Nutrition Library

Iron

General Information
  • Iron is an important trace element and is of central importance in human metabolism.
  • According to WHO, iron deficiency (and thus anemia) is the most common nutrient deficiency worldwide.
  • Iron deficiency and iron deficiency anemia are also common in Western industrial nations, especially among children, women of childbearing age, and pregnant women. Statistics are similar for Europe and the United States.
  • Iron is therefore a critical nutrient for these groups and requires greater nutritional attention. This is true even for those eating an omnivorous diet with animal products.
  • Iron is predominantly present in plant-based foods in the trivalent form (Fe3+, non-heme iron), which has limited bioavailability (approx. 10%). However, iron absorption, which requires conversion of iron into its divalent form (Fe2+), can be significantly increased by combining it with vitamin C (which quadruples iron absorption), citric acid, or beta-carotene.
Why Do We Need Iron?
  • Central role in oxygen transport (70% of iron is contained in hemoglobin and myoglobin)
  • Important for cellular energy generation
  • Supports the immune system
      • Important for DNA synthesis
      • Cofactor of some enzymes and has a share in antioxidative processes
      • Fatty acid synthesis
      Possible Reasons for Iron Deficiency

      Low intake:

      • Diet contains few iron-containing foods (see below)

      Increased intake requirements:

      • Childhood, growth, pregnancy, lactation
      • Blood loss (menstruation, frequent blood donation, injury)
      • Competitive sports

      Reduced absorption due to:

      • Gastrointestinal disorders such as gastritis, inflammatory bowel disease, celiac disease
      • Polyphenols (high coffee/tea consumption)
      • Simultaneous intake of magnesium, calcium, or zinc
      • High intake of oxalic or phytic acid (cereals, soy products)
      • Interaction with medication (impairs iron absorption/utilization): e.g., antacids, aspirin, bisphosphonates, laxatives, paracetamol/acetaminophen

      Important to know:
      Polyphenols, such as phytic acid and oxalic acid, also have positive properties that are important for the body. For example, phytic acid also has an antioxidant effect, strengthens the immune system, and has a positive effect on blood sugar. Polyphenols also have antioxidant and anti-inflammatory properties, so it’s the quantity that matters.

       

      Symptoms of Deficiency
      • General: fatigue, decreased performance, lack of concentration, sensitivity to cold
      • Skin/hair: pale skin, hair loss, brittle nails
      • Cardiovascular system: cardiac arrhythmia, dizziness, shortness of breath under stress
      • Immune system: susceptibility to infections
      • Mucous membranes: angular cheilitis, glossitis (tongue burning), atrophy of the mouth/nasal mucosa
      • Pregnancy: increased risk of miscarriage and premature birth
      Recommended Intakes

      Recommended intake for adults:

      • German/Austrian/Swiss recommendation (D-A-CH): premenopausal women 15 mg/day, postmenopausal women 10 mg/day, men 10 mg/day
      • USA Food and Nutrition Board (FNB): premenopausal women 18 mg/day, postmenopausal women 8 mg/day, men 8 mg/day

      Pregnant women:

      • according to D-A-CH: 30 mg/day
      • USA Food and Nutrition Board (FNB): 27 mg/day

      Breastfeeding women:

      • according to D-A-CH: 20 mg/day
      • USA Food and Nutrition Board (FNB): 9 mg/day

      Children and adolescents depending on age:

      To improve the bioavailability of iron from plant-based foods, it is important to combine them with foods rich in vitamin C (e.g., citrus fruits, peppers, potatoes, cabbage, spinach, tomatoes, black currants, etc.)

        The Best Plant Sources (per 100 g)

        Iron is primarily found in nuts, seeds, whole grains, and legumes:

        • Pumpkin seeds – 12.5 mg
        • Sesame – 10 mg
        • Hemp seeds, peeled – 9.6 mg
        • Millet – 9 mg
        • Flax seeds – 8.2 mg
        • Pistachio nuts – 7.3 mg
        • Oatmeal – 5.8 mg
        • Apricots, dried – 4.4 mg
        • Almonds – 4.1 mg
        • Hazelnuts – 3.8 mg
        • Tofu – 3.7 mg
        • Lentils, cooked – 3.6 mg
        • Spinach – 3.4 mg
        • Salsify, raw – 3.3 mg
        • Cooked chickpeas – 2.7 mg
        • Walnuts – 2.5 mg
        • Plums, dried – 2.3 mg
        • Whole rye bread – 2 mg
        • Kale – 1.9 mg
        • Whole grain pasta, cooked – 1.7 mg
        • Arugula – 1.5 mg
        • Beetroot – 0.9 mg
        Sources
        • Gröber, U. (2011): Micronutrients. Metabolic tuning – prevention – therapy. 3rd ed. Wissenschaftliche Verlagsgesellschaft mbH Stuttgart
        • https://apps.who.int/iris/bitstream/handle/10665/177094/9789241564960_eng.pdf?sequence=1
        • https://apps.who.int/iris/bitstream/handle/10665/43894/9789241596657_eng.pdf?sequence=1