Normal folic acid range
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Normal Folic Acid Range: An Overview
Recommended Dietary Intake of Folic Acid
Folic acid, a vital B vitamin, is essential for numerous bodily functions, including DNA synthesis and repair, and red blood cell formation. The recommended dietary intake of folic acid varies by demographic factors such as age, sex, and physiological conditions. In Europe, the recommended intake for men ranges from 200 to 300 µg/day, while for women, it ranges from 170 to 300 µg/day . However, women with a history of pregnancies affected by neural tube defects (NTDs) are advised to take 4000 µg/day of supplemental folic acid when planning subsequent pregnancies, whereas those without such a history are recommended to take 400 µg/day to prevent NTDs .
Serum Folic Acid Levels
Serum folic acid levels are a critical indicator of folate status in the body. Normal serum folic acid levels in healthy individuals typically range from 5.9 to 21.0 µg/mL, with a mean of 9.9 µg/mL . In patients with megaloblastic anemia due to folic acid deficiency, levels are usually below 4.0 µg/mL . Another study found that serum folic acid levels in control subjects ranged from 2.0 to 28.0 µg/mL, with a mean of 7.8 µg/mL .
Impact of Folic Acid Fortification
The introduction of mandatory folic acid fortification in cereal-grain products in the United States in 1998 significantly impacted serum folate levels. Post-fortification, the reference range for serum folate was found to be 13.1-74.3 nmol/L, and the prevalence of low serum folate concentrations (<6.8 nmol/L) decreased dramatically from 16% to 0.5% . This fortification has been beneficial across various segments of the population, including the elderly, who saw an increase in high serum folate concentrations (>45.3 nmol/L) from 7% to 38% .
Folic Acid Intake and Homocysteine Levels
Folic acid intake is also crucial for regulating plasma homocysteine levels, a risk factor for cardiovascular diseases. A daily dose of 650 µg of supplemental folic acid is effective in normalizing elevated plasma homocysteine levels . Studies have shown that even a low intake of 100 µg/day can significantly reduce plasma homocysteine levels in individuals with higher baseline levels .
Optimal Red Blood Cell Folate Concentration
For women of reproductive age, maintaining an optimal red blood cell (RBC) folate concentration is crucial for preventing NTDs. The threshold for optimal RBC folate concentration is estimated at 906 nmol/L . Achieving this level typically requires a steady intake of folic acid, with studies indicating that RBC folate concentrations can increase 1.78-fold from baseline with an intake of 375-570 µg/day over a median period of 36 weeks .
Conclusion
In summary, the normal range for serum folic acid levels in healthy individuals is generally between 5.9 and 21.0 µg/mL. Recommended dietary intakes vary, with specific higher doses advised for women at risk of NTDs. Folic acid fortification has significantly improved folate status in populations, and even low doses of folic acid can effectively reduce homocysteine levels. Maintaining optimal RBC folate concentrations is essential for preventing NTDs, highlighting the importance of adequate folic acid intake.
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