Pregnancy, nutrition, and why you are what your mother eats
The food a foetus is exposed to can affect how the child develops, even into adulthood
Babies with limited nutrition in the womb can suffer if, after birth, they are overnourished. Photograph: Thinkstock
Forget the old adage that “you are what you eat”. That was the last decade’s breaking news. The new message coming down the line is that you are, in fact, what your mother eats. Or, more specifically, what your mother ate during pregnancy.
Dr Cora Doherty is an Irish neonatal consultant who has been working in the UK (currently at University Hospital of Wales, Cardiff) for the past couple of decades. She recently presented a talk to the Irish Food Writers’ Guild entitled “You are what your mother eats”.
Her presentation took in reptiles and rodents, world wars and lost tribes, genetic programming and global health epidemics. But for the most part it asked the question: how might our changing diet be affectingn the long-term health of the growing foetus? Her answers were remarkable.
Infection, once the biggest threat to human life, has a major competitor today in the form of non-communicable diseases such as type 2 diabetes, cardiovascular disease and cancer. The statistics for diabetes alone are frightening. Type 2 diabetes affects about 360 million people worldwide, with that figure predicted to rise to one billion within two decades. For scientists such as Doherty, any sudden change such as this begs the question: why? What has changed to cause this epidemic?
Clearly, our diet has changed. Much of our food contains significantly fewer micro-nutrients than estimated in Victorian times, and our obsession with fad diets is unabated. In recent decades our sugar intake has increased tenfold and our fat intake doubled, including many dangerous new forms such as trans fats.
But when it is considered in the context of “programming”, the impact of diet on our health becomes startling. In his article entitled “Long-term Programming Effects of Early Nutrition” (Journal of Perinatology, 2005), Prof Alan Lucas defined programming as the idea that “an insult or stimulus at a critical or sensitive period of development can have long-term or lifetime effects on an organism”.
Research has shown that a dose of drugs such as steroids or testosterone administered to foetal or infant rats will have a far greater impact on the rat’s later life than the same dose given to the adolescent rat.
Scientists can’t very well go around giving pregnant women high dosages of drugs to research whether a similar correlation can be found in human foetal and infant development. But history has given us several striking case studies.
In the 1990s, Prof David Barker examined ledgers kept by an English midwife in the years directly after the first World War, a period of nutritionally deficient diets throughout Britain. The detailed information in these ledgers allowed for later follow-up. The results showed that in men followed up at the age of 64, those who had lower birth weights had been more likely to develop diabetes and hypertension.
Evidence of the long-term effect of various famines experienced during the second World War has shown similar results. Those babies born during or directly after the Dutch Hunger Winter of 1944-45, within the community that was cut off from its surrounding farmland, were more likely to have diabetes and impaired glucose levels later in life. And babies born directly after the Leningrad siege of 1941-44 were half a kilo below average birthweight, and with similar implications later in life.
To understand why this might be the case, Doherty’s talk brought us back to 1992, to a hypothesis dubbed the “thrifty phenotype” (Hales & Barker, 1992) which posits that the foetus adapts in the womb to prepare itself for the environment it expects to be born into.
Specifically, a limited supply of nutrients to the foetus triggers early-life metabolic adaptations to help prepare the child for a nutrient-poor environment.
Poor in nutrients
Evidence suggests that the foetus responds by redirecting bloodflow to prioritise brain development over organs such as the liver, kidney and pancreas. This “brain-sparing” instinct works well in cases where that environment is poor in nutrients.
However, problems can arise for those who experience limited nutrition in the womb followed by overnutrition postbirth. As Doherty put it, children who are born small and stay small don’t stress their systems in the manner of those who grow too fast. For the latter cases, many of the adult symptoms that develop correlate directly with those associated with key noncommunicable diseases, that threaten global health today.
The research Doherty presented, about which she is planning to write a book, clearly suggests that the long-term effects of nutrition during pregnancy may be far greater than we have understood. She is keen to stress that we can take simple steps (see panel) to improve diet during pregnancy and in the early stages of development, when breastfeeding has well-documented protective effects.
Aoife Carrigy is incoming chair of the Irish Food Writers’ Guild.
Food foundations: Tips for improving diet during pregnancy
Eat leafy vegetables (and flaxseed, etc) for omega 3
Eat your five a day (but avoid packets of pre-washed fruit and veg)
Eat fish regularly (choose those with low mercury levels)
uts are good (seek advice if you have a family history of nut allergy)
Choose non-processed foods to decrease trans fats (some doughnuts contain 37 per cent trans fats)