Serum Folate
Serum folate reflects short-term folate intake from diet, supplements, and folic acid fortification. Across US males aged 30 to 39, the median serum total folate in NHANES 2017-March 2020 is 12.4 ng/mL.
Unit: ng/mL · 12 slices · age and sex · 1 source
Filed under panels: Vitamins · topics: Nutrition
Serum folate is the standard short-term marker of folate status, reflecting intake over the preceding days. NHANES measures total serum folate by liquid chromatography mass spectrometry as the sum of individual folate forms (5-methyltetrahydrofolate, folic acid, and other species). RBC folate is a more stable longer-term marker and is reported separately. Folate measurements use the NHANES pre-pandemic folate subsample weight WTFOLPRP applied directly.
Population Distribution
Browse by Demographic
| Age (years) | male (ng/mL) | female (ng/mL) |
|---|---|---|
| 20-29 | 6.2–23.3 (12.3) | 5.4–30.0 (13.7) |
| 30-39 | 5.2–26.8 (12.4) | 6.2–39.1 (14.9) |
| 40-49 | 6.2–26.2 (13.5) | 5.6–37.2 (14.4) |
| 50-59 | 5.2–35.1 (14.6) | 6.9–39.0 (16.6) |
| 60-69 | 7.6–35.3 (17.1) | 6.1–50.9 (18.6) |
| 70+ | 7.5–53.5 (20.9) | 7.7–53.9 (22.6) |
Frequently Asked Questions
How does serum folate differ from RBC folate?
Serum folate reflects recent intake (days), while RBC folate reflects status over the preceding 2-3 months because folate is incorporated into red cells during their formation. Both are reported separately on this site.
Why is the left tail of the population distribution narrow?
The US food supply has been fortified with folic acid since 1998, which lifted the left side of the population distribution compared with pre-fortification cohorts. The shape of the distribution shown here reflects the post-fortification US adult population.
Why does the distribution differ between males and females?
Reproductive-age women are more likely to take supplements containing folic acid, which raises serum folate. The age and sex slices on this page reflect that pattern in the population data.