Tea after buckwheat: how drinks affect iron absorption

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.

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

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