by Heidi Green
June 29, 2012
Pregnant or breastfeeding? The latest webinar from the National Healthy Mothers, Healthy Babies Coalition, “Powerhouse Nutrients for Pregnancy and Lactation: Evidence-Based Guidelines for Optimum Growth and Development,” by Mary Harris, PhD, RD, provides some key insights that can help you make the best nutrition decisions for you and your baby.
Dr. Harris identified five powerhouse nutrients, but tailored her talk to address the three most important ones: folic acid, vitamin D, and omega-3 DHA.
Only 30 to 40 percent of women of childbearing age (typically defined as 15–44 years of age) take supplements; as a result, many fall short in their consumption of folic acid. If unexpected pregnancy occurs (as the Guttmacher Institute estimates it does for 49 percent of pregnant U.S. women each year), this shortfall can leave women and their babies at risk for pregnancy complications.
Traditionally, the Centers for Disease Control and Prevention (CDC) and Institute of Medicine (IOM) have recommended that women who may become pregnant consume 400 micrograms (mcg) of folic acid per day in order to prevent neural tube defects, such as spina bifida, and macrocytic anemia. Because these conditions can develop early in pregnancy—before a woman even knows she is pregnant—folic acid should be part of her diet even before pregnancy. According to Dr. Harris, an estimated 40 to 60 percent of neural tube defects are preventable with folic acid supplements.
The latest Dietary Reference Intake (DRI) guidelines from the IOM’s Food and Nutrition Board raise the bar for folic acid intake during pregnancy, setting the goal at 600 mcg per day: 400 from supplements and fortified foods and 200 from food sources. New research suggests that folic acid at these levels might decrease the incidence of preterm birth, and lower the risk of preeclampsia.
There are many dietary sources of folic acid (folate), including:
A major source of dietary folic acid is enriched flour from the flour fortification program, named by the CDC as one of the top 10 greatest public health achievements of the last decade. The program was expected to increase dietary folic consumption by 100 mcg per day, but has actually more than doubled that (about 220 mcg/day increase). Although it was theoretically expected to decrease neural tube defects by 50 to 70 percent, the effect has been more modest; since the fortification program was launched in the U.S., the incidence of neural tube defects has decreased by not quite 40 percent.
There has been some recent evidence, Dr. Harris reports, of health risks posed by high folic acid levels. Specifically, 1000 mcg per day has been associated with a threefold increase in risk of colon cancer recurrence, and 5000 mcg per day has been associated with hypermethyation of DNA, which she explains is “a condition associated with development of cancers of all types.” However, these levels are far beyond what is recommended by leading health authorities.
According to Dr. Harris, vitamin D deficiency (less than 50 nanomoles per liter) and insufficiency (<75-80 nmol/L) are widespread among pregnant women. The IOM estimates 5 to 29 percent of pregnant women have an inadequate intake of vitamin D.
While the evidence is inconclusive, Dr. Harris suggests that vitamin D might be protective against preeclampsia, diabetes, and infectious disease. The literature is mixed, and more studies are underway to gain a clearer picture of the relationship between vitamin D and pregnancy. According to the American College of Obstetricians and Gynecologists, there is no need for routine screening of vitamin D deficiency in pregnancy, although it may be indicated for women at high risk. When severe deficiency is identified, women may be treated safely with 1000 to 2000 IU per day. For most women, the Dietary Recommended Intake for vitamin D is 600 IU a day, both during pregnancy and when breastfeeding. Pregnant women should limit their vitamin D intake to the amount in prenatal vitamins, until the results of ongoing random controlled trials are available.
The American Academy of Pediatrics (AAP) recommends that all babies receive a supplement of 400 IU/day. Infants who are exclusively formula fed will get this amount in the fortified formula they drink. All other infants—including those entirely or partially breastfed—need to be given daily vitamin D supplements. Once a child is eating vitamin D fortified foods (soy products, dairy products, cereals) or drinking four cups (32 ounces) of vitamin D fortified liquid a day, there is no need to supplement with vitamin D. Breast milk is one of few vitamin D rich foods. However, human milk was never meant to be a primary source for vitamin D.
Vitamin D is produced by the human body in response to sunlight. Unfortunately, concerns over skin burns and cancers make sunlight a risky source. There are few natural dietary sources of vitamin D, so most Americans must satisfy their vitamin D needs by eating or drinking foods fortified with vitamin D. The National Institutes of Health (NIH) provides a short list of selected food sources:
Dr. Harris notes that vitamin D supplementation of 1000 IU per day is recommended during lactation to maintain optimal levels. Mothers wanting to satisfy their babies’ vitamin D needs through breast milk may do so, according to one closely-watched randomized-controlled pilot study, by taking 6000 IU of vitamin D in addition to their prenatal vitamin. Although the AAP does not recommend supplementation at this level, it is far below the amount thought to cause toxicity (greater than 40,000 IU per day), and seems to achieve adequate vitamin D levels in both mother and child.
Omega-3 fatty acids
You can’t talk about omega-3 fatty acids without talking about fish, in spite of ongoing controversy about fish and mercury consumption during pregnancy. Dr. Harris makes the case for “safe seafood” in her presentation, beginning with benefits of seafood consumption:
Fish is a rich source of omega-3 docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), as well as vitamin D and selenium. The research is mixed on the value of fish consumption with regard to preterm birth and gestational length, but Dr. Harris notes that the “greatest effects are seen [when] comparing women who consume little or no fish to those who consume two or more servings a week” and that there are “little additional effect” for those who eat large amounts of fish.
As a result of studies detailing cognitive and visual benefits, Dr. Harris concludes that “most studies have found that although fish contain [mercury], the positive benefits of fish outweigh any negative effects.”
In spite of these benefits, many pregnant women have reduced their fish consumption—and, thus, their intake of DHA—since 2004. That year, the Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) issued a joint Advisory on Seafood in Pregnancy. The advisory was largely favorable on fish consumption, noting that “[f]ish and shellfish are an important part of a healthy diet … A well balanced diet that includes a variety of fish can contribute to heart health and children’s proper growth and development. So, women and young children in particular should include fish or shellfish in their diets due to the many nutritional benefits.” The report went on to recommend eating up to 12 ounces (two average meals) a week of a variety of lower-mercury fish or shellfish, including up to half that much of albacore tuna. It also recommended skipping fish “higher on the food chain” that would have accumulated higher levels of mercury, including shark, swordfish, king mackerel, and tile fish.
However, many pregnant women chose to reduce or eliminate fish from their diet. While a 2000 national survey found that pregnant women typically consumed 2.9 ounces of fish, post-advisory, that figure fell to 1.89 per week (2008 data).
Fish consumption was low, too, among lactating mothers, at just 2.1 ounces per week in 2008.
While there currently is no DRI for omega-3 DHA, the World Association of Perinatal Medicine suggests 200 mg DHA per day. The USDA’s latest dietary guidelines recommend seafood for women who are pregnant or breastfeeding:
Women who can’t (or won’t) eat fish can take supplements, a minimum of 200 mg DHA per day during pregnancy. In pregnancy, up to 2700 mg of omega-3 fatty acids (920 mg DHA, 1300 mg EPA) have been used safely. Frozen or coated capsules can make supplements more palatable.
Find out more
For more information about folic acid, see the CDC website. For details about vitamin D recommendations, see the NIH website. For more about omega-3 recommendations, see the FDA website.
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