Iron & oxygen carriage
Anemia↓
Also searched as Anemia.
You want it high: enough oxygen-carrying capacity means blood that can actually deliver what you breathe in.
In depth
How well your blood carries oxygen. It drops (anemia) most often from low iron, sometimes from low B12 or folate, and sometimes because inflammation locks away the iron you already have. The cause matters more than the number.
What drives it
Iron status increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Iron gatekeeper hormone reduces it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Kidney increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Tissue renewal increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Calms body-wide inflammation reduces it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Inflammation signal (IL-6) reduces it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Micronutrient status increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Digestion increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Gut barrier increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Gum health increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Liver increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Women's hormone balance increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Oxidative stress reduces it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts. PMID 835510 · PMC7005133
Physical performance increases it.
The mechanism that makes iron supplementation fail: anemia of inflammation is characterized by the insufficient production of erythropoietin and decreased response of erythroid progenitors to EPO. In addition, it inhibits the release of iron from the body stores and alters the iron status after being stimulated by hepcidin. Inflammation locks iron away - so oral iron given into an inflammatory state does not reach the marrow. Anemia affects 1.62 billion people. And the periodontal link is measured: a meta-analysis of sixteen studies on hemoglobin and iron metabolism in periodontitis - though the authors call the association still controversial and ask for larger cohorts (PMC7005133; PMID 835510). REFUTED ON A SECOND READING. This link was shown by linked steps until a source was opened that does not support it: “Endurance training and sex did not affect Hb FSR.” — Hemoglobin synthesis rates in young trained and untrained males and females are not different. Physiological Reports, 2025, 13(8). doi 10.14814/phy2.70311 · PMID 835510 · PMC7005133
What it drives
It increases Resists infection.
The headline on this pathway is a disappointment and it must stay there: the lack of effect of prophylactic vitamin C supplementation on the incidence of common cold in normal populations throws doubt on the utility of this wide practice. Regular supplementation decreases cold duration by 8 percent (3-12) and severity by 15 percent (CI 9-21) - but does not reduce how often you get one. With one striking exception that defines WHO it works for: a subgroup of six studies of marathon runners, skiers, and soldiers exposed to significant cold AND/OR physical stress experienced, on average, 50 percent reduction in common cold incidence. Extreme physical stress is the condition under which it prevents. (PMC10712193; PMC7356429; PMC1160577). REFUTED ON A SECOND READING. This link was shown by linked steps until a source was opened that does not support it: “such individuals therefore have an increased susceptibility to a variety of infectious diseases || Such an approach may be beneficial in treating infectious diseases that are exacerbated by iron supplementation. || to limit iron availability to invading microbes in a process termed nutritional immunity” — Iron in Infection and Immunity. Cell Host & Microbe, 2013, 13(5), 509-519. doi 10.1016/j.chom.2013.04.010 · PMID 23684303 · PMC10712193
It reduces Daily energy.
10.3390/nu13114008 — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.3390/nu13114008
It increases Physical performance.
10.1371/journal.pone.0001920 — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.1371/journal.pone.0001920
It increases Memory & focus.
10.3390/brainsci11060777 — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.3390/brainsci11060777
It increases Cardiac output.
10.3389/fcvm.2022.856246 — https://www.merckmanuals.com/professional/cardiovascular-disorders/heart-failure/heart-failure-hf — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.3389/fcvm.2022.856246
It increases Mood.
This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). Sources: PMID 29626044; PMC9745472; doi 10.1017/S0007114517000691. doi 10.1017/S0007114517000691 · PMID 29626044 · PMC9745472
It increases Hair.
10.21608/efmj.2018.67528 — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.21608/efmj.2018.67528
It increases Immune balance.
10.26641/2307-0404.2025.4.348337 — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.26641/2307-0404.2025.4.348337
It increases Recovery.
10.1371/journal.pone.0334499 — This link rests on the reviews of this outcome as a whole. No effect size specific to this arm has been reported, so it is shown at reduced weight. (from the reviews of this outcome). doi 10.1371/journal.pone.0334499
It increases Nails.
10.1186/s13256-021-03024-9 — Drawn from reviews of neighboring outcomes rather than from studies of this outcome itself, which is weaker evidence, and the map marks it so. doi 10.1186/s13256-021-03024-9
It increases Body temperature control.
10.3390/jfmk10030362 — Drawn from reviews of neighboring outcomes rather than from studies of this outcome itself, which is weaker evidence, and the map marks it so. doi 10.3390/jfmk10030362
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.