Iron in foods

Which foods contain the most iron?

The table below is translated from US Department of Agriculture (USDA) data in the NIH fact sheet. Servings are US measures: 3 ounces is about 85 g, 1 ounce is about 28 g, and 1 cup is about 240 mL. Values are rounded. ^[1]

One point needs attention when carrying the table over to Türkiye. The NIH states that flours are fortified with iron in the US and that about half of dietary iron comes from bread, cereal and other grain products; the bread and cereal values in the table may reflect this fortification. ^[1] In Türkiye, according to the 2020 report by Ministry of Health experts, a proposal for mandatory iron fortification of flour was forwarded to the Ministry of Agriculture and Forestry, but no regulation on this had been made as of the date of the report. ^[5] The iron content of bread and grain products in Türkiye is therefore understood from the value on the product label, not from the US table.

The “Type of iron” column in the table is based on the NIH’s general rule: plant foods and fortified products contain only nonheme iron; meat, seafood and chicken contain both. Because eggs are not mentioned separately in this general rule, they are not classified in the table.

Why do heme and nonheme iron matter?

According to the NIH, heme iron is absorbed better than nonheme iron and is less affected by other components of the meal. In a Western-type diet, about 10–15% of total iron intake is heme iron. Iron absorption is about 14–18% in a mixed diet containing substantial amounts of meat, seafood and vitamin C, and 5–12% in a vegetarian diet. ^[1]

This difference shows that the milligram values in the table cannot be compared directly: the amount that passes into the body from a serving of meat containing 2 mg of iron and from a serving of chickpeas containing 2 mg of iron is not the same.

Which foods increase and decrease absorption?

According to the NIH summary: ^[1]

• Enhancers: Vitamin C (ascorbic acid) and meat, poultry and seafood increase nonheme iron absorption.
• Inhibitors: Phytate in grains and legumes and polyphenols in some plant foods reduce nonheme iron absorption.
• Calcium: Unlike the other inhibitors, it can reduce absorption of heme iron as well as nonheme iron; this effect has not been conclusively proven.

The NIH also states that in a typical Western-type diet these enhancing and inhibiting effects are weakened, so they change the iron status of most people only slightly. ^[1]

How much do tea and coffee reduce iron absorption?

Hurrell and colleagues compared absorption of radiolabeled iron from a bread meal in adults with different beverages drunk with the meal. All beverages containing polyphenols reduced iron absorption, depending on their total polyphenol content. The reduction in absorption relative to water was 79–94% for black tea, 84% for peppermint tea, 71% for cocoa and 47% for chamomile tea. Coffee was also a strong inhibitor. Adding milk to tea and coffee changed this effect very little or not at all. ^[2]

This result matters because black tea is a common part of the daily diet in Türkiye. However, the study measured absorption at a single meal; it did not measure whether drinking tea leads to iron deficiency in the long term. The result is read together with the NIH assessment that these effects are weakened in a mixed diet. The timing of tea and coffee for people with iron deficiency or on iron treatment is covered separately.

Is spinach really an iron store?

Boiled spinach contains about 3 mg of iron in half a cup; this is at the same level as the lentils and tofu in the table. The NIH, however, states that some plant foods such as spinach seem to be good sources of iron but their iron is poorly absorbed because of polyphenols that reduce iron absorption. ^[1] That is, spinach contains iron, but its reputation as the “best source of iron” is exaggerated relative to its content.

Does cooking in an iron pot help?

The systematic review by Alves and colleagues covered 11 studies in low- and middle-income countries examining iron cookware, or iron pieces placed in the pot during cooking, in children and women of reproductive age. Significant increases in hemoglobin or iron indicators were seen in half of the cookware studies (4 of 8) and one third of the iron-piece studies (1 of 3). Positive results were reported in 4 of the 8 studies in children and 2 of the 7 studies in women. The proportion using the cookware every day ranged between 26.7% and 71.4%. ^[3]

The authors state that, with reasonable use, this method may help reduce iron deficiency anemia, particularly in children, but that more research is needed for efficacy and safety. These studies were conducted in countries where iron deficiency is widespread; whether the same result would occur in a kitchen in Türkiye is not known. ^[3]

Iron in vegetarian and vegan diets

The NIH reports that the iron requirement of vegetarians is 1.8 times higher than for a diet containing meat. The reason is that heme iron in meat is absorbed better than nonheme iron in plant foods, and that meat, poultry and seafood also increase nonheme iron absorption. ^[1]

The prominent elements among sources of iron in a plant-based diet are iron-containing foods such as legumes, tofu, nuts and fortified grains, and vitamin C, which increases absorption. The NIH table shows that lentils, chickpeas, beans and tofu can provide 2–8 mg of iron per serving. ^[1] A food list, however, does not show a person’s iron status; the status is understood only with blood tests such as ferritin and hemoglobin.

Daily requirement and intake in Türkiye

According to the 2015 EFSA opinion, the population reference intake (PRI) is 11 mg per day for adult men and postmenopausal women and 16 mg for premenopausal women. In calculating these values, EFSA assumed an absorption of 16% in men and 18% in women from a mixed Western-type diet. ^[4] The US values reported by the NIH are 8 mg for men and 18 mg for women aged 19–50. ^[1]

The 2020 report by Ministry of Health experts reports that in the Türkiye Nutrition and Health Survey (TBSA) 2010, iron intake in women fell below the requirement in almost every age group starting from ages 2–5. According to the report, in TBSA 2017, the iron intake of 66.4% of individuals aged 15 and over was below the EFSA reference values. ^[5] These proportions are based on food intake; intake below the reference does not mean every individual has iron deficiency, but it is a reason to review the diet for iron.

This page provides nutrition information; diagnosed iron deficiency or anemia is corrected not by food alone but with a treatment planned by a physician.