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Smoking status: not checked. Vitamin A: what these mean for you changes depending on whether you smoke or used to, and you have not told us. That check was skipped.
Head-to-head evidence comparison — which supplement is right for you?
Shiitake vs Vitamin A: Vitamin A has the stronger overall evidence (7 vs 4.5/10); they're alternatives for support immune system — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Vitamin A wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Too few graded studies
1 of 1 studies with measurable effects showed benefit.
Top outcomes
Verdict
Limited support
2 of 9 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Shiitake and Vitamin A have evidence — compare verdict strength side-by-side.
5-15g dried mushroom or 1-3g extract daily
With meals, Divided doses if using higher amounts
Shiitake extract (standardized to polysaccharides)
The appropriate advice depends on the form of vitamin A, the reason for use, age, pregnancy status and total intake from all products. SupStack has not established a self-directed dose for this held use.
With fat-containing meal, Any time of day
Mixed carotenoids or low-dose retinyl palmitate
and 2 more not shown
4 weeks
8-12 weeks
4-8 weeks
2-4 weeks
2-4 weeks
4-8 weeks
With chronic excess
Critical Review on the Anti-Tumor Activity of Bioactive Compounds from Edible and Medicinal Mushrooms over the Last Five Years
Nutrients (2025) · Review
In recent years, the incidence rate of cancer has been on the rise all over the world, and the age of cancer patients has shown a younger trend, which seriously endangers patients' health.
Vitamin B12 sources in non-animal foods: a systematic review
Critical reviews in food science and nutrition (2023) · Systematic review
In the last decade, more sensitive method for real B12 determination was used, the liquid chromatography-electrospray ionization tandem mass spectrometry chromatograms.
Anti-Cancer Potential of Edible/Medicinal Mushrooms in Breast Cancer
International journal of molecular sciences (2023) · Review
In this article, we reviewed mushrooms showing antineoplastic activity again breast cancer cells, especially focusing on the possible bioactive compounds involved and their mechanisms of action.
Effects of primary or secondary prevention with vitamin A supplementation on clinically important outcomes: a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis
BMJ open (2024) · Meta analysis · n=1671672
Vitamin A did not reduce mortality in individually randomised trials (RR 0.99, 95% CI 0.93 to 1.05; I²=32%; p=0.19; 105 trials; moderate certainty), and this effect was not affected by the risk of bias.
Vitamin and Mineral Supplementation During Pregnancy on Maternal, Birth, Child Health and Development Outcomes in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis
Nutrients (2020) · Meta analysis · n=451723
IFA supplementation showed notable improvement in maternal anemia and the reduction in low birthweight, whereas LNS supplementation had no apparent effect on outcomes; further research that compares LNS and MMN supplementation could help understand differences with these commodities.
Vitamin A supplements for reducing mother-to-child HIV transmission
The Cochrane database of systematic reviews (2017) · Meta analysis · n=7298
Five trials in Malawi, South Africa, Tanzania and Zimbabwe, none of whose participants received antiretroviral therapy. Four trials had 6995 women and one had 303.
Vitamin A has a higher evidence score (7/10 vs 4.5/10) and wins in 2 of 3 categories.
Both Shiitake and Vitamin A score equally (75) for support immune system.
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.