Can I take Vitamin A and Vitamin D3 together?

Possibly, but with caution. Vitamin A and Vitamin D3 have a documented caution-tier interaction. High-dose vitamin A (retinol) can antagonize vitamin D activity by competing for the shared RXR nuclear receptor.

What kind of interaction is it?

Caution: an interaction that may reduce efficacy or raise side-effect risk and warrants monitoring.

Is this interaction backed by published research?

Yes. NutriStack lists 3 citation rows for the Vitamin A + Vitamin D3 pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Interaction databaseSupplement × SupplementReviewed May 2026

Vitamin A and Vitamin D3, a caution.

Q: How does this affect a NutriStack Stack Score?

-5 to your Stack Score per scored caution row.

High-dose vitamin A (retinol) can antagonize vitamin D activity by competing for the shared RXR nuclear receptor.

3 primary source citations. Moderate evidence. Last verified May 30, 2026.

Open the interaction checker →Read the methodology

One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.

Sourcing standards·Evidence tiers

From the interaction database

What the row says.

Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.

At a glance

Substances: Vitamin A and Vitamin D3
Pair type: Caution, Synergy
Evidence (highest tier): Moderate
Source citations: 3 sources
Stack Score effect: −5 to your Stack Score (per scored caution row).
Scope: Supplement × Supplement
Last verified: May 30, 2026

Caution · Moderate evidence

Caution

What is happening. High-dose vitamin A (retinol) can antagonize vitamin D activity by competing for the shared RXR nuclear receptor.

Mechanism. Both vitamins' nuclear receptors (RAR and VDR) require RXR as a heterodimerization partner. Excess retinol saturates RXR, reducing VDR-RXR formation and D3 signaling.

Recommendation. If supplementing both, keep vitamin A under 10,000 IU and ensure adequate D3 (2000+ IU). Balanced ratios are key.

Sources (2)

Synergy · Moderate evidence

Synergy

What is happening. At balanced physiological ratios, vitamins A and D work synergistically on immune regulation and gene expression.

Mechanism. RAR-RXR and VDR-RXR heterodimers regulate overlapping gene sets. At physiological ratios, they cooperatively modulate immune cell differentiation, antimicrobial peptide expression, and Th1/Th2 balance.

Recommendation. Balanced supplementation (e.g., cod liver oil ratios) supports immune function. Avoid mega-dosing either one alone.

Sources (2)

Cannell JJ et al. On the epidemiology of influenza. Virol J. 2008
Chang MC, Choo YJ. Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis.. Nutrients. 2023. PMID 36771225

Stack Score

How this pair moves the number.

Effect on the composite score

If both Vitamin A and Vitamin D3 are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).

The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.

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