Revolutionary research has shown that environmental factors such as diet can activate or deactivate certain genes. This can make us and our children more or less vulnerable to many diseases.
Epigenetics is a new scientific field that has changed the way we think about genetics. We had always assumed that our genetic material was predetermined and beyond our influence. But researchers have challenged this assumption. They showed that lifestyle decisions can influence our genes by changing our epigenome, allowing us to adapt better to the environment. Interestingly, the changes in our epigenome are not permanent and can be changed by modifying our lifestyle.
Just as you are able to press a switch and turn a light bulb on or off, you can do the same with your genes. Certainly it’s not as simple, but lifestyle factors turn different sets of genes on while switching others off. From https://sakaridixon.wordpress.com/2012/07/04/getting-back-in-the-zone/
What is most striking is that recent research has placed a large burden on all of us. Scientific studies on animal models have shown that epigenetic changes can be passed from the parent to the offspring. Although in humans this has not been studied as much due to ethical reasons, recent studies are pointing that epigenetic inheritance also occurs in us. Recent research suggested that diet during pregnancy critically influences the epigenetic inheritance of the embryo. Epigenetic studies have shown that pregnant women on unhealthy high calorific diets, increased the likelihood of their children developing obesity compared to those that ate a healthy diet. This shows that pregnant mothers are more responsible for their children’s future health than previously thought.
Genes contain the DNA that codes for proteins which in turn determine our phenotype. Epigenetics studies the chemical compounds that bind and modify DNA, telling it what to do. In fact these chemical compounds are like labels and are referred to as epigenetic markers. The addition of methyl groups, called methylation, is one of many ways that genes can be tagged. Scientists have shown that methylating genes causes inactivation. Conversely, removal of methyl groups activates genes. The methyl group is added to the base cytosine at carbon 5 of the ring forming 5-methylcytosine.
Our lifestyle plays a big role in gene control mediated by epigenetic mechanisms like methylation. a) Certain genes can be switched on by the removal of methyl groups. b) Meanwhile addition of methyl groups to cytosines will turn genes off so that the protein they would normally express is not synthesised
Many studies are actually pointing that both parents may be responsible for their children’s health before they are actually born. We already knew that a certain type of diet could influence a person by making them more or less likely to develop certain diseases. Previously it was believed that when the offspring was conceived, the epigenetic tags from the parents genetic material were chopped off. Actually, this is not the case at all and in fact these markers are actually inherited. An obese person has more methylation on genes that are responsible for mobilizing lipids from adipose tissue. Due to these genes being inactivated, the fat deposits build up faster. The children of obese people inherit these markers, putting them at a greater risk to becoming obese.
But not all of them actually develop obesity and many people have asked why. The reason is that individuals with epigenetic tags that say ‘obesity’ can make lifestyle decisions that may reverse the situation. For example, they might decide to eat healthily for the rest of their life causing their methyl markers to be removed.
What is fascinating about this, is that we can make positive changes to our health by inducing epigenetic changes. We may be doomed by our parents to have a greater risk of obesity but we can change our destiny by making good decisions. Eating healthily and having an active lifestyle will cause certain genes to be switched on while others will be turned off and reduce the risk of many diseases.
Epigenetics is also involved in cancer, where individual cells may have more methylation than normal. This will cause the inactivation of certain genes such as tumor suppressor genes, making it more likely for the cell to divide uncontrollably. The opposite can also be true; too little methylation may activate certain genes called oncogenes, that promote cell growth causing cancer.
A study carried out by Zeng et al showed that a component in green tea called epigallocatechin-3-gallate has the ability to influence the epigenome, decreasing the risk of breast cancer. The compound was tested on a cell line of breast cancer cells to investigate its effect on the expression of various genes. One important observation was that this compound enhanced the expression of p53. This is a tumour suppressor gene that kills cells that divide uncontrollably, preventing tumor formation.
An epigenetic mechanism involving methylation was shown to be responsible for these observations. Zeng showed that epigallocatechin-3-gallate was able to inhibit an enzyme called DNA methyltransferase. This enzyme catalyses the addition of methyl groups to DNA. Due to inhibition of this enzyme, there was little methylation of the p53 gene so the gene was active, being able to control cell growth. This investigation suggests that drinking green tea on a daily basis may lower the risk of breast cancer by switching on genes that protect our cells via epigenetic mechanisms.
A compound in green tea has been shown to prevent methylation of a gene (p53) involved in tumor prevention. Drinking green tea is likely to have a beneficial outcome in preventing breast cancer by switching p53 on
Other studies have shown that traits like behavior are inherited epigenetically as well. Experiments carried on female mother rats and their pups demonstrated that psychological factors such as the amount of care given have an impact on the pups behavior as they grow. The study showed that highly nurtured rat pups grew out to be calm adults. On the other hand, the pups that were not given much attention by their mothers went on to become nervous. This difference was not genetic but epigenetic. The scientists showed that the Glucocorticoid receptor gene was involved. Highly nurtured rats had little methylation on the gene so it was active. Meanwhile low nurtured rats had a highly methylated Glucocorticoid receptor gene that was inactive. This study clearly showed how crucial early life environmental factors are in determining behavior in the offspring through epigenetic modifications.
Witzmann, S. R., Turner, J. D., Mériaux, S. B., Meijer, O. C., & Muller, C. P. (2012). Epigenetic regulation of the glucocorticoid receptor promoter 17 in adult rats. Epigenetics, 7(11), 1290–1301. doi:10.4161/epi.22363
Zeng, L., Holly, J. M. P. & Perks, C. M. (2014). Effects of Physiological Levels of the Green Tea Extract Epigallocatechin-3-Gallate on Breast Cancer Cells. Frontiers in Endocrinology, 5, 61. doi:10.3389/fendo.2014.00061