Epigenetics Part 3

INTRODUCING THE FETAL ORIGINS HYPOTHESIS…..

This theory was proposed by David Barker back in the nineties, he hypothesised that children of low birth weight had an increased risk to a range of pathologies in adult life that children of a healthy weight. These illnesses were hypertension, type 2 diabetes and cardiovascular disease. His conclusion subsequently supported by clear and extensive research, was that adequate nutrition during fetal development is absolutely critical to the offspring's health outcomes in later life.¹

So what about OVERNUTRITION during pregnancy?

Did you know that overnutrition is actually a form of malnutrition!

Guess what? An increased risk of the pathologies for undernutrition of the fetus has also been established for overnutrition of the fetus!^2,3

So a baby that is born below or above normal birth weight both have an increased risk of a range of illnesses in later life!

This is heavily influenced by environmental factors like mums diet!

Maternal diets high in fats and sugars (carbohydrates) contribute to high birth weight in children and also leads to an increased risk for pathologies like diabetes in later life. This is thought to be due to epigenetic reprogramming of metabolic pathways in the fetus. Causing changes like decreased insulin sensitivity and increased adiposity (fat tissue) which are all prerequisites for diabetes!³

So essentially, a diet that is high in particularly fats and lipids leads to too much glucose and fats, which are the substances our cells and fetal cells use for energy. The fetus adapts to this high fat and high glucose environment by becoming less sensitive to glucose and also stores excess energy as fat. These changes increase the risk of type 2 diabetes, obesity and cardiovascular disease in later life!^2,4-6

 THE DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE HYPOTHESIS is our final destination….

The moral of the story is, when possible a women should attempt to be in a healthy weight range before getting pregnant and very importantly eat a well-balanced diet during pregnancy. This message is primarily targeted at those who have the means to do this. In first world countries like Australia, the US and UK the obesity epidemic is a major concern. Yes obesity has grievous consequences for those afflicted, but spare a thought for the population of humans that don’t have a say in this plight. The unborn child is inherently vulnerable and utterly dependent on the mother at this time. We are only just starting to grasp the significance of modifiable behaviours during this period and the lasting effects that can result on a life…….MATERNAL HEALTH MATTERS

References

1.  Cutfield WS, Hofman PL, Mitchell M, Morison IM. Could epigenetics play a role in the developmental origins of health and disease? Pediatr Res. 2007 May;61(5 Pt 2):68R-75R.

2.  Muhlhausler BS, Ong ZY. The fetal origins of obesity: early origins of altered food intake. Endocr Metab Immune Disord Drug Targets. 2011 Sep 1;11(3):189-97.

3.  Dyer JS, Rosenfeld CR. Metabolic imprinting by prenatal, perinatal, and postnatal overnutrition: a review. Semin Reprod Med. 2011 May;29(3):266-76.

4.  Stocker CJ, Arch JR, Cawthorne MA. Fetal origins of insulin resistance and obesity. Proc Nutr Soc. 2005 May;64(2):143-51.

5.  Martinez JA, Cordero P, Campion J, Milagro FI. Interplay of early-life nutritional programming on obesity, inflammation and epigenetic outcomes. Proc Nutr Soc. 2012 May;71(2):276-83.

6.  Rkhzay-Jaf J, O'Dowd JF, Stocker CJ. Maternal Obesity and the Fetal Origins of the Metabolic Syndrome. Curr Cardiovasc Risk Rep. 2012 Oct;6(5):487-495.

Epigenetics Part 2

THE DARK SIDE OF EPIGENETICS…..

Epigenetic modifications in expression of our genome can occur throughout our lifetime, however they are most critical in the early years of life particularly in the embryonic development of the fetus. This is an absolutely critical timepoint as epigenetic modifications here will have life-long effects.¹

Are you wondering how a mother can contribute to the epigenetic modifications in her unborn child based of her own behaviour?

Lets look at a striking example of how vital MATERNAL MENTAL HEALTH is during pregnancy…

A cohort study followed a selection of women who were pregnant in New York at the time of the World Trade Centre terrorist attacks, a portion of these women subsequently developed post-traumatic stress disorder (PTSD). At birth cortisol levels of the infant were collected.  Cortisol is known as ‘the stress hormone’ its levels in the body are controlled by the hypothalamus in the brain. Cortisol has many functions one of which is stimulating ‘anti-stress pathways’ in the body. It was shown that cortisol levels in both the mothers with PTSD and their child were lower than normal. It was hypothesised that stress experienced by the mother during the terrorist attacks and thereafter had caused epigenetic modifications in the development of the fetuses hypothalamus and the adjoining stress pathways. Subsequent research provided further evidence that these children showed greater distress then other children in response to stressful stimuli.^2-4

In the last blog we mentioned that epigenetic modification seems to be preparatory survival modifications for the offspring in later life so you may think, well how would this be an effective survival modification?

Perhaps thousands of years ago there was an advantage for a child to be born more ‘sensitive’ and ‘hypervigilant’, particularly if your village was prone to Sabre Tooth tiger attacks. So the mothers trauma in these cases may confer a survival advantage for her alert offspring. However, for those children growing up in a first world country where danger of this nature is rare it may actually be a deleterious modification to the child’s physiology leading to variety of potential psychological conditions like anxiety disorders .^2-4

In short, stress is a significant factor in affecting fetal development, it is something every mother should attempt to address and minimise IF POSSIBLE!

Potentially modifiable behaviours in developed countries like obesity, alcohol intake and smoking also cause epigenetic changes in their offspring and will be discussed in upcoming blogs. Stay tuned for Epigenetics Part 3 in which we discuss one of the most DEADLY EPIDEMICS of modern times and its impact on fetal development….

References

1.  Rivera RM, Bennett LB. Epigenetics in humans: an overview. Curr Opin Endocrinol Diabetes Obes. 2010 Dec;17(6):493-9.

2.  Yehuda R, Cai G, Golier JA, Sarapas C, Galea S, Ising M, et al. Gene expression patterns associated with posttraumatic stress disorder following exposure to the World Trade Center attacks. Biol Psychiatry. 2009 Oct 1;66(7):708-11.

3.  Yehuda R, Engel SM, Brand SR, Seckl J, Marcus SM, Berkowitz GS. Transgenerational Effects of Posttraumatic Stress Disorder in Babies of Mothers Exposed to the World Trade Center Attacks during Pregnancy. The Journal of Clinical Endocrinology & Metabolism. 2005;90(7):4115-4118.

4.  Karr-Morse R. Scared Sick : The Role of Childhood Trauma in Adult Disease. New York: Basic Books; 2012 [Available