(and what their parents ate, and their parents, and their parents…)
You were just a twinkle in their eyes when your parents’ diet and lifestyle choices began to affect you — and they’re still having an influence today. HFG senior nutritionist Rose Carr explains why.
Genes that shift gears
To enjoy good genes, you have to choose your parents wisely. (If only we could!) Of course, the genes for blue eyes or baldness are inherited blueprints that we can’t change, but we all have a second genetic code that we can influence — the epigenome.
Have you ever wondered why identical twins, whose DNA is practically the same, become less alike with age? It’s because their individual epigenomes, which are unique, have either activated or silenced different genes. This genetic switching happens right from conception and continues throughout our lifetime — and experts think that nutrition plays a major role.
As we know, many aspects of a pregnant woman’s lifestyle, such as smoking or drinking alcohol, can harm her child. But mum’s diet can have a huge impact on her child’s future health, too, and we’re just starting to see how.
Reams of research suggest that an expectant mother who overeats, thereby consuming excess kilojoules, could well be ‘programming’ her unborn child to become obese. A landmark US study shows that pregnant women who carry excess weight or develop gestational diabetes (partly as a result of their eating habits) give birth to babies who are predisposed to heart disease and type 2 diabetes as adults.
So, having blamed our unhealthy lifestyles for these midlife health problems for so long, should we accept that they’re simply our genetic inheritance? No — we need to remember that a healthy approach to diet and exercise can help combat the effects of any such programming in the womb.
The importance of dad’s diet
Still, these findings don’t mean that men are off the hook. More and more scientific evidence (mainly, but not exclusively, from animal studies) shows that the father-to-be also exerts an influence on the foetus — and it’s more than the gift of his DNA.
Expectant mums know they need enough folate to help prevent miscarriages and birth defects. But what about dad? A Canadian study links folate-deficient fathers to heightened rates of various birth defects in their offspring. Although this research was on animals, it shows that sperm carry not only a genetic map for the child’s development, but also a memory of dad’s environment, and possibly of his diet and lifestyle.
Animal trials also suggest that male obesity can affect foetal development, increasing a child’s future chances of becoming obese or developing type 2 diabetes. As a result, researchers advise that men pay careful attention to their food and lifestyle choices before they try to conceive a child, just as women do.
Grandparents’ genetic gifts
Think of these genetic shifts as evolution in action. Though scientists once assumed these changes had no knock-on effect on future generations, there’s some evidence that they form a major part of the gene parcel we hand on to our children and our children’s children.
A Swedish study supports this theory. When researchers studied the offspring of villagers who’d experienced a fluctuating food supply in the early 1900s, they made the most surprising discovery. The grandchildren of villagers who’d lived through a food shortage from the ages of 8–12 years had extended lifespans. Why? Well, some animal studies suggest that eating a restrictive diet could prolong our lives.
In this particular case, the Swedish villagers, who would have been lean as youths, may have passed these genes onto their grandchildren. Another theory is that the grandchildren are the lucky beneficiaries of their grandparents’ robust metabolisms, which were switched on by the scarcity of food in their youth.
In contrast, the grandchildren of villagers who had enjoyed an abundance of food in their youth suffered both a shortened life expectancy and a heightened risk of type 2 diabetes. Interestingly, this link was sex specific, meaning the men’s experience affected only their male descendants, and the women’s affected only their female descendants.
Leave a healthy genetic legacy
Prospective parents should take note of these new findings, but they’re equally relevant to the rest of us. Adopt these simple dietary changes, and you’ll help optimise your genetic switches.
The science of taste
Expectant mothers who enjoy a healthy diet can sway their kids’ food choices in a positive way. They do this naturally, because their amniotic fluid and breast milk absorb the flavours from the foods they eat.
In a study of the way flavour preferences develop, groups of pregnant women drank carrot juice during either the first two months of lactation or their last trimester, while another group of women avoided carrots and carrot juice altogether.
The impact of this behaviour on their offspring is fascinating. When the infants were weaned (at approximately 6 months of age), those who’d been exposed to the flavour of carrot, in either amniotic fluid or breast milk, ate more carrot-flavoured cereal and made fewer facial expressions of distaste than the other babies.
Sadly, this phenomenon has a negative flip side. One animal study suggests that a mother’s junk-food diet can affect her unborn baby, desensitising the parts of the body that control pain, feelings of reward and addictive behaviour. So if her child develops a heightened preference for junk food in later life, this may explain why.
To ensure healthy development of your child’s brain and eyes, you need to consume an adequate amount of DHA, one of the two long-chain omega-3 fats. But before you reach for fish-oil supplements, consider this: A 2013 review, which appeared in The American Journal of Clinical Nutrition, concludes that taking omega-3s in the form of supplements during pregnancy doesn’t necessarily enhance the child’s cognitive or visual development. You need to source these long-chain omega-3s from your diet, especially during the second half of pregnancy. The easiest way to do this is to eat oily fish, such as trout, salmon and tuna, at least two to three times a week.
Nuts to allergies
Mounting evidence shows that a mother-to-be who eats nuts could lower her child’s risk of having a nut allergy. In 2013, researchers in the US asked more than 8,000 allergy-free pregnant women to add nuts to their diet. The results were the opposite of what you might expect: Those who ate 28g of nuts (about a handful) more than five times a week reduced the risk of nut allergy in their children by up to 69 per cent. These women also reported having a higher consumption of fruit and vegies than the other women in the study, and were more likely to introduce their children to nuts at a younger age. (Remember: Whole nuts are a choking hazard for children under the age of 5, so feed them smooth nut pastes instead.)
The dangers of alcohol
Pregnant women who drink alcohol are putting their babies at risk of foetal alcohol syndrome, among other developmental disorders. A 2013 UK study links drinking during the first three months of pregnancy to lower birth weight and premature birth. Researchers also found an association between drinking during the period leading up to conception and a higher risk of restricted foetal growth, indicating that this too may be a critical time to make healthy lifestyle decisions.
Unlike expectant mothers, future fathers haven’t had to curb their alcohol consumption for their unborn baby’s sake — until now. Last year, animal research linked male alcohol consumption with foetal abnormalities for the first time.
Before conception, diet is key
It’s becoming clear that from the moment we’re conceived, and even before, our mother’s diet plays an enormous role in shaping our genes — and a recent study proves it.
In a 2010 US study, researchers compared babies who were conceived during Africa’s rainy season, when food is scarce, with those conceived in the dry season. Blood samples revealed that the genes of rainy-season babies had higher levels of a chemical compound that experts associate with the risk of certain diseases. This was proof that the women’s pre-pregnancy diets had a critical effect on their offspring.
Though scientists are unsure of the consequences this could have for the children’s health, it’s the first time we’ve seen how a human mother’s diet can affect her baby before conception.
Food and pregnancy
The answers to your most pressing questions.
Q. How should my husband and I prepare when we’re planning for pregnancy?
If you and your partner are thinking about having a baby, both of you need to consider making some positive diet and lifestyle changes. The choices you make now could have long-term consequences for your child. Be practical and remember that it’s your overall diet that counts, not just one week, one day or one meal.
Q. What if I can’t bring myself to eat because of morning sickness?
If you find that you can’t eat without vomiting when you’re pregnant, you’ll have to accept that your diet simply isn’t going to be as good as you want it to be. You can only ever do your best! When you do feel well, make the most of it by eating plenty of fresh healthy foods.
Q. Help! I already have kids, and I didn’t pay attention to my diet during my pregnancies.
Even if your diet was less than ideal before or during your pregnancies, it’s not too late to ensure that your children eat nutritious foods, and to have a healthy influence on their habits. This also applies if your children are now adults. Make the decision to get your own diet and lifestyle on track, because this can help your children think about the kinds of healthy changes they can make before they conceive or while they’re pregnant. It’s never too late to be a positive influence on future generations.