Student Project Summary: The Impact of Maternal Nutrition on the Epigenome

by Gena on December 3, 2012

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Phew. As of 5 pm, my genetics lab is finally done for the semester, and I can now focus exclusively on the upcoming final. Yesterday on Facebook, I mentioned that my final presentation topic in the class was the effect of maternal nutrition on the epigenome, with a specific focus on obesity. A few of you mentioned that you’d like a broad summary when the presentation was done, so I’m recapping it for you now. If genetics isn’t really your thing, feel free to skip this one! As a person who has studies nutrition, though, I found the research really interesting, and thought some of you might as well Smile

To many of you in this science and nutrition savvy audience, “epigenetics” is probably a very familiar phrase. Though I’d studied epigenetics briefly when I took nutrition classes, it’s not really a phenomenon I understood well until I took genetics this year. Epigenetics is the study of heritable changes to DNA that don’t involve a change in DNA nucleotide sequence. Very roughly translated, this means changes to DNA that are environmentally triggered, rather than resulting from a quantitative trait that has been passed down from your parents (like eye color, for example, or having a widow’s peak). The “epigenome” is of interest to researchers for a host of reasons, but they are of particular interest to those who study nutrition because they have been implicated heavily in changes to human metabolism.

My presentation today was interested in how on particular environmental influence–maternal nutrition–will impact a child’s propensity toward obesity. The results are interesting; I studied both how famine/malnourishment will impact offspring, and how a “junk food” maternal diet (which is defined differently, according to the study) will impact offspring. The result, interestingly, can be similar, for a variety of reasons. Both fasting/malnourishment during pregnancy and a high-fat or “junk food” diet during pregnancy are associated with offspring’s having a higher disposition toward obesity later in life.

It’s been thought for some time that, when children develop in utero under famine conditions and go on to have low birth weight, they are predisposed toward being overweight later in life. This is called the “thrifty genotype” hypothesis, and the idea is that the child’s metabolism and insulin sensitivity is modulated to fit fasting conditions; when the child is later born into either adequate food or abundance, the child’s metabolic tendency is still to conserve energy (thriftiness). Weight gain therefore results from a discrepancy between the gestational environment and the environment a child grows into.

The hypothesis was first put forth in 1962, and since then it has been largely validated by further research. It has proven to be especially helpful in studies of developing nations, where it is possible for famine to exist alongside a new growth of high-energy fast foods and processed foods. It was also borne out by studies of children born after the post-WWII Dutch famine of 1944. Children whose mothers were pregnant during the famine demonstrated higher rates of insulin resistance and cardiovascular disease later in life.

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An image from the Dutch “hunger winter” of 1944.

I thought this was all very interesting, but I was also interested in learning how a high-energy, low-nutrient diet—a diet similar to what we call the “SAD” diet—will impact a child’s propensity for weight gain. As it turns out, a high fat and low nutrient diet is also associated with offspring’s having a predisposition toward obesity, for different reasons. One reason is that high-fat and low-nutrient diets have been shown to repress genes that code for developing children’s opioid receptors, which allow for sensations of stimulation and reward. When these receptors are dulled, individuals with repressed gene expression may seek out high fat and high sugar foods later in life. Interesting that two totally different scenarios—feast and famine—can possibly have a similar result.

There are obviously thousands of other reasons why obesity happens, and even within the two scenarios I looked at, I focused only on very specific genes (a handful of six) and the mechanisms by which they are changed. These six genes alone don’t account for the whole problem, and my understanding is also limited: I am but a struggling student, not a scientist! But the research did show me how vital good maternal nutrition is, and how sensitive our DNA is to environmental influence.

It also presents an additional account for obesity, which is often attributed (too simplistically) to either conscious lifestyle choices on the one hand, or to intractable genetic inheritance on the other. Everything I’ve read about in my studies so far suggests both that we have the power to turn a lot of genes on and off, and that there are certain genetic variables we can’t help. This presentation confirmed that feeling. Even though some of the diabetes and metabolic syndrome statistics were sobering, it also presented me with some hope that education about nutrition and access to healthy food can certainly do mothers and children a world of good. So many of you, my readers, are doing your best to share food that is both healthful, nutrient-rich, and satisfying with others, and that is a part of the puzzle.

On that note, this tired blogger is taking a few hours off. I’ll see you tomorrow with a product review and wonderful giveaway you will not want to miss!

xo

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{ 35 comments… read them below or add one }

Sarah December 3, 2012 at 8:09 pm

What a coincidence! I went to a talk with Dr. Karl last night (an Australian science celebrity), and someone asked a question about the link between the gut microbiome and obesity….and he went off on a bit of a tangent and discussed the epigenetic changes after the Dutch famine!

Two questions: 1) when you say “high fat” diet, what are we talking about? E.g., How high? And does it only apply when the sources of fat are “bad” (although there seems to be so much debate about which fats are truly bad and which are good these days)? 2) do you know if there is any similar study linking premature birth (and therefore low birth weight) to obesity?

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Gena December 3, 2012 at 8:19 pm

Sarah,

I actually was surprised that the source of fat was unspecified in the studies I looked at. As was the food in question, though, I am pretty sure we’re not talking about avocados, nuts, and olive oil here :) Three studies specified “a junk food diet” verbatim, and these are mainstream standards, not food blog standards. The amount was sometimes unspecified as well, but where it was mentioned, it was 60% and up.

Keep in mind, however, that I’m an undergrad student and was limited to 5-10 references. I was pushing it at 12! I’m sure more info is out there, but for the purposes of an in class presentation, I could only go so far.

Huge coincidence, as my second choice of a topic was the microbiome and obesity :)

G

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Gena December 3, 2012 at 9:01 pm

Oh gosh! You had a second question: I didn’t delve into premature birth, though I have heard mentioned that there is a connection (if low birth weight is across the board a risk factor for metabolic syndrome, then of course it’s very possible). Ginny Messina may know more about this than I do. If you’d like to peek at my references, shoot me an email and I’ll send the bibliography over.

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sarah December 6, 2012 at 8:17 am

Thank you! 5-10 references…that would absolutely kill me. I am definitely a reference hoarder though, and it’s a really bad habit. I always say to myself: “If I just have one more reference, then I can start writing my lit review.” Not a good way to get things done. I’ll have a look in the literature myself and see if I can find anything about premature babies and obesity. I seem to recall hearing it somewhere, and I am interested because my niece was premature, so I’m constantly keeping her in mind, particularly when I hear things like this.

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The Delicate Place December 3, 2012 at 8:13 pm

nicely done! a couple years ago when i worked at hershey medical center, my department was focused on epigenetic changes in regards to type 1 diabetes using transgenic mouse models. every job i take i try not to become paranoid about the what ifs/etc regarding genes being turned on or off due to environmental stress or heredity. it’s overwhelming at times!

these days, since i work in ALS research, i’m all about ‘stressing’ my mitochondria by sprinting, practicing brain teasers and eating healthfully.

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Angela December 3, 2012 at 8:38 pm

Nice work! I looked to my Google reader hoping to find a post that was NOT a recipe (almost all of the blogs I read regularly are vegan food blogs, haha) and saw this! As someone studying nutrition with an interest in epigenetics/nutrigenomics, this kind of stuff is fascinating to me. I hope you’ll post more about what you’re learning.
I’m feeling the end of semester crunch right now, too. Hope you get some much deserved rest in!

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Taylor December 3, 2012 at 9:50 pm

Awesome! There is a documentary available on youtube you might enjoy discussing many of these same topics called, “The Ghost in your Genes”. We watched it in my genetics class in college. Very interesting!

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Michelle December 3, 2012 at 10:25 pm

Fascinating post Gena! Thank you. I imagine our various genes to be like standing under a light bulb string. I carry the gene for ankylosing spondylitis (arthritis of the spine) but it’s not activated yet – or I haven’t pulled the light switch for this particular gene. I hope that with my continued healthy eating and minimally ‘processed’ eating I can avoid activating this gene.

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Gena December 3, 2012 at 10:56 pm

I like that analogy, Michelle :)

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Gabby @ the veggie nook December 3, 2012 at 10:30 pm

This research is really cool Gena! You should share your school stuff more often, although I’m sure you’re way too busy to do that!

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Gena December 3, 2012 at 10:58 pm

Thanks Gabby! I would like to share more often, but I’m usually too tired for anything other than food porn. That said, it is fascinating stuff…so long as it’s not orgo ;-) (Well, I guess everything biological is orgo…but you know what I mean!)

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Lou December 3, 2012 at 11:10 pm

This is seriously fascinating Gena – thanks for explaining it all in “Layman’s” terms for us un-scientific (but interested) folk!

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Jane Plass December 3, 2012 at 11:20 pm

Really interesting, Gena. Thanks for the summary!

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Claire December 3, 2012 at 11:26 pm

This is a fascinating research area! I did a project for a public health class earlier this semester on how environmental chemicals affect children’s risks for obesity, and there’s so much to learn about epigenetics, nutritionally related and otherwise. I’m actually taking genetics right now, too, and our final lab project has to be on drosophila eye genes, so I’m pretty jealous of your topic haha.

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Gena December 4, 2012 at 9:26 am

I spent a ton of time with drosophila at the start of the semester, fear not ;-)

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Kari @ bite-sized thoughts December 4, 2012 at 12:00 am

I love this post Gena – I always love it when I get to read science-y posts and this is one on a topic that I care a lot about :) I work more with mental health myself but have colleagues that focus on childhood obesity and I think more and more people are realising that we need to be doing things right from conception rather than leaving it until later in life!

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Ashley December 4, 2012 at 12:34 am

Although I wish I found more interest in genetics while I was studying in undergrad, I know I would have a deeper appreciation for it now. Thanks for the summary of your report, I think information like this is a great reminder of the importance of a woman not only taking care of herself, but the importance of nutrition during a pregnancy. Good luck on your test!

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Gena December 4, 2012 at 9:26 am

Thanks Ashley!

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Mélanie December 4, 2012 at 8:20 am

Wow, thanks for sharing this information with us Gena. And thanks for explaining it in a way someone with an undergrade in arts can understand :) I love studies that look at how our choice can have an impact on our (or our children’s) health. Very empowering. And also very appropriate for me, as I am currently 6 months pregnant. On that note, I’m off to eat my maple-hemp oatmeal :)

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Gena December 4, 2012 at 9:25 am

All best to you in your pregnancy, Melanie!

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lysette December 4, 2012 at 10:20 am

Thank you for making the language of your study so accessible. Much “food for thought” *groan*. I would definitely enjoy reading more posts from your studies.

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Sara @ sarasmiles December 4, 2012 at 11:47 am

Oh my gosh, this post is super interesting! You made me want to email my mom and ask her how she ate while pregnant with me! I’m not obese-I’m very healthy-but it is interesting how it has an impact.

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Michelle December 4, 2012 at 12:26 pm

Wow, thanks so much for the information Gena! Very interesting, I really appreciate the post!

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Claire December 4, 2012 at 1:10 pm

This is such interesting research. Shows just how important nutrition is before little ones get to make their own choices on what to eat. I guess what they receive during pregnancy can set them up for life and affect their desires and what they call ‘home’ when it comes to food.

My Mum always reminds me that I was her only pregnancy of 3 where they tested her for diabetes and I was diagnosed type 1 at age seven. Dairy/sugar culprits? Maybe. :-)

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Jacqueline December 4, 2012 at 2:38 pm

Hi Gena!

I am currently writing my research paper for my MPH program. It is about factors in obesity prevention in children. I was wondering if you could share some of your sources with me regarding a maternal “junk food” diet. It would be such help!

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Cat December 4, 2012 at 8:32 pm

Excellent post Gena, so interesting!

This really saddens me:

“developing nations, where it is possible for famine to exist alongside a new growth of high-energy fast foods and processed foods”

It upsets me that in countries recovering from famine, fast food companies are setting up shop where the people are predisposed to obesity. Instead of seeing improvements in their health, it’s more likely that they will go quickly from a starved population to an obese population, with all of the problems that entails.

If only fast food companies would act ethically and assume responsibility for their impact instead of exploiting new markets of already disadvantaged and vulnerable people. If only governments had the power and knowledge to stop them! Children’s nutrition is so important in developed countries as the key to resolving our population’s health issues in the future, even despite our wealth and oversupply of food. How much more important is it to help prevent the same tragedy happening to the children of families who don’t have such privileges.

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Victoria December 5, 2012 at 7:13 am

Thanks Gena for your post! This fascinates me for a number of reasons. I’m a Canadian nutritionist. When my second child was born 28 years ago my diet had been poor, inadequate in many nutrients, yet sufficient in calories. She was born full term at a healthy weight (7lbs, 8oz) but by 6 weeks my doctor was concerned about her weight (and recommended I only breastfeed her every second feeding and give her apple juice for the opposite feedings…which even before i educated in nutrition didn’t sound like sound advice, so i ignored.) My daughter has struggled with her weight all her life. Her whole-foods plant-strong (she eats eggs occasionally) caloric intake needs to be lower than someone else her activity level and BMI. I watched a documentary recently about “obesogenics” …I believe it was on a show filmed here in Canada and hosted by David Suzuki, called “The Nature of Things.” Fascinating studies going on with the link between pesticides, BPA’s, etc and obesity. When I was 3 months pregnant with my daughter a mosquito spraying truck came down our street and sprayed over me before I could get out of the way. I’ve always wondered if something happened that day! Anyway, wondering if your familiar with the book “Genetic Nutritioneering” by Jeffrey Bland? It was written in 1999.

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Anne P December 5, 2012 at 9:50 am

How interesting! We talked about this in one of my classes in school, too, and it’s all fascinating. I especially found it interesting that both starvation during pregnancy AND over eating during pregnancy can eventually lead to the same outcome in the baby.

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Kathleen December 5, 2012 at 11:56 am

What a great project! I bet this is one of the highlights of your post-bacc career so far. I think this type of research is really important not only for the health of future generations, but also for helping the general public understand that obesity is not any specific person’s “fault”. I think awareness of factors such as the ones you described can really help discourage fat shaming as we come to understand how complicated weight gain and loss really is.

On another note, I’m finally able to enjoy my regular healthy diet, however the first 18 weeks of my pregnancy were absolutely miserable and I struggled to keeping anything down. I felt extremely guilty that days passed where not a single vegetable entered my system. Water was even a hurdle and I found myself relying on rice noodles, tofu and organic root beer on the worst days. Before becoming pregnant I envisioned eating the “perfect” diet, but my body had other ideas. I hope other pregnant women out there who suffer from severe morning sickness as I did know that they can only do their best with what their body will allow! Thanks for the great insight, Gena.

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Rebecca Gallo December 18, 2012 at 9:25 pm

Oh, I understand that guilt, Kathleen! Thankfully, I gave up guilt along about the second pregnancy when I realized I was on a very different journey. I actually threw out any pregnancy books I had! I’ve had severe hyperemesis with each of my 5 children and been amazed by their birthweights (all 7 lbs and up) and subsequent health. (My own personal conclusion is that we are made to be amazingly resilient.) I find it really strange, given all the advice re nutrition during pregnancy. I was on plenty of anti-nausea drugs also – not in order to eat or drink as that was impossible – but to keep me out of the hospital at least. I didn’t receive supplemental feeding. I did start eating some in the last trimester – was able to force it down. But only whatever worked at the time and it was different with each child. I would love to see some research done on the subsequent health of children whose mothers suffered from severe hyperemesis. I’m guessing it would be a smaller pool but it may also shed light on the famine/overfeasting relationship with obesity. Although actually I’m more interested in any other health issues that would show up. So far my kids are all slender (along with their wonderful chubby baby years). My oldest is 14 yrs. My husband and I are both slender and we eat okay – not SAD but also not super healthy. We do pretty much cook everything from scratch and one of my children developed post-infectious IBS a couple of years ago which keeps us pretty food-conscious if not health-conscious!

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Jo December 5, 2012 at 2:46 pm

Thanks so much for posting this! As a biology grad student (albeit in molecular ecology and entomology) I always love learning more about science. I hope non-science inclined readers of yours read this as well. We can always use more science in the public eye! What a fascinating topic. Thanks again!

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Christine December 5, 2012 at 11:24 pm

Loved reading this. Thanks for sharing. I’ve read a tiny bit about epigenetics and I’m very interested in multiple factors that can cause obesity. Just curious- have you come across any literature on exposure to environmental toxins during pregnancy affecting likelihood of obesity in offspring?

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Lia December 6, 2012 at 9:52 am

That’s really interesting. I’d love to hear more about that. So what diets of mothers was the best for preventing obesity? Aside from common sense. I didn’t know if you had read some studies regarding that. Thanks for sharing what you’re learning.

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Carissa December 7, 2012 at 10:59 am

Thank you so much for the explanation in down to earth terms! This is amazing research & it fascinates me to learn about how even things before our birth impact our lives.

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Micki December 8, 2012 at 1:42 pm

Loved your insights!
Funny that I ended up finding you at a site where I couldn’t disagree more (that raw food is a particularly good idea and that veganism is, too).
I would like to add to what you noted about epigenetics and maternal nutrition. It is regarding one of the fat soluble nutrients that has been ‘forgotten.’ It is vitamin K; especially vitamin K2. Among the 4 fat soluble nutrients, A-D-E-K, K is the only one that does not have a dedicated serum carrier, whereas the other 3 do. Vitamin K2, which is proving to be incredibly powerful and which is nearly missing in most diets, is a ball-buster nutrient/hormone that happens to be carried in the serum via the very same lipoprotein carriers as cholesterol (!) and there is evidence that more intake of vitamin K2 will ‘improve’ cholesterol readings (!). Only no one has put this together. LDL and HDL carry cholesterol AND long-chain menaquinones or short-chain menaquinones, respectively.
Also, vitamin k is a huge, huge player in gene expression.
Vitamin K2 is a powerful antioxidant, anti-inflammatory that no one knows about.
Vitamin K is mostly insufficient in diets because we have made the mistake of thinking vitamin K1, phylloquinone found in leafy greens, is the only and/or ‘best’ form of vitamin K and that our gut bacteria make vitamin K2 which bolsters our vitamin K status. Only the gut bacteria DO make vitamin k2, but it is for them…not us.
So now that we are a nation without enough vitamin K2 to activate or carboxylate the so-called K-dependent proteins beyond the coagulation cascade, we are a nation set up for atherosclerosis, CVD, osteoporosis, diabetes, arthritis, and cancer.
Pregnant women need enough vitamin K2 and sulfur to create the healthiest brains. Most are deficient in both nutrients as well as other nutrients.
And as far as raw…well, we are the cooking ape. We diverged from the other great apes because we cooked. As a result, we obtained more nutrients, our brains grew bigger and better, our jaws became smaller (didn’t need to chew all that tough, raw food with softer, cooked foods), and our guts shrank. Thus, we are the cooking ape!
Read Wrangham’s Catching Fire or see Homo incendius.
Meeting nutritional need via a raw and/or vegan diet is nearly – if not entirely – impossible. Fermenting the food might help, as this creates long chain menaquinones (vitamin K2), but how many raw vegans do this or even know about it?
Gene expression IS definitely affected by the fat soluble nutrient vitamin k2, which is (hilariously) high in high fat foods (cheeses, yogurt, egg yolks, animal fats) as well as no-fat foods (natto, sauerkraut, beet kvass, kimchi) but the fact is that our genes, our health, our brains, our bones, our cardiovascular system, our kidneys, our livers ALL need more vitamin k2. For those who want to stay vegan: FERMENT THE CRAP OUT OF AS MUCH FOOD AS YOU CAN!!

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