What is a supplement-to-supplement interaction?

A supplement-to-supplement interaction occurs when two vitamins, minerals, or herbs affect each other's absorption, metabolism, or effectiveness. For example, calcium blocks iron absorption, while vitamin C enhances it. These are different from drug interactions — they happen between nutritional supplements you take daily.

Is this a drug interaction checker?

No. NutriAudit's Supplement Interactions Checker focuses on supplement-to-supplement interactions — how vitamins, minerals, and herbs interact with each other. Drug interaction checkers (like Drugs.com) check how medications interact, but miss how your daily supplements affect each other.

What are the most dangerous supplement interactions?

High-risk supplement interactions include: Iron + Zinc (compete for absorption), Calcium + Iron (calcium blocks iron absorption), Zinc + Copper (high zinc depletes copper), Vitamin E + Vitamin K (may interfere with clotting), and St. John's Wort + Antidepressants (risk of serotonin syndrome).

How do I avoid supplement interactions?

Space competing supplements 2+ hours apart, follow recommended ratios (e.g., Calcium:Magnesium ~2:1, Zinc:Copper ~10:1), and use a supplement stack safety checker like NutriAudit to analyze all your supplements together for interactions, overlaps, and safe dosages.

What supplements should not be taken together?

Common supplements that should not be taken at the same time include: Calcium and Iron (calcium blocks iron absorption), Zinc and Iron (compete for absorption), Zinc and Copper (high zinc reduces copper absorption), and Vitamin E and Vitamin K (interference with clotting). Space these 2+ hours apart.

Supplement Interactions Checker — Supplement-to-Supplement Interaction Tool

What Is a Supplement Interactions Checker?

A supplement interactions checker is an online tool that detects interactions between two or more vitamins, minerals, or herbal supplements. Unlike drug interaction checkers (such as Drugs.com), NutriAudit focuses specifically on supplement-to-supplement interactions — for example, calcium blocks iron absorption, high-dose zinc depletes copper, and vitamin D3 and K2 work synergistically for bone health. NutriAudit covers 25+ known interaction pairs with dosage and timing guidance from 5 regional safety standards (US FDA, EU EFSA, AU TGA, CN CNS, JP MHLW).

How Supplement Interactions Work

Supplement interactions occur when two or more ingredients affect each other's absorption, metabolism, or effectiveness. These can be negative (reducing absorption or causing side effects) or positive (enhancing benefits when taken together).

Types of Interactions

Absorption Inhibition — One ingredient blocks or reduces the absorption of another (e.g., Calcium reduces Iron absorption)
Competition — Two minerals compete for the same absorption pathway (e.g., Iron and Zinc)
Ratio Imbalance — Optimal ratios between nutrients are disrupted (e.g., Calcium:Magnesium should be ~2:1)
Side Effects — Combining certain supplements increases risk of adverse effects

Common High-Risk Interactions

Iron + Zinc — compete for absorption; take separately
Calcium + Iron — calcium blocks iron absorption; space 2+ hours apart
Vitamin E + Vitamin K — high-dose Vitamin E may interfere with Vitamin K clotting function
St. John's Wort + Antidepressants — risk of serotonin syndrome

Supplement Interactions Checker

Taking Multiple Supplements?

What Is a Supplement Interactions Checker?

How Supplement Interactions Work

Types of Interactions

Common High-Risk Interactions

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