Iron: Deficiency, Diet & Supplements

One of the most common supplements in the world is iron, but the average person knows surprising little about what iron is, how it works in the body, and what options are available for keeping levels up. Since the World Health Organization recognizes iron deficiency as the most common nutrient deficiency globally, I think it’s something we should all be well informed about. 

I put together this guide based on the questions I get about iron most frequently, common misconceptions, and important nutrition knowledge I think everyone should have. I really hope this information is going to be relevant to you whether you’re a menstruating human or not, whether you eat animal foods or plant-based, and whether or not you’ve ever taken a nutrition class.

Part I: Iron 101

First, let’s talk about what iron even is. That seems like a good place to start.

Iron is a mineral. It is considered an essential mineral, meaning that we must consume it through diet, our body cannot make it. 

The main function of function of iron in the body is making up hemoglobin. Hemoglobin is the component of your red blood cells that transports oxygen from your lungs to other parts of your your body. 

Iron also plays an important role in the production and breakdown of neurotransmitters like dopamine and serotonin. (1) You can think of these as “mood chemicals” because they play a huge role in our moods and behaviour.

Because of this, iron is an important nutrient in maintaining healthy energy levels and mental health. It also helps maintain healthy hair, skin, and nails because of it’s role in overall cell health.

Daily Requirements: How Much to Eat

Recommended dietary intake for adults rages from 8mg/day for men and 18mg for women aged 19-50. Pregnant women have the highest needs, at 27mg/day.

The reason for the large difference in recommended intake for men and women is because of menstruation. While men lose only small amounts of iron through skin and intestines each day, women lose that amount plus additional iron through their periods.

Pregnant women have increased blood volume and since about two thirds of the iron in the body is used to make up hemoglobin in the blood, this leads to a much increased need for iron.

Tip: This chart gives great context for the iron content of different foods in relation to how much you need each day.

Iron Deficiency: Symptoms and Testing

When it comes to iron deficiency, people most at risk are those with:

  • Low dietary iron intake.

  • Impaired iron absorption from low stomach acid or other drugs/supplements.

  • High iron losses from heavy periods or gastrointestinal bleeding.

  • Increased needs depending on life stage, such as pregnancy.

Common symptoms of iron deficiency include:

  • Feeling tired all the time

  • Quick heart beat

  • Feeling super cold

  • Trouble concentrating or “brain fog”

  • Feeling dizzy/fainting

  • Looking more pale than usual

  • Getting sick a lot (poor immunity)

Test, Don’t Guess!

If you have those symptoms, book an appointment with your doctor for bloodwork before you change anything. It’s important to confirm that you have an iron deficiency, not a more serious underlying condition. Knowing your numbers will also help you with making the connection to what it feels like when your levels are low, so you can be more in tune with your body and feel when your levels start to dip.

The most common form of iron deficiency is a lack of red blood cells called iron deficiency anemia. This can easily be assessed through a blood test, usually a complete blood count which looks at your red blood cells (remember that’s hemoglobin) among other things. Serum ferritin is another option for lab testing which gives an idea of your iron stores as well.

PART II: Iron in Your Diet

Most people should be able to get enough iron through a carefully planned diet, and shouldn’t need to rely on a supplement to meet their requirements.

Whether you’re vegetarian, vegan, pescatarian, or completely omnivorous, you will need to be educated and put some thought into where your iron is coming from.

Heme vs. Non-Heme Iron

One of the most common misconceptions about iron is that you need to eat red meat to get enough of it in your diet. This couldn’t be further from the truth and is actually a dangerous myth.

There are two types of iron that you will get through your diet: heme iron and non-heme iron.

Heme iron comes from animals, while non-heme iron comes from plants (with the new exception of plant-based heme iron, soy leghemoglobin, created by GMO yeast fermentation and used in a food product called the “Impossible Burger” (2)).

Generally speaking, heme iron from animals has a higher absorption rate thanks to its superior bioavailability. But does that mean it’s really the best type of iron? Turns out, no!

Heme iron acts as a pro-oxidant in the body which can lead to increased risk of heart attack, stroke, type II diabetes, and especially cancer. (3). It is not considered safe to fortify foods with heme iron, because of increased cancer risk, and consuming high amounts of heme iron through diet also increases risk.

Non-heme iron, on the other hand, has not been associated with increased cancer, heart attack, stroke or diabetes risk. In fact, high dietary iron from non-heme sources (plant-based iron) is shown to be protective against all of these conditions (4). It’s safe to add to food, safe to consume as a supplement, and relatively easy to consume through a whole food diet.

Increasing Iron Intake & Absorption

Since non-heme iron is generally less bioavailable than heme iron, there are some steps you will want to take to maximize your dietary iron intake. If you’re trying to avoid supplements and have been tested to confirm your iron is low, you may still be able to get enough from food alone.

My favourite sources of non-heme iron to include daily are:

  • Spinach

  • Kale

  • Beans & lentils

  • Blackstrap molasses

  • Tempeh & tofu

  • Pumpkin seeds

  • Dark chocolate (seriously)

But if your iron is low, you might need to do more than just eat more iron. You’ll have to get a bit more strategic...

Vitamin C

The most powerful vitamin in preventing and reversing iron deficiency is actually vitamin C. Adding vitamin C to a meal containing plants high in iron cam actually boost the bioavailability by up to six times, sometimes surpassing the bioavailability of even heme iron sources.

The reason vitamin C works to increase iron absorption is because it counters the effect of phytates, a common “anti-nutrient” found in plants like beans, whole grain, seeds, and nuts. Instead of trying to avoid phytates completely (they also fight cancer!), adding more vitamin C to the diet will help unlock some of the iron they were bound to. 

Adding vitamin C to meals can be as simple as squeezing lemon onto your steamed kale or spinach, adding lime to your black bean burrito bowl. The key here is that they must be consumed TOGETHER to get the effect.

Onions & Garlic

Adding garlic and onions to the cooking water when you make whole grains like brown rice or quinoa is also a way to effectively increase iron bioavailability. You don’t need to add too much, either! Research found 0.25-0.5 gram of garlic to 10g of grain, and 1.5-3 grams of onion to 10g of grain was enough to benefit from the increase. (5)

Fermentation, Soaking & Sprouting

How your food is prepared can also increase the bioavailability of iron!

Fermenting products high in phytates can also increase the bioavailability of iron! This tip isn’t as quick and easy as adding vitamin C, but if you eat bread, choosing a fermented sourdough or rye bread can mean higher iron absorption. (6)

Soaking grains and beans before cooking them also decreases phytate content and makes iron more accessible. That means soaking your steel cut oats  or lentils overnight, draining and rinsing them before cooking make a big difference! (7)

Sprouting is also a effective way to reduce phytic acid. It’s a bit more time consuming to do yourself, but you can also purchase sprouted versions of you favourite grains and legumes at most stores these days if you wanted to try incorporating more sprouted foods. 

Cast Iron Cookware

Using a cast iron pan can also increase the iron in your food, because they release iron as they are used (especially if cooking acidic foods). However, it’s hard to know how much iron is being released by your cast iron pans so it shouldn’t be relied on exclusively. 

Beware of Iron Inhibitors

There are certain things you might be eating that can block iron absorption. If your iron levels are an issue, you may want to be mindful of the following:

  • Dairy: Calcium inhibits iron absorption, so if you eat dairy try not to consume it within the same meal as your high-iron foods. Note that non-dairy milks are also fortified with calcium, so adding almond milk to your green smoothie may create the same conflict! (8)

  • Coffee & tea: Polyphenols in coffee (9) and tea (black, camomile, and peppermint) (10) can interfere with iron absorption if consumed together.

Part III: Supplementing with Iron

Sometimes people with low iron levels might think the solution is to eat more meat, but this isn’t supported by research so if you are low in iron and you are trying to resolve that with diet, following the tips outlined in the previous section is your best course of action.

If your levels are very low are you’re feeling really terrible, an iron supplement can help bring them up quickly and effectively. If you have a hard time keeping your levels up with food alone (because of pregnancy, or a bleeding condition) you may also need to take an iron supplement to stay healthy.

However, supplementing can increase iron levels quickly and efficiently to help you feel better faster. If your healthcare provider has recommended an iron supplement you should definitely take that recommendation seriously. 

You have different options for iron supplements, here are some of the most common:

  • Ferrous Fumarate

  • Ferrous Sulphate

  • Ferrorous Gluconate

  • Ferrous Diglycinate

  • Ferrous Bisglycinate

Ferrous Fumarate, Ferrous Sulphate & Ferrous Gluconate

These forms of iron are very common and inexpensive. They’re the most likely to be recommended by your medical doctor and available at pharmacies. 

Ferrous fumarate and sulphate pills often provide up to 300mg of iron per dose, which can be confusing for people who know they need around 18-27mg per day. This is because of poor absorption, by giving a high dose of poorly absorbed iron, you are increasing the change that enough will be absorbed to help fight deficiency. 

However, iron is only absorbed in the small intestine, so whatever remains unabsorbed (of that original 300mg) will continue travelling through the body and end up in the colon where it is known to cause stomach problems like gas, bloating, and even lead to black stools.

Ferrous gluconate is an organic molecule and may be more well tolerated. However, this may also be due to the fact that ferrous gluconate products usually contain lower doses of iron and therefore lead to less undigested iron in the colon. 

Ferrous Diglycinate & Ferrous Bisglycinate

These forms of iron are known as ‘amino acid chelates’ because they are bound to amino acids. They are more bioavailable, which means that the doses can be much lower, leading to less undigested iron making it out of the small intestine. 

Research shows that these types of iron supplements lead to fewer gastrointestinal side effects, but are just as effective in terms of increasing iron levels. Amino acid chalets may even have a longer-lasting effect on iron stores once the supplement is stopped. 

My Favourite Iron Supplements

I’m not a doctor and do not recommend taking an iron supplement without consulting a doctor first! If you have been told to take an iron, here are some of my favourites.


Thorne Ferrasorb

With 36mg of  iron per cap, this supplement can help increase your iron stores with fewer side effects than other common iron supplements. It also contains Vitamin C and B-vitamins to increase bioavailability and support energy levels. 

Floradix Floravital

This liquid iron supplement is much more expensive, but if you’re looking for a liquid option this one is very effective. (Note: This exact formula is gluten-free, but others from the same brand are not so double check which one you’re buying if you have Celiac disease!)

 Lucky Iron Fish

This inexpensive iron dish can be boiled in water with a touch of acid (like lemon juice) and it will release iron. The water can then be used for cooking or drinking to get extra iron in the diet. The fish adds 4-8mg iron to the water when used as directed and it lasts about 5 years, so it can be an easy and cheap way to get more iron in without taking a pill.


I really hope that this gives you all the information you need to prevent iron deficiency! If you want to see more in-depth posts like this on my site please leave a comment letting me know that this was helpful. Of course if you have any questions, let me know and I’ll do my best to help.

Ashley Sauvé2 Comments