Supplements and Lansoprazole.
Lansoprazole, sold under the brand names Zoton, Prevacid, is a proton pump inhibitor (PPI): it suppresses gastric acid production by inhibiting the H+/K+ ATPase pump.
Lansoprazole is a proton pump inhibitor. It sits second in England's PPI prescribing volume, after omeprazole. The drug binds irreversibly to the H+/K+ ATPase in gastric parietal cells, suppressing acid secretion for around 24 hours per dose. What matters for supplement interactions is downstream. Sustained low gastric acid changes how four nutrients are absorbed. Vitamin B12 needs acid to dissociate from food protein. Magnesium drops slowly enough that hypomagnesaemia from PPI use is in NICE guidance and warrants annual electrolyte checks. Iron absorption falls, especially the non-haem iron in plant sources. And calcium has its own bone fracture signal in long observational cohorts. NICE recommends reviewing PPI indication annually and stepping down where possible. The interaction surface here is absorption, not CYP metabolism. If you have been on lansoprazole more than two years, ask for a B12 and magnesium check at your next blood draw.
Below are the 8 documented pairs we have explicitly assessed against Lansoprazole in the Distil database: 7 amber and 1 green. The pairs cluster around 1 mechanism: Absorption interference. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Last reviewed 13 June 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Absorption interference
Amber Does Calcium interact with ?
Calcium carbonate, the most common supplement form, needs stomach acid to dissolve, so lansoprazole can reduce how much calcium you absorb from it. Calcium citrate does not depend on stomach acid and is the better choice on a long-term PPI. If you stay on carbonate, taking it with food rather than on an empty stomach also helps.
Evidence: Supported by human study data.
Amber Does Iron interact with ?
Non-haem iron from supplements absorbs less well in a low-acid stomach, so chronic lansoprazole use reduces iron uptake from a standard ferrous sulphate or ferrous fumarate tablet. Iron bisglycinate is less pH-dependent and a better choice on a long-term PPI. Taking iron in the morning on an empty stomach with vitamin C also helps. Always confirm ferritin is in the deficient range before supplementing iron.
Evidence: Supported by human study data.
Amber Does Magnesium interact with ?
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Supplementing magnesium is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
Evidence: Supported by human study data.
Amber Does Magnesium Glycinate interact with ?
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Supplementing magnesium is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
Evidence: Supported by human study data.
Amber Does Magnesium L-Threonate interact with ?
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Magnesium L-threonate is still elemental magnesium, so supplementing is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
Evidence: Supported by human study data.
Amber Does Vitamin B Complex interact with ?
A B complex contains vitamin B12, and long-term lansoprazole use reduces stomach acid and slows how well your body absorbs B12 from food. After about two years of daily use, B12 deficiency becomes notably more likely, and a standard B complex dose may not fully offset it. If you take lansoprazole long term, ask your GP about an annual B12 blood test.
Evidence: Supported by human study data.
Amber Does Vitamin B12 interact with ?
Long-term lansoprazole use reduces stomach acid and slows how well your body absorbs vitamin B12 from food. After about two years of daily use, B12 deficiency becomes notably more likely. If you take lansoprazole long term, ask your GP about an annual B12 blood test.
Evidence: Supported by human study data.
Green Does Vitamin C interact with ?
Vitamin C and lansoprazole are worth knowing about rather than a problem. Vitamin C is less stable when the stomach is less acidic, and acid-lowering medicines like lansoprazole modestly reduce the amount of vitamin C in your blood. The drop is small, it is the medicine affecting the vitamin rather than the other way round, and it does not stop you taking a vitamin C supplement. If anything, people on long-term acid-lowering treatment are the ones who may benefit most from keeping a good vitamin C intake.
Evidence: Supported by human study data.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
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How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyA full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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