The purpose of this study is to investigate if B vitamin substitution have effect on NFL (neurofilament light protein) plasma levels and neurocognitive performance in HIV-infected individuals with increased plasma homocysteine

Inclusion Criteria:

1. The ability to understand and give informed consent to participate.
2. HIV-1 infected with stable ART > 12 months
3. Plasma HIV-RNA < 50 copies/ml
4. Plasma homocysteine ≥ 12 μmol/L (subjects with < 12 μmol/L will be included in the analysis of secondary endpoint 3 (see 5.4).
5. Male or female, age 18 or older.

Exclusion Criteria:

1. Treatment with trimethoprim-sulfamethoxazole or methotrexate
2. Ongoing B6, B12 or folate substitution
3. Antiepileptic treatment
4. Small bowel or ventricular resection
5. Disturbed absorption in small bowel (Mb Crohn, untreated coeliac disease)
6. Ongoing neurological disease or severe psychiatric disease
7. Any malignant tumor in the history.
8. Severe ongoing infection or opportunistic infection
9. AUDIT > 7 for men and > 5 for women
10. MADRS > 20
11. Significant B12 or folate deficiency that indicate substitution (all subjects will be offered adequate substitution, they will be included in the analysis of secondary endpoint 3 (see 5.4)).
12. Pregnancy at screening visit, or planning pregnancy during study period is an exclusion criteria. (Not due to toxicity of Triobe, but to elevated risk of being prescribed B-vitamins outside of trial. If study object gets pregnant during study, she can continue the study but must be excluded if she starts treatment with other B-vitamin treatment than Triobe.)