Iron absorption linked to autoimmune gastritis: Bryan Johnson's warning

Biohacker Bryan Johnson says he has autoimmune gastritis, which reduces stomach acid and iron absorption, explaining years of low ferritin. After oral iron failed to raise his iron stores, he’s opted for iron infusions and regular ferritin monitoring; the article notes that about 1 in 4 Americans may have insufficient iron intake or absorption, highlighting a broader public-health issue.