Whether Some Prenatal Supplements Contain Too Much Folic Acid

Since the discovery of the role of folate intake in the prevention of neural tube defects (NTDs) during pregnancy, the units in which recommendations for folate intake are expressed have changed, according to Leila Saldanha, PhD, RD, nutrition scientist under contract to the National Institutes of Health (NIH) Office of Dietary Supplements.

In older recommendations, units of measure for folic acid were expressed as mcg (or mg). However, new US Food and Drug Administration (FDA) labeling regulations issued in July 2016 mandated that all natural and synthetic forms of folate be expressed as mcg dietary folate equivalents (DFEs) on food and supplement labels.¹ In addition, the FDA revised the Daily Value (DV) for folic acid intake in pregnant women to 600 mcg DFE, equivalent to 360 mcg folic acid.

With this in mind, Dr Saldanha and colleagues performed a study to assess the labeling of synthetic folic acid content in prescription and non-prescription prenatal supplements to determine how these products adhered to FDA labeling requirements.

For their study, they used data from NIH’s Dietary Supplement Label Database and DailyMed entered between September 2015 and March 2019. A total of 53 prescription and 120 non-prescription prenatal supplement labels were included in their analysis.

To make comparisons with official recommendations for the prevention of NTDs, which are stated in mcg folic acid, Dr Saldanha and colleagues converted all natural and synthetic folate amounts declared on prenatal supplement labels to equivalent folic acid amounts using the conversion factors 1 mcg food folate = 0.6 mcg folic acid and 1 mcg L-5-methylfolate = 1 mcg folic acid

Ultimately, the results of the study showed that all prescription and most nonprescription labels indicated that folic acid in prenatal supplements exceeded the revised DV.

Furthermore, Dr Saldanha and colleagues noted that current recommendations for folic acid intake are somewhat conflicting and likely need harmonization. The National Academies of Science, Engineering, and Medicine (NASEM) Food and Nutrition board established the Recommended Dietary Allowance (RDA) of 600 mcg DFE (or 360 mcg folic acid), and Tolerable Upper Intake of 1000 mcg folic acid for pregnant women, while the US Preventive Services Task Force (USPSTF) recommends that all women who are planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400 to 800 mcg) folic acid.^2,3

Nutrition411 discussed these findings further with Dr Saldanha.

Nutrition411: Could you discuss the key findings from your study on folic acid in prenatal supplements?

Dr Saldanha: One thousand mcg was the most common recommended dose on prescription labels, while 800 mcg was the most common recommended dose on nonprescription labels.

Ninety-two percent of prescription and 9% of nonprescription prenatal supplements exceed the old daily recommended amount of 800 mcg per day of folic acid for pregnant women. All of the prescription and 94% of nonprescription prenatal supplements we examined exceed the RDA and revised DV of 360 mcg folic acid per day for pregnant women.

Approximately 32% of prescription and 25% of nonprescription prenatal supplements contained synthetic L-5-methylfolate, a relatively new source of folate. Companies are replacing folic acid with synthetic L-5-methylfolate, which is claimed to be safer than folic acid.

N411: What are some potential issues that could arise from overconsumption of folic acid in pregnant women?

Dr Saldanha: Folate that is naturally present in food is not harmful to healthy individuals. However, pregnant women should avoid consuming folic acid in supplements in amounts above 1000 mcg (the Tolerable Upper Intake), unless recommended to do so by a healthcare provider.

N411: How can providers use the findings from your study in practice, especially given current recommendations for folic acid intake in pregnant women?

Dr Saldanha: NASEM’s Food and Nutrition Board established the RDA of 360 mcg and Tolerable Upper Intake of 1000 mcg for pregnant women, and the FDA revised its DV to 600 mcg DFE folate, or 360 mcg folic acid, in 2016 to reflect this.

The USPSTF recommendation states that all women who are planning or capable of pregnancy should take a daily supplement containing 0.4 to 0.8 mg (400 to 800 mcg) folic acid. Currently, most folate-containing dietary supplements meet these recommendations.

N411: What main takeaways about your study would you like to leave with health care providers?

Dr Saldanha: Providers should become aware of the changes in the labeling of folic acid on supplement labels, so they may help pregnant women make informed choices when selecting products. While recommendations are expressed as mcg of folic acid, the new labels must state the amounts in mcg of folate. However, the FDA will permit companies to list in addition the amounts in mcg folic acid.

The new DV is now 600 mcg DFE. A 100% DV label declaration is equal to 360 mcg folic acid using the conversion factor of 1 mcg folate = 0.6 mcg folic acid. This amount is less than 400 to 800 mcg folic acid recommended by the USPSTF.

Leila Saldanha, PhD, RD, is a nutrition scientist under contract to the National Institutes of Health Office of Dietary Supplements.

References:

1. Food labeling: revision of the nutrition and supplement facts labels. US Food and Drug Administration. https://www.regulations.gov/document?D=FDA-2012-N-1210-0875. May 27, 2016. Accessed June 19, 2019.

2. Dietary reference intakes tables and application. Food and Nutrition Board. The National Academies of Sciences, Engineering, and Medicine. http://www.nationalacademies.org/hmd/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx. Accessed June 19, 2019.

3. US Preventive Services Task Force. Folic acid supplementation for the prevention of neural tube defects: US Preventive Services Task Force recommendation statement. JAMA. 2017;317(2):183-189. doi:10.1001/jama.2016.19438.

4. Saldanha L, Dwyer J, Potischman N, Andrews K. Folic acid and folate in prenatal supplements: labeled amounts compared to recommendations. Paper presented at: Nutrition 2019; June 9, 2019; Baltimore, MD. https://eventscribe.com/2019/ASN/fsPopup.asp?Mode=posterInfo&PosterID=204052.