Saturday Nov 5, 2016 (foodconsumer.org) -- Taking folic acid or folate supplements during early pregnancy can increase risk of gestational diabetes mellitus, according to a new study released recently in the medical journal Diabetes Care.

The study showed that women supplemented with folic acid supplements daily in the first trimester were 120% more likely to develop gestational diabetes mellitus than those who did not use the supplements.

Fangbiao Tao at Anhui Medical University in Hefei, China and colleagues conducted the China-Anhui Birth Cohort Study involving 3,474 pregnant women in the Anhui Province of China and found the association between folic acid supplementation and elevated risk for gestational diabetes mellitus.

Among women taking folic acid supplements during the first trimester, those who were also overweight or obese before pregnancy were 463% more likely to suffer gestational diabetes mellitus than those who had a healthy body weight and never used folic acid supplements.

Supplementation with folic acid alone prior to pregnancy or in the second trimester alone was not so apparently linked to an increased risk of gestational diabetes mellitus.

Gestational diabetes mellitus more likely develops in women in certain ethnic groups, particularly at older ages.  The condition results in few symptoms although it may increase risk of some complications such as pre-eclampsia, depression and use of a Caesarean section.  Left untreated, gestational diabetes mellitus can lead to stillbirth.

Gestational diabetes mellitus can also affect the baby born to the woman with this condition.  The typical after-birth implications include having high excess body weight, low blood sugar after birth and jaundice.  The affected children are also at high risk for development of overweight and type 2 diabetes mellitus, according to wikipedia.

Folic acid or folate is often added to prenatal vitamins to prevent birth defects, that is, neural tube defects.   This chemical is also commonly used in flours - a practice called fortification of folate in flours.  Researchers have now found exposure to excess synthetic folate harmful to men and women who are not at the child-bearing age.  Studies have found long-term high exposure to synthetic folic acid or folate associated with increased cancer risk.

According to the report, folic acid supplementation has been associated with elevated risk of oral cleft malformations, asthma/respiratory tract infections, small-for-gestational-age infants, and cancers

High maternal serum concentrations of folate are also linked to increased risk of insulin resistance in children and gestational diabetes mellitus.  Experimental studies have proved that high folic acid promotes glucose intolerance and insulin resistance in male offspring fed a high fat diet.

This current study indicates that the supplementation with folic acid during early pregnancy can increase risk of gestational diabetes mellitus.

How could folic acid supplementation increase risk of gestational diabetes mellitus? Folate at high concentrations promotes metabolism of vitamin B12 potentially leading to vitamin B12 deficiency and it may participate in the pathogenesis of gestational diabetes mellitus by increasing insulin resistance, according to the report.  It is also possible that intact or un-metabolized folic acid in the blood decreases natural killer cell cyto-activity which may be involved in the development of gestational diabetes mellitus.

Folic acid is a naturally occurring vitamin found largely in green vegetables.  No studies have linked consumption of foods rich in natural folic acid to increased risk of gestational diabetes mellitus.   Pregnant women should eat adequate amounts of fruits and vegetables in addition to other types of vitamin rich foods to make sure they have sufficient intake of folic acid.  (David Liu)

Beibei Zhu, Xing Ge, Kun Huang, Leijing Mao, Shuangqin Yan, Yeqing Xu, Sanhuan Huang, Jiahu Hao, Peng Zhu, Ying Niu, Shilu Tong and Fangbiao Tao, , Folic Acid Supplement Intake in Early Pregnancy Increases Risk of Gestational Diabetes Mellitus: Evidence From a Prospective Cohort Study, Diabetes Care 2016 Mar; 39(3): e36-e37. http://dx.doi.org/10.2337/dc15-2389

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