Scientists studied how omega-3 fatty acids—nutrients found in fish and some plant oils—affect mood and thinking abilities. They gave mice different amounts of omega-3s from before birth through adulthood and tracked their behavior and brain activity. Mice that didn’t get enough omega-3s showed more anxiety and worry-like behavior, while mice that got plenty of omega-3s seemed calmer and less anxious. The researchers found that omega-3s work by changing how certain brain chemicals are made. This suggests that getting the right amount of omega-3s during pregnancy and childhood might help protect kids’ mental health as they grow up.

The Quick Take

  • What they studied: How different amounts of omega-3 fatty acids—from not enough to plenty—affect anxiety, mood, and memory in developing animals from before birth to adulthood
  • Who participated: Male mice whose mothers ate different diets during pregnancy. The mice continued eating the same diets after birth until they were fully grown
  • Key finding: Mice that didn’t get enough omega-3s were more anxious and restless, while mice that got plenty of omega-3s were calmer. The difference showed up in their behavior and in how their brain cells worked
  • What it means for you: Getting enough omega-3s during pregnancy and childhood may help reduce anxiety and support better mood. However, this was a mouse study, so we need human research to know if the same applies to people. Talk to your doctor about omega-3 intake during pregnancy

The Research Details

Researchers divided pregnant mice into three groups: one eating a normal diet, one eating a diet very low in omega-3s, and one eating a diet very high in omega-3s. The baby mice stayed on the same diet their mothers ate after they were born and weaned, continuing through adulthood. The scientists then tested how anxious the grown mice were by watching how they behaved in different situations—like exploring a maze with open spaces that made them nervous. They also looked at the mice’s brains to see which genes were turned on or off, which tells us how brain cells were working.

This approach is powerful because it follows the animals from the very beginning of life, when the brain is developing, all the way to adulthood. This lets researchers see how long-term differences in nutrition affect both behavior and the actual structure and function of the brain. By looking at both behavior and brain chemistry, the study provides clues about how omega-3s might work to affect mood and anxiety.

Following animals from before birth through adulthood is important because the brain develops over a long time. By studying the entire period, researchers can see if early nutrition affects how the brain works later in life. Looking at both behavior (how the animals act) and brain chemistry (which genes are active) helps explain the ‘why’ behind the behavior changes, not just the ‘what’

This was a controlled laboratory study where researchers carefully managed every aspect of the mice’s diet and environment, which is good for finding cause-and-effect relationships. The study measured multiple things—behavior, brain genes, and brain chemicals—which strengthens the findings. However, because this was done in mice, not humans, we can’t be sure the same effects happen in people. The study also only looked at male mice, so we don’t know if female mice would respond the same way

What the Results Show

Mice that didn’t get enough omega-3s showed clear signs of anxiety and worry. They moved around more than normal mice, suggesting restlessness. When placed in situations designed to make them nervous (like an open maze), they showed more anxiety-like behavior. They also spent more time frozen and inactive, which can be a sign of depression-like behavior.

In contrast, mice that got plenty of omega-3s were noticeably calmer. They moved around less in normal situations and showed less anxiety when placed in nerve-wracking situations. They explored more confidently in the open maze test, suggesting they felt less afraid.

When scientists looked inside the brains, they found that omega-3 levels changed which genes were active. In mice without enough omega-3s, certain genes related to stress hormones were turned up too high. In mice with plenty of omega-3s, genes related to learning and memory were more active. These brain changes help explain why the mice behaved differently.

The study found that omega-3 deficiency specifically affected the brain’s stress response system—the part that handles worry and fear. A stress hormone called AVP was overactive in omega-3-deficient mice, which is linked to anxiety and depression in research. In omega-3-enriched mice, genes involved in learning and memory formation were more active, suggesting these mice might have better cognitive abilities. The changes happened in key brain areas responsible for emotion and memory, including the hippocampus and hypothalamus

Previous research has suggested that omega-3s are important for brain health, but most studies looked at short-term effects or only at certain life stages. This study is notable because it looked at the entire lifespan from before birth to adulthood, showing that timing matters. The findings align with human research suggesting omega-3s help with anxiety and mood, but this animal study provides a clearer picture of how omega-3s actually change the brain at a chemical level

This study was done in mice, not humans, so we can’t automatically assume the same effects happen in people. The study only looked at male mice, so we don’t know if female mice or humans would respond the same way. The researchers didn’t measure all possible brain chemicals or behaviors, so there may be other effects they didn’t detect. Additionally, the study didn’t compare different types of omega-3 sources or look at what happens if someone changes their omega-3 intake later in life

The Bottom Line

Based on this research, getting adequate omega-3s during pregnancy and childhood appears important for mental health (moderate confidence level, based on animal research). Current health guidelines recommend pregnant women get 200-300 mg of DHA (a type of omega-3) daily. Good sources include fatty fish like salmon, sardines, and mackerel, or supplements. However, this study was in mice, so talk to your doctor before making major dietary changes during pregnancy

Pregnant women and parents of young children should pay attention to this research, as it suggests omega-3 nutrition during early development may matter for anxiety and mood. People dealing with anxiety or depression might also find this interesting, though more human research is needed. This research is less relevant for people without plans for pregnancy or those already past early childhood development

In the mouse study, effects showed up throughout development and were clear by adulthood. In humans, we’d expect changes to happen gradually during pregnancy and childhood, with effects becoming more noticeable over months and years rather than days or weeks. If you’re considering omega-3 supplementation, give it at least 2-3 months to see potential effects on mood or anxiety

Want to Apply This Research?

  • Track daily omega-3 intake in grams or servings of omega-3-rich foods (fatty fish, walnuts, flaxseeds, or supplements). Set a goal of 2-3 servings per week of fatty fish or equivalent supplementation, and log weekly anxiety or mood scores on a 1-10 scale
  • Add one omega-3-rich food to your diet each week—try salmon on Monday, walnuts as a snack on Wednesday, or ground flaxseed in smoothies on Friday. If you’re pregnant or planning pregnancy, discuss omega-3 supplementation with your doctor and track your intake to ensure you’re meeting recommendations
  • Create a monthly mood and anxiety check-in where you rate your overall anxiety level and mood. Track this alongside your omega-3 intake over 3-6 months to see if there’s a pattern. Note any changes in sleep quality, focus, or stress levels. Share this data with your healthcare provider to discuss whether omega-3 changes are helping

This research was conducted in mice and has not been tested in humans. While the findings are interesting, they should not be used to diagnose, treat, or prevent any medical condition. Pregnant women and people with anxiety or mood disorders should consult with their healthcare provider before making significant dietary changes or starting supplements. This article is for educational purposes only and is not a substitute for professional medical advice. Always speak with a doctor before starting any new supplement regimen, especially during pregnancy or while breastfeeding.