By Dr. Mercola
Omega-3 fats are known as essential fatty acids because the only way you can get them is via your diet. In pregnant women, consuming enough omega-3 fats is especially important, as they’re important for the baby’s visual and cognitive development.
In the US, most Americans’ diets are seriously lacking in omega-3 fats. Women tend to become further depleted during pregnancy, as the fetus uses omega-3s for nervous system development. After birth, omega-3s are again used to make breast milk, and for women on their second or third pregnancy, levels may be extremely low.
Generally, with each subsequent pregnancy, women become further depleted in omega-3s.1 New research from the University of Alberta and the University of Calgary in Canada further confirmed that most pregnant women are seriously lacking in these beneficial fats.
Most Pregnant or Breastfeeding Women Aren’t Getting Enough Omega-3s
The American Dietetic Association and Dietitians of Canada recommend that pregnant and lactating women (along with all adults) consume at least 500 milligrams (mg) of omega-3s, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), daily.
The European Commission recommends that pregnant and lactating women consume a minimum of 200 mg of DHA, in particular, per day.2 In a study of more than 2,000 women, the majority did not meet these recommendations. In fact, only 27 percent of pregnant women and 25 percent of women at three months postpartum met the EU’s DHA recommendation.3
Overall, 79 percent of the omega-3s in the women’s diets came from seafood, fish, and seaweed products, with the majority from salmon, however this often wasn’t enough to provide therapeutic levels of omega-3s that are critical for infant development.
Health Canada recommends pregnant women consume one to two portions a week of fish high in omega-3 fats to help increase levels. The study also found that women taking an animal-based omega-3 fat supplement were much more likely to meet the recommendations.
Women who took a supplement containing DHA were 10.6 and 11 times more likely to meet the current EU consensus recommendation for pregnancy and postpartum, respectively. The researchers noted, “…taking a supplement significantly improved the likelihood that they would meet recommendations.”
Unfortunately, nearly half (44 percent) of the women who reported taking an omega-3 fat supplement during pregnancy were no longer doing so while breastfeeding at three months postpartum, a period of crucial development for the infant.
The researchers recommended nutritional counseling and education to help women understand that the omega-3 supplement offers continued benefits during breastfeeding and should be continued beyond pregnancy.
The Importance of Omega-3 Fats During Pregnancy
It's important to realize that your body cannot form omega-3 fats, so a fetus must obtain all of its omega-3 fats from his mother's diet. Hence, a mother's dietary intake and plasma concentrations of DHA directly influence the DHA status of the developing fetus, which can impact your child's brain development.
Research has linked inadequate intake of omega-3 fats in pregnant women to premature birth, increased risk of preeclampsia, and low birth weight, in addition to hyperactivity in children. Adding EPA and DHA to the diet of pregnant women has also been found to benefit visual and cognitive development in the baby, while also reducing the risk of allergies in infants.4
After delivery and while breastfeeding, omega-3 fats continue to be important, both for baby and for mom. In women, low levels of omega-3 are linked to an increased risk of postpartum depression.5 In children, supplementation early in life increases intelligence.
In one study, a group of infants received either an omega-3 fat supplement or a placebo.6 Tests to evaluate their cognition were given every six months starting at age 18 months and continuing until they were 6 years old.
While no changes were noted in the early test done at 18 months, the study found that infants consuming omega-3 fats outscored the placebo group later, between 3 and 5 years old.
The omega-3 fat group scored higher on rule learning, vocabulary, and intelligence testing, which suggests early omega-3 fat supplementation, during the key period when your child’s brain is still developing, may pay off with greater intelligence in the pre-school and school-aged years.
Omega-3 levels even appear to influence sleep in children. Children taking daily supplements of omega-3 fats had nearly one hour more sleep and seven fewer waking episodes per night compared with children taking a placebo.7
Should Pregnant Women Eat Fish?
Fish has always been one of the best sources for the animal-based omega-3 fats EPA and DHA, but as levels of pollution have increased, this treasure of a food has become less and less viable as a primary source of healthy fats.
The good news is that about 70 percent of tested wild-caught fish consumed in the US contain relatively low levels of mercury.8 However, fish like tuna, marlin, shark, barracuda, and swordfish have some of the highest levels of contamination.
So while consuming fish can certainly be beneficial, pregnant women in particular should be sure to choose the right kinds of fish to receive maximum benefits with minimal exposure to pollutants like mercury.
Mercury can cross the placenta to harm the rapidly developing nervous system in your baby, including the brain. Studies have associated prenatal methylmercury exposure with impaired development of sensory, motor, and cognitive functions, resulting in learning difficulties, poor coordination, and inability to concentrate.
About 10 percent of the US population—including many children, pregnant women, and women of childbearing age, in particular—have mercury levels above the levels currently recommended for fetal and child health.
The US Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) are in the process of updating the national advisory for fish consumption for pregnant women, nursing mothers, women of childbearing age, and young children. They now recommend pregnant women eat 8 to 12 ounces of a variety of fish each week from choices that are lower in mercury.
Tuna Is a Large Source of Mercury Exposure
They recommend avoiding high-mercury fish including tilefish from the Gulf of Mexico, shark, swordfish, and king mackerel, and limiting white (albacore) tuna to 6 ounces a week. The lower mercury fish choices they recommend include salmon, shrimp, pollock, tilapia, catfish, cod and, unfortunately, tuna (light canned).
Tuna is one of the largest sources of mercury exposure in Americans’ diets, and anyone who wants to reduce their mercury intake probably needs to eat less of it. Research published in 2010, which quantified the contributions to total mercury in the US seafood supply by 51 different varieties of fish and shellfish, found that tuna was responsible for more than one-third of Americans' total exposure to methylmercury.9
According to the author:
"The analysis performed here identifies the relative importance of different fish and shellfish as sources of mercury in the US seafood supply and proposes improved consumer advice, so that the public can benefit from fish consumption while minimizing mercury exposure.
Except for swordfish, most fish with the highest mercury levels are relatively minor contributors to total inputs.
Tuna (canned light, canned albacore, and fresh/frozen varieties) accounts for 37.4 percent of total mercury inputs, while two-thirds of the seafood supply and nine of the 11 most heavily consumed fish and shellfish are low or very low in mercury. Substantial improvement in risk communication about mercury in fish and seafood is needed; in particular, several population subsets need better guidance to base their seafood choices more explicitly on mercury content."
Further, a 2012 report by the Mercury Policy Project offers risk management advice for schools and parents, and warns that canned tuna is a major source of mercury exposure in children, which has implications for pregnant women as well.10 Based on average contamination levels in tested samples, small children should eat light tuna no more than twice a month, according to the Mercury Policy Project, and albacore tuna should be avoided entirely.
Which Fish Are the Best Sources of Omega-3 Fats?
In addition to contamination concerns, the tuna population has also been decimated due to over-fishing, so I believe it is best to avoid tuna and make better choices when consuming seafood. Wild-caught Alaskan salmon, for example, is one very low mercury fish. Farmed salmon may contain only about half of the omega-3 of wild salmon and may also contain harmful contaminants, including environmental toxins, synthetic astaxanthin, and genetically engineered organisms from the grain feed they’re given – so choosing wild-caught Alaskan is important.
Unfortunately, salmon are often mislabeled. Studies have shown that as much as 70 percent to 80 percent of the fish marked "wild" are actually farmed. Avoid Atlantic salmon, as typically salmon labeled "Atlantic Salmon" currently comes from fish farms.The two designations you want to look for are: “Alaskan salmon,” and “sockeye salmon,” as Alaskan sockeye is not allowed to be farmed. So canned salmon labeled "Alaskan Salmon" is a good bet, and if you find sockeye salmon, it's bound to be wild.
Cod and catfish, while lower in mercury, also primarily come from aquatic fish farms these days, so aren’t one of the best options.Other fish with short life cycles also tend to be better alternatives in terms of fat content, so it’s a win-win situation – lower contamination risk and higher nutritional value. A general guideline is that the closer to the bottom of the food chain the fish is, the less contamination it will have accumulated. This includes:
Sardines, in particular, are one of the most concentrated sources of omega-3 fats, with one serving containing more than 50 percent of your recommended daily value.11 In addition, look for fish that contains the Marine Stewardship Council (MSC) label. The MSC label on wild-caught fish identifies seafood that is caught using sustainable, eco-friendly methods.
What’s the Optimal Source of Omega-3 Fats?
While a helpful form of omega-3 (ALA) can be found in flaxseed, chia, hemp, and a few other foods, the most beneficial form of omega-3 -- containing the two fatty acids DHA and EPA, which are essential to brain function -- can only be found in fish and krill. While your body can convert ALA into DHA/EPA, it only does so at a very low ratio, and only when sufficient enzymes (that many people are deficient in) are present. You’re probably aware that if you don’t eat a lot of fish, you can supplement your diet with omega-3 fats with fish oil. Less widely known is that you can also get your omega-3s from krill oil, and it may, in fact, be preferable to do so.
The omega-3 in krill is attached to phospholipids that increase its absorption, which means you need less of it, and it won't cause belching or burping like many other fish oil products. Additionally, it naturally contains astaxanthin, a potent antioxidant—almost 50 times more than is present in fish oil. This prevents the highly perishable omega-3 fats from oxidizing before you are able to integrate them into your cellular tissue.
In laboratory tests, krill oil remained undamaged after being exposed to a steady flow of oxygen for 190 hours. Compare that to fish oil, which went rancid after just one hour. That makes krill oil nearly 200 times more resistant to oxidative damage compared to fish oil! When purchasing krill oil, you'll want to read the label and check the amount of astaxanthin it contains. The more the better, but anything above 0.2 mg per gram of krill oil will protect it from rancidity.
If you don’t regularly eat safe forms of fish like wild Alaskan salmon or sardines, I recommend supplementing with krill oil before and during pregnancy, and while breastfeeding. Infants receive vital DHA through your breast milk, so if you can continue breastfeeding through at least the first year, you will give your child a great head start for success in life. Then, as soon as your child can safely swallow a capsule, he or she can start taking a high-quality krill oil supplement. The capsules should be kid-sized – about half the size of a regular capsule – and odor-free, making them easy and palatable for kids to swallow.