By Deborah Freudenmann, BHSc Naturopathy
If you’ve ever started an iron supplement and ended up feeling bloated, constipated, or stomach pain… you’re not imagining it. I can’t tell you how many women I’ve met who’ve tried iron tablets and were left feeling worse.
Iron deficiency is the most common nutrient deficiency in the world, and women are right at the centre of it. Between menstrual blood loss, pregnancy, and the demands of our reproductive years, many of us live in an ongoing state of depletion.
For decades, the advice has been simple “take an iron supplement”. But is it that simple?
Up to 40% of women experience gut side effects and often stop before their levels are restored.
So, what’s really happening here?
The functional medicine lens: why iron drops in the first place
Low iron is almost never a standalone issue.
In functional medicine, iron deficiency is a message from the body, not just a number on a test. It’s often the end result of a chain of imbalances like low stomach acid, inflammation, nutrient deficiencies, or chronic loss.
Heavy periods, fibroids, or endometriosis can cause constant losses. Low stomach acid in women under stress or on restrictive diets can make absorption difficult. Gut inflammation, celiac disease, or H. pylori infection can all block uptake, and postpartum depletion adds another layer.
Even inflammation itself can hide iron from the bloodstream. Ferritin the storage form of iron rises when the body is inflamed, giving the illusion of “normal” iron stores even when cells are starving for oxygen.
Infections are also key hidden driver of chronic low iron. This happens because iron is both a nutrient and a weapon… microbes need it to thrive, so your immune system hides it during infection. While this helps protect you short-term, chronic or low-grade infections can lock iron away long-term, leaving cells starved of oxygen and energy.
This is where functional testing matters. Ferritin alone rarely tells the full story. Looking at serum iron, transferrin saturation, total iron-binding capacity (TIBC), and CRP (C-reactive protein) or ESR (Erythrocyte Sedimentation Rate) both to be able to detect inflammation, give a clearer picture of what your body is doing.
Iron deficiency is rarely about a lack of iron itself it’s about the terrain it lives in. Context, absorption, inflammation, and demand all shape how your body uses what you give it.
Why synthetic iron is so hard on the gut
Most prescription and over-the-counter tablets use ferrous sulfate, a cheap, synthetic form that rarely feels good in the body. Only about 10 - 15% is absorbed the rest lingers in the gut, irritating the lining, feeding unwanted bacteria, and sparking oxidative stress. Doesn’t sound good, does it?
This is why so many women notice bloating, constipation, or nausea soon after starting. That unabsorbed iron disrupts digestion, slows motility, and fuels inflammation in the very place we need calm the most, the gut.
And sooo, the very supplement that’s supposed to restore energy ends up stealing it. It’s not that your body rejects iron, it’s rejecting the form it’s given.
Gentler forms that actually work
If you’ve ever given up on iron tablets because they made you feel worse, there’s good news, not all forms behave the same way.
Food first, always. Wholefood sources like liver (or liver capsules) are nature’s most balanced form of iron, they’re not isolated minerals, but concentrated foods rich in vitamin A, copper, and B vitamins that help your body use iron effectively. Liver supports the entire process of red blood cell formation, not just the iron component.
When supplementation is still needed, certain forms are far gentler than standard tablets. Heme iron polypeptide (HIP), derived from animal sources, closely mimics how we absorb iron from food, making it one of the most bioavailable and gut-friendly options.
Iron bisglycinate is another excellent choice as it’s bound to the amino acid glycine, which helps protect the gut lining, enhances absorption, and dramatically reduces side effects.
Why food-based iron feels different
Iron from real food particularly heme iron from meat or liver is absorbed two to three times better than the non-heme form in plants or synthetics. But it’s not just about the form; it’s the synergistic “whole” of it all.
In food, iron is surrounded by natural cofactors that help your body recognise and use it, such as copper to transport it, vitamin A to release it from the liver, and B vitamins to build hemoglobin and energy.
That’s why a small, consistent increase in nutrient-dense foods; a little red meat, a few bites of liver, or wholefood powders can have such a noticeable impact. You’re not just topping up a mineral; you’re replenishing the whole system that depends on it.
How to support absorption naturally
Small daily habits make all the difference:
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Pair iron-rich meals with vitamin C like citrus, kiwi, capsicum it can triple absorption
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Eat protein alongside iron to support stomach acid production
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Avoid tea, coffee, or calcium close to meals; they bind to iron!
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Nourish your gut with collagen, bone broth, and fermented foods to strengthen absorption
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Go steady, not heavy; smaller, regular doses are easier to tolerate than one large hit
Different stages, different needs
Iron requirements shift as we move through life.
In our teens and twenties, growth and cycles raise demand. Pregnancy and postpartum deplete it. In perimenopause, heavier bleeding can make deficiency flare again, while after menopause, the risk flips and iron overload becomes more likely if we keep supplementing out of habit.
That’s the beauty of functional health; your needs aren’t static, and that’s why your approach shouldn’t be either.
Where Chief Nutrition fits in
Not everyone loves liver (I get it). That’s why finding real-food sources that feel practical matters.
Chief Nutrition’s range brings the “food-first” approach to everyday life.
The Chief Liver Capsules are made from 100 % grass-fed beef liver one of the richest natural sources of heme iron, vitamin A, copper, and B vitamins. Unlike synthetic supplements, they provide iron in its complete, biologically active form alongside the very cofactors your body needs to use it.
For those who prefer food itself, Chief’s Biltong offers another beautiful, natural source of heme iron and complete protein an easy way to nourish and rebuild your stores without the digestive side effects that often come with tablets.
This is what “functional nutrition” really means supporting the whole system rather than isolating a single nutrient.
Final thoughts
The problem isn’t that women can’t tolerate iron it’s that we’ve been given the wrong kind: isolated, synthetic, and out of sync with how our bodies were designed to absorb.
When you choose forms your body recognises like natural beef liver and nourish your gut and hormones along the way, iron stops being a struggle.
References
Tolkien Z, Stecher L, Mander AP, Pereira DI, Powell JJ. Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis. PLoS One. 2015 Feb 20;10(2):e0117383. doi: 10.1371/journal.pone.0117383. PMID: 25700159; PMCID: PMC4336293.
Li H. Iron and the Intestinal Microbiome. Adv Exp Med Biol. 2025;1480:345-360. doi: 10.1007/978-3-031-92033-2_22. PMID: 40603801.
https://www.health.tas.gov.au/sites/default/files/2021-11/High_Iron_Foods.pdf
Milman N, Jønsson L, Dyre P, Pedersen PL, Larsen LG. Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy in a randomized trial. J Perinat Med. 2014 Mar;42(2):197-206. doi: 10.1515/jpm-2013-0153. PMID: 24152889.
Hallberg L, Brune M, Rossander L. The role of vitamin C in iron absorption. Int J Vitam Nutr Res Suppl. 1989;30:103-8. PMID: 2507689.
Monsen ER. Iron nutrition and absorption: dietary factors which impact iron bioavailability. J Am Diet Assoc. 1988 Jul;88(7):786-90. PMID: 3290310.
