What is the difference between dairy and lactose?

Image of different dairy sources, milk, butter, cottage cheese, yoghurt

Erin Dwyer - Research Dietitian, 21 November 2018

Dairy and lactose are often words used interchangeably when people are talking about their diet. These two words however have very different meanings – especially when it comes to FODMAPs

So let us clear it up

Dairy:

Dairy refers to the group of foods made from animal milk products; it includes milk, yoghurt, cheese and ice cream.
Dairy products provide us with calcium to strengthen our bones and teeth; it helps us feel full and satisfied and contributes to maintaining a healthy weight (1) .
Chemically, dairy is composed of all three macro nutrients – carbohydrates (sugars), proteins and fats.
Some people (mainly children) can be intolerant of dairy proteins and therefore cannot tolerate any dairy products; however, they often grow out of this.
If you tolerate lactose, dairy foods can be included freely when on a low FODMAP diet.

Lactose:

Lactose is the name of the naturally occurring sugar in dairy. This lactose sugar is what can be poorly digested in the intestines for people who are sensitive to lactose.
Lactose can be poorly digested in some people because they may not have sufficient amounts of the enzyme lactase being produced in their body. The enzyme separates the lactose sugar molecule in two, so it can be digested.
If you are sensitive to lactose, you can still safely include many dairy foods in your diet, for example hard cheese, butter and small serves of milk and yoghurt. There are also now numerous lactose free dairy products available in stores worldwide which means you can enjoy the health benefits of dairy without the lactose.
When people misunderstand the difference between lactose and dairy it often ends in them over restricting their dairy intake and missing out on this highly nutritious food group.

Take-home messages:

If you are sensitive to lactose, your diet should ideally be lactose-restricted, but not lactose-free diet as most people can tolerate 12-15 g of lactose per day (equivalent to about 250 ml of regular milk), and possibly more if lactose intake is spread out over the day. Don’t worry about negligible amount of lactose in medications (usually less than that in 12 ml of milk!).
A lactose-reduced diet should not be ‘dairy-free’, since many dairy products are very low in lactose (such as hard cheeses and butter). Higher lactose foods (such as milk and yoghurt) are also safe to consume in small serving sizes.
A dairy-free diet is only required if you are sensitive to cow's milk protein.
Getting the diet right is important because dairy products are rich natural sources of calcium, phosphorus, vitamin D and B12.
When eating out on a low FODMAP diet, a dairy free option will mean there is no lactose, but it may contain other FODMAPs
When choosing low lactose or lactose free products (e.g. plant based milks), look for calcium fortified options