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High dietary iron increases oxidative stress and radiosensitivity in the rat retina and vasculature after exposure to fractionated gamma radiation

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This rat study, run at a space agency facility, asked whether a high-iron diet changes the retinal and vascular response to low-dose fractionated gamma radiation. The high-iron diet raised plasma and liver iron, altered the radiation response of serum antioxidant markers, and shifted oxidative-stress gene expression in retina and aorta. The motivation is that astronauts eat iron-fortified foods and accumulate body iron in flight.

Key numbers

  • Diets: 45 mg iron per kg (adequate) versus 650 mg iron per kg (high); fed 2 weeks before and throughout irradiation; n = 8 per group (Methods, p. 5; Results, p. 2). The Methods phrase the doses as “per kg body weight”, while the Results describe 650 mg iron per kg as dietary iron content.
  • Radiation: 3 Gy total from cesium-137, 37.5 cGy every other day for 8 fractions (Abstract; Methods).
  • High-iron diet raised plasma iron by 33% and liver iron by 26% relative to the adequate diet (Results, p. 2; values cited from the group’s earlier report).
  • Background stated by the authors: astronauts on the International Space Station consume 20 ± 6 mg iron per day, with intakes as high as 47 mg per day from fortified commercial foods (Introduction, p. 2).

Methods (brief)

Four-group factorial design in a tissue-sharing project. Serum antioxidant analytes, 8-OHdG immunostaining of retinal sections (n = 3 per group) and qRT-PCR panels of oxidative-stress, inflammation, cell-death and vascular-remodeling genes in retina and aorta.

Evidence fitness

Supports animal evidence that dietary iron loading increases oxidative-stress signaling and can interact with another stressor. It does not establish a human dose-response, and the high-iron diet is a supra-nutritional experimental load. Reference-intake figures quoted in the introduction are background and are not used from this paper.

Limitations

Small groups, gene-expression endpoints without functional vision outcomes, a single radiation type, and an internal inconsistency in how the diet dose is expressed. The iron status data are carried over from a companion publication rather than reported in full here.

Update history

No substantive edit history is available in this build. The full commit record is available in git.

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