Understanding Iron: What It Does and Why It Matters

Iron deficiency is the most common nutrient deficiency in the world, affecting an estimated 1.27 billion people globally. New Zealand is no exception, with the most recent national nutrition survey finding that more than one in seven women aged 31 to 50 had inadequate iron intakes, and that the prevalence of iron deficiency in women had more than doubled over the preceding decade.

Iron is involved in processes ranging from energy production to immune function - and if you’ve had bariatric surgery, there are additional reasons to pay close attention to your intake. In this article, we explore the role of iron, factors that impact absorption, and how to make informed decisions about your iron intake.

The role of iron in the body 

Iron has several roles in the body, and its influence is wider than many people realise. Its most well-known role is in oxygen transport. Iron is a key component of haemoglobin - the protein in red blood cells that picks up oxygen in the lungs and delivers it throughout the body. 

Beyond oxygen transport, iron contributes to:

• Energy production - iron plays a role in energy metabolism, which is why adequate iron intake is an important part of maintaining energy levels 
• Immune system function - your immune system relies on iron to function normally
• Cognitive function - iron contributes to normal cognitive function, including concentration and mental performance
• Cell division - iron is necessary for the normal process of cell division

How much iron do you need?

In New Zealand, the Recommended Dietary Intake (RDI) for iron varies depending on age, gender and life stage:

Women who menstruate are particularly susceptible to low iron, especially if periods are heavy. When you consider that the recommended daily iron intake for premenopausal women is more than double that of men, it is not hard to see why so many women struggle to get enough.

Factors that impact iron absorption

It’s important to understand that not all dietary iron is absorbed equally. There are two types of iron found in the food we eat: 

• Haem iron - found in animal foods like red meat, liver, poultry and seafood
• Non-haem iron - found in plant sources such as legumes, leafy greens and fortified cereals

Haem iron is more bioavailable than non-haem iron, meaning that it is more readily absorbed by the body. Non-haem sources of iron can still be valuable to include, and pairing with vitamin C rich foods may help to support the absorption of iron. 

There are also a few factors that can reduce iron absorption, including: 

• Tea and coffee - the tannins and polyphenols in tea and coffee may reduce iron absorption when consumed with meals. If iron intake is a concern, it may be worth having your tea or coffee between meals rather than with them
• Calcium - calcium-rich foods and supplements, while important for other reasons, compete with iron for absorption when consumed at the same time. It is generally suggested to separate iron and calcium supplements by at least two hours
• Phytates - found in wholegrains, legumes and some nuts, phytates can bind to iron and reduce how much the body absorbs. Preparation methods such as soaking or sprouting may help reduce phytate content

This doesn’t mean you need to avoid these foods altogether, but it may be worthwhile being mindful of timing and combinations, particularly if you know your iron intake needs extra attention. Working with a nutritionist can help to provide more specific guidance on this. 

Iron considerations after bariatric surgery

If you have had bariatric surgery, iron is one nutrient that may require more attention as there are a few changes that may impact your iron intake and absorption: 

• Smaller meal sizes - you are eating less food overall, which naturally means less opportunity to take in iron through your diet
• Changes to the digestive tract - some procedures alter the parts of the digestive tract where iron is typically absorbed, which can impact how efficiently the body takes up iron from food
• Reduced stomach acid - stomach acid helps the body absorb iron from food, and production is typically lower after surgery
• Dietary changes - some people eat less red meat after surgery due to tolerance changes, which may reduce haem iron intake

Even with a well-planned post-surgery diet, meeting your iron needs through food alone may require more thought and planning than you might expect. This is one of the reasons ongoing nutritional monitoring is generally considered an important part of post-bariatric care. 

How do you know if your iron intake is adequate?

The most reliable way to understand your iron status is through a blood test arranged by your nutritionist. Key markers typically assessed include ferritin (which reflects stored iron), haemoglobin, and iron saturation. How you feel day to day is influenced by many things, so blood tests provide a much clearer picture than guesswork.

It is also worth knowing that having too much iron can cause symptoms that overlap with having too little - including fatigue and brain fog. This is one of the reasons self-supplementing without knowing your levels is not recommended, and why a blood test is always the best starting point.

If you have not had your iron levels checked recently, it is worth having that conversation with your healthcare provider.

A note on supplementation

Not all iron supplements are the same, and finding the right one for your situation matters. The form, dose and timing of an iron supplement can all influence how well it works for you and how well you tolerate it.

Before starting or changing your iron supplements, it’s important to work with an experienced clinician who can take into account your dietary patterns, any surgical history, your relevant blood results, and advise on a supplementation routine that is appropriate for you.

Summary

Iron is an essential mineral that plays a variety of important roles in the body, particularly regarding oxygen transport and energy production. For women - and for anyone who has had bariatric surgery - paying attention to iron intake is an important part of your nutritional wellbeing.

If you have questions about your iron intake, a blood test is generally the best place to start. Once you know where your levels sit, you and your healthcare provider can work out the right next steps for you.

Tric Multi Vitamins with Iron

At Tric Nutrition, we offer multivitamins that include iron in two different strengths - 24mg and 60mg. If you have had bariatric surgery, we encourage you to work with your healthcare team to determine which option is most appropriate for you.

Browse our multivitamins

Always read the label and use as directed. If symptoms persist, see your healthcare professional. Vitamins and minerals are supplementary to and not a replacement for a balanced diet.

Bariatric Blood Reviews

If it's been a while since your bloods were checked, or you're unsure whether your supplement routine is right for your surgery type, Tailor Clinics offers bariatric blood reviews for any patients, regardless of where you’ve had surgery. If you’d like to find out more, contact reception@tailorclinics.co.nz  

References:

• Australian National Health and Medical Research Council & New Zealand Ministry of Health. (2017). Nutrient reference values for Australia and New Zealand. https://www.nrv.gov.au
• University of Otago & Ministry of Health. (2011). A focus on nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. Ministry of Health. https://www.health.govt.nz/publications/a-focus-on-nutrition-key-findings-from-the-200809-nz-adult-nutrition-survey
• Wang, L., Liang, D., Huangfu, H., Shi, X., Liu, S., Zhong, P., Luo, Z., Ke, C., & Lai, Y. (2024). Iron deficiency: Global trends and projections from 1990 to 2050. Nutrients, 16(20), 3434. https://doi.org/10.3390/nu16203434

The information in this article is general in nature and intended for educational purposes only. It is not a substitute for individualised medical or nutritional advice. Always consult your healthcare provider for guidance specific to your situation. Tailor Clinics is part of the same group as Tric Nutrition.