Does dairy affect iron absorption?

Although there's a theoretical relationship between dairy and iron, studies show no significant effect of dairy food consumption on iron absorption.

Dairy foods contain nutrients like calcium, casein and phosphate that may compete with iron at absorption sites in the gut.¹ This is what's known as a 'mechanistic' relationship, meaning we base our understanding on the relationship between these nutrients based on the mechanisms of digestion we know happen in our gut.

Real world studies (also known as in vivo studies) test what happens in real life conditions. One in vivo study showed the reduction in iron absorption from one meal with the addition of dairy foods was 0.2% lower or less.² This shows that in real life conditions, consuming dairy foods has no significant effect on iron absorption. The nutritional benefits of dairy foods likely outweigh the slight inhibitory effect they may have on iron availability.

In young children, excessive cow's milk intake is a recognised risk factor for iron deficiency. This is less about calcium blocking absorption and more because very large volumes of milk can displace iron-rich foods from the diet. Ensuring children consume a balanced diet that includes iron-rich foods is important for supporting adequate iron intake and healthy growth and development. 

If you are worried about yours or your family’s iron levels, it’s a good idea to get a blood test from your GP. If your iron levels are within normal levels, there's no need to be too concerned about the types and combinations of foods you're eating. If you have an iron deficiency however, it's a good idea to get specialised advice from a dietitian about ways to get more iron in your diet. They'll also have advice on how to organise your diet to improve your iron absorption.

References

1. Jackson, L. S., & Lee, K. (1992). The effect of dairy products on Iron Availability. Critical Reviews in Food Science and Nutrition, 31(4), 259–270. doi:10.1080/10408399209527573
2. Galan, P., Cherouvrier, F., Preziosi, P., & Hercberg, S. (1991). Effects of the increasing consumption of dairy products upon iron absorption. European Journal of Clinical Nutrition, 45(11), 553–559.