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Hot on the heels of a recently published genomic study correlating blood iron levels with healthy aging, more research is suggesting high systemic iron levels can be linked with reduced life expectancy. The current research does not prove a causal relationship between high iron levels and shorter lifespans, but it does support advice recommending iron supplementation is only necessary in people with a diagnosed iron deficiency.

The new study builds on a growing body of research linking irregular systemic iron levels with a number of different diseases. The majority of prior study on the topic has been epidemiological, highlighting correlation but not demonstrating causation. The new research deployed an increasingly popular statistical technique called Mendelian randomization, designed to better investigate possible causal connections in observational studies.

The researchers first investigated genetic data from 48,972 subjects to find correlations between gene variants and systemic iron levels. Three specific gene variants were implicated in abnormal systemic iron homeostasis.

The researchers then looked at a much larger genomic dataset, encompassing over one million subjects, to measure the association between these genetic markers and overall life expectancy. The results revealed a consistent association between reduced life expectancy and a genetic predisposition to higher iron levels.

“We have known for a long time that having too much or too little iron in your system can have serious impacts on your health, and that effectively modifying iron levels can help many people with underlying conditions,” says Dipender Gill from Imperial College London, and supervisor on the research. “Our findings build on previous work to clarify that picture further, showing that people who have genetic predisposition to slightly raised levels of iron in the body have reduced life expectancy on average.”

Iyas Daghlas, co-author on the new research from Harvard Medical School, stresses these findings should not be applied directly to clinical practice at this stage as plenty more work is needed to understand the relationship between iron levels and general health. Plus, there is an urgent need to investigate whether iron supplementation is dangerous if people are boosting their levels when they do not need to.

“These findings should not yet be extrapolated to clinical practice, but they further support the idea that people without an iron deficiency are unlikely to benefit from supplementation, and that it may actually do them harm,” says Daghlas. “We emphasize that these results should not be applied to patient populations with a compelling reason for iron supplementation, such as patients with symptomatic iron deficiency anemia, or in patients with heart failure.”

The new research was published in the journal Clinical Nutrition.

Source: Imperial College London