Folic acid from fortified foods and unmetabolized folic acid in people
What it found
In 144 healthy Brazilian adults, higher folic acid intake from fortified foods was linked to more unmetabolized folic acid in the blood.
Women had higher levels of unmetabolized folic acid than men.
What they found
Studies in people
Fortified foods and blood levels
Unmetabolized folic acid in the blood rose as folic acid intake from fortified foods increased. People in the highest group for this blood marker ate more folic acid and less choline, methionine, and vitamin B6 than those in the lowest group.
Differences between women and men
Women had higher blood levels of both total folate and unmetabolized folic acid compared to men. Being male was linked to lower odds of having higher levels of unmetabolized folic acid in the blood.
Amounts from fortified foods
Folic acid added to fortified foods made up almost half (48.4%) of all the folate these participants took in through their diet. No one in the group took in more than the upper limit of 1 mg per day for folic acid.
Folate deficiency still present
Even with mandatory fortification, 10 out of 144 participants (6.9%) had low folate levels in their blood. Eight of those 10 were men. No one lacked vitamin B12.
What the authors conclude
- They conclude that unmetabolized folic acid in the blood is directly linked to how much folic acid people get from fortified foods.
- They suggest that other nutrients like choline, methionine, and vitamin B6 might also play a role in how the body handles folic acid, but this needs more research.
How it was done
Brazil requires wheat and maize flour to be fortified with folic acid to help prevent birth defects. The authors wanted to see how much unprocessed folic acid builds up in the blood of people eating these fortified foods.
They measured blood levels and tracked the diets of 144 healthy adults in São Paulo who did not take vitamin supplements. Participants recalled everything they ate on two separate days, about 45 days apart. Blood samples were taken after an overnight fast of at least 8 hours.
What it can’t tell you
- Because this study looked at people at a single point in time, it can only show a link between fortified food intake and blood levels, not prove one causes the other.
- The group was small and recruited by convenience in one city, so the results may not reflect what happens in the wider population.
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 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error