DHA comes from the linolenic acid in some plants and seeds. Certain fatty fish—such as salmon, sardines, and trout—are high in DHA because they eat a lot of algae, which is high in linolenic acid. Same deal with chickens; if they eat high-quality feed with a lot of flaxseeds, their eggs will be very high in DHA.
In every baby’s brain, there’s a building boom.
Huge amounts of iron, proteins, and fatty acids are put to work in a construction frenzy that begins mere weeks after sperm meets egg. New cells, new synapses, new neurons—the fetal brain can make up to a quarter million every minute.
It takes a lot of raw materials to keep up that pace.
Some of the human brain’s most important abilities are cemented before birth. We build our capacity for things like memory and higher cognition in the womb, and that capacity is all we have as long as we live.
Neuroscientist Carol Cheatham is working to find out exactly how the nutrients a mom passes on to her baby—first through the placenta and later through her breast milk or in formula—can affect brain power for life.
She’s taking a close look at one particular nutrient: DHA, a fatty acid found in certain fish and eggs, and now in baby formula and prenatal vitamins throughout the U.S.
In Cheatham’s lab in Kannapolis, North Carolina, a baby named Lincoln sits on his mom’s lap, watching pictures of toys flash on a screen in front of him. Covering his scalp like a helmet is a net of 128 soft, spongy suction cups.
Each of the suction cups is a sensor that picks up on electric impulses from Lincoln’s brain. This is how Cheatham measures memory and cognition in study subjects who can’t talk yet.
She’s studying Lincoln and other six-month-olds, some formula-fed and some breastfed, to find out how the fatty acids in their food affect their developing brains.
The electric impulses from the sensors create an image, a curving line that shows Lincoln’s brain activity as he checks out each passing toy.
Most babies’ brains produce a line that plunges when a new toy appears on the screen, meaning that the brain is hard at work processing the image. Then the line sweeps back up, rising into an arc—that’s the brain committing the image to memory—before settling back to the baseline.
When a familiar toy appears, the line dips only slightly before flattening out again. The brain realizes it’s seen the toy before, so it doesn’t expend the energy to process it again.
When the waves for new toys and for familiar toys are virtually identical, Cheatham says, “it means the baby can’t tell the difference between old and new pictures. The brain is processing like crazy on both kinds, trying to figure out what they are. It’s like it’s not putting them into memory at all.”
Doctors have said for a long time that baby brains fed on breast milk perform better, but Cheatham is finding that the difference isn’t as simple as breastfeeding versus formula-feeding.
The breastfeeding advantage disappears when a mom can’t synthesize the fatty acid DHA, Cheatham says. About 7 percent of U.S. women can’t. There’s less DHA in their plasma during pregnancy—meaning that less DHA reaches the fetus during crucial brain-development time—and lower DHA in their breast milk.
Cheatham’s still analyzing data from this study, but her early results show that babies whose brains have trouble remembering are those who don’t get enough DHA.
If you have kids, or even if you don’t, you may have seen the letters DHA on all kinds of product labels in the grocery store. In 2008, U.S. manufacturers started putting it in supplements, prenatal vitamins, and infant formula. In fact, you’d be hard-pressed to find prenatal vitamins and infant formula that don’t include DHA.
You need DHA (or docosahexaenoic acid) throughout your life to keep your brain functioning at its best. But DHA is especially important for the hungry baby brain. It powers the development of vision, attention, memory, and cognitive functioning.
“It’s in every cell wall, it’s in every neuron,” Cheatham says. “It allows things to move in and out of the neurons more freely. It allows receptors to implant themselves in the synapses more readily.”
Your body makes DHA from the food you eat, namely omega-3 fatty acids. When a baby has a DHA deficiency, it could mean that the breastfeeding mom needs to cut down on omega-6 fats and add more omega-3 fats to her diet.
“But you also have to consider mom’s genotype,” Cheatham says. “If you have a certain genetic makeup, you can take the fatty acid from flaxseed, nuts, and plants, and turn it into DHA inside your body.” But another genetic makeup may prevent some of us—about 7 percent of the U.S. population—from making our own DHA.
“If mom has a genotype where she can’t make her own DHA, she’s not going to have sufficient DHA to pass across the placenta or through her breast milk,” Cheatham says. These mothers should be taking DHA supplements.
Unfortunately, clinical trials haven’t been able to prove that DHA from supplements and infant formula has the same benefits as DHA made in the body. “On a molecular level, it looks for all the world like it should have an effect,” Cheatham says. “But only about 60 percent of trials have found that it does.” She thinks the genetic difference in a small percentage of study participants is skewing the results.
In Canada, about 11 percent of the population can’t make their own DHA. In eastern China, it’s 50 percent. In the Inuit, it’s nearly 100 percent. “For generations, the Inuit have had a really fatty-acid-rich diet,” Cheatham says. “So the gene for making DHA has actually disappeared from their entire genome.”
The same thing could happen in other populations through fetal programming, which refers to the way babies are conditioned for the world by their experience in the uterus and the placenta.
“One thing I know about the human body is that it doesn’t put a lot of effort into things that aren’t necessary,” Cheatham says. “It has a lot of redundant systems, but if one system’s working fine, the redundant one will back off.”
Babies today are getting lots of supplemental DHA, in addition to what most mothers produce naturally. Additional amounts come from prenatal vitamins—which most mothers continue to take while breastfeeding—or from infant formula.
And the result, Cheatham theorizes, “is that the system thinks there’s a lot of DHA in the world and that there’s no need to make it. And then at 12 months, when the baby’s weaned off of formula and it comes time for the system to take over, where is the system? It’s been down-regulated to the point that it may not be able to be up-regulated again.”
So what does all this new DHA in our systems mean for developing fetuses? Or for long-term health in adults? And how can we make sure each infant gets the specific nutrients he or she needs?
It’ll take more studies and bigger sample sizes to answer all Cheatham’s questions. So far, her samples have been relatively small, mainly because it’s tough to find participants who belong to that 7 percent of the population who can’t make DHA.
It’s even tougher to find the 2.5 percent of U.S. babies who not only can’t make their own DHA, but whose mothers also can’t make DHA. That’s a group Cheatham would really like to look at more closely.
She’ll find bigger samples in Singapore, Vietnam, and eastern China, where the typical diet is high in fish and 50 percent of the population cannot make DHA. She and her colleagues have already proposed some preliminary studies in China.
Without a genetic test, there’s no way to know whether you’re part of the 7 percent, Cheatham says. But finding out could make a powerful difference in a baby’s life.
Children with cognitive delays caused by nutrient deficiency may never catch up with their peers when it comes to brain power. And a better understanding of individual differences in fatty-acid requirements can help doctors and parents make sure each child gets the right diet for optimal brain development.
“It may be a pie-in-the-sky idea,” she says, “but I’m hoping that one of the things that’ll come out of my research eventually is that testing for this becomes routine. It’s not difficult. We just take saliva and run it upstairs to the genetics lab.”