Vitamin B9 (Folic Acid)

VITAMIN B9 (FOLIC ACID)

• Folic acid present in leafy vegetables.
• Absorbed from upper part of jejunum.
• Active form of folic acid is Tetra Hydro Folic Acid (THFA)
• THF serves as a carrier of one-carbon (C₁) unit during several biosynthetic reactions like nucleic acid and amino acid metabolism.
• THF acts as a carrier of one carbon unit.
• Folic acid is necessary in pregnancy (first trimester). 

Sources of one carbon groups-

• The major point of entry of one carbon unit is Methylene THF.
• Serine is the most important source of one carbon units
• Serine Hydroxyl Methyl Transferase is the enzyme involved in pathway.
• Major circulating form of folic acid- methyl THF.
• As an acceptor of one carbon unit from various donors-

1. Serine to glycine conversion
2. Histidine breakdown

• As a donor of one carbon unit to various acceptors-  Conversion of glycine to serine
• 5-formyl –tetrahydrofolate is more stable and is used pharmaceutically.

 Biochemical assessment of folate deficiency-

1. Blood level- normal level in serum is about 2-20 nanogram/ml
2. Histidine load test or FIGLU excretion test
3. AICAR excretion (amino imidazole carboxamide ribose 5 phosphate)
4. Peripheral blood picture– tear drop shaped cells 

Vitamin B9 deficiency-

Clinical manifestations-

1. Reduced DNA synthesis
2. Megaloblastic anaemia
3. Homocysteinemia
4. Neural bifida spina
5. Folic acid and vitamin B, supplementation in megaloblastic anemia leads to improvement by increased DNA synthesis in bone marrow cells.
6. Cancer
7. Glossitis

•  Daily dosage of Folic acid per day-

• Healthy adults          200 mcg
• Pregnancy                500 mcg
• Lactation                  300 mcg
• Children                   80-120 mcg

• Absorbed from upper part of jejunum.
• Active form of folic acid is Tetra Hydro Folic Acid (THFA)
• THF serves as a carrier of one-carbon (C₁) unit during several biosynthetic reactions like nucleic acid and amino acid metabolism.
• THF acts as a carrier of one carbon unit.

 Sources of one carbon groups-

• The major point of entry of one carbon unit is Methylene THF.
• Serine is the most important source of one carbon units
• Serine Hydroxyl Methyl Transferase is the enzyme involved in pathway.
• Major circulating form of folic acid- methyl THF.
• As an acceptor of one carbon unit from various donors-

1. Serine to glycine conversion
2. Histidine breakdown

• As a donor of one carbon unit to various acceptors-

1. Conversion of glycine to serine

• 5-formyl –tetrahydrofolate is more stable and is used pharmaceutically.

Biochemical assessment of folate deficiency-

1. Blood level- normal level in serum is about 2-20 nanogram/ml
2. Histidine load test or FIGLU excretion test
3. AICAR excretion (amino imidazole carboxamide ribose 5 phosphate)
4. Peripheral blood picture

• Deficiency- megaloblastic ananemia