Nutrient Spotlight on Iron

This post is part of the series Nutrient Spotlight... meant to explore the what, why, where, and how of important dietary players, with some culinary inspiration to get you started.

This edition of Nutrient Spotlight highlights iron — an essential mineral found in every cell of the human body.

What is it? // Why do I need it?

Iron functions primarily as a carrier of oxygen in the blood, increasing blood supply and promoting tissue growth. Iron also provides energy, and plays supporting roles in immune health, promoting strong hair, skin and nails, as well as female fertility. It is crucial a woman increases iron stores prior to pregnancy, as the female body often uses its own iron to supplement the growing baby, putting the woman at risk of postpartum anemia. Low maternal levels may also increase risk of infections, preterm delivery + low infant birth weight.

Additionally, adequate iron levels help protect against lead absorption, and can help mitigate the effects for those exposed to lead. In conjunction with a diet rich in calcium and vitamin C — two nutrients that improve iron absorption — the body is able to not only limit the absorption of lead but also promote its excretion.

Iron deficiency is not uncommon in the United States, affecting as much as 7% of the population. Symptoms of deficiency include fatigue, dizziness, lightheadedness, fast heart rate or sensation of an abnormal heartbeat, shortness of breath, brittle nails, pallor, or a craving for ice and, in severe cases, for other “non-foods” like detergent, chalk, dirt – a disorder called pica. (Learn about the many different types of anemia from the Mayo Clinic.)

Excess iron, from diet and/or supplementation, may cause constipation or result in other forms of mild to serious GI distress. Extremely high iron levels are not too common, but may raise disease risk, most dangerously for a genetic disorder called hemochromatosis (if predisposed), coma or worse.

Where can I find it?

There are two forms of dietary iron: heme iron from animal foods + non-heme iron from plant foods. Heme iron is the richest and most readily utilizable form. While many plant foods rank highly in terms of total amount of iron, the human body is far less efficient at absorbing non-heme iron – between 3 and 15% of what’s available (compared to about 25% for heme iron).

Animal sources of heme iron include lean beef + beef liver, chicken, turkey breast, lean pork and hard-boiled egg. High amounts of iron are present in several types of seafood, notably cooked oysters, canned sardines, and canned light tuna.

Plant-based sources of non-heme iron include spinach, Swiss chard and other dark leafy greens, white and kidney beans, chickpeas, lentils, tofu and edamame, cashews and pistachios, sesame seeds and pepitas, whole grains and whole grain bread, fortified cereal and enriched rice, green peas, broccoli, skin-on potato, dried figs and raisins, dark chocolate, and blackstrap molasses.

There are a few additional things you can do diet-wise to maximize absorption + utilization:

+ Combine iron-rich foods with those high in vitamin C (e.g., red/orange/yellow produce + spices like turmeric).
+ Take caffeinated beverages + high-calcium foods/MVIs/supplements (including antacids) between instead of with meals, as caffeine + calcium inhibit absorption, OR consider adding vitamin C-rich foods to offset some inhibition.
Phytate, or phytic acid, a compound common in whole grains, legumes, nuts and seeds, may decrease absorption. Some minimization of effects comes through soaking, sprouting or toasting these ingredients. Additionally, choose grain products that rise through yeast or sourdough fermentation, e.g., bread instead of crackers.
+ Soybeans also contain compounds that bind to iron and therefore lower iron absorption. However, iron in soy-based foods appears to be in a form that makes it well-absorbed and therefore not an issue.
+ The jury is still out on whether or not oxalate, or oxalic acid — common in spinach, collards, tomato, pineapple and figs, beans, olives, beets, carrots and celery, rhubarb, and all types of potatoes — is a factor for iron absorption. Research as yet shows little to no inhibition related to oxalate; more so an issue for calcium absorption. That said, it still bears keeping in mind if you have low iron.

Otherwise in the kitchen, cooking in cast-iron cookware, especially with acidic ingredients (such as tomato, citrus fruits, pineapple, vinegars or apple cider), actually gives you a bump of natural iron — up to 20% more!

+ Smoky braised collards (GF + V)
Creamy carrot red lentil soup with crunchy almond-coconut dukkah (GF + V)
+ Smoky Ethiopian lentils (GF + V)
+ Chana dal with spinach, cucumber and pomegranate arils (GF + V)
+ Sunny yellow chopped salad with chickpeas (GF + V)
Raw celeriac salad with chickpeas and lemon-thyme vinaigrette (GF + V)
+ Besan/chickpea flour crackers OR Fresh herb besan crackers OR Socca (besan flour) flatbread (GF + V)
Calzones with Cretan braised greens (V)
+ Garden glut succotash with barley, basil and poached eggs
+ Shortcut ravioli with peas, spinach, mint and ricotta + brown butter spinach pan sauce (V)
+ Grilled beef tri-tip, corn and pickled cherry (romaine) salad (GF)
+ Composed Thai steak salad (GF)
+ Herb and onion all-meat (beef) balls (GF)
+ Salmon en papillote with Swiss chard, zucchini and tomato (GF)
+ Smoked salmon kedgeree with spinach, green peas, leek and Basmati rice (GF)
+ Hiyayakko — Japanese cold tofu (GF + V)
+ Dark chocolate (flourless) stout torte (GF)
+ Pumpkin granola with cashews and dried fruit (GF + V)
+ Golden (milk) bites (GF + V)
+ Multi-grain and seed English muffins

How much do I need?

The guidelines below reflect the needs of adults, including the increased needs during conception, pregnancy, and breastfeeding. (Recommendations for infants, children and teens here.)

Adult Men (19-50 years old): 8 mg per day
Adult Women (19-50): 18 mg per day
All Older Adults (51+): 8 mg per day
Pregnant Adult Women: 27 mg per day
Breastfeeding Adult Women
: 9 mg per day

Consuming enough iron can be difficult for some groups. A daily supplement* may be required to meet the recommended intake if you:

+ are vegan or vegetarian;
+ are a pre-menopausal female currently having menstrual periods, especially those with heavy losses;
+ are an athlete, especially if female, a youth, and/or an endurance athlete;
+ regularly donate blood;
+ have cancer, especially if undergoing chemotherapy;
+ have a GI disorder, such as Celiac disease, ulcerative colitis or Crohn’s, or have undergone certain GI surgical procedures, including intestinal resection or gastrectomy;
+ have chronic heart failure.

The tolerable upper limit** (UL) for men + women 14 years of age or older is currently set at 45 mg per day of iron.

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A well-planned diet, even vegetarian or vegan, can meet the nutrient needs** of people from all stages of life, including competitive endurance athletes. All it takes is a little diligence in menu planning.

Cheers, Heather

Tell me… What are your main sources of iron? Do you find it difficult to get enough?

*If supplementation for iron is warranted, be aware that most gummy vitamins do not contain any or adequate amounts of iron – look for chewable or swallow-able vitamins, and always discuss supplementation with your physician before beginning.

**Prior to beginning any new vitamin or mineral supplement regime, always consult first with your physician to check blood levels and discuss potential interactions, as well as a Registered Dietitian Nutritionist to check your current diet to further assess needs.

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Check out my downloadable nutrition guides!

p.s. I love hearing from you! Check back if you ask a question, because I’ll answer it here.

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From the Author Get Schooled Nutrient Spotlight


    • Heather Goesch, MPH, RDN, LDN says:

      Interesting. I wasn’t aware that eating iron-rich foods, such as red meat or raisins (or for a smaller amount of the mineral, dark chocolate), would offset any potential “side effects” of donating blood! My thought was simply to hydrate well the day before. Good to know, thanks… and thank you for donating!

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