Dear Dr. Eva,
Can you explain epigenetics and telomeres? There are a lot of supplements out now that are supposed to lengthen people’s life by making their telomeres longer. Any truth to that?
Juan P. de Leon
I notice that you are using the name of Ponce de Leon, the Spanish explorer who came to Florida in 1513 looking for the Fountain of Youth. He did not find it. The search for longer life is as old as humans’ recognition of death. People have always looked for ways to lengthen our lives. The science of telomeres is complex and rapidly evolving, but two key points are clear:
1) At this time there is no known way to lengthen telomeres. So far, no scientific studies have shown that any drug, supplement, diet, exercise or lifestyle change can lengthen telomeres. Factors that were associated with premature death: smoking, higher alcohol consumption, high blood pressure, high-fat diet, obesity, inactivity, and chronic physical stress such as chronic infections. In blood testing, high LDL cholesterol, high blood sugar, and decreased kidney function all predicted earlier death, but short telomere length did not.
2) Even more important, it’s not clear that lengthening telomeres is a good idea. Longer telomeres are associated with longer life, but they are also associated with an increased rate of several kinds of cancer. Long life does not necessarily mean long, healthy life.
So, what are telomeres?
Telomeres are caps of genetic material that cover the end of each chromosome (see illustration). They were discovered in 1939. To discuss telomeres, we first need to get on the same page about some basics of genetics. Genes are located on the DNA double helix. Genes carry all the instructions to make and maintain our bodies. Every inherited characteristic is passed on through genes. Chromosomes are structures in the nucleus of each cell that contain the DNA. Every gene functions by producing a specific protein, then these proteins cause effects in the body.
Are you with me so far? Look up and take a deep breath, and let’s continue. Factors that were associated with premature death: smoking, higher alcohol consumption, high blood pressure, high-fat diet, obesity, inactivity, and chronic physical stress such as chronic infections. In blood testing, high LDL cholesterol, high blood sugar, and decreased kidney function all predicted earlier death, but short telomere length did not.
Each chromosome is made of DNA, which is tightly coiled around proteins called histones. There are 23 pairs of chromosomes in every cell, except for egg and sperm cells, which have just one set of 23 chromosomes each. It has long been known that chromosomes include a lot of other material in addition to the genes. Only about 1% of the material in chromosomes is made up of genes. The other 99% includes histones (proteins) and strings of DNA which do not code for proteins (non-coding DNA). In the past, histones and non-coding DNA were thought of as protective material whose only function was to prevent damage to the genes. The old name for non-coding DNA was “nonsense DNA.”
In recent decades, research has shown that histones and non-coding DNA control the activity of genes, turning genes on and off so that proteins are made in the right amounts and at the right times. Histones, non-coding DNA, and a process called DNA methylation all influence genes to produce more protein, less, or none of it. Epigenetics is the study of how these factors outside the genes affect gene activity.
Telomeres and longevity
Every time a cell divides, the two new cells have shorter telomeres than the parent cell did. Part of the telomere is used up in the process of cell division. The more times a cell divides (copies itself), the shorter its telomeres become. When the telomere becomes too short, the cell can’t divide. Inability of cells to divide leads to aging because the body loses the ability to repair damage. While this suggests that longer telomeres should mean longer life, research results in this area are uncertain, confused, and contradictory. Telomeres seem to be be longer in longer-lived people, but it’s unclear whether longer telomeres themselves cause long life, or if they are a result of other processes that lead to longevity. Longer telomere length does not necessarily lead to longer life. Small mammal species like mice have much longer telomeres than humans, but much shorter lifespans. On the other hand, women’s telomeres tend to be longer than men’s, and women on average live five years longer than men.
A 2016 study followed 4,500 middle-aged people to see which of 20 risk factors best predicted death within five years. In addition to telomere length, some of the risk factors looked at were smoking, blood pressure, diabetes, body weight, and exercise habits. In this study, longer telomeres were not associated with longer life. Factors that were associated with premature death: smoking, higher alcohol consumption, high blood pressure, high-fat diet, obesity, inactivity, and chronic physical stress such as chronic infections. In blood testing, high LDL cholesterol, high blood sugar, and decreased kidney function all predicted earlier death, but short telomere length did not.
After diving extensively into this topic, it seems to me that the science of epigenetics and telomeres is fascinating but not yet clinically useful. Don’t waste your money on products that claim to lengthen telomeres. Boring as it is, the conclusions of research into longevity show what we already suspected: whatever lifespan you are genetically likely to have, you can live longer by avoiding tobacco and alcohol, limiting fat in your diet, and keeping physically active.
- Eva Hersh is a family physician. Send your comments and questions to her by email at email@example.com
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