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Head-to-head evidence comparison — which supplement is right for you?
Vitamin C wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
12 of 17 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
12 of 13 studies with measurable effects showed benefit.
Top outcomes
500-1000mg
With meals, Split doses if taking >500mg
Ascorbic acid or buffered vitamin C
20-40mg extract (standardized to 0.5% agnuside)
Morning, Consistently at same time daily
Standardized extract (0.5% agnuside or 0.6% aucubin)
Ongoing
1-2 weeks
4-8 weeks
With high doses (>2g)
1-3 cycles
2-3 cycles
1-2 cycles
Vitamin C supplementation for prevention and treatment of pneumonia
The Cochrane database of systematic reviews (2020) · Meta analysis · n=2774
We are uncertain of the effect of vitamin C supplementation on mortality due to pneumonia (RR 0.21, 95% CI 0.03 to 1.66; 1 study, 57 participants; very low-quality evidence).
Vitamin C supplementation in pregnancy
The Cochrane database of systematic reviews (2015) · Meta analysis · n=20038
Conversely, the risk of term PROM was increased when supplementation included vitamin C and vitamin E (average RR 1.73, 95% CI 1.34 to 2.23; 3060 participants; two studies; I² = 0%).
Enhanced Vitamin C Delivery: A Systematic Literature Review Assessing the Efficacy and Safety of Alternative Supplement Forms in Healthy Adults
Nutrients (2025) · Systematic review
Most studies (77%) had a low risk of bias.
Vitex agnus-castus in premenstrual syndrome: A meta-analysis of double-blind randomised controlled trials
Complementary Therapies in Medicine (2019) · Meta analysis · n=1878
Vitex significantly reduced overall PMS symptom scores vs placebo
Herbal medicine for depression and anxiety: A systematic review with assessment of potential psycho-oncologic relevance
Phytotherapy research : PTR (2018) · Systematic review
Overall, 45% of studies reported positive findings with fewer adverse effects compared with conventional medications.
A Critical Approach to Evaluating Clinical Efficacy, Adverse Events and Drug Interactions of Herbal Remedies
Phytotherapy research : PTR (2016) · Review
A critical evaluation of the clinical data regarding the adverse effects has shown that herbal remedies are generally better tolerated than synthetic medications.
Based on 3 meta-analyses of sepsis patients. One study showed RR 0.60 for mortality reduction, but another showed increased risk (RR 1.21). Evidence quality rated as low to very low. Effect limited to intravenous administration in critically ill patients.
Based on meta-analysis of RCTs showing large effect size. Most effective for irritability, mood swings, and breast tenderness. Standardized extracts (Ze 440, BNO 1095) had strongest evidence. High heterogeneity noted between studies.
AI-estimated from published studies. Interpret as directional guidance.
Vitamin C has a higher evidence score (8/10 vs 7/10) and wins in 2 of 3 categories.
No known interactions between Vitamin C and Vitex have been documented in our database. However, always consult a healthcare provider before combining supplements.