Iron

Definition

Iron (Fe) is part of the family of mineral salts. Iron exists in two forms in the body: the iron associated with hemoglobin, also known as 'heme iron' (70%) and "non-heme iron" (30%), which is its stored form.

Role in the body

Iron plays an essential role in many biological functions.

• Tissue oxygenation: it helps to create hemoglobin (a molecule found in red blood cells that transports oxygen to tissue) and myoglobin (a molecule in muscle cells in which muscle oxygen is stored)
• Numerous metabolic reactions: it helps to create essential enzymes.

Sources in vegetables and other foods

Source: Ciqual

Foods with the highest iron content	mg/100g
Cooked black pudding/blood sausage	22
Roasted pigeon meat	20
Lamb liver, clams	14
Cocoa powder, stewed rabbit, chicken liver	10-12
Cooked kidneys, soya flour, pheasant, dried lentils	8-9
Mussels, wheat germ, dried white beans, roasted pistachio	7-8
Foie gras, sunflower seeds, oysters, calf's liver, enriched cornflakes, pâté de campagne, fresh parsley, roast venison, wheat, dried apricot, cashew nuts, Muesli	5-6
Almonds, oatmeal, whelks, horse meat, hazelnuts, roast beef, wholegrain flour, boiled beef, cooked prawns, cooked lentils, dandelion, steak, dried dates	3-4

In addition to the overall quantity of iron found in foods, its bioavailability must be considered as well. In general, the iron contained in plants and dairy products (non-heme iron) is less bioavailable, i.e., not as readily absorbed by the body, than the iron in meat products (heme iron). However, some factors make non-heme iron more bioavailable, such as the presence of Vitamin C in the rest of the meal. In France, 75% of all iron consumed is provided by plant-based foods and by milk and its derivatives, while 25% is provided by meat and fish.

Recommended intake

The RDA (Recommended Daily Amount) of iron is 14 mg/day. The RNAs (Recommended Nutritional Allowances) are given for the French public by age bracket in mg/day.

Age bracket	RNA in mg/day
Ages 1-3	7 mg
Ages 4-9	7 mg
Ages 10-12	8 mg
Boys, ages 13-19	12 mg
Girls, ages 13-19	14 mg
Adult men	9 mg
Menstruating women	16 mg
Menopausal women	9 mg
Pregnant women	25-35 mg
Nursing women	10 mg

Deficiency / Excess

In France, average daily iron intake is 16.7 mg in men aged 45 to 60 and 12.3 mg in women aged 35 to 60 (SUVIMAX study). That same study revealed that 23% of women of childbearing age have inadequate stores of iron (compared with just 5% of menopausal women), and 4.4% have such low levels of iron that they are at risk of iron deficiency anaemia. At advanced stages, iron deficiency can lead to anemia, i.e., lower concentrations of hemoglobin in the blood. More moderate iron deficiency can result in reduced exercise capacity and diminished intellectual performance, lower resistance to infections, problems during pregnancy, etc. Excess iron can be harmful as well, particularly if Vitamin C is present, in which case it can increase oxidative stress and the spread of free radicals (molecules responsible for aging and certain diseases).

Disadvantage

Only a fraction of the iron we consume is actually absorbed by the intestine (and passes into the bloodstream). Approximately 25% of the iron in meat products, and only 10% of the iron in plants and dairy products, is absorbed. But these percentages will depend on the body's needs: the more your body is lacking in iron, the greater the rate of absorption. These absorption rates may rise or fall depending on the overall composition of the meal.

Tips / advice from the nutritionist

Combine dried vegetables that provide a source of iron (lentils, chickpeas, dried beans) with vegetables that are high in Vitamin C (parsley, peppers, broccoli, etc.), to help your body absorb the iron more efficiently.

To learn more

Site of the French Food Safety Agency (AFSSA)