Not All Iron Is Created Equal

A typical prescription when you are low in iron is to take an iron supplement. With so many supplements out there, it may be hard to choose, and so you might just go with the most popular product, Feramax. By the name, it sounds like it might just do the trick.

The company that owns Feramax boasts that it is the #1 recommended over-the-counter iron supplement in Canada, because of its high dose of iron and a supposed lowered toxicity profile. But when I looked at the ingredients in the actual supplement, I balked. I couldn’t believe that medical doctors and pharmacists recommended this product over others just because of its high doses, and overlooked the many harmful non-medicinal ingredients in it.

Let’s take a look at why iron isn’t the only thing to look at in iron supplements:

Each Feramax tablet contains:

Iron 40 mg. Other Ingredients: Calcium Carbonate, Cellulose Acetate, FD & C Red #40, FD & C Yellow #6, FD & C Blue No.2, Hypromellose, Magnesium Stearate, Maltodextrin, Microcrystalline Cellulose, Polydextrose, Polyethylene Glycol, Sodium Starch Glycolate, Titanium Dioxide, Triacetin.

There are 14 non-medicinal ingredients, 7 of which are proven to be directly harmful, 2 of which are potentially harmful, and 4 of which are inert at low doses, or potentially harmful if you are sensitive to it. Let’s take a closer look.

Calcium carbonate

This is a form of calcium found in some supplements and also in antacid tablets like Tums. While not directly harmful, even small amounts of this substance taken when not needed can impact stomach acid levels and affect digestion and absorption of food. For a deeper dive into why you should avoid antacid medication, read this article on The Burning Truth About Antacids.  Also, calcium carbonate is not the most absorbable form of calcium and it is better to assess your need for calcium supplementation with your ND based on your dietary consumption.

Cellulose acetate

This compound is part of the tablet coating. Cellulose acetate is also used in eyeglasses, cigarette filters, and playing cards.  The American Polymer Standards Corporation straight-up says it may be harmful if ingested.1 Why is it in medicine?

Artificial colours: FD & C Red #40, Yellow #6, Blue #2

These 3 artificial colours are perhaps the biggest culprits. Countless reports and studies have come out over recent years showing the harmful effects of food dyes. Specifically, artificial colours have been implicated as exacerbating attention deficit and hyperactivity disorders in children,2 allergies, learning impairment, and even cancer.3


Basically, this is natural fibre that has been modified (ie is semi-synthetic), and is usually used as artificial tears in products like Visine®. But after feeding it to rats and not observing any big changes, the FDA approved it as a direct and indirect food additive4.

Magnesium Stearate

Like hypromellose, the purpose of magnesium stearate in medications is lubrication for manufacturing and also for moving along the digestive tract. It is mostly inert, and for this reason is found in many supplements and medications, although at high doses it has been linked with suppressed immunity, poor intestinal absorption, and contamination5.


This ingredient is a starch usually made from corn. Despite being “generally recognized as safe” and therefore approved as a food additive, it turns into sugar in the body and can raise the blood sugar and contribute to weight gain, insulin insensitivity, and diabetes6. Keep in mind as well, that corn is one of the top genetically modified foods and there has been no long term studies on the health implications of GMO products.

Microcrystalline cellulose

Microcrystalline cellulose (MCC) is refined wood pulp. While sounding strange, that’s not the part that is dangerous about MCC. MCC is actually a nanoparticle, meaning it’s so small that it enters cells freely, and once there, they accumulate over time and can clog up cell functions like cotton in a jar, leading to dysfunction and toxicity.  The smaller the particle, the more dangerous they are, so the FDA has banned all MCC smaller than 5 microns in size, but nanoparticle size regulation is sparse for manufacturing companies7.


This is a non-digestible starch that ferments in the large intestine. Interestingly, the unique fermentation of polydextrose has been shown to positively affect the gut bacteria (ie improve the microbiome) and even improve mineral absorption in the large intestine. Because of this, it is possible that polydextrose is the most helpful ingredient besides iron in Feramax. However, in people that are sensitive to changes in the microbiome (eg those with SIBO or fibre sensitivity), polydextrose can cause intestinal gas, bloating, stomach cramps, and diarrhea8.

Polyethylene Glycol (PEG)

Simply put, this is a laxative put into the medicine because iron is known to be a little constipating to some people. Like polydextrose, it is a non-digestible fibre that pulls water into the colon to help hydrate stools. If you are sensitive to fibre and non-digestible starches, you can end up with gas, cramps, nausea, and diarrhea.

Sodium starch glycolate

This compound absorbs water quickly and helps tablets and pills dissolve. It’s fairly inert, except that it is made from either wheat or corn, which can trigger sensitivities in people with celiac disease or corn allergies.

Titanium dioxide

This is used as a colorant, and like the other artificial colours, it has a slew of health implications. Among them, it has been implicated in lowered immune system function, with some studies showing DNA damage by titanium dioxide nanoparticles, albeit marginal damage. It has also been shown to cause kidney damage in mice, and to induce small intestine inflammation9. Again, why do we have to sacrifice our health for the colour of our vitamins?


While being generally recognized as safe, in low-dose human studies, animal studies show that Triacetin is moderately toxic by all injection routes, with animals showing weakness, difficulty moving and breathing, muscular tremors, occasional convulsions and hemorrhage in the lung.

What does all that mean?

It is important to note that the dosages in the supplements are generally lower than what is seen in most of the toxicity studies. That being said, even though studies haven’t shown direct acute toxicity, there can be significant long-term chronic cumulative toxicity that leads to vague symptoms like fatigue, weight gain, indigestion, and malaise. Why risk it with your iron supplement that is meant to make you feel better in the long run?

Choose supplements with the least non-medicinal ingredients, or at least ones that don’t contain the worst of them, artificial colours, titanium dioxide, maltodextrin and triacetin.

For example, another iron supplement called Floradix has these non-medicinal ingredients:

Non-medicinal ingredients: extracts of carrot, stinging nettle, spinach, couch grass, bitter fennel, kelp, hibiscus; juice concentrates of pear, black grape, black currant, orange, blackberry, cherry and red beetroot; in a base of honey, extracts of rosehip, wheat germ and yeast, natural orange flavour, purified water and ascorbic acid (antioxidant). The only thing that could improve in this supplement from an ingredient perspective is “natural orange flavour”  – usually this is code for chemical.

There are other options for your health! We find it is best to determine why your iron is low in the first place. To get to the root of your health concerns work with a Naturopathic Doctor today!

  1. American Polymer Standards Corporation, on Celluose Acetate
  2. Arnold, L. E., Lofthouse, N., & Hurt, E. (2012). Artificial food colors and attention-deficit/hyperactivity symptoms: conclusions to dye for. Neurotherapeutics, 9(3), 599-609.
  3. Stokes, M. (2010). How bad is red 40 and other food dyes? blog, November/December 2010
  4. Burdock, G. A. (2007). Safety assessment of hydroxypropyl methylcellulose as a food ingredient. Food and Chemical Toxicology45(12), 2341-2351.
  5. Axe on Magnesium stearate, 2017.
  6. Hofman, D. L., Van Buul, V. J., & Brouns, F. J. (2016). Nutrition, health, and regulatory aspects of digestible maltodextrins. Critical reviews in food science and nutrition56(12), 2091-2100.
  7. Burdock, G (2007). Nanotechnology, Benefits vs toxic risks. New Hope Network.
  8. do Carmo, M., Walker, J., Novello, D., Caselato, V., Sgarbieri, V., Ouwehand, A., … & dos Santos, E. (2016). Polydextrose: physiological function, and effects on health. Nutrients8(9), 553.
  9. Yigsaw, 2016. 5 DANGEROUS INGREDIENTS IN YOUR VITAMINS AND DIETARY SUPPLEMENTS. American College of Healthcare Sciences.

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