Yeap, I am serious: you are not only what you eat, but also what your mother eats. I can see your eyes squinting, your nose crinkling, and your lips pouting. You are quite skeptical, aren’t you? Let’s see if I can convert you to a devotee to our mother-worshiping clan!

So you’ve grown up all your life firmly believing that your dad was the unsung hero who gave you that crucial chromosome Y or X to turn you into a strong masculine boy or a sweet sexy girl, right? Who can imagine that what your mum had in her breakfast bowl could actually select for your sex as well? Well, ask the scientists! New research by the Universities of Exeter and Oxford provided the first evidence that mothers’ diet at the time of conception did make a difference. 56% of the women in the group with highest energy intake at conception had sons, compared with 45% in the lowest group. Higher food quality and diversity including certain nutrients such as potassium, calcium and vitamins C, E and B12 also favour the development of male embryos. No wonder more males are born in times of plenty, and more females in times of want. More interestingly, there was also a strong correlation between women eating breakfast cereals (with bananas of course) and producing sons, probably due to high level of glucose (indicating food abundance and therefore favourable environment for raising boys) and potassium. The old wives’ tale is actually right. “Eat bananas, you’ll have a boy.”

What your mum eats during pregnancy and breastfeeding can significantly imprint your eating habit as well. A study from London’s Royal Veterinary College found out that rats born to mothers fed the ‘junk food’ diet (i.e. yummy doughnuts, muffins, chips, etc.) during gestation and lactation were 95% more likely to develop an exacerbated preference for junk food as well, fatty, sugary and salty foods, you name it. These offspring ate 22% more than their normal counterparts, and without doubt had higher body weigh and BMI. So the short message for all mums-to-be: please be careful with what you eat since what you put in your mouth will find their way to your kid’s mouth later.

Here comes the scary part: diseases. They are all in our genes, I hear you saying. Yes, but not ‘all’. It is kind of easier to convince people that super-size giant babies are more likely to get obesity and diabetes later in life with the ‘they were born that way’ argument. However, on the other end of the spectrum, underweight tiny little babies born to undernourished pregnant mothers also experience much higher risk of developing metabolic diseases, including coronary heart disease, diabetes, insulin resistant, high blood pressure, high triglyceride level, impaired sugar metabolism, impaired liver development, etc. They are also more likely to develop affective disorders such as depression when they reach adolescence and adulthood. Studies from my department in Cambridge in rodent models reveal an even more concerning fact: maternal malnutrition during pregnancy can significantly affect longevity. Mice that experienced some protein-restricted diet during lactation, not during pregnancy or later in life, ended up with highest longevity of more than 800 days (compared to the normal control of 765 days). By contrast, those pups born to mothers with poor diet during pregnancy, but being fed with palatable diet (i.e. equivalent to obesity-induced diet in human, full of fat and sugar) later in life showed a rapid catch-up growth accompanied by a reduced lifespan of ~517 days. This huge difference in lifespan in mice induced by dietary changes is equivalent to tens of years of human life. You get the picture!

So I guess we have more to thank your wonderful mothers than just our coming into this world. Boy or girl, big or small, easy-going or fastidious, healthy or feeble, long-lived or short-lived, you are really what your mother eats.

Cottrell EC, Ozanne SE (2008) Early life programming of obesity and metabolic disease. Physiol Behav 94:17-28

Ozanne SE & Hales CN (2004) Lifespan: catch-up growth and obesity in male mice. Nature 427: 411-2

Mathews F, Johnson, PJ, Neil A (2008) You are what your mother eats: evidence for maternal preconception diet influencing foetal sex in humans. Proc Biol Sci 275: 1661-8

Bayol SA, Farrington SJ, Stickland NC (2007) A maternal ‘junk food’ diet in pregnancy and lactation promotes an exacerbated taste for ‘junk food’ and a greater propensity for obesity in rat offspring. Br J Nutr 98: 843-51