Is it any coincidence that the most laidback people I’ve ever met hail from Brazil, land of fish and coconuts?
The mellowness of Brazilians came to mind when I read a study on prenatal stress to be published next month in the International Journal of Neurodevelopmental Medicine. The researchers, including lead author Carlos Galduróz, are biologists at Universidade Federal de São Paulo (in Brazil).
It’s been long known that significant prenatal stress — characterized by a blitz of the stress hormone cortisol — harms a fetus. Prenatal stress results in an increased risk of premature birth and low birthweight. In humans, it’s linked with anxiety, attention deficit disorder, impaired memory, low test scores in childhood, and depressive behavior in adulthood. Rats whose mothers are exposed to extreme stressors are likelier to have impaired motor skills and are slower to learn.
Intriguingly, there’s evidence that the mother’s diet might offset some of these disadvantages. A baby whose stressed-out mom ate “special” foods during pregnancy and lactation may fare better than one whose equally stressed -out mom ate a normal diet.
Galduróz and his colleagues were curious to know if the composition of fat in a prenatal diet might make the difference. So, during the equivalent of second and third trimester, they subjected some of the rats in their study to extreme stress — restraint and bright lights for forty-finve minutes, three times daily. Some of these pregnant rats were fed a diet high in omega-3 fatty acids, the kind found in salmon, sardines, and other fish. Others were fed a diet high in saturated fatty acid from coconut milk. A third group ate normal rat chow.
As expected, babies of stressed-out moms had lower birth weights. The surprise came three weeks later: Babies whose moms ate fish oil or coconut fat diets during pregnancy and lactation gained weight quickly. So quickly, in fact, that they became the same weight as the babies whose moms weren’t stressed during pregnancy. In other words, fish and coconut fats reversed the impact of low birthweight, a potentially dangerous effect of prental stress.
That’s not all.
Babies exposed to prenatal stress were more active (restless) than other pups if their moms were on a regular or coconut-oil diet. Interestingly, if a stressed-out mother was on a fish oil diet, her pups were not more restless than those of pups with non-stressed moms.
In an earlier study by the same authors, adult rats whose moms ate a coconut fat or fish oil-based diet released fewer stress hormones (a reduced corticosteroid response) than rats whose moms ate a normal diet.
Many studies have shown that fish oil, omega-3s, modulate mood by reducing the stress response. This has been shown in rat studies, and also in many (but not all) human studies. Is it possible that when a mother consumes food containing omega-3s, her babies are less agitated? Are they happier? Of course, rodents express anxiety, neuroticism, and depression differently from human babies. But the healing effect of nutrients is fascinating. Do stressed-out moms on fish-and-coconut diets have happier, healthier babies than their equally stressed peers who don’t eat as well?
For the real possibility that fish and coconut oil have prenatal physical and psychological perks, I link to a favorite recipe here. It’s for moqueca, a stew made of fish and coconut fats, from Bahia, the Coconut Coast of Brazil.
*If you like this blog, click here for previous posts and here to read a description of my most recent book, Do Gentlemen Really Prefer Blondes?, on the science behind love, sex, and attraction. If you wish, check out my forthcoming book, Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy.
If you were to take the Trier Social Stress Test (TSST), as nearly one hundred fifty pregnant women did in a study led by Sonja Entinger at the University of California at Irvine, you’d be led to a windowless room with a video camera and instruments that measure your vital signs. There, an assistant would ask you to sit and be hooked up to instruments that measure your vital signs. In the room you’d also find three men and women sitting at a table, waiting for you.
They are your interview panel.
Facing them belly-on, your instructions are to pretend that you’re applying for a job and must deliver a five-minute speech to convince them that you’re right for the position. Someone would say 1-2-3-GO, and you’d start babbling, hopefully coherently. If you have nothing more to say before your time is up, one of your interviewers will blandly instruct you to continue. Run out of words again and twenty seconds of eerie silence will fill the room. And when you’re finally done, you’ll be asked to do a bit of mental math — say, to count down, in increments of thirteen, from a large prime number like 54,499. Before and afterward the fifteen minute ordeal, a researcher will enter the room and hand you a swab to collect your saliva for testing.
Analyzing all the data from their study, including an analysis of body language and hormone levels of women who took the TSST, the UC Irvine researchers confirmed something remarkable: the further along a woman was in her pregnancy, the less stressful she found the stress test. Compared to their stress levels in second trimester (17 weeks), volunteers in their third trimester (31 weeks) had lower blood pressure, slower heartrates, and lesser spike in the hormone cortisol. Pregnant women also did not stress out as much as nonpregnant controls who took the same tests at the same time intervals. This was not the first study that found that pregnant women, especially those in third trimester, are calmer than nonpregnant women under the same (short and moderately stressful) circumstances. But it was the first time that the same women were tracked at different stages of gestation.
So what is that makes pregnant women more Zen as they approach their due date? The likely answer is that the body reduces the sensitivity of cortisol receptors, even though baseline levels of the stress hormone are higher. In other words, it takes more stress hormones than usual to get the nervous system all hot and bothered. At the same time, the placenta increases production of an enzyme that changes cortisol to an inactive form, meaning that less of the toxic stuff filters through to the baby. Near the end of pregnancy, probably to calm you down before labor and help you bond with the baby, your body also produces more of the nervous-system soothing hormones oxytocin and prolactin.
All this is good news for moms who are slammed with short-term mild to moderate stress late in their pregnancies.
But there’s an even bigger surprise to come out of this. You may think this is your body subconsciously protecting the baby at a time of stress. But it’s just as likely that it works the other way around: your baby protecting you (as well as herself), because her placenta is responsible for at least some of the stress-dampening response to cortisol. It’s a beautiful idea — mother and child soothing one another in the face of life’s assaults.