Check your supplement stack
for interactions.
See what competes, what combines well, and when to take everything. Built for people who take their stack seriously.
Stack
6 supplements
Stack review
1 flagZinc and Iron compete for the same absorption pathway. Take at least 2 hours apart.
Supplements
You're probably taking something wrong.
Zinc blocks iron. Calcium competes with magnesium. Your morning stack might be cancelling itself out. OnDose checks every combination against published research.
Both use the same transporter. Taking them together can cut absorption by up to 50%.
Vitamin C converts iron into a form your gut absorbs more easily. Pair them.
High doses compete for the same pathway. Separate by at least 2 hours.
K2 directs the calcium that D3 helps absorb. They work better together.
350+
Compounds
covered
100+
Interactions
checked
37K+
Barcodes
indexed
100%
Every source
cited
Stay on dose.
OnDose builds your daily schedule based on absorption science so you don't have to think about it.
Absorption windows
Grouped by when and how your body absorbs each supplement.
Food requirements
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Conflict separation
Competing supplements placed in different timing windows.
Good morning.
4 this morning, 3 this evening.
Morning
5000 IU
2 x 1000 mg Softgels
18 mg · Empty stomach
15 mg
Evening
400 mg
600 mg
100 mcg
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Vitamin D3 + K2 Complex
Sports Research
Softgel · 1 Softgel
4 active ingredients
From the blog
Research worth reading.
Zinc and iron: why timing matters more than you think
Both minerals use the same absorption pathway. Taking them together can cut absorption by up to 50%. Here's what the research says and what you can do about it.
Magnesium and vitamin D: why they need each other
Vitamin D gets all the attention. But without enough magnesium, your body can't activate it. Here's how the two nutrients depend on each other.
Ashwagandha and thyroid medication: what the research says
Ashwagandha can raise T3 and T4 levels. If you take levothyroxine or other thyroid medication, this interaction is clinically meaningful. Here's what the research shows and when to talk to your doctor.
The beginner stack: 5 supplements that actually have evidence
Vitamin D3, magnesium, omega-3, vitamin K2, and creatine. Five supplements with decades of research, widespread deficiency data, and a clear reason to exist. What to take, how much, and when.
You spent hours choosing
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they work together.
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350+
Supplements
100+
Interactions
Every
Source cited
Stack
6 supplements
Stack review
1 flagZinc and Iron compete for the same absorption pathway. Take at least 2 hours apart.
Supplements