Which vitamin is necessary for the conversion of tryptophan to niacin and is also involved in the metabolism of homocysteine?

A Vitamin C
B Vitamin B2
C Vitamin B6
D Vitamin B9 ✓

Explanation

Vitamin B9, also known as folate, is necessary for the conversion of tryptophan to niacin and is also involved in the metabolism of homocysteine, an amino acid that is associated with an increased risk of cardiovascular disease.

Mnemonic

Folate = For Homocysteine → regulates homocysteine levels

Source

Harper's Biochemistry
Vitamins Biochemistry Folate metabolism Hard MEDICAL Confidence: medium