Scientists discovered that when pregnant sheep get extra methionine (a building block found in protein), it changes how their babies’ genes work before they’re even born. Researchers looked at sheep eggs and early embryos and found that the extra methionine created changes in DNA patterns. When they tested genes that were affected, they found that two specific genes became less active and made it harder for embryos to develop properly. This research suggests that what mothers eat during pregnancy might have bigger effects on babies than we previously thought, working through a process called epigenetics where diet changes how genes turn on and off.

The Quick Take

  • What they studied: Whether giving pregnant sheep extra methionine (a protein building block) changes how their babies’ genes work before birth
  • Who participated: 16 pregnant sheep (8 that got extra methionine and 8 that didn’t), plus their eggs and early embryos
  • Key finding: Extra methionine changed DNA patterns in over 2,000 locations in sheep eggs and over 100 locations in embryos. When scientists turned off two specific genes that were affected, embryo development dropped by 9-16%
  • What it means for you: This suggests that what pregnant people eat might affect their babies’ genes in ways we’re just beginning to understand. However, this was done in sheep, so we need human studies before making recommendations for pregnancy nutrition

The Research Details

Scientists studied 16 pregnant sheep, giving half of them extra methionine (a nutrient found in protein-rich foods) and keeping the other half as a comparison group. They collected eggs from these sheep and looked at the DNA patterns using advanced technology that can read every single spot where genes are marked. They then bred the sheep and collected early embryos to see if the changes from the mother’s diet carried forward. Finally, they tested what happened when they turned off specific genes that had been changed by the methionine, to understand if those changes actually mattered for development.

The researchers used a technique called whole-genome bisulfite sequencing, which is like taking a detailed photograph of every place in the DNA where a special chemical marker sits. These markers don’t change the DNA itself, but they control whether genes turn on or off. This is called epigenetics - it’s like having a dimmer switch on a light instead of just an on-off switch.

The study also looked at mitochondrial DNA, which is the genetic material in the tiny power plants inside our cells. This is important because mitochondria provide energy for cells to work properly.

Understanding how diet changes gene expression is crucial because it could explain why some babies are born healthier than others and why some health problems run in families. If we can show that what mothers eat directly changes how babies’ genes work, it might help doctors give better nutrition advice during pregnancy. This research also helps us understand ‘fetal programming’ - the idea that what happens before birth can affect health for the rest of a person’s life.

This study was well-designed with a clear comparison between treated and untreated animals, which is important for showing cause and effect. The researchers used cutting-edge technology to measure DNA changes very precisely. However, the sample size was relatively small (16 sheep), and this was done in animals, not humans. The functional testing (turning off genes) was done in lab conditions, not in living animals, so we need to be careful about assuming the same effects would happen in real pregnancy. The study was published in a respected journal focused on epigenetics, which is a good sign of quality.

What the Results Show

When pregnant sheep received extra methionine, it created changes in DNA patterns at 2,056 different locations in their eggs. These changes were quite widespread across the genome. The researchers also found 17 spots in the mitochondrial DNA (the power plant DNA) that were changed, with most of them becoming more marked rather than less marked.

When the researchers looked at early embryos from these treated mothers, they found 113 spots in the regular DNA that were changed. Interestingly, the embryos showed 22 changed spots in their mitochondrial DNA, with most of these being more marked. This suggests that some of the mother’s dietary effects might be passed to the baby through the mitochondria.

When scientists tested two specific genes that were changed in the embryos (called SCRIB and CERS3), turning them off caused serious problems. Turning off SCRIB reduced the number of healthy embryos that developed by 16.4%, while turning off CERS3 reduced it by 9.5%. These results suggest that the genes changed by the mother’s diet actually matter for whether embryos develop properly.

The overlap between changes in eggs and embryos was interesting: while most changes didn’t directly carry over to embryos, some mitochondrial changes did appear in both, suggesting that mitochondrial DNA changes might be more stable and heritable than regular DNA changes.

The study found that mitochondrial DNA seemed to be more affected by maternal methionine than regular DNA, and these changes were more likely to be passed to embryos. This is significant because mitochondria control energy production in cells, and proper energy is essential for embryo development. The fact that 5 mitochondrial DNA changes appeared in both eggs and embryos suggests these might be particularly important for passing maternal effects to offspring. The researchers also noted that some genes showed opposite patterns - less marked in eggs but more marked in embryos - suggesting that the embryo might actively change these marks after fertilization.

Previous research has shown that maternal diet affects offspring health, but most studies looked at the final outcome (like birth weight) rather than the actual DNA changes. This study is more detailed because it directly measures how diet changes DNA patterns. Other studies in different animals have shown that methionine and related nutrients affect gene expression, so this finding fits with existing knowledge. However, most previous work hasn’t looked as carefully at mitochondrial DNA changes, making this study’s findings about mitochondria relatively novel. The study also goes further than most by testing whether the changed genes actually affect development.

The biggest limitation is that this was done in sheep, not humans, so we can’t directly apply these findings to pregnancy nutrition advice yet. The sample size of 16 sheep is relatively small, which means the results might not be completely reliable - larger studies might find different patterns. The functional testing (turning off genes) was done in lab conditions with isolated embryos, not in living pregnant animals, so the real-world effects might be different. The study doesn’t tell us whether these changes actually affect the health of the lambs after birth or throughout their lives. We also don’t know if the effects would be the same with different amounts of methionine or at different times during pregnancy. Finally, the study measured DNA changes but didn’t measure whether these changes actually led to different amounts of protein being made in the cells.

The Bottom Line

Based on this research alone, we cannot make specific recommendations about methionine supplementation during pregnancy. This is animal research that needs to be followed by human studies. Current pregnancy nutrition guidelines already recommend adequate protein intake (which contains methionine), and there’s no evidence that extra supplementation beyond normal amounts is helpful. Pregnant people should follow their doctor’s or nutritionist’s advice about prenatal vitamins and diet. Confidence level: Low - this is preliminary research in animals that needs human confirmation.

This research is most relevant to scientists studying how diet affects fetal development and to doctors who advise pregnant patients about nutrition. Pregnant people should be aware of this research direction but shouldn’t change their diet based on this single animal study. People interested in epigenetics and how environment shapes health should find this interesting. This research is NOT a reason to start taking methionine supplements during pregnancy without medical advice.

If these findings eventually apply to humans, the effects would begin during pregnancy (when the mother’s diet affects the developing baby’s genes) and might influence health throughout the child’s life. However, we don’t yet know if these DNA changes actually cause health differences in real life. It could take many years of research to understand the full impact.

Want to Apply This Research?

  • Track daily protein intake (in grams) and food sources of methionine (meat, eggs, dairy, nuts, seeds) during pregnancy planning or pregnancy. Note any prenatal supplements being taken and discuss with healthcare provider.
  • Users could log their daily protein intake and ensure they’re meeting recommended amounts (71g per day for pregnant people) through varied food sources rather than supplements. The app could provide education about methionine-rich foods and help users understand that adequate protein intake is already part of standard pregnancy nutrition.
  • Long-term tracking could include monitoring overall diet quality during pregnancy, prenatal vitamin compliance, and health outcomes at birth. Users should discuss any supplementation plans with their healthcare provider and track what they discuss.

This research was conducted in sheep and represents early-stage science. These findings do not yet apply to human pregnancy and should not be used to make decisions about prenatal supplementation. Pregnant people should consult with their healthcare provider or registered dietitian before making any changes to their diet or taking supplements. Current evidence supports adequate protein intake during pregnancy as part of standard prenatal care, but this study does not provide evidence that extra methionine supplementation is beneficial or safe. Always follow your doctor’s recommendations for prenatal nutrition.