Vitamin C and Increased Serum Free Thyroxine Levels

Doses used in studies

g/day: 1 (median 1, IQR 1–1) — 1 study

Time to effect

Median: 3.7 months · IQR 3.7 months–3.7 months · Range 3.7 months–3.7 months — Reported in 1 of 1 study

1 of 1 paper

Vitamin C supplementation in patients with hypothyroidism requiring high-dose levothyroxine: a proof-of-concept pilot study.

2025-10-23
RCT · n = 6
Frontiers in endocrinology 16
- Adnan Agha
- Bachar Afandi
- Javed Yasin
- Charu Sharma
- Mohammad Hamdan Alshaer
- Mouza Ali Saif Alshamsi
- Dana Ebraheim Yaaqeib
- Bayena Khamis Eshaq Alblooshi
- Juma AlKaabi

PubMed: 41210509
DOI: 10.3389/fendo.2025.1679835

2 Insights on

Increased Serum Free Thyroxine Levels

High evidence
Clinical

the vitamin C group showed greater changes in ... TSH levels (mean reduction 4.08 vs 2.35 mU/L; difference 1.73, 95% CI: -2.14 to 5.60) ... After ANCOVA adjustment for baseline values, the between-group difference remained ... marginally significant TSH (adjusted p=0.043)

Effect: Beneficial
Effect size: Moderate
Significant: Yes
Dose: 1g daily