this is an incomplete comparison, with only some features of dietary restriction effects being the same as removal of the pituitary. For one thing, life extension is not produced when this gland is removed, and for another the effects on levels of growth hormone are not the same. When an animal no longer has its pituitary it cannot produce growth hormone in anything like previous quantities. But on long-term dietary restriction, growth hormone might continue to be produced, although experimental results to date are confusing. In fasting (short-term dietary restriction) growth hormone production certainly is increased.
From an evolutionary viewpoint it is worth considering that there would be nothing to be gained by an organism (animal or human) investing valuable energy in producing a hormone which is designed to make it grow during a period of extreme food shortage. A further interesting observation is that when animals have their pituitary gland removed they automatically start to eat at a level similar to that applied during dietary restriction. In this instance it makes evolutionary sense for the animal which is no longer producing growth hormone to automatically require less nutrition, since its growth and repair mechanisms will be somewhat reduced in their need for raw materials.
Weindruch and Walford ask whether the rejuvenating effect seen after hypophysectomy is not actually the result of voluntary dietary restriction which follows it. They then pose the same question, but extend it somewhat, asking that if the rejuvenating effect of hypophysectomy is the result of voluntary dietary restriction, why do the animals not enjoy an extension of their lives? Answers to such questions are not always available, but it seems unlikely that the pituitary gland controls ageing, although it is certainly involved in it.
The complex interactions of hormones and ageing can also be simplified at this point to suggest that dietary restriction, amongst its other benefits, improves hormonal balance, and that at least some of its benefits relate to the influence it has on growth hormone. So should we supplement with ornithine or arginine? For the increase in youthfulness, possibly, if that end is desired, and if the cautions listed in this chapter are followed (remembering that dietary restriction will achieve this as well, and that growth hormone will be stimulated by periodic short fasting ). But, as far as is now known, amino acids used to stimulate growth hormone will have little if any effect on life extension.
Whether antioxidant nutrition affects life extension is our next target for investigation.