According to the Barker Hypothesis (Barker & Osmond, 1986), an inadequate maternal diet before the birth of a child may expose him or her to a number of degenerative diseases in later life. The diseases in question include heart disease, stroke, hypertension, metabolic syndrome, type 2 diabetes, obesity, and certain forms of mental illness.
Barker and his team suggest that by preventing poor nutrition of expectant mothers, and ensuring that the developing baby reaches a normal birth weight, many adult diseases of lifestyle can be prevented.
These authors also point out that countries could save millions of dollars if they didn't have to pay for the cost of health treatment associated with these illnesses, and suffer the loss of productivity that goes hand in hand with diseases of lifestyle.
In 1986, Barker and Osmond, who were associated with the MRC, Environmental Epidemiology Unit at the University of Southampton in England, did a study to determine if the dietary changes caused by the Second World War lowered the incidence of heart disease in the United Kingdom.
Until then, the idea that strict rationing during the war (which reduced fat and sugar intake to an absolute minimum for the duration of the war and quite a few years afterwards) had a positive effect on heart disease was a popular belief in medical and nutrition circles.
Instead of seeing a dramatic decrease in the occurrence of coronary heart disease, Barker and Osmond found that the war and the enforced dietary changes had little effect on the incidence of the condition.
What they found was that the highest incidence of heart disease occurred in the poorest areas of England and Wales. They then came to the conclusion that ischaemic heart disease is strongly correlated with both neonatal and postneonatal mortality. "It is suggested that poor nutrition in early life increases susceptibility to the effects of an affluent diet."
This means that if a child is deprived of adequate nutrition before birth, and for the first two years after birth, the child will be more likely to develop diseases like heart disease, metabolic syndrome and/or type 2 diabetes, obesity, high blood pressure, stroke, and even mental illnesses.
Emphasis on obesity
Many other studies have confirmed the Barker Hypothesis. One of the topics that is most relevant to nutrition in the New Millennium is of course the application of this hypothesis to the obesity epidemic.
In view of the fact that over 50% of adults in the United Kingdom and the USA are now classified as overweight or obese, and obesity in children has increased by 40%, Vickers and coworkers (2007) in Australia suggest that obesity in later life is “programmed in utero”.
Their expansion of the Barker Hypothesis says that if a foetus is exposed to malnutrition in the uterus and for the first two years of life, the child will adapt to its negative environment by adjusting its metabolism to make use of the available nutrients.
Subsequently, as the child grows older and is exposed to a western diet that's high in fat, low-fibre carbohydrates and energy, it will still be using this overabundant food in a thrifty manner and start gaining weight. In later life, the undernourished child will become obese, which will in turn expose him or her to other diseases of lifestyle such as type 2 diabetes and heart disease.
Other researchers in Australia have suggested that maternal obesity may also predispose unborn children to the risk of developing obesity as they grow older (Armitage et al, 2008).
At present, researchers are identifying more and more conditions that have their origin in those crucial nine months before birth and the first two years of life. But we don't yet know exactly how this damage can be reversed.
In the absence of clear-cut solutions, nutritionists can only emphasise the practices we know will ensure the healthy development of the infant. These include the following:
1) Parental health
Parents who intend starting a family should be as healthy as possible. This includes both parents, but the mother in particular. Both parents should preferably not be overweight or obese. Losing weight before conception with a balanced diet, so that the mother isn't undernourished, is a good preventative measure. Consult a dietician to help you lose weight sensibly before you conceive and to ensure that you're eating the best possible diet for your circumstances.
On the other hand, any woman who is underweight should try and gain some weight before conception to give her baby the best chance in life.
Both parents should also not smoke or drink alcohol during the period of conception. Pregnant women shouldn't smoke, drink alcohol or take any medications, including over-the-counter preparations, herbal products or high-strength vitamin pills (to prevent vitamin A toxicity), unless prescribed by their doctor or gynaecologist. Pregnant women should under no circumstances take slimming pills or use a very-low-energy diet to try to control their weight.
The use of folic acid supplements before conception, and of iron, folic acid, calcium and omega-3 fatty acid supplements during pregnancy, may be beneficial. But discuss such supplementation with your doctor or dietician before you take a supplement that could be potentially harmful.
2) Balanced diet
Make sure that you are eating a healthy, balanced diet during pregnancy. If in doubt, consult a dietician to help you with a diet prescription that will ensure that you and your unborn child obtain optimum nutrition without gaining excessive weight.
Special emphasis should be given to eating fresh vegetables and fruit, low-fat milk and dairy products, whole grains and cereals, lean meat, fish, eggs, legumes and poly- or monounsaturated fats (olive oil).
According to international recommendations, a pregnant woman who starts her pregnancy with a normal weight should gain between 11.5 and 16 kg over the nine-month period of her pregnancy. Both inadequate and excessive weight gain during pregnancy may predispose your child to obesity in later life and should be avoided. Babies with a low birth weight start their lives at a disadvantage.
Exclusive breastfeeding of infants for the first six months of life by mothers eating a well-balanced diet will ensure that children have the best chance to be healthy and avoid adult-onset diseases.
Hopefully, the studies that are investigating the Barker Hypothesis will come up with additional solutions to combat the long-term effects of poor nutrition before and soon after birth.
(Dr I V van Heerden, DietDoc, registered dietician) References:
(Armitage JA et al (2008). Developmental origins of obesity and the metabolic syndrome: the role of maternal obesity. Front Horm Res, 36:73-84; Barker DJP, Osmond C (1986). Diet and coronary heart disease in England and Wales during and after the second world war. Journal of Epidemiology & Community Health, 40:37-44; Vickers MH et al (2007). Is later obesity programmed in utero? Curr Drug Targets, 8(8):921-34.)