Theories of Aging

Thank you all for participating in this discussion on aging and the science behind it.

Let me introduce our Chief Technology Officer, Prof. Robert Kam-Ming Ko. He is currently the Professor in the Division of Life Science at the Hong Kong University of Science & Technology. After graduating from the Chinese University of Hong Kong, he went on to Canada and obtained his Ph.D. in pharmacology at the University of British Columbia in 1990.

He then returned to Hong Kong to pursue his research work on Chinese herbal medicine. His research focuses on antioxidant and immunomodulatory properties in Chinese tonifying herbs in establishing their scientific basis in terms of modern medicine. He has edited three books and published more than 180 scientific papers and book chapters on related topics.

I trust that this information would be sufficient to qualify him as an expert in his field.

Let us start with the theories of aging.

Aging is a consequence of changes that are harmful, progressive, and thus far irreversible in most living organisms, including humans. Age-associated damage occurs to biomolecules, cells, and organs. Diseases such as arthritis, osteoporosis, heart diseases, cancer, Parkinson's disease, and Alzheimer's disease occur more frequently with old age.

The biochemical mechanism of aging has long been an area of intensive research, and a number of theories of aging have been proposed, including the neuro-endocrine theory, which links aging to hormonal changes; immunological theory, which attributes aging to immune system dysfunction; telomerase theory, which relates to the shortening of chromosomes during cell division; and oxidative stress theory, which refers to free radical damage to cells; stem cell exhaustion, which refers to the decline in the regenerative potential of tissues due to decreased number of stem cells, and the decline in their abilities to differentiate.

Among these theories, it is reasonable to distinguish those that attempt to establish primary causes of aging from those that are secondary. For example, the telomerase theory may be secondary since the decrease in telomerase activity can be caused by the increase in cellular oxidative stress.

In gerontology, the study of aging, oxidative stress is increasingly recognized as the primary cause of aging.

The role of mitochondrial decay in aging

If oxidative stress is indeed the primary factor in skin aging, it is important to understand its roots. Scientists now believe that oxidative stress may be caused by mitochondrial decay. Mitochondria, the chief producers of both energy and oxidants inside the cell, play a critical role in the process of aging.

As energy producers, mitochondria convert unusable forms of energy into a usable chemical form known as adenosine triphosphate (ATP), which is required for all vital cellular chemical reactions throughout the body. During the metabolic cycle of ATP production, oxidants are released from the mitochondria as harmful by-products that can damage important biomolecules, such as DNA, lipids, and proteins. At the same time, the mitochondria themselves are also victims of this metabolic cycle of ATP production as they are highly susceptible to damage by the oxidants thus released.

Over time, largely due to cumulated damage by the oxidants, the functional capabilities of mitochondria deteriorate; the production of ATP declines and the release of oxidants increases. The latter inflicts greater damage to the mitochondria, which in turn results in accelerated oxidant production. This is the vicious cycle of mitochondrial decay. If left unchecked, mitochondrial decay leads to cumulative damage in cellular biomolecules, resulting in a host of age-related diseases.

Effects of mitochondrial decay on the skin

The skin is the body's largest organ. The consequence of cumulative damage in skin cell biomolecules is a corresponding increase in the depletion of important extracellular components, such as collagen, elastin, and hyaluronic acid, among others. The loss of these significant components is manifested in the appearance of wrinkles, fine lines, droopiness, pigmentation, puffiness, skin inelasticity, enlarged pores, dryness, and a dull skin tone.

Conclusion

An increasing amount of scientific evidence confirms that mitochondrial decay is the fundamental cause of aging; therefore, scientists are endeavoring to find remedies to reverse the declining functional capabilities of mitochondria due to aging.

More information on mitochondrial decay and theories of aging can be found at these independent websites:

National Institutes of Health (http://www.nih.gov)

PubMed (http://www.ncbi.nlm.nih.gov/pubmed)

Natural Standard (http://www.naturalstandard.com)