Transsulphuration

Question 1

Transsulphuration

Answer 1

Question 2

Transsulphuration cycle (CBS):
Genes

Answer 2

CBS converts homocysteine to cystathionine

Question 3

Transsulphuration cycle (CBS):
SNP

Answer 3

C669T SNP at rs234706 ↑ CBS activity = less homocysteine converted and potential ↓ SAMe. Faster conversion to ammonia (pressure on urea cycle) increasing the need for glutathione

Question 4

Transsulphuration cycle (CBS):
Recommendations

Answer 4

Increase zinc, choline and TMG (e.g., beetroot). Neutralise the ammonia (↓ animal protein, probiotics to ↓ bacterial production, supplement activated charcoal. Limit sulphur-containing foods, e.g., eggs

Question 5

Neurotransmitters
Gene

Answer 5

MTHFR essential for 5-MTHF, thus biopterin and synthesis of serotonin, dopamine, adrenaline etc. SAMe-dependent COMT breaks down dopamine, adrenaline and noradrenaline. COMT also converts active oestrogen to less active oestrogen

Question 6

Neurotransmitters
SNP

Answer 6

rs4680 ― the A allele is associated with ↓ COMT activity:

‒ AA = excessive catecholamines ― also associated ↑ oestrogen (and hence breast cancer, etc.).

‒ GG = fast metabolism of catecholamines.

Question 7

Neurotransmitters
Recommendations

Answer 7

Choline, betaine, folate and B12-rich foods support the production of SAMe. Avoid exogenous oestrogens (e.g., avoid plastic, anti-perspirants, dairy products, etc.).

Question 8

Urea cycle (eNOS):
Genes

Answer 8

eNOS is responsible for generating nitric oxide from arginine, which plays a key role as a vasodilator.

Question 9

Urea cycle (eNOS):
SNP

Answer 9

At rs1799983 the T allele is associated with ↓ eNOS activity and nitric oxide linked to slower ammonia detoxification, ↑ free radical levels and an ↑ risk of cardiovascular disease

Question 10

Urea cycle (eNOS):
Recommendations

Answer 10

– Increase antioxidants (‘rainbow of colour’).

– Moderate intake of ammonia-generating foods (↓ animal protein).

– Support NO production with L-arginine and beetroot juice