By Matthew Ruscigno, MPH, RD
True or False: The iron that our bodies require is the same element found in a cast-iron skillet.
This is a real true or false question on my college exam, and it fools a surprising number of my students. Iron is greatly misunderstood as a nutrient, especially when it comes to vegetarian and vegan diets.
The mineral is found all over the earth and is essential to red blood cells transporting oxygen and nutrients to every cell in our body, connecting us directly to the land we live on. Pretty amazing, right?
But iron deficiency is the most common nutrient deficiency in North America, with symptoms including fatigue, pale skin, weakness and inability to maintain body temperature. And as vegetarians and vegans, it’s worth paying special attention to make sure we’re getting enough.
So how much iron do we actually need?
Recently in the U.S., the Dietary Reference Intakes (DRI) gave new recommendations for iron, specifically for vegetarians, that are 1.8 times higher than the general population. As my colleagueJack Norris points out, this increase is not based on actual research on vegetarians, but simply because the iron in plant foods is not as easily absorbed as the iron in animal products (more on this in just a minute).
As a result, many experts in vegetarian nutrition believe that these recommendations are much higher than needed.
My take on it: if you eat a varied, healthy plant-based diet that includes a balance of grains, legumes, nuts and seeds, and fruits and vegetables — and follow the recommendations below — I don’t believe it is necessary to keep close track of iron intake.
Iron from plants vs. iron from animals
To better understand what we need to do to ensure our bodies are getting enough iron, we first have to accept two facts about iron — painful as they are for vegetarians and vegans to hear:
- There are two types of iron — heme, which is found in animal foods, and non-heme, which is from plants. It is true that heme iron (the kind from animals) is better absorbed than non-heme iron.
- Vegetarians and vegans may have lower iron stores than omnivores.
But don’t fret your vegetarian brain over these issues. We’ll see that in fact it’s not all that difficult to get the iron you need on a plant-based diet.
As for #2, it’s important to note that while vegetarians have lower stores of iron than omnivores, theydo not have higher rates of anemia. In the research, many vegetarians’ stores are “low-normal,” but this does not mean less than ideal! Actually, there’s some evidence that says low-normal iron stores are beneficial: improved insulin function and lower rates of heart disease and cancer.
How to get enough iron on a plant-based diet
You can start by making sure that you’re eating foods that contain substantial amounts of iron. Some of the best plant sources of iron include:
- Legumes: lentils, soybeans, tofu, tempeh, lima beans
- Grains: quinoa, fortified cereals, brown rice, oatmeal
- Nuts and seeds: pumpkin, squash, pine, pistacio, sunflower, cashews, unhulled sesame
- Vegetables: tomato sauce, swiss chard, collard greens,
- Other: blackstrap molasses, prune juice
But here’s the key: It’s not how much iron you consume, but how well you absorb it.
So paying attention to make sure you’re absorbing your iron is just as important as making sure you’re taking in enough. And fortunately there is a lot you can do to increase the absorption of non-heme iron!
5 ways vegetarians and vegans can absorb more iron
1. The less you eat, the better it is absorbed.
Seriously! I know people who take one 15 milligram pill a day and think they are covered, but it doesn’t work that way. When consuming higher amounts of iron at one time, the percentage that our bodies absorb is actually lower than when your meal contains only a few milligrams. Plant-based foods may contain less iron than animal foods, but eating smaller amounts throughout the day is a great way to increase absorption.
2. Eat non-heme iron foods with vitamin C foods, and absorption can increase as much as five times.
Five times! Culturally these combinations are already happening: think beans and rice with salsa,falafel with tomatoes and hummus with lemon juice. The iron in beans, grains and seeds is better absorbed when combined with the vitamin-C found in fruits and vegetables. Bonus: some iron sources, like leafy greens, broccoli, and tomato sauce already contain vitamin-C.
3. Avoid coffee and tea when eating high-iron meals.
Coffee (even decaf!) and tea contain tannins that inhibit iron absorption. I recommend avoiding them an hour before or two hours after your meal.
4. Cast-iron skillets increase iron absorption.
The answer to the true or false question is true! Cooking with an old school cast-iron skillet increases the iron in your meal — especially when you cook a vitamin-C containing food in it.
Even better, a cast-iron skillet purchase puts you in the realm of official serious cook. I bought mine almost 10 years ago for $8 and it is one of my most valued possessions. (Yes, I’m that much of a food nerd that a skillet is one of my most valued possessions!)
5. It pains me to say this, but you may want to avoid spinach as an iron source.
Spinach contains oxalates that block absorption. Sucks, right? There is some disagreement in the research about this, but with all of those other iron-containing plant foods, why not try some new ones?
And for the record, even if you take an iron supplement, you should still follow the advice above. I recommend that if my clients take one, they break it in half and take half in the morning and half at night, always with meals or juice.
Iron doesn’t have to be a problem in a plant-based diet
Follow these principles, eating good sources of iron throughout the day and keeping up with the absorption principles above, and you’ll find that it’s not hard to get enough iron in your diet, even as a vegetarian or vegan.
All of that said, iron is one of the few nutrients where a deficiency both immediately affects your health and is detectable, so if you have any iron-deficiency symptoms I recommend getting blood work with your doctor. It is affordable, reliable and easy to interpret. And iron levels bounce back quickly when using the methods above or supplementation.
I’ll leave you with a fun fact about iron in plant-based diets (well, fun to a food nerd at least):
Some research shows that vegans have higher iron levels than vegetarians.
The difference between vegetarians and vegans is eggs and dairy products, and the latter contain almost no iron. When someone goes from vegetarian to vegan they are replacing dairy products with plant-based ones, all of which contain some iron, therefore increasing the total iron in the diet.
With this information and a little effort you can get all of the iron you need from plants to be a healthy and strong vegetarian!
Matthew Ruscigno, MPH, RD is a vegan of 15 years, Chair of the Vegetarian Nutrition Group of the American Dietetic Association and is an athlete that has completed iron-distance triathlons, solo 24-hr mountain bike races and ultra-runs. He writes at True Love Health and recently launched his Day in the Life of Vegan Athletes video series.