Too little iron and you can suffer from fatigue, weakness and impaired immunity, but too much can increase the risk of liver disease, heart disease and diabetes.
For older Americans, nutrient deficiency is a common problem, but when it comes to iron, the research shows that excess iron is the problem. Two new studies suggest iron overload not only puts your health at risk, it’s also deadly.
Unlike nutrients such as vitamin C, your body doesn't have a way of getting rid of excess iron, so it gets stored in the liver, heart and pancreas. Over time, the excess iron can damage these organs.
I’ve known this for years, and I’ve advised against iron supplements, but now new studies provide further confirmation.
Four Times More People Had Iron Overload than Deficiency
In a 2001 study, researchers tested the iron stores of more than a thousand Americans over the age of 67. They found depleted iron stores in three percent of these people, compared to 13 percent with elevated iron stores. So, the number of people with too much iron was four times the number who were deficient.To see whether excess iron is relevant to life expectancy, biochemists from Denmark analyzed several population studies. In their 2011 paper they concluded that those with a higher iron status "have an increased risk of premature death."
Whether iron is the true culprit can't be determined from observational studies. All that can be said is that it's linked in some way to a shorter lifespan.
To see whether it's more likely to be the cause of shorter life, and not just an unexplained association, a researcher from Harvard Medical School and another from Imperial College London collaborated on a study that used a method that predicts iron status by looking at genetic variations.
From genetic data on 49,000 people, they were able to find three variants linked to a person's iron levels. They then used this information to screen lifespan data on datasets from over a million people.
Those with variants that predisposed them to higher iron levels had a reduced life expectancy. The researchers suggested the "increased mortality risk reported in prior observational studies may reflect causal relationships."
Harvard Researcher: Iron Supplements May Be Harmful
An estimated one in every six Americans take iron supplements either on their own or as part of a multivitamin, and both members of the team warned that people who have no clinical reason to take iron supplements should be wary of doing so.Dr. Dipender Gill from Imperial College of London said, "While we did not look directly at the impact of taking supplements, our results suggest that there is a need to better understand the health implications of people boosting their iron levels with supplements when they don’t need to.”
IyasDaghlas from Harvard added, "These findings...further support the idea that people without an iron deficiency are unlikely to benefit from supplementation, and that it may actually do them harm."
While premenopausal women might need extra iron because of iron loss during their monthly cycle, the takeaway for men and postmenopausal women is to take a supplement only if a blood test shows you need it. They published their research in the journal Clinical Nutrition in June.
Longevity Genes Linked to Iron Metabolism
A second study backs up the advice of the Harvard and Imperial College scientists to be cautious with iron supplementation.In this study, geneticists from the University of Edinburgh, Scotland, and the Max Planck Institute for Biology of Aging in Germany, examined genetic data to find genes linked to three characteristics of biological aging:
- Lifespan
- Healthspan, or years lived disease free
- Longevity, living to a ripe old age.
Their analysis pointed to ten areas of the genome that appeared directly linked to the characteristics of biological aging and found that genes associated with iron were over-represented in all three.
In other words, they concluded that genes involved with metabolizing iron in the blood -- and thus preventing its excess -- are at least partly responsible for a healthy and long life.
Dr. Paul Timmers, a member of the research team, explained, "We are very excited by these findings as they strongly suggest that high levels of iron in the blood reduces our healthy years of life, and keeping these levels in check could prevent age-related damage.
"We speculate that our findings on iron metabolism might also start to explain why very high levels of iron-rich red meat in the diet has been linked to age-related conditions such as heart disease."
Poor Genes? Be a Blood Donor
If you don't have the advantage of having the right genes, you can keep your iron levels down by being a regular blood donor.To lower your intake of iron, limit red meat, which contains highly absorbable heme iron, and check product labels to avoid iron-enriched or fortified foods.
To reduce absorption, take vitamin C away from meals, as this enhances iron absorption, while drinking tea and coffee with meals lowers absorption. Fibrous foods like vegetables also contain chemicals that reduce iron absorption.
- https://pubmed.ncbi.nlm.nih.gov/11237943/
- https://academic.oup.com/clinchem/article/57/3/459/5621203
- https://www.imperial.ac.uk/news/200373/raised-iron-levels-linked-reduced-life/
- https://www.clinicalnutritionjournal.com/article/S0261-5614(20)30336-8/fulltext
- https://www.nature.com/articles/s41467-020-17312-3
- https://www.ed.ac.uk/news/2020/blood-iron-levels-could-be-key-to-slowing-ageing
