Chromosomes and genes contain the blueprint for your physical characteristics. But your parents' health and diet before you were conceived can also affect how your genes are expressed – and impact your long-term health.
See also the studies mentioned in the news item:
Dominguez-Salas et al 2014 - Maternal nutrition at conception modulates DNA methylation of human metastable epialleles
30 April 2014 - BBC News - Pre-pregnancy diet 'permanently influences baby's DNA'
What’s known as the “periconception period” covers the final stages of egg and sperm growth, fertilisation and embryo development before implantation into the uterus. During this time, the overall health of the egg, sperm and embryos are highly susceptible to changes in the environment.
Both under-nutrition (through deliberate calorie restriction) and over-nutrition (through diets high in calories, fats and sugars) in parents during this time can have major impacts on fertility and the long-term health of children.
A recent study published in Nature Communications provides a good illustration of how this works. It described how mothers' seasonal dietary changes prior to conception affected epigenetic changes in their children.
Your parents' health before conception can also affect your weight as an adult. A study in mice, for instance, has shown that when two-cell embryos from diabetic mothers are transferred into mothers without diabetes, development is still negatively affected. These embryos have higher rates of congenital and growth abnormalities compared to offspring from mothers with normal glucose levels.
In terms of fathers' roles, obese mice that were fed high-fat diets before conception had children and grandchildren with increased fat levels.
In general terms, the main epigenetic modifications are DNA methylation (where methyl is added to certain spots) and modifications in the histone (changes to the scaffolding through which DNA is stored). Such modifications are stable in normal cells, but following fertilisation, a mother’s health can dramatically affect the methylation and histone state of the embryo.
Both methylation and histone modifications are affected by diet, environmental chemicals, drugs and ageing. And when they’re induced by poor diet, these changes can have multi-generational effects (as shown in the study of mice on high-fat diets).
The link between macronutrient (the types of food we need in large amounts such as protein, fat and carbohydrates) intake prior to conception and the health outcomes of babies is well known. But the impact of poor diet before pregnancy in both mothers and fathers is becoming increasingly important as we learn more about its impact on development and subsequent health.