Prof B L Kaul
Ageing is the process of becoming old. The term refers to humans, many other animals and plants. There are certain examples of potentially immortal organisms like bacteria, perennial plants and some simple animals which continuously keep on dividing. In a broader sense, ageing means the process wherein single cells within a many-celled living organism stop dividing. It also refers to the individuals of a population getting older.
In human beings ageing means accumulation of bodily changes over time resulting in physical, psychological and social changes. With increasing age reaction time may decrease but memories and general knowledge typically increase. Ageing also increase the risk of many diseases such as dementia, diabetes, stroke, heart disease and cancer. Almost 150,000 people die every day across the whole world, with almost 2/3rds dying from age-related causes.
WHY DO WE AGE?
There have been many theories and hypothesis about ageing. Some of these are:
Peter Medawar and Leo Szilaid hypothesis – According to this hypothesis, ageing is caused by DNA damage resulting in the loss of genetic information. It is not universally accepted.
Leslie Orgel’s ”Error catastrophic hypothesis”- According to this hypothesis, mistakes made during the DNA copying process lead to changes in genes, including those needed to make the protein machinery that copies DNA. This leads to the disruption of copying until a person’s genome has been incorrectly copied – leading to death.
Denhem Herman’s ”Free radical theory of ageing”- This theory blames ageing on unpaired electrons that quickly move around within cells damaging DNA through oxidation, particularly mitochondria – the powerhouses of cells. Experiments on rats have not supported the concept that consuming antioxidants can extend life span. It has now been demonstrated that positive health benefits attainable from an antioxidant rich diet are more likely caused by stimulating the body’s enzymes that eliminate free radicals, not as a result of antioxidant activity itself. However, we do know that free radicals cause mutations to the nuclear and cell genomes. Mitochondrial decline is certainly a hallmark of ageing and can lead to dysfunction of organs. It is now almost clear that ageing isn’t caused by mutations in nuclear DNA.
The latest view is that ageing andthe diseases that come with it are multifactorial. These include genome instability,removal of chromosomal endcaps, the telomeres, loss of healthy protein maintenance, dysfunction of mitochondria, accumulation of senescent cells that inflame healthy cells,exhaustion of stem cells and altered intercellular communication.
Can ageing be slowed down?
Although we cannot stop ageing process completely, the molecules mechanisms underlying ageing show that it is regulated by certain cellular processes. It may be possible to slow down the ageing process by influencing cellular processes and improve our health as we age.
Diet directly affects ageing. If we eat less as we age, we can expect to live longer. The traditional thought that our life is controlled by some external superior power does not appeal in the face of scientific knowledge that has accumulated over the years. We know that in most animals, exercise and diet are the main influences on the rate of ageing. It has been observed that in some animals, reducing food intake leads to a healthier and often longer life. It seems that it is not so much the amount of food we eat that influences the ageing process in the body, but rather what we eat.
There is now evidence to prove that the individual nutrients in food have a direct effect on an animal’s health and ageing process. Experiments carried out on fruit flies have shown that if fed on a diet high in proteins and amino acids – they die earlier than flies fed on a balanced diet. Some studies have also shown that a reduced intake of certain aminoacids has a positive effect on health in humans as well. These findings suggest that avoiding a high-protein diet may prolong life span and improve health in old age. In India we know that people who take restricted vegetarian diet live longer than those who eat oil-rich and non-vegetarian foods. The ascetics, fakirs and sadhus feeding on a minimal diet are known to live healthier and longer lives. On the contrary, obese individuals are often afflicted with diseases such as diabetes, liver and kidney diseases, and their lifespan is impacted.
It is doubtless that the quality and quantity of the food we eathas a direct impact on our health and the ageing process. The good bacteria found in our gut help us digest food and also seem to have a direct effect on our health and the ageing process. This has been proven by experiments on animals like some fish. In younger humans the bacteria in the intestines thrive but they seem to reduce as we grow old. It is important to maintain the populations of these bacteria as we age by consuming more yogurts and by taking food supplements rich in these useful bacteria.
While nobody can stop us from dying, we can live healthier and longer lives by accepting that ageing is a reality of life and we should try to live it gracefully.
Credit Ian Stuart– Hamilton Professor of Developmental Psychology, University of Glamorgan. Wales.
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