Non-infectious diseases like metabolic disorders or neurodegenerative conditions have been rising with each generation. Studies show that although human genes have not changed much in the last few generations, gene expression has changed. These changes in gene expression are studied by epigenetics. A new study shows that such epigenetic gene changes can also be transmitted to multiple generations.
Traditionally, medicine has known about two important risk factors for various ailments, genetics, and environmental factors, including lifestyle choices. Hence, for a long, it was believed that most diseases occur in genetically predisposed people when they are exposed to certain environmental triggers. Such triggers include infections, toxins, dietary factors, etc.
Hence, in genetically predisposed individuals, wrong dietary choices and obesity lead to diabetes. Similarly, metabolic disorders, exposure to toxins, and infections increase the risk of autoimmune diseases, dementia, and even various cancers. Nonetheless, these theories fail to explain the rise of specific health conditions. Thus, researchers thought that there must be something more. Something they are still failing to understand.
They noticed that many people have become predisposed to health conditions like neurodegenerative disorders, obesity, diabetes, heart disorders, and cancers, and their bodies seem to be unable to cope with these health issues. It appears as if some genetic changes have occurred in the population. However, geneticists say there is no such evidence that human genes have changed significantly in the last century.
Nonetheless, health experts noticed that though human genes have not changed significantly in the last few decades, gene behavior has changed. Or more specifically, gene expression has changed, with some gene parts becoming more active and others less active, which explains why people have become prone to certain health disorders in the last century.
It appears that these changes in gene expression have occurred due to brisk lifestyle and environmental changes. Like people have become increasingly sedentary, they have started consuming processed foods and more. These changes caused in gene expression due to lifestyle and environmental changes are called epigenetic changes.
With a better understanding of epigenetics, researchers were, for the first time, able to explain why certain population groups have become prone to specific health conditions. However, what is worrisome is that these epigenetic changes can also be inherited. It means that coming generations are becoming prone to metabolic disorders due to inherited changes in gene expression, though gene structure has not changed significantly.
This theory that epigenetic changes in the gene can be inherited still has to be fully proven. Most evidence to date comes from observations rather than from some firm evidence. However, things are changing fast, and more and more studies are proving the notion that epigenetic changes can be inherited.
In the latest study published in the journal Proceedings of the National Academy of Sciences (PNAS), researchers focused on the epigenetic mark (called H3K27me3), known to repress affected genes. By studying the nematode worm C. elegans, researchers could demonstrate that epigenetic marks were inherited even by the third generation of the worms.
It means that faulty lifestyle choices like binge eating and a sedentary lifestyle can cause epigenetic changes in genes or alter gene expression. These changes can then be passed to the next generation. Once the offspring or grandoffspring have inherited these epigenetic changes, they are at an even greater risk of metabolic disorder. It also means that by making positive lifestyle changes, we can make positive epigenetic changes and ensure healthy offspring.
Therefore, those living with faulty lifestyles need to understand that they are not harming their health but also increasing the risk of certain health conditions for coming generations.