Folic acid from fortified flour and unmetabolized folic acid in blood
What it found
In 144 healthy Brazilian adults, higher folic acid intake from fortified foods was linked to higher blood levels of unmetabolized folic acid.
This was a cross-sectional study, so it cannot prove cause and effect.
What they found
Studies in people
Folic acid intake and UMFA
People who ate more folic acid from fortified foods had higher levels of unmetabolized folic acid in their blood. This was a positive correlation.
Other nutrients and UMFA
Higher intakes of choline, methionine and vitamin B6 were linked to lower unmetabolized folic acid levels. People with the lowest UMFA levels ate more of these nutrients.
Folate status
About 7 in 100 people had low folate levels, and about 12 in 100 had high folate levels. No one was deficient in vitamin B12.
Sex differences
Women had higher folate and unmetabolized folic acid levels than men. Men had higher homocysteine levels.
Fortified foods in diet
Fortified foods provided almost half of the total folate intake. None of the participants ate more than the upper limit for folic acid.
What the authors conclude
“UMFA concentrations were directly influenced by folic acid intake from fortified foods in a healthy convenience sample of adult Brazilians exposed to mandatory flour fortification with folic acid.”
Also in their conclusions
- They conclude that unmetabolized folic acid concentrations are directly influenced by folic acid intake from fortified foods in healthy Brazilian adults exposed to mandatory flour fortification.
- They say that dietary intake of methyl donor nutrients may also be associated with unmetabolized folic acid concentrations, and that more research is needed on the relationship between unmetabolized folic acid and betaine, choline, methionine, and vitamins B2, B6 and B12.
How it was done
Brazil has required wheat and maize flour to be fortified with folic acid since 2004. The authors wanted to see how folic acid from fortified foods relates to unmetabolized folic acid levels in the blood.
They studied 144 healthy Brazilian adults who did not take supplements. They measured blood levels of folate, unmetabolized folic acid, vitamin B12 and homocysteine, and asked about diet using two 24-hour recalls.
What it can’t tell you
- This was a cross-sectional study, so it can show a link but cannot prove that folic acid intake causes higher unmetabolized folic acid levels.
- The study cannot show whether unmetabolized folic acid levels affect health, because no health outcomes were measured.
Who paid
- Funding
- Funded by Intramural CDC HHS (from the PubMed record).
- Authors work at
- University of São Paulo, Brazil; d National Center for Environmental Health, USA
The paper
- Title
- Association between Serum Unmetabolized Folic Acid Concentrations and Folic Acid from Fortified Foods
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Palchetti CZ, Paniz C, de Carli E, et al (2017). Association between Serum Unmetabolized Folic Acid Concentrations and Folic Acid from Fortified Foods. Journal of the American College of Nutrition. doi:10.1080/07315724.2017.1333929Free full textPubMed 28895788DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error