Which minerals' absorption does oat consumption block?

Oats Primarily Block Iron Absorption Due to Their Phytate Content

Oats primarily block the absorption of iron due to their high phytate content, which forms insoluble complexes with iron and reduces its bioavailability. 1

Minerals Affected by Oat Consumption

• Iron absorption is markedly inhibited by oat products, with studies showing significant reduction in non-heme iron absorption due to the high phytate content in oats 1
• Zinc absorption can also be impaired by oats, though the effect is less pronounced than with iron 2
• Calcium absorption may be affected to a minor degree by the phytate in oats, but this is generally considered less significant than the effects on iron 3

Mechanism of Mineral Blocking

• Phytic acid (inositol hexaphosphate) in oats binds to minerals, forming insoluble complexes that prevent absorption in the intestinal tract 1, 2
• Oat phytate is particularly problematic because:
  • It shows high resistance to exogenous phytase enzymes 1
  • The endogenous phytase in oats is often inactivated during heat treatment used to prevent rancidity during storage 1

Impact on Nutritional Status

• The inhibitory effect of oats on iron absorption is significant enough to be a serious consideration if oat products are regularly consumed 1
• This is especially concerning for populations at risk for iron deficiency, including children, teenagers, and women of reproductive age 1
• In studies, iron absorption from oat-based meals can be as low as 2-3%, even in iron-deficient individuals 2

Strategies to Improve Mineral Absorption from Oats

• Adding vitamin C (ascorbic acid) to meals containing oats can significantly enhance non-heme iron absorption 4

  • Vitamin C is a powerful enhancer that can counteract the inhibitory effects of phytate 4
  • Consuming vitamin C-rich foods with oat-based meals is recommended by health authorities to improve iron absorption 4

• Processing techniques can reduce phytate content and improve mineral bioavailability:

  • Malting and soaking oats can reduce phytate content by up to 75%, significantly improving both iron and zinc absorption 5
  • Adding citric acid to oat-based foods can improve iron absorption by approximately 54% 6
  • Enzymatic dephytinization using phytase can increase iron absorption by 78% by reducing phytate content 6

Special Considerations

• For individuals following plant-based diets who rely heavily on oats, the risk of mineral deficiency is higher due to:

  • Exclusive reliance on non-heme iron sources, which have lower bioavailability (1-15%) compared to heme iron (15-40%) 4
  • Higher overall phytate intake from multiple plant sources 3

• Individuals with low serum ferritin concentrations (indicating low iron stores) can absorb non-heme iron better than those with high ferritin levels, which may partially compensate for phytate inhibition 4

• The impact of oat consumption on mineral status should be monitored in vulnerable populations, particularly in those following plant-forward diets 3