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Key points
- A woman's diet during pregnancy may influence her child's mental health.
- The Mediterranean diet and diets lower in glycemic load were found to be beneficial to a baby's mental health.
- Although more research is needed, it’s reasonable to encourage women to adopt natural, whole foods into their diets and minimize processed foods.
What we eat is important to our health. It plays a role in preventing and treating obesity, diabetes, and heart attacks. But does it play a role in mental health, too? Increasing evidence suggests it does. This is the emerging field of nutritional psychiatry. Surprisingly, it gets more complicated than just what we eat as individuals. It turns out that what our mothers ate while they were pregnant with us might also play a role in our health, possibly for life.
We have long known that health behaviors during pregnancy, such as smoking and alcohol use, can adversely affect a child’s development. We’ve also known that vitamin deficiencies, such as folate, can play a role. But does diet more broadly affect a child’s future health? The answer increasingly appears to be yes. What a woman eats during pregnancy impacts the baby’s brain development and can alter epigenetics, which determine the genes that get turned on or off. These, in turn, can have effects on health throughout life, influencing a person’s weight and risk for diabetes. It may also affect mental health.
Researchers in the Newborn Epigenetics Study (NEST) looked at 325 women and infant pairs to determine if diet around the time of conception played a role in a child’s temperament and mental health between the ages of 1 and 2 years old. They looked at two different types of dietary patterns: the Mediterranean diet and the glycemic load.
In one published paper, they found that adherence to a Mediterranean diet (MD), even some of the time, resulted in reduced risk of atypical, maladaptive, and autism spectrum behaviors in the children between the ages of one and two years old. Women with the highest adherence to the MD compared to those with the lowest adherence had children who were less likely to be depressed or anxious and more likely to be socially related.
In a second paper, the researchers focused on the glycemic load of women’s diets around the time of conception. This is a metric that includes the glycemic index of foods, or how fast specific foods increase your blood sugar, and also the total carbohydrate content of foods. They divided the women into three groups, from the highest to lowest glycemic load. The women who had the highest glycemic load were much more likely to have children who showed signs of mental health problems when they were one to two years old. The children overall were four times more likely to have anxiety. There were gender differences in the children, too. The boys were four to seven times more likely to have anxiety, sleep problems, impulsivity, or problems with empathy, and almost 10 times more likely to display maladaptive behaviors. The girls were 15 times more likely to display anxiety-related behaviors.
All of this suggests that a mother’s diet may play a much larger role in a child’s mental health than most people currently realize.
The chicken or the egg?
One of the obvious critiques of this study is a phenomenon called reverse causation. In this case, it raises the question of whether anxiety or depression are actually causing the changes in diet as opposed to the other way around. In other words, it’s possible that the women who were not eating the healthiest diets were already depressed or anxious. We’ve all heard of stress eating. Maybe it’s as simple as that. The women who were already depressed or anxious tended to eat more junk food. If this were true, it wouldn’t be surprising that their children would be more likely to have depression or anxiety. Unfortunately, this research didn’t look at this possibility.
However, based on other research in the field of nutritional psychiatry, there is reason to believe it’s not as simple as stress eating. We know that an unhealthy diet affects levels of inflammation, hormones, sleep quality, epigenetics, and many other factors. These are known to have an effect on mental health and also on a developing fetus.
Does changing diet actually change mental health?
At this point, we don’t have research demonstrating that pregnant women changing their diets leads to better mental health outcomes for their children. However, we do have research showing that a change in diet can improve mental health. One of the best trials is called the SMILES trial. This study looked at 67 people with major depression and assigned half of them to a Mediterranean diet and the other half to a control social support group. At the end of 12 weeks, 32 percent of the people in the Mediterranean diet group had remission of their depression compared to only 8 percent of those in the control group. Additional studies of other dietary interventions for other mental disorders are underway now.
What should pregnant women eat?
At this point, without definitive evidence, it’s difficult to say what impact changing a pregnant woman’s diet will have on her baby’s mental health. Nonetheless, it’s reasonable to encourage women to adopt more natural, whole foods into their diets and minimize processed foods. These two recommendations are typically part of the Mediterranean diet. In particular, foods that have a lot of added sugars should be minimized, as these are high in glycemic load.
Clearly, with the rates of obesity, diabetes, and mental health disorders all increasing simultaneously in young people, more research on the impact of a mother’s diet on her children’s health is warranted.
