The research evidence that I have reviewed in the previous chapters shows overwhelmingly that life span can be extended from the limits we now seem to take for granted, and the best way to set about achieving this appears to be the slowing down of metabolic rates which in turn reduces free radical activity. Throughout it has been dietary changes (most commonly a reduction of calorie intake without any reduction in other nutrient intake) which have come to the fore as the most effective strategy for achieving this. Other means, which may be supportive of dietary strategies, include those which lower the body's core temperature and metabolic activity, often employing 'mind' power techniques in one way or another.
Is it safe for humans?
Only a few years ago, despite having a deep knowledge of the effectiveness of dietary restriction on life extension, some experts seemed reluctant to believe that this sort of approach could be applied to humans. For example, in his major work Secrets of Life Extension (Harbor, San Francisco, 1980) John Mann states:
At present there is no safe way to apply the calorie restriction techniques towards the extension of human life. They would have to be started shortly after weaning and continued
thirty years or more. The mortality rate would be high, and if a person did survive, his mental, emotional, and social development would be distorted by the drastic experience.
So John Mann, as recently as 1980, felt obliged to warn off seekers of a longer life span with this categorical statement that while these methods were OK for fruit flies and mice, there was no way humans were going to be able to benefit from the knowledge by applying modified versions to themselves.
And yet less than a decade later Drs Weindruch and Walford came to a vastly different opinion; that life extension through dietary modification is not only possible but safe. They arrived at this conclusion largely from having successfully conducted a lengthy series of dietary interventions involving adult animals, where, by skillful and slow introduction of dietary restriction, they have avoided the hazards which Mann seemed to believe were automatically built in to the process (and which might well be if early intervention is attempted, before maturity?.
Cautions
A first and vital caution is therefore that dietary restriction techniques should never be applied to children. In this context a child is someone who has not yet completed growth, and for safety's sake this rule should apply to anyone under 20 years of age. This ban, however, does not apply to periodic therapeutic fasting (see Chapter 13) or to the use of antioxidant nutritional strategies, but it certainly does apply to the methods of caloric restriction which I describe later in this part of the book.
No attempt should be made to deliberately increase growth hormone production in any child, by any means at all, unless under the guidance of a medical expert.
Evidence abounds of an adult human's ability to withstand lengthy periods of caloric and general dietary restriction (starvation) for periods of up to two months, as long as liquids are available. If supplements are provided, starvation (restriction of food involving not only calories but all nutrients) for up to six months is possible (depending on available body tissues) without serious long-term effects. However, similar (or even much
shorter) periods of dietary restriction involving children would produce marked malnutrition, and probable irreversible stunting and damage to immune and other functions. So, on no account must this be tried.