Intestinal copper absorption

evidence_span

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experimental_model

Controlled copper intake and stable-isotope balance study

exposure

Twelve men; 0.7, 1.6 or 6 mg/day intake periods with an oral 3 mg isotope challenge

limitations

The isotope challenge was the same at each dietary background. Similar fractional absorption under this test does not mean copper absorption is invariant at every dose.

nutrient_topic

Copper research collection; topical membership is not evidence of a direct dietary effect. · Copper

organism

Human men

plain_language

In this experiment, excretion changed more clearly than the measured absorption fraction.

primary_references

[copper-p12844388] Adaptive responses in men fed low- and high-copper diets. (2003). https://pubmed.ncbi.nlm.nih.gov/12844388/ DOI: 10.1079/bjn2003887

tissue_or_cell_type

Whole-body copper handling

Copper: transport, cuproenzymes, deficiency, excess and nutrient interactions (2026-09-17) · lines 1378–1389

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Controlled copper intake and stable-isotope balance study · source_derived_draft · unverified_draft

### copper-copper-absorption-adaptation True fractional copper absorption after the standardized tracer dose was about 48% at both low and high background intakes, without a significant difference. Condition category: normal nutrient_topic: Copper research collection; topical membership is not evidence of a direct dietary effect. plain_language: In this experiment, excretion changed more clearly than the measured absorption fraction. organism: Human men tissue_or_cell_type: Whole-body copper handling experimental_model: Controlled copper intake and stable-isotope balance study limitations: The isotope challenge was the same at each dietary background. Similar fractional absorption under this test does not mean copper absorption is invariant at every dose. exposure: Twelve men; 0.7, 1.6 or 6 mg/day intake periods with an oral 3 mg isotope challenge evidence_span: {"source_cache": "artifacts/copper-research/12844388.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "5b6c40ba96ca6bba0b6d377caf643f3aebba366919c889e2e8f10be4b23a0def", "start_char": 0, "end_char": 1336, "text_sha256": "5b6c40ba96ca6bba0b6d377caf643f3aebba366919c889e2e8f10be4b23a0def"} [copper-p12844388] Adaptive responses in men fed low- and high-copper diets. (2003). https://pubmed.ncbi.nlm.nih.gov/12844388/ DOI: 10.1079/bjn2003887

availability_state

nutrient_deficiency Imported condition classification; unverified.

evidence_span

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experimental_model

Factorial dietary copper, iron and ascorbate feeding experiment

exposure

Copper 0.42 versus 5.74 micrograms/g diet; iron 38 versus 191 micrograms/g; ascorbate 0 versus 1%, for 20 days

limitations

Animal feed concentrations cannot be converted into a human supplement rule. Baseline copper status modified effects.

nutrient_topic

Copper research collection; topical membership is not evidence of a direct dietary effect. · Copper

organism

Rat

plain_language

The same iron exposure had different effects depending on the starting copper supply.

primary_references

[copper-p3337044] Adverse effects of high dietary iron and ascorbic acid on copper status in copper-deficient and copper-adequate rats. (1988). https://pubmed.ncbi.nlm.nih.gov/3337044/ DOI: 10.1093/ajcn/47.1.96

tissue_or_cell_type

Intestinal uptake, blood and tissues

trigger_kind

nutrient_deficiency Imported condition classification; unverified.

Copper: transport, cuproenzymes, deficiency, excess and nutrient interactions (2026-09-17) · lines 1144–1155

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Factorial dietary copper, iron and ascorbate feeding experiment · source_derived_draft · unverified_draft

### copper-iron-lowcu-absorption High dietary iron reduced copper absorption in copper-deficient rats but not in copper-adequate rats in the factorial study. Condition category: nutrient_deficiency nutrient_topic: Copper research collection; topical membership is not evidence of a direct dietary effect. plain_language: The same iron exposure had different effects depending on the starting copper supply. organism: Rat tissue_or_cell_type: Intestinal uptake, blood and tissues experimental_model: Factorial dietary copper, iron and ascorbate feeding experiment limitations: Animal feed concentrations cannot be converted into a human supplement rule. Baseline copper status modified effects. exposure: Copper 0.42 versus 5.74 micrograms/g diet; iron 38 versus 191 micrograms/g; ascorbate 0 versus 1%, for 20 days evidence_span: {"source_cache": "artifacts/copper-research/3337044.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2302118b1dad186fdee87512abf58f47a36d430e329057c87b24e57e52e331cc", "start_char": 0, "end_char": 882, "text_sha256": "2302118b1dad186fdee87512abf58f47a36d430e329057c87b24e57e52e331cc"} [copper-p3337044] Adverse effects of high dietary iron and ascorbic acid on copper status in copper-deficient and copper-adequate rats. (1988). https://pubmed.ncbi.nlm.nih.gov/3337044/ DOI: 10.1093/ajcn/47.1.96

cross_nutrient

Copper (affected_nutrient)

evidence_span

{"source_cache": "artifacts/zinc-signaling-sources/3968585-abstract.txt", "locator": "Primary indexed abstract", "file_sha256": "ca588cec5326d23dd5f8c9b409ea66fc415043b95af456399e495b8131c8f6ed"}

experimental_model

Isolated vascularly perfused intestine from diet-conditioned rats

exposure

Dietary copper/zinc variation for one week versus direct luminal-metal variation.

limitations

Ex-vivo perfusion and extreme luminal exposure differ from whole-animal feeding; increased metallothionein-bound copper alone did not prove reduced net absorption.

nutrient_topic

Zinc research collection; topical membership is not evidence of a direct dietary effect. · Zinc

organism

Rattus norvegicus

plain_language

At high luminal exposure, copper entry or transfer was inhibited.

primary_references

[zn-sig-3968585] Copper and zinc absorption in the rat: mechanism of mutual antagonism. (1985). https://pubmed.ncbi.nlm.nih.gov/3968585/ DOI: 10.1093/jn/115.2.159

tissue_or_cell_type

Small-intestinal mucosa and portal effluent

Zinc: transport, enzyme loading, deficiency and nutrient interactions (2026-09-17) · lines 957–969

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Isolated vascularly perfused intestine from diet-conditioned rats · source_derived_draft · unverified_draft

### zn-sig-luminal-zinc-copper High luminal zinc reduced both mucosal cytosolic copper and copper transfer into portal effluent in the perfused-rat-intestine experiments. Condition category: normal nutrient_topic: Zinc research collection; topical membership is not evidence of a direct dietary effect. plain_language: At high luminal exposure, copper entry or transfer was inhibited. organism: Rattus norvegicus tissue_or_cell_type: Small-intestinal mucosa and portal effluent experimental_model: Isolated vascularly perfused intestine from diet-conditioned rats limitations: Ex-vivo perfusion and extreme luminal exposure differ from whole-animal feeding; increased metallothionein-bound copper alone did not prove reduced net absorption. exposure: Dietary copper/zinc variation for one week versus direct luminal-metal variation. cross_nutrient: Copper (affected_nutrient) evidence_span: {"source_cache": "artifacts/zinc-signaling-sources/3968585-abstract.txt", "locator": "Primary indexed abstract", "file_sha256": "ca588cec5326d23dd5f8c9b409ea66fc415043b95af456399e495b8131c8f6ed"} [zn-sig-3968585] Copper and zinc absorption in the rat: mechanism of mutual antagonism. (1985). https://pubmed.ncbi.nlm.nih.gov/3968585/ DOI: 10.1093/jn/115.2.159

cross_nutrient

Copper (affected_nutrient); Intestinal mucosal copper retention (increased_endpoint)

evidence_span

{"source_cache": "artifacts/zinc-signaling-sources/479878-abstract.txt", "locator": "Primary indexed abstract", "file_sha256": "643b0358984f3caac8a20e3202c14a073d11ff88758c7a9637b6f8523195658b"}

experimental_model

Dietary radiotracer experiments in rats

exposure

High dietary zinc or copper and reciprocal 64Cu/65Zn absorption measurements.

limitations

High animal dietary concentrations are not human intake thresholds. Copper displacement from metallothionein was the authors’ mechanistic interpretation.

nutrient_topic

Zinc research collection; topical membership is not evidence of a direct dietary effect. · Zinc

organism

Rattus norvegicus

plain_language

Very high zinc trapped more copper in the intestine while less was absorbed.

primary_references

[zn-sig-479878] Intestinal metallothionein and the mutual antagonism between copper and zinc in the rat. (1979). https://pubmed.ncbi.nlm.nih.gov/479878/ DOI: 10.1016/s0162-0134(00)80054-9

tissue_or_cell_type

Small intestine

Zinc: transport, enzyme loading, deficiency and nutrient interactions (2026-09-17) · lines 901–913

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Dietary radiotracer experiments in rats · source_derived_draft · unverified_draft

### zn-sig-zinc-copper-absorption Rat diets with zinc up to 450 mg/kg did not change 64Cu absorption; 900 mg/kg reduced it by about 40% and increased mucosal 64Cu uptake. Condition category: normal nutrient_topic: Zinc research collection; topical membership is not evidence of a direct dietary effect. plain_language: Very high zinc trapped more copper in the intestine while less was absorbed. organism: Rattus norvegicus tissue_or_cell_type: Small intestine experimental_model: Dietary radiotracer experiments in rats limitations: High animal dietary concentrations are not human intake thresholds. Copper displacement from metallothionein was the authors’ mechanistic interpretation. exposure: High dietary zinc or copper and reciprocal 64Cu/65Zn absorption measurements. cross_nutrient: Copper (affected_nutrient); Intestinal mucosal copper retention (increased_endpoint) evidence_span: {"source_cache": "artifacts/zinc-signaling-sources/479878-abstract.txt", "locator": "Primary indexed abstract", "file_sha256": "643b0358984f3caac8a20e3202c14a073d11ff88758c7a9637b6f8523195658b"} [zn-sig-479878] Intestinal metallothionein and the mutual antagonism between copper and zinc in the rat. (1979). https://pubmed.ncbi.nlm.nih.gov/479878/ DOI: 10.1016/s0162-0134(00)80054-9

availability_state

biomarker_context Imported condition classification; unverified.

evidence_span

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experimental_model

Controlled sequential dietary vitamin C intervention

exposure

Fourteen-week feeding study: 65, 5, 605 and 5 mg vitamin C/day in successive periods

limitations

Short sequential study; ceruloplasmin activity differs from protein concentration and whole-body copper stores. No universal vitamin C threshold is established.

nutrient_topic

Copper research collection; topical membership is not evidence of a direct dietary effect. · Copper

organism

Human men

plain_language

The activity change did not demonstrate loss of body copper.

primary_references

[copper-p3694287] Effect of varying ascorbic acid intakes on copper absorption and ceruloplasmin levels of young men. (1987). https://pubmed.ncbi.nlm.nih.gov/3694287/ DOI: 10.1093/jn/117.12.2109

tissue_or_cell_type

Copper absorption, retention and circulating markers

trigger_kind

biomarker_context Imported condition classification; unverified.

Copper: transport, cuproenzymes, deficiency, excess and nutrient interactions (2026-09-17) · lines 1118–1129

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Controlled sequential dietary vitamin C intervention · source_derived_draft · unverified_draft

### copper-ascorbate-copper-retention The study found no significant vitamin-C-period effect on copper absorption, retention, serum copper or ceruloplasmin protein despite the oxidase-activity change. Condition category: biomarker_context nutrient_topic: Copper research collection; topical membership is not evidence of a direct dietary effect. plain_language: The activity change did not demonstrate loss of body copper. organism: Human men tissue_or_cell_type: Copper absorption, retention and circulating markers experimental_model: Controlled sequential dietary vitamin C intervention limitations: Short sequential study; ceruloplasmin activity differs from protein concentration and whole-body copper stores. No universal vitamin C threshold is established. exposure: Fourteen-week feeding study: 65, 5, 605 and 5 mg vitamin C/day in successive periods evidence_span: {"source_cache": "artifacts/copper-research/3694287.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "37e70fcbc672023cd6c3616b4a1171c6ded4caafe4e3c14d4f80c6abca490e68", "start_char": 0, "end_char": 1031, "text_sha256": "37e70fcbc672023cd6c3616b4a1171c6ded4caafe4e3c14d4f80c6abca490e68"} [copper-p3694287] Effect of varying ascorbic acid intakes on copper absorption and ceruloplasmin levels of young men. (1987). https://pubmed.ncbi.nlm.nih.gov/3694287/ DOI: 10.1093/jn/117.12.2109

cross_nutrient

Copper (affected_nutrient); Intestinal copper absorption (unchanged_endpoint); Rat intestinal metallothioneins measured without isoform resolution (binding_proteins)

evidence_span

{"source_cache": "artifacts/zinc-signaling-sources/3968585-abstract.txt", "locator": "Primary indexed abstract", "file_sha256": "ca588cec5326d23dd5f8c9b409ea66fc415043b95af456399e495b8131c8f6ed"}

experimental_model

Isolated vascularly perfused intestine from diet-conditioned rats

exposure

Dietary copper/zinc variation for one week versus direct luminal-metal variation.

limitations

Ex-vivo perfusion and extreme luminal exposure differ from whole-animal feeding; increased metallothionein-bound copper alone did not prove reduced net absorption.

nutrient_topic

Zinc research collection; topical membership is not evidence of a direct dietary effect. · Zinc

organism

Rattus norvegicus

plain_language

More copper on a binding protein did not always mean less copper absorption.

primary_references

[zn-sig-3968585] Copper and zinc absorption in the rat: mechanism of mutual antagonism. (1985). https://pubmed.ncbi.nlm.nih.gov/3968585/ DOI: 10.1093/jn/115.2.159

tissue_or_cell_type

Small-intestinal mucosa and portal effluent

Zinc: transport, enzyme loading, deficiency and nutrient interactions (2026-09-17) · lines 943–955

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Isolated vascularly perfused intestine from diet-conditioned rats · source_derived_draft · unverified_draft

### zn-sig-mt-binding-not-absorption After the tested dietary conditioning, high zinc increased metallothionein-bound copper without changing intracellular copper concentration or significantly altering measured copper absorption in the perfused intestine. Condition category: normal nutrient_topic: Zinc research collection; topical membership is not evidence of a direct dietary effect. plain_language: More copper on a binding protein did not always mean less copper absorption. organism: Rattus norvegicus tissue_or_cell_type: Small-intestinal mucosa and portal effluent experimental_model: Isolated vascularly perfused intestine from diet-conditioned rats limitations: Ex-vivo perfusion and extreme luminal exposure differ from whole-animal feeding; increased metallothionein-bound copper alone did not prove reduced net absorption. exposure: Dietary copper/zinc variation for one week versus direct luminal-metal variation. cross_nutrient: Copper (affected_nutrient); Intestinal copper absorption (unchanged_endpoint); Rat intestinal metallothioneins measured without isoform resolution (binding_proteins) evidence_span: {"source_cache": "artifacts/zinc-signaling-sources/3968585-abstract.txt", "locator": "Primary indexed abstract", "file_sha256": "ca588cec5326d23dd5f8c9b409ea66fc415043b95af456399e495b8131c8f6ed"} [zn-sig-3968585] Copper and zinc absorption in the rat: mechanism of mutual antagonism. (1985). https://pubmed.ncbi.nlm.nih.gov/3968585/ DOI: 10.1093/jn/115.2.159