The Safety of Plant vs. Animal Iron

It is commonly thought that those who eat plant-based diets may be more prone to iron deficiency, but it turns out they’re no more likely to suffer from iron deficiency anemia than anybody else. This may be because not only do those eating meat-free diets tend to get more fiber, magnesium, and vitamins like A, C, and E, but they also get more iron.

The iron found predominantly in plants is non-heme iron, which isn’t absorbed as well as the heme iron found in blood and muscle, but this may be a good thing. Avoidance of heme iron may be one of the key elements of plant-based protection against metabolic syndrome and may also be beneficial in lowering the risk from other chronic diseases such as heart disease.

The data linking coronary heart disease and the intake of iron in general has been mixed. This inconsistency of evidence may be because of where the iron comes from. The majority of total dietary iron is non-heme iron, coming mostly from plants. So, total iron intake is associated with lower heart disease risk, but iron intake from meat is associated with significantly higher risk for heart disease. This is thought to be because iron can act as a pro-oxidant, contributing to the development of atherosclerosis by oxidizing cholesterol with free radicals. The risk has been quantified as a 27 percent increase in coronary heart disease risk for every 1 milligram of heme iron consumed daily.

The same has been found for stroke risk. The studies on iron intake and stroke have had conflicting results, but that may be because they had never separated out heme iron from non-heme iron, until now. Researchers found that the intake of meat (heme) iron, but not plant (non-heme) iron, was associated with an increased risk of stroke.

The researchers also found that higher intake of heme iron—but not total or plant (non-heme) iron—was significantly associated with greater risk for type 2 diabetes. There may be a 16 percent increase in risk for type 2 diabetes for every 1 milligram of heme iron consumed daily.

The same has also been found for cancer, with up to 12 percent increased risk for every milligram of daily heme iron exposure. In fact, we can actually tell how much meat someone is eating by looking at their tumors. To characterize the mechanisms underlying meat-related lung cancer development, researchers asked lung cancer patients how much meat they ate and examined the gene expression patterns in their tumors. They identified a signature pattern of heme-related gene expression. Although they looked specifically at lung cancer, they expect these meat-related gene expression changes may occur in other cancers as well.

We do need to get enough iron, but only about 3 percent of premenopausal white women have iron deficiency anemia these days. However, the rates are worse in African and Mexican Americans. Taking into account our leading killers—heart disease, cancer, and diabetes—the healthiest source of iron appears to be non-heme iron, found naturally in abundance in whole grains, beans, split peas, chickpeas, lentils, dark green leafy vegetables, dried fruits, nuts and seeds.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations—2013: Uprooting the Leading Causes of DeathMore Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

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82 comments

John B
John B8 months ago

Thanks Dr. Greger for sharing the info.

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heather g.
heather gabout a year ago

Who knows - only having blood-works done will reveal the true stats

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Jim Ven
Jim Venabout a year ago

thanks for the article.

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Siyus Copetallus
Siyus Copetallusabout a year ago

hank you for sharing.

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Telica R.
Telica Rabout a year ago

Thanks

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william Miller
william Millerabout a year ago

Thanks

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Rita Odessa
Rita Odessaabout a year ago

I don't eat animals but I have had an iron issue it's okay now, I have a magnesium issue and I have a B12 (very mild deficiency) I eat more cereal for B12, I drink magnesium and my iron is okay now, yes for some of us going off meat wasn't easy but I am still happier not eating animals and supplementing my diet I eat well and enjoy the foods I do eat.

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Suzana Megles
Suzana Meglesabout a year ago

Hooray for pl;ant-based iron. Thank you Dr. McGregor!

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Randy Q.
Past Member about a year ago

tyfs

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Randy Q.
Past Member about a year ago

tyfs

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