Concern has been raised about the potential negative effects of unmetabolized folic acid (UMFA), but research on the safety of UMFA is lacking.
After consumption, folic acid must be converted into a usable form by the enzyme dihydrofolate reductase (DHFR). However, DHFR can become easily saturated, leading to a build-up of UMFA. The 2007–2008 National Health and Nutrition Examination Survey (NHANES) found that UMFA was detectable in >95% of Americans who provided serum samples.[1]. UMFA doesn’t behave like natural folate in the body and is generally thought to have no biological effects. However, exactly how UMFA interacts with the body is poorly understood, and it’s unclear whether there are any health risks with long-term exposure.[2]
Preliminary research has raised the concern that UMFA might negatively affect immune function and have an inhibitory effect on normal folate metabolism, but further research is needed.[3][4][5]
References
- ^Pfeiffer CM, Sternberg MR, Fazili Z, Yetley EA, Lacher DA, Bailey RL, Johnson CLUnmetabolized folic acid is detected in nearly all serum samples from US children, adolescents, and adults.J Nutr.(2015-Mar)
- ^Fardous AM, Heydari ARUncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review.Nutrients.(2023-Nov-06)
- ^Troen AM, Mitchell B, Sorensen B, Wener MH, Johnston A, Wood B, Selhub J, McTiernan A, Yasui Y, Oral E, Potter JD, Ulrich CMUnmetabolized folic acid in plasma is associated with reduced natural killer cell cytotoxicity among postmenopausal women.J Nutr.(2006-Jan)
- ^Carolyn Ledowsky, Abela Mahimbo, Vanessa Scarf, Amie SteelWomen Taking a Folic Acid Supplement in Countries with Mandatory Food Fortification Programs May Be Exceeding the Upper Tolerable Limit of Folic Acid: A Systematic ReviewNutrients.(2022 Jun 29)
- ^Clovis Paniz, Juliano Felix Bertinato, Maylla Rodrigues Lucena, Eduardo De Carli, Patrícia Mendonça da Silva Amorim, Guilherme Wataru Gomes, Cecília Zanin Palchetti, Maria Stella Figueiredo, Christine M Pfeiffer, Zia Fazili, Ralph Green, Elvira Maria Guerra-ShinoharaA Daily Dose of 5 mg Folic Acid for 90 Days Is Associated with Increased Serum Unmetabolized Folic Acid and Reduced Natural Killer Cell Cytotoxicity in Healthy Brazilian AdultsJ Nutr.(2017 Sep)