1) The results of the limited number
of long term intervention studies which have been reported.
2) Studies on the origin and
evolution of life and interspecies comparisons of metabolic rates and life span.
3) Life span experiments in other
species in which the diet and antioxidant gene expression is modified so as to alter
endogenous free radical reaction levels.
4) The emerging understanding of the
relationship between antioxidants, redox-sensitive transcription factors and gene
expression.
5) The age-related decline in
activation thresholds of key transcription factors and its normalization by antioxidants.
6) The growing number of studies
which implicate free radical reactions in the pathogenesis of specific diseases.
Multiple mechanisms of aging operate
in parallel. Defective mitochondria and membranes, genetic factors, glycation and free
radicals may all contribute to the aging process. Nevertheless, we are now finding that
redox-modulated processes are central to most of the models of aging. The discovery of the
antioxidant network and its capacity to modulate gene expression has linked genetic aging
theories to free radicals, and offers a powerful explanation of our vulnerability to
chronic disease in later life.
Even though the 'free radical'
diseases include the two major causes of premature death - cancer and atherosclerosis,
which leads to cardiovascular disease - as yet, there is no evidence that the maximum
human life span of 110 -120 years will be increased by antioxidant intervention.
The important thing is that most of
us now live forty years less than the maximum human life span, and often our later years
are blighted by degenerative disease.
There is now compelling evidence
that a considerable part of the deterioration in health we experience in the second half
of life may not originate in inevitable, irreversible, gene mutations or failures, but
rather involve cumulative free radical damage and shifts in the activation thresholds of
genes, potentially preventable and reversible by good diet and antioxidant
supplementation.
For the first time in evolution, humans stand at the
threshold of understanding how we may overcome the limitations of the genes we have
inherited. That the means may not involve the exotic technology of genetic engineering and
gene splicing but common natural nutrients our grandparents knew of is truly humbling