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Tea after buckwheat: how drinks affect iron absorption

Why tea and coffee with buckwheat or legumes lower iron absorption, when to drink them instead, and what helps.

  • · updated
  • 3 min read
  • 6 sources

How we write. Every figure comes from the abstract of a verified study; tables are computed by the CookCount calculator. This article is not a substitute for medical advice. More on our method

Contents
  1. Tea and coffee
  2. Milk and cheese
  3. What helps
  4. Top sources of vitamin C

Buckwheat with a cup of tea is a familiar breakfast for many. For iron, though, it’s one of the least helpful pairings. That’s because food iron comes in two forms. Heme iron — in meat and fish — is absorbed well and barely depends on the rest of the meal. Non-heme iron — in buckwheat, legumes, greens and eggs — is absorbed less well, and it depends a lot on what you eat and drink with it (Hurrell, Egli, 2010).

Tea and coffee

In a study by Hurrell and colleagues (1999), people ate the same bread meal with different drinks. Compared with water, black tea cut iron absorption by 79–94%, cocoa by 71%, peppermint tea by 84% and camomile by 47%. The more polyphenols in the cup, the stronger the effect. Adding milk to tea or coffee made almost no difference.

Coffee works the same way: a cup with a hamburger meal cut iron absorption by 39%, tea by 64% (Morck et al., 1983). A key detail from that study: coffee an hour before the meal had no effect, while coffee an hour after the meal inhibited absorption as much as drinking it with the food.

If iron matters to you, have tea and coffee at least an hour before an iron-rich meal or 1–2 hours after it — not straight away.

Milk and cheese

Calcium also hinders iron: 165 mg of calcium from milk or cheese (a little over half a glass of milk) lowered absorption by 50–60% (Hallberg et al., 1991). So buckwheat porridge with milk isn’t the best choice either if iron matters to you.

What helps

  • Vitamin C at the same meal noticeably boosts non-heme iron absorption: it keeps iron from forming insoluble compounds and converts it to a form the gut absorbs more easily (Hallberg et al., 1989). Bell pepper and kiwi are good sources.
  • Meat or fish in the same dish: muscle proteins boost plant iron absorption — in a study by Hurrell and colleagues (2006) beef increased it by 180% compared with egg white protein.

Top sources of vitamin C

FoodVitamin C per 100 g
Red bell pepper128 mg
Kiwi92.7 mg
Broccoli91.3 mg
Strawberries59.6 mg
Orange59.1 mg
Cabbage36.6 mg

The CookCount diary flags these combinations automatically: add buckwheat and tea to the same meal and you’ll see a tip.

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Sources

Each study is checked against PubMed; links open its record.

  1. Hurrell, Egli, 2010. Iron bioavailability and dietary reference values. Am J Clin Nutr. PMID 20200263
  2. Hurrell et al., 1999. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. PMID 10999016
  3. Morck et al., 1983. Inhibition of food iron absorption by coffee. Am J Clin Nutr. PMID 6402915
  4. Hallberg et al., 1991. Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans. Am J Clin Nutr. PMID 1984335
  5. Hallberg et al., 1989. The role of vitamin C in iron absorption. Int J Vitam Nutr Res Suppl. PMID 2507689
  6. Hurrell et al., 2006. Meat protein fractions enhance nonheme iron absorption in humans. J Nutr. PMID 17056805

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