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Stable-isotope methods for assessment of folate bioavailability
J F Gregory1, L B Bailey, J P Toth
1Food Science and Human Nutrition Department, University of Florida, Gainesville 32611-0163.
The American Journal of Clinical Nutrition
|February 1, 1990
Summary
Stable-isotope-labeled folates can be used to study folate absorption and metabolism in humans. Deuterium-labeled folic acid forms showed equivalent absorption and metabolism, validating their use in bioavailability studies.
Area of Science:
- Biochemistry
- Human Nutrition
- Pharmacokinetics
Background:
- Folate is essential for human health, and understanding its absorption and metabolism is crucial.
- Stable-isotope-labeled compounds are valuable tools for in vivo metabolic studies.
- Previous methods for studying folate bioavailability had limitations.
Purpose of the Study:
- To evaluate the utility of stable-isotope-labeled folates for human studies.
- To assess the simultaneous in vivo use and relative bioavailability of two deuterium-labeled folic acid forms.
- To validate a protocol for in vivo folate bioavailability research.
Main Methods:
- Adult male subjects (n=11) received folic acid saturation doses prior to the study.
- Subjects consumed two deuterium-labeled folic acid forms: 3',5'-bideuterofolic acid and glutamate-tetradeuterofolic acid.
- Urinary excretion of labeled folates was measured over 48 hours to quantify relative bioavailability.
Main Results:
- Urinary excretion of deuterated folates was 5-6% of the ingested dose over 48 hours.
- The molar ratio of labeled folates in urine mirrored the ingested ratio.
- No significant difference was observed in the molar ratios, indicating equivalent absorption and metabolism.
Conclusions:
- Stable-isotope-labeled folates, specifically deuterium-labeled folic acid, are suitable for in vivo human studies.
- The developed protocol is valid for assessing folate bioavailability.
- This method allows for reliable quantification of folate absorption and metabolism.