Iron Intake: Navigating Between Deficiency and Excess
Iron 101; a study examining iron status in vegans, vegetarians, and pescatarians & iron doesn't have to be a concern in plant-based diets.
Takeaways
There are two types of iron: animal- or plant-derived
Heme iron (animal-derived) is better absorbed than nonheme iron (plant-derived)
The importance is how well you absorb iron, not how much you consume
The human body lacks a mechanism to eliminate excess iron, which can be toxic in high amounts (be careful when supplementing without medical guidance)
On a plant-based diet, you don’t necessarily need a supplement
Iron status was not different between the dietary groups [vegans, vegetarians, and pescatarians].1
“Oh, you are primarily on a plant-based diet… Are you sure you don’t miss critical nutrients? Like B12? Iron? Proteins? Essential fatty acids? Calcium?” and the list goes on. While these are important questions one should raise when shifting to a plant-based diet, my duty as an ambassador is to provide more detailed answers.
⚔️ Let’s get straight into the iron talk. Why is it a double-edged sword?
Because the quantity we store in our bodies impacts our health tremendously. Too much or too little may disserve you.
⚖️ The balance of iron in the body is a sensitive topic. If we don’t consume enough, we risk anemia. But if we overindulge, we open the door to type 2 diabetes and arthritis to cardiovascular diseases, neurological conditions like Alzheimer’s and Parkinson's, colorectal cancer, and inflammatory disorders.2
Why is that so?
🤨 The human body lacks a mechanism to eliminate excess iron. Free iron molecules are highly toxic and readily oxidize and reduce, creating powerful oxidant species in the blood that can damage DNA.
Therefore, it is crucial to recognize these risks and find the right balance in our diets to maintain smooth oxygen transport and beyond.
Plant vs. animal iron
There are two types of iron:
1️⃣ Heme found in animal foods: 13–35% absorption
2️⃣ Nonheme found in plants: 2–20% absorption
Indeed, heme iron is better absorbed than nonheme iron. Absorption amounts also depend on dietary inhibitors (see below) and health status.
The Norwegian case study
To put things in perspective, I looked up a recent study (2021) examining iron status and the prevalence of iron deficiency in vegans, vegetarians, and pescatarians using more than one blood marker (previous research highlighted the importance of considering multiple indicators of iron).
Taking out a couple of study limitations, the outcome is encouraging. Here are a few highlights from the authors:
Iron supplementation was low in the cohort, which means the participants must be getting iron from their diets
Participants had been following these diets for several years, indicating that their dietary and supplement habits were likely consistent
Participants may have expertise in preparing nutrient-dense plant-based meals
We could extrapolate these results on Norwegians to other nationalities from developed nations where access to plant-based nutritious food isn’t an issue and people following such a diet are often well-educated.
Any thoughts? Are you on iron supplements?
The rest of the article may serve as a reminder for plant-based veterans. For new plant-curious readers, let’s find out more about the topic.
Keep your iron storage filled
If you were wondering about the best plant sources of iron to keep you rolling, I’ve got you covered.
📚 Looking for more information about milligrams of iron per serving of the above foods? The USA National Institutes of Health (NIH) has provided a table.
🌱 The spinach case: It breaks my heart to say it, and the heart of our old friend Popeyes, too. Spinach has low iron bioavailability because it contains oxalates, a fervorous iron ligand.3 The research on this topic is somewhat divided, so I’d not rely too much on spinach for iron… Be creative with other iron-containing plant foods.
👌 Remember the vitamin C boost: To enhance the body’s absorption of iron, especially the nonheme form, drink a glass of citrus juice with your meal, combine the meal with foods rich in vitamin C, such as broccoli and tomato sauce, eat an orange as dessert, or add lemon juice to the dish— you probably heard it already, as this is ancient knowledge.4
How much iron should I ingest at every meal?
👀 Is there such a thing at all? Yes. When you consume a lot of iron at one time, your body absorbs a lower percentage than when your meal contains only a few milligrams.
🤏 What great news for plant-eaters. Why? We hear that plant-based foods may contain less iron than animal foods, but consuming smaller amounts throughout the day increases absorption.
🧐 How much iron do you actually need on a daily basis? Check out the website of the USA National Institutes of Health (here). The recommended amounts will depend on gender and age.
To avoid when eating iron-rich foods
⛔️ Dietary inhibitors — these are molecules that mess with iron absorption. They are also called anti-nutrients, for example, phytic acid, tannins, and polyphenols5 (yes, the same ones that confer health benefits such as antioxidation or anti-inflammation. Here, unfortunately, they restrict dietary nonheme iron absorption.) Booh!
🥹 If your iron storage is somewhat on the low side, register the image above in your mind. Some health practitioners recommend avoiding tea or coffee (even decaf!) an hour before or two hours after a meal. Yes, no more dark chocolate as dessert. Also, are you ready to skip the after-a-meal espresso ritual or pass on the tannin-rich red wine?
Bottom line
It is important to remember that your healthy state will depend on how well you absorb iron, not how much you consume. This is true for meat eaters, too.
Yearly blood checks might be a good idea to monitor iron levels and other essential nutrients.
"Iron doesn't have to be an issue in a plant-based diet. A varied, well-rounded diet will most likely mean you don't need supplementation" by Matt Ruscigno, dietitian (quote from The Plant-based Athlete).Inspiration corner
😃 Beyond iron, do you need help remembering what food products are rich in what elements? A cheat sheet on your kitchen wall can help you navigate these murky waters. I recently got the one below to decorate mine (in French, though).
🏃♀️Until next week, ensure your iron level allows you to run at your pace!
Xoxo,
Fernanda
PS1: Other articles you might find interesting:
PS2: Find my archive here! Do you know that clicking in the heart or leaving a comment helps others discover this newsletter? Thank you for supporting my work.
Henjum S. et al., Iron Status of Vegans, Vegetarians and Pescatarians in Norway. Biomolecules. 2021 (link)
Makes sense. I guess this should be documented in studies on people eating omnivorous diets. But I am new to the dangers of excess iron
It is my belief that nature does things for a good reason. Why do you think the iron in vegetable is more difficult to assimilate? Do you think it means we are biologicaly carnivore?