Iron is a fundamental nutrient vital for overall health and well-being. It is key in essential bodily functions, including oxygen transport, energy production, and immune system support[1]. As a critical component of haemoglobin, iron ensures that oxygen reaches every cell in the body, fuelling physical and cognitive activities[2]. Despite its importance, many people struggle to meet their daily iron needs, leading to potential health challenges.
According to the NHS, the recommended daily iron intake varies by age and gender, with adult men requiring 8.7mg and women needing 14.8mg per day due to the additional demands of menstruation[3]. Children and adolescents also have varying requirements, emphasising the need for balanced nutrition during growth stages.
In this blog, we explore the factors that enhance and inhibit iron absorption, the types of dietary iron, and practical tips to optimise iron uptake.
Key Takeaways
- • Vitamin C (e.g., oranges, broccoli), vitamin A, beta-carotene (e.g., carrots, spinach), and pairing with animal-based foods can significantly improve iron bioavailability.
- • Polyphenols (tea, coffee), phytates (whole grains, nuts), calcium (dairy), and excess fibre can hinder absorption. Adjusting meal timing and preparation methods helps counteract these effects.
- • Pregnant and menstruating women, vegetarians, children, adolescents, older adults, and individuals with absorption issues (e.g., coeliac disease) should prioritise optimising iron intake.
Types of Dietary Iron
1. Heme Iron
Heme iron is derived from animal-based sources and is easily absorbed by the body[4].
Common Sources of Heme Iron[4]:
- • Lean red meat
- • Poultry (e.g., chicken, turkey)
- • Fish (e.g., salmon, tuna)
2. Non-Heme Iron
Non-heme iron comes from plant-based sources and is less readily absorbed by the body[4].
Common Sources of Non-Heme Iron[4]:
- • Leafy green vegetables (e.g., spinach, kale)
- • Legumes (e.g., lentils, chickpeas, beans)
- • Nuts and seeds (e.g., almonds, pumpkin seeds)
- • Fortified cereals and bread
Bioavailability of Heme vs Non-Heme Iron
The bioavailability of heme iron is approximately 15-35%, while non-heme iron has a much lower absorption rate of 2-20%[5]. This difference occurs because heme iron is absorbed directly into the bloodstream through the small intestine. In contrast, non-heme iron requires conversion into a soluble form during digestion[6], which can be influenced by dietary factors.
Factors That Enhance Iron Absorption
1. Role of Vitamin C
Vitamin C plays a crucial role in iron absorption by converting non-heme iron into a more soluble and absorbable form[7]. Including vitamin C-rich foods alongside non-heme iron sources can significantly boost uptake.
Examples of Vitamin C-rich foods[8]:
- • Fruits: Oranges, strawberries, and kiwis
- • Vegetables: Bell peppers, broccoli, and tomatoes
Tip: Pair non-heme iron foods, such as lentils or spinach, with a squeeze of lemon juice or a serving of orange slices for enhanced absorption.
2. Foods with Vitamin A and Beta-Carotene
Vitamin A and beta-carotene improve iron bioavailability by facilitating its transport and utilisation in the body[9]. Adding foods rich in these nutrients to your diet can optimise iron absorption.
- • Foods Rich in Vitamin A: Liver, eggs, and dairy products[10].
- • Foods Rich in Beta-Carotene: Carrots, sweet potatoes, and dark leafy greens[11].
Tip: Pair an iron-rich meal with a side of sautéed carrots or spinach cooked in olive oil to maximise absorption.
3. Pairing with Animal-Based Foods
Heme iron, found in animal-based sources like meat, poultry, and fish, can enhance the absorption of non-heme iron when consumed together[4]. Combining these iron sources creates a synergistic effect, improving overall iron uptake.
Tip: Add grilled chicken or fish to a salad with spinach and lentils for a well-balanced, iron-boosting meal.
4. Cooking Methods
The way you prepare food can impact its iron content and bioavailability. Using cast iron cookware can increase the iron content of your meals[12], especially when cooking acidic foods like tomato-based dishes.
Tips for Cooking:
- • Use cast iron pots and pans to enrich meals with iron naturally.
- • Avoid overcooking iron-rich vegetables, as prolonged heat can diminish their nutrient content. Opt for steaming or sautéing instead to retain maximum benefits.
Factors That Inhibit Iron Absorption
1. Polyphenols
Polyphenols are natural compounds in tea, coffee, wine, and certain plant foods that can hinder iron absorption, especially non-heme iron[13]. Consuming these beverages or foods near mealtimes can significantly reduce the amount of iron absorbed by the body.
Tip: Avoid drinking tea or coffee with meals. Instead, enjoy these beverages between meals to minimise their impact on iron uptake.
2. Phytates
Phytates, present in whole grains, nuts, seeds, and legumes, are known to bind to iron and other minerals, reducing their bioavailability[14]. While these foods are nutritious, their phytate content can inhibit iron absorption if not managed properly.
Tips to Reduce Phytates:
- • Soak grains, nuts, and legumes before cooking to reduce phytate levels[15].
- • Try sprouting or fermenting foods to enhance their nutritional value and improve iron absorption[16].
3. Calcium
Calcium, found in dairy products and fortified foods, competes with iron for absorption in the digestive tract[17]. This competition can diminish iron uptake efficiency when consumed with iron-rich foods.
Tip: Schedule calcium-rich foods or supplements at a different time from iron-rich meals to maximise the absorption of both nutrients[18].
4. Excess Fibre
While fibre is essential for digestive health, excessive intake can interfere with iron absorption by binding to iron in the digestive system, making it less available for the body to use[19].
Tip: Maintain a balanced fibre intake and pair high-fibre foods with absorption enhancers like vitamin C or heme iron sources to counteract this effect.
By being mindful of these factors and adjusting meal timings or preparation methods, you can optimise iron absorption and support overall nutritional health.
Who Needs to Focus on Iron Absorption?
Certain groups are at a higher risk of iron deficiency and should prioritise improving iron absorption:
- • Pregnant and Menstruating Women: Increased iron needs during pregnancy and blood loss during menstruation require enhanced intake[20].
- • Vegetarians and Vegans: Relying on non-heme iron necessitates pairing with absorption enhancers like vitamin C[13][21].
- • Children and Adolescents: Rapid growth increases iron requirements for development and cognitive health[1].
- • Individuals with Absorption Issues: Conditions like coeliac disease or Crohn’s disease impair iron uptake[1].
Iron Supplements: When Diet Isn’t Enough
For individuals struggling to meet their iron requirements through diet alone—such as pregnant women, vegetarians, or those with absorption issues—iron supplements can be a valuable addition. Supplements are available in various formats, including iron tablets liquids, and gummies, tailored to meet different needs. However, it’s crucial to take supplements under medical supervision to avoid side effects like constipation, stomach pain or iron toxicity[3]. Pairing supplements with vitamin C can further enhance absorption, ensuring maximum benefits.
Conclusion
Iron is essential for maintaining energy, cognitive function, and overall well-being, but optimising its absorption is key to addressing deficiencies effectively. Enhancing iron uptake through small changes—like pairing iron-rich foods with vitamin C, reducing inhibitors like phytates, or using cast iron cookware—can significantly improve iron levels.
For those unable to meet their requirements through diet alone, supplements offer an effective alternative. Always seek medical advice before starting supplementation to ensure safe and effective use.
Explore high-quality iron supplements from trusted brands at Nature’s Fix to support your optimal health and well-being journey.
FAQs
1. What foods improve iron absorption?
Vitamin C, A, and beta-carotene-rich foods like oranges, carrots, and spinach boost iron absorption[7][9]. Pair them with iron-rich foods for better uptake.
2. What inhibits iron absorption?
Polyphenols (in tea/coffee), phytates (in whole grains/nuts), and calcium can hinder iron absorption[13][14][17]. Avoid consuming these with iron-rich meals.
3. Can supplements improve iron absorption?
Iron supplements boost levels, especially when paired with vitamin C[22]. Always take them under medical guidance to ensure safe use.
4. What are the side effects of iron?
Common side effects of iron include constipation, feeling sick or stomach pain [3]. Excessive intake may lead to toxicity. Stick to recommended dosages to avoid complications.
References
1 – https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
2 – https://www.ucsfhealth.org/education/hemoglobin-and-functions-of-iron
3 – https://www.nhs.uk/conditions/vitamins-and-minerals/iron/
4 – https://www.redcrossblood.org/donate-blood/blood-donation-process/before-during-after/iron-blood-donation/iron-rich-foods.html
5 – https://pubmed.ncbi.nlm.nih.gov/3290310/
6 – https://pmc.ncbi.nlm.nih.gov/articles/PMC2725368/
7 – https://www.ncbi.nlm.nih.gov/books/NBK448204/
8 – https://www.healthline.com/nutrition/vitamin-c-foods
9 – https://pubmed.ncbi.nlm.nih.gov/9482776/
10 – https://www.healthline.com/nutrition/foods-high-in-vitamin-a
11 – https://www.mountsinai.org/health-library/supplement/beta-carotene
12 – https://appetise.io/blog/does-cooking-with-cast-iron-boost-iron-intake
13 – https://www.ncbi.nlm.nih.gov/books/NBK448204/
14 – https://www.healthline.com/nutrition/phytic-acid-101
15 – https://www.healthline.com/nutrition/how-to-reduce-antinutrients
16 – https://www.medicalnewstoday.com/articles/322336
17 – https://pubmed.ncbi.nlm.nih.gov/21462112/
18 – https://www.ncbi.nlm.nih.gov/books/NBK56060/
19 – https://www.medicalnewstoday.com/articles/321286
20 – https://pmc.ncbi.nlm.nih.gov/articles/PMC5748777/
21 – https://pmc.ncbi.nlm.nih.gov/articles/PMC6367879/
22 – https://www.ncbi.nlm.nih.gov/books/NBK557376/
