Consumers and Health

Popeye, 90 years of spinach. ABCs of iron-rich foods

January 20, 2019

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On 1/17/19 ‘Popeye the Sailorman’ blew out its 90th candle, thanks to the comic strip art of Elzie Crisler Segar. Who convinced several generations that the iron in canned spinach was useful in carrying oxygen to ‘Popeye’s’ muscles. But this is not quite the case. Instead, here is the ABC of foods where the precious mineral is found, and its health benefits.

The iron in spinach

Spinach offers vitamins, folic acid, dietary fiber. However, the appreciable amount of iron in raw spinach (2.9 mg/100g) is not easily assimilated by our bodies.

In fact, the Istituto Superiore di Sanità (ISS) explains that ‘in foods, iron is present in two forms with different nutritional importance:

iron

heme,

more easily assimilated, found in meat and fish and linked to proteins, the

hemoproteins,
iron

non-eme

, of plant origin in inorganic form.

The difference between these two types of iron is in the different mechanism by which it is assimilated: iron

heme

is absorbed by highly specific sites in the intestinal mucosa and is not affected by the presence of substances that decrease (inhibitors) or increase (promoters) its assimilation; for iron

non-heme

there are no specific mechanisms, absorption is variable and is influenced by the presence of inhibitors or promoters’.

Iron, in what foods is it found?

Among foods of animal origin.

, the highest amounts of iron in heme form are found in:

– liver (18 mg per 100 g porcine, 12.6 sheep, 8.8 beef),

– fish (from 14.4 mg in corvina to 5.8 in mussels),

– beef (1.9 mg per 100 g in tenderloin, for example), pork (1.2 mg in 100 g steak, for example) and other species (1.7 mg skinless turkey drumstick, 1.4 chicken),

– Egg yolk (4.9 mg).

In plant-derived foods, however, the highest iron (non-eme) contents are offered by, among others:

– Fresh salads (green radicchio 7.8 mg per 100 g, rughetta 5.2),

– dried fruits and oilseeds (5.3 mg sunflower seeds and dehydrated apricots, 2.6 walnuts)

– Soybean meal (6.9 mg),

– dark chocolate (5 mg),

– Legumes (raw beans 8 mg, boiled 2 mg),

– Whole grains (uncooked brown rice 1.6 mg, boiled 0.5 mg).

The iron content

in foods, raw and cooked, can be checked by consulting CREA’s Food Composition Tables.

Iron from plants, how to promote absorption

I vegetarians and vegans especially-having excluded animal sources of iron (heme) from their diets-they need to pay attention to the food combinations they follow, so as to favor the absorption of iron (non-heme) contained in vegetables. Some brief recommendations to follow.

Lemons and citrus fruits

– and, more generally, sources of vitamin C-promote the body’s absorption of iron.

Conversely, the absorption of iron (non-heme) found in plant foods is negatively affected by the following factors:

– consumption in the same meal of foods that contain calcium (e.g., dairy products) and tannins (tea and coffee),

– presence of phytates (naturally occurring in grains and legumes), which can be neutralized by prolonged soaking in warm water with half a lemon.

Iron, what health benefits?

EFSA (
European Food Safety Authority
) has validated the scientific substantiation of a number of health benefits associated with dietary iron intake. Therefore, the European Commission has authorized the use of several ‘health claims‘ on products that are ‘sources of iron’. That is, solid foods that contain 2.1 mg per 100 g (or per serving, if the package contains only one serving), or half as much in the case of beverages. (1)

Iron contributes particularly to the following physiological functions of the human body:

– cognitive function,

– energy metabolism,

– formation of red blood cells and hemoglobin,

– Oxygen transport in the body,

– functioning of the immune system,

– Reduction of fatigue and fatigue,

– Iron intervenes in the process of cell division. (2)

Marta Strinati and Dario Dongo

Notes

(1) See reg. EC 1924/06 (‘Nutrition & Health Claims Regulation‘). For the purpose of definition , reg. EU 1169/11 (‘Food Information Regulation‘), Annex XIII, Part A, points 1 and 2

(2) Cf. reg. EU 432/12, consolidated text as of 2.8.17 at https://eur-lex.europa.eu/legal-content/IT/TXT/?qid=1547915547678&uri=CELEX%3A02012R0432-20170822

Marta Strinati

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Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".