Do Coffee and Caffeine Inhibit Iron Absorption?
Caffeinated foods and beverages have become staples in most modern-day diets.
Coffee is among the most popular, with 80% of US adults drinking it (1, 2).
Caffeine is a natural stimulant. However, some claim it interferes with the absorption of certain nutrients, such as iron.
As a result, some people have been advised to avoid coffee and caffeine.
Here’s everything you need to know about how coffee and caffeine affect iron absorption.
Coffee and Caffeine Can Inhibit Iron Absorption
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Several studies have found that coffee and other caffeinated drinks can reduce iron absorption.
One study found that drinking a cup of coffee with a hamburger meal reduced iron absorption by 39%. Drinking tea, a known inhibitor of iron absorption, with the same meal reduced iron absorption by a whopping 64% (3).
Another study found that drinking a cup of instant coffee with a bread meal reduced iron absorption by 60–90% (4).
What’s more, the stronger the coffee or tea, the less iron absorbed (3).
However, caffeine alone does not seem to be the main substance interfering with iron absorption.
In fact, one study found that caffeine itself only binds to about 6% of the iron from a meal. Given that this is a relatively small amount, other factors must affect iron absorption (5).
Furthermore, regular coffee consumption may also have an effect on iron storage levels.
A large study found that among elderly people, each weekly cup of coffee was associated with a 1% lower level of ferritin, a protein that indicates iron storage levels (6).
However, it’s important to remember that the effects of coffee and caffeine on iron absorption seem to depend on when you drink your coffee. For example, drinking coffee one hour before a meal had no effect on iron absorption (7).
Summary:
Drinking coffee and other caffeinated beverages with a meal is associated with a 39–90% reduction in iron absorption. However, caffeine itself only binds a small amount of iron.
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Other Substances Affect Iron Absorption
Caffeine is not the only substance known to interfere with iron absorption.
The polyphenols found in coffee and tea are thought to be major inhibitors of iron absorption.
These include chlorogenic acid, which is found mainly in coffee, cocoa and some herbs. Also, tannins found in black tea and coffee inhibit iron absorption (4, 8).
These compounds bind with iron during digestion, making it more difficult to absorb (9, 10).
Their effect on iron absorption is dose-dependent, meaning that iron absorption decreases as the polyphenol content of the food or beverage increases (9, 11).
In one study, drinking beverages containing 20–50 mg of polyphenols per serving reduced iron absorption from a bread meal by 50–70%. Meanwhile, beverages containing 100–400 mg of polyphenols per serving reduced iron absorption by 60–90% (4).
Another study found that consuming 5 mg of tannins inhibited iron absorption by 20%, while 25 mg of tannins reduced it by 67% and 100 mg by 88% (9).
Summary:
The polyphenols in coffee and tea inhibit iron absorption by up to 90%. The more polyphenols you consume, the more they may inhibit absorption.
The Type of Meal Affects Iron Absorption
Iron absorption is complex and affected by many dietary factors.
Evidence suggests that the type of food you eat has a greater influence on iron absorption than the effect of drinking coffee or caffeinated drinks.
Certain types of foods enhance iron absorption, while others inhibit it. The type of iron you consume is also important.
Iron is present in food in two forms — heme and non-heme iron.
Non-heme iron, which is found mainly in plant-based foods, is relatively unstable and affected by many dietary factors. Only 2–20% of non-heme iron is absorbed (10).
In contrast, heme iron, which is found only in animal tissues (meat, poultry and seafood) has a much higher absorption rate of 15–35%. This is because it is absorbed intact and not influenced by other dietary factors (12).
Thus, coffee and caffeinated drinks are more likely to inhibit the absorption of non-heme iron from plant-based foods but have very little effect on heme iron from animal foods.
In addition, including animal protein, vitamin C and copper in meals can enhance non-heme iron absorption and reduce the negative effects of coffee and caffeinated drinks on iron absorption (13).
As a result, your food choices and the type of iron you consume will determine the effect of coffee and caffeinated drinks on iron absorption.
Summary:
Many dietary factors influence iron absorption. Coffee and caffeinated products can inhibit absorption of non-heme iron found in plant-based foods. However, they have little effect on heme iron found in animal tissues.
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Should You Reduce Your Coffee and Caffeine Intake?
Several studies show that coffee and caffeine are not associated with iron deficienc
