Iron Supplements… are you doing it right?

By Anita Kappukatt, ND

I’ve been getting a lot of questions from women about low iron and fatigue lately!  I’m surprised at how little people are informed about iron supplementation when they are prescribed it.  How long should you take it? Can you take it with food? Is there anything that will boost it’s absorption? Are there side-effects?  There are a few things you should know, whether you are trying to get your stores up for functional reasons, or whether you are preventing an iron-deficiency anemia.  I have seen many-a-case where a patient will just switch to a better iron supplement and feel better within days – after having taken a previous prescription for years!  The product you choose will make a huge difference, especially if your iron stores are low!

What are some signs that I may need to supplement?

Iron is an essential mineral and is involved in oxygen transport, energy production, and neurotransmitter production. The World Health Organization considers iron deficiency to be the largest international nutritional disorder.  Although anemia is the best-known consequence of iron deficiency, a number of other signs and symptoms can manifest: fatigue, low motivation, decreased aerobic capacity of your muscles, muscle fatiguability, trouble concentrating, mood disturbances, hair loss, restless legs syndrome, heavy menstrual periods, and impaired immune function.

Lab tests and iron stores

A common lab test to investigate your iron levels is to measure your serum ferritin.  Ferritin is a protein that binds iron so it can be stored in your body, and generally,  the number reflects your iron stores.  Except in the elderly.  A normal serum ferritin level doesn’t rule out an iron deficiency in the geriatric population.  Also, serum ferritin levels may increase in the presence  of inflammatory conditions, infections, cancer, or heavy alcohol use – giving you a false reading of your iron stores. When the available iron in your body can’t meet your physiological needs, your iron stores can be depleted.  This can happen because of:

1) insufficient iron intake or absorption, (even carnivores need to take heed of efficient absorption)

2) chronic blood loss, (common with certain chronic diseases, or even heavy menstrual periods)

3) increased physiological need for iron, (think pregnancy).

When looking at this lab test, you have to remember that it’s a snap shot in time – a series of measurements can give you a better picture of what’s going on, along with a good history-taking (dietary intake, symptoms, presence of medical conditions).

[There are also a few studies that tell us to suspect an iron deficiency in people with BEETURIA – the appearance of red/pink urine after eating beets! The beeturia typically resolves or decreases after supplementing with iron. In theory, iron and beet pigment share the same transport across the intestinal wall, and when you’re iron-deficient, the body compensates by increasing iron (and therefor, beet pigment) absorption. This pigment will then be removed in the feces, not the urine. Weird!]

Here are some general facts you should know when you’re thinking about iron supplementation:

Heme iron is much better absorbed than non-heme iron, about 15-30% absorbed, depending on your stores. It is found in animal products, so it’s off-limits to vegetarian/vegan dieters. Heme iron is a go-to for getting your stores to jump up quickly, and it’s absorption is not significantly affected by the foods you eat.

Non-heme iron can be found in plant foods and is the most common supplemental form.  It’s absorption ranges from 2-20%, and this absorption is significantly influenced by the foods that are churning around in your stomach with it. There are a variety of forms available on the shelf, and some forms are better than others in terms of absorption and side-effects.

Recommended dietary allowances in females are 18mg/day for 19-50 year-olds, and 27mg/day when pregnant.  In males, 8mg/day aged 19 and older is recommended.  You may need to consume more if taking any medication or food that interferes with absorption.  The amount of iron stored in your body also affects the way your you absorb iron.  It does get more complicated! This is why it’s best to consult with a health practitioner before grabbing something off the shelf.

The most common side-effects of iron supplements are constipation, nausea and abdominal discomfort. These symptoms are dose-related and vary with different forms of iron. Splitting your dose into smaller doses throughout the day, and taking your supplement after a meal can help curb some of the unpleasantness.  Taking the supplement with a meal may block some absorption.

Stomach acid increases the absorption of iron, so taking acid-blocking drug therapies for heart burn can decrease your absorption of iron. Iron also tends to bind certain antibiotics, osteoporosis and thyroid medications – so ask your doctor if you should separate the doses by a number of hours.

High doses of calcium and dairy can inhibit iron absorption. This may not make a difference if you aren’t deficient, but if you have low stores, I would avoid taking the two together.

Non-heme iron supplementation can compete with zinc and copper absorption!  According to Dr. Alan Gaby, you can get around this if you use smaller doses of of iron or zinc, or if you just separate the doses (if you use a high dose of both). Yes, ‘high’ and ‘low’ doses are vague – ask a knowledgeable practitioner if you are taking either of these, and if it would be a problem.

Iron-containing multivitamins tend to decrease the bioavailability of the iron. Vitamin C alone, has been found to enhance absorption of non-heme iron.  It does not make a difference for heme iron, which is complexed to a protein and is more efficiently absorbed.

The polyphenols in coffees, teas, wines and some fruits can significantly decrease non-heme iron absorption. Vitamin C can reverse some of these effects!

Phytic acid can significantly reduce non-heme iron absorption. Watch out vegetarians – phytic acid is found in grains, leafy greens, soy and other legumes. :(  Fermented soy are OK, however, and don’t affect absorption as much!

Blackstrap molasses is a rich source of bioavailable iron! At 2.3mg per tablespoon and 50-97% absorption of iron (compared to 2-20% for non-heme), this food has been used traditionally for pregnant women to increase their iron intake!


Gaby, Alan. 2011. Nutritional Medicine. Fritz Perlberg Punlishing: Concord, NH.
Natural Standard Professional Monograph, Copyright © 2012 (
Lab Tests Online. “Ferritin”

Disclaimer: The information provided here does not replace individualized treatment. A knowledgeable healthcare provider can provide you with particular dosages, expertise and an integrated plan to help you achieve your health goals.