Does obesity impact folate metabolism?

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Today’s guest post comes from Carolyn Crist.  You can find more on Carolyn at the bottom of this post.  

At the University of Georgia, a group of nutrition professors are investigating how obesity may affect folate metabolism during pregnancy. With an increasingly obese population and folate recommendations based on studies from the 1990s, they surmise that obese mothers may need more folate during pregnancy.

They recently conducted a pilot study of both normal weight and obese women to measure how the recommended dose — 400 micrograms — is metabolized in the blood over 10 hours. The study, published in the International Journal of Obesity earlier this month, shows that there’s a significant difference between the two groups.

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Serum folate response follow a single dose of folate (Silva et al, Int J Obesity, 2013)

The researchers administered a dose of folic acid to 16 normal-weight women with a BMI between 18.5 and 24.9 and 16 obese women with a BMI over 30.  Before the folate was administered, fasting serum folate was lower among participants in the obese group, while their red blood cell folate was higher. During the first three hours after folate administration, serum folate levels were 34% lower in the obese women, and the overall folate response after 10 hours was also lower in obese women. 

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Area under the curve for serum folate following folate ingestion (Silva et al, 2013, Int J Obesity)

“It’s quite important to determine whether or not this recommended amount of folic acid should be tailored and based on body weight,” said Lynn Bailey, the lead researcher. “In the pharmaceutical arena, many drugs are prescribed based on body weight, but that’s not the case for this vitamin.”

Getting enough folic acid before and during the first month of pregnancy prevents most neural tube defects — birth defects of the brain and spinal cord — that lead to spina bifida, nerve damage, paralysis, or an undeveloped brain. Folate can reduce these rare neural tube defects from about 2 in 1,000 births to about 1 in 1,000, according to the Office of Dietary Supplements.

Bailey, who has studied folic acid, maternal health, and birth defects for more than three decades, has previously published research that shows obesity is associated with an increased risk of having a pregnancy affected by a neural tube defect.

“We really think this research has translational potential because it could result in a change in the way the public health recommendations are defined,” she said. “If it is based on BMI, we could overcome the negative impact of obesity on developing embryos that don’t receive a sufficient amount of folic acid.”

The U.S. Preventive Services Task Force and Office of Dietary Supplements have recommended 400 to 800 micrograms of folic acid for women of child-bearing age since 1996, and USPSTF reaffirmed the recommendation in 2009. Spokespeople from both groups said further research is needed to determine whether a change is warranted. USPSTF reviews recommendations every five years, and folic acid isn’t currently on the list for USPSTF to update.

“To update this recommendation, the task force will examine all available and current evidence on this topic,” said Mark Ebell, a University of Georgia professor of clinical epidemiology and member of the USPSTF. “We must determine the balance of benefits and harms for folic acid supplementation.”

A new Centers for Disease Control and Prevention study, published in the Journal of Nutrition this month, states that though the majority of women do use folate during pregnancy, only half of pregnant women are using the supplement during the first trimester, when it matters most.

“We found the good news that a majority of pregnant women did report taking a supplement, but it was important to look at the breakdown by trimester,” said Amy Branum, author of the paper and staff member at the CDC National Center for Health Statistics. “We wanted to see how many in the first trimester were taking folic acid because it’s a critical period for neural tube defect development.”

Branum and co-workers investigated data about nearly 1,300 pregnant women surveyed from 1999 to 2006 in the National Health and Nutrition Examination Survey, an annual CDC survey used to evaluate health in the nation. Previous analytical studies haven’t tracked folate use and status in particular, especially by marking trimesters through red blood cell data.

More than three-fourths, or about 77 percent, said they used a supplement in the previous 30 days, usually a multivitamin with folic acid and iron. About 55 percent of women in their first trimester took a supplement compared with 76 percent in their second trimester and 89 percent in their third trimester. Red blood count folate status, which indicates the actual presence of folate in the blood, was also lowest in the first trimester and highest in the third trimester.

“It was nice to study recent data of pregnant women,” said Branum, who has researched longitudinal studies about pregnant women in the 1950s and 1960s. “We’re finding ways to use this data and make it useful to the public and medical community.”

Carolyn Crist

Carolyn Crist

Carolyn Crist is a freelance writer pursuing her master’s degree in Health and Medical Journalism at the University of Georgia. She graduated from UGA in 2010 with degrees in newspapers and English and worked as an education and political reporter.

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