When considering a new dietary pattern, it’s normal to wonder if you’ll be able to meet all of your nutritional needs. I was there once too, wondering if I could meet my body’s needs while eating only plants. The good news is, you totally can! This post is all about iron. How much you need, the differences between heme and non-heme iron, factors affecting absorption and where to get it in your plant-based diet.
What is Iron?
Iron is an essential mineral that serves some important purposes in the body. It’s required in the maintenance of healthy cells, it is needed to convert food into energy the body can use and it helps maintain a healthy immune system.
Another important role iron plays is in the formation of hemoglobin which helps red blood cells transport oxygen from the lungs to the rest of the body via the circulatory system. When you’re iron deficient, your body can’t make enough red blood cells to circulate oxygenated blood around your body. As a result, those who are iron deficient tend to feel tired and weak.
Types of Iron
Iron is a vital nutrient but we only require small amounts. It is important to remember that too much can be toxic. The body has no known mechanism for clearing excess iron, so regulation is important. How well our body can regulate iron absorption depends on the type, which I will explain below.
Iron comes in two forms:
Heme Iron – from animal foods such as meat and eggs.
Non-Heme Iron – from plant foods like legumes, nuts and seeds.
What’s the difference? Well, heme iron is more readily absorbed, but absorption is not easily regulated. This can be dangerous, as the body can’t clear excess iron on its own. Too much iron can cause damage to the brain, liver, heart and other organs. This leads to an increased risk of diabetes, heart disease, cirrhosis and other disorders. While heme iron is more readily absorbed, it’s also been linked to increased risk of certain cancers. This is partly due to the fact that iron acts as a pro-oxidant, generating cancer-causing free-radicals in the body and inhibiting antioxidants.
Non-heme iron is not as readily absorbed, but very well regulated. When your iron levels are low, your intestines will boost absorption rates. When iron levels are sufficient, the intestines work to block the absorption of non-heme iron to protect you from iron toxicity. Unfortunately, it can’t block the absorption of heme iron very effectively. Thus, the consumption of non-heme iron from plant sources is safe and carries less risk of harmful effects.
Iron deficiency anemia is the most common nutrient deficiency in the world. It occurs when the body has insufficient amounts of iron to produce enough hemoglobin for your red blood cells. Remember, the hemoglobin is what allows your red blood cells to transport oxygen.
In the initial stage, your body isn’t getting as much iron as it needs, so your iron stores begin to get depleted. At this point, your body will try to compensate by increasing absorption rates from the food you eat. This stage typically goes unnoticed and generally has no symptoms.
Once your iron stores are depleted, the production of your red blood cells begins to suffer. At this point, you’ll start to notice some symptoms.
Symptoms of iron deficiency include:
Dizziness or lightheadedness
Shortness of breath
Cold hands and feet
Restless leg syndrome
If you are experiencing some of these symptoms you should see your doctor. They can check your iron levels with a routine blood test and suggest the best course of treatment for you.
How Much Do You Need?
How much should you consume to avoid deficiency? Well, it varies by age and gender. Growing kids need a little more during important growth phases. Menstruating women, as well as pregnant or lactating women also need more than men do. For reference, the recommended daily intake (RDI) of iron for men is 8mg per day, and for women is 18mg per day. After menopause, however, the RDI for adult women is reduced to 8mg per day.
See the chart below for values recommended by the dieticians of Canada.
|1-3 years old||7mg||7mg|
|4-8 years old||10mg||10mg|
|9-13 years old||8mg||8mg|
|14-18 years old||11mg||15mg|
|19-50 years old (or menopause)||8mg||18mg|
While vegetarians and vegans don’t have higher rates of iron deficiency anemia, it’s still important to make sure you’re consuming enough. It’s suggested that vegans and vegetarians aim for 1.8 x the recommended daily intake. This would make change the RDI to 14mg for men and post-menopausal women, and 32mg for women of childbearing age. Don’t sweat this too much though, as vegans and vegetarians tend to consume more iron (and more nutrients in general) than their meat-eating counterparts anyway. However, women of childbearing age are at greater risk of iron deficiency anemia due to blood loss during menstruation. Therefore, it is important to be mindful of iron intake, especially if you have a history of anemia.
Plant-Based Sources of Iron
Some great plant-based sources of non-heme iron include:
*Natto – 15mg/cup
*Morel mushrooms – 12.2mg/100g
*Soybeans – 8.8mg/cup
*Roasted pumpkin seeds – 8mg/100g
*Dried apricots – 7.5mg/cup
*Lentils – 6.6mg/cup
*Other beans – 4-7mg/cup cooked (depending on variety)
*Amaranth – 5.2mg/cup cooked
*Tofu & Tempeh – 3-4mg/6oz serving
*Baked potato – 3.2mg/each, large, skin on
*Quinoa – 2.8mg/cup cooked
*White button mushrooms – 2.7mg/cup cooked
*Sesame seeds – 1.3mg/tbsp
*Broccoli – 1mg/cup
You’ll also find iron in other foods like fortified cereals and dark green leafy vegetables. Just be aware that the high oxalate content of certain greens (like spinach, swiss chard and beet greens) can inhibit absorption.
This is not meant to be a complete list but should give you a good idea of where you can get your iron when eating plant-based.
Although non-heme iron is not as readily absorbed, there are some things you can do to increase its absorbability.
You can increase absorption rates significantly by including a source of vitamin C in the same meal as your non-heme iron source. This is pretty easy to do; in fact, you may be doing it already without even realizing it. This can be as simple as squeezing some citrus over your salad of dark leafy greens or including some high vitamin C foods in your meal.
High vitamin C foods can be found in both the fruit and vegetable world. Vegetables containing good amounts of vitamin C include things like sweet bell peppers, broccoli, brussels sprouts, cabbage, kohlrabi, snow peas and cauliflower.
Fruits with high amounts of vitamin C include guava, papaya, kiwi, citrus fruits, strawberries, pineapple, cantaloupe and mango.
It’s advisable to refrain from drinking coffee or tea with your meals, or within an hour before eating. The tannins they contain can significantly reduce iron absorption. This is especially important for women of childbearing age, who are at higher risk or iron deficiency.
Phytic acid or phytates, while having many health-promoting properties, can partially inhibit mineral absorption, including iron. These are found plant foods like grains, legumes, nuts and seeds. Soaking, sprouting or fermenting foods can reduce the amount of phytates present, increasing absorbability of iron.
Another way to increase iron absorption is by consuming foods from the allium family. Alliums include foods like garlic and the different types of onions. They are pungent foods commonly used in cooking to build flavours. They are well known for their cancer-fighting properties but have another great benefit as well. Alliums have been found to help improve the absorbability of minerals like iron and zinc in foods. So, including some alliums in your iron-rich dish is a great idea for increased absorbability.
It’s important to remember that you can have too much of a good thing. This is definitely the case with iron. It is recommended not to exceed 45mg per day, especially heme iron which your body cannot regulate very well. Due to the risks associated with too much iron, you should only consider supplementation as a last resort, and only under the care of a physician.
If you are iron deficient, talk to your doctor about trying to treat it with food first. While iron supplements can be helpful for those in need, they increase oxidative stress in the body. They also come with some unpleasant side effects, including stomach pain, constipation, nausea and vomiting.
The Bottom Line
Iron is an important mineral for our health, but too much can lead to toxicity. While heme iron from meat and eggs is easily absorbed, it is not easily regulated. Non-heme iron from plants is well regulated by the body to help protect us from getting too much. While non-heme iron is not as easily absorbed, there are strategies to help improve absorption rates. Some as easy as including vitamin C rich foods or alliums with your meal. While supplementation can be helpful for those who are deficient, they come with side effects and other concerns, so should only be considered under the care of your doctor.
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Feature image credit: Photo by chuttersnap on Unsplash