Which three nutrients have studies shown to reduce plasma homocysteine concentrations?

Which three nutrients have studies shown to reduce plasma homocysteine concentrations?

• A. Folic acid; Vitamin B6; Vitamin B12
• B. Folic acid; Vitamin C; Vitamin D
• C. Vitamin B6; Vitamin B12; Vitamin E
• D. Folic acid; Niacin; Thiamine

Answer: (A)

The key idea is how homocysteine is processed in the body. Homocysteine levels in the blood are lowered when the two main metabolic pathways that handle it are well supported by vitamins that act as cofactors. One pathway remethylates homocysteine to methionine and needs folate (as 5-methyltetrahydrofolate) with vitamin B12 as a cofactor. The other pathway directs homocysteine into cysteine production (transsulfuration) and requires vitamin B6 as a cofactor. When folate, B6, and B12 are adequately available, both routes function efficiently, pulling homocysteine down into downstream products and lowering its plasma concentration. Studies consistently show that supplying folic acid together with vitamins B6 and B12 reduces plasma homocysteine levels. The other listed vitamins don’t have a direct critical role in these metabolic steps, so they don’t produce the same effect on homocysteine.

The key idea is how homocysteine is processed in the body. Homocysteine levels in the blood are lowered when the two main metabolic pathways that handle it are well supported by vitamins that act as cofactors. One pathway remethylates homocysteine to methionine and needs folate (as 5-methyltetrahydrofolate) with vitamin B12 as a cofactor. The other pathway directs homocysteine into cysteine production (transsulfuration) and requires vitamin B6 as a cofactor. When folate, B6, and B12 are adequately available, both routes function efficiently, pulling homocysteine down into downstream products and lowering its plasma concentration. Studies consistently show that supplying folic acid together with vitamins B6 and B12 reduces plasma homocysteine levels. The other listed vitamins don’t have a direct critical role in these metabolic steps, so they don’t produce the same effect on homocysteine.