Lactose Intolerance in Adults: Do I really need to cut out dairy?

1 Oct

If you've ever experienced bloating, gas or abdominal discomfort after drinking milk or eating dairy, you may have wondered whether lactose could be the culprit.

But lactose intolerance doesn't necessarily mean you need to say goodbye to dairy altogether.

Understanding how lactose is digested, how much you can tolerate, and which dairy foods are naturally lower in lactose can help you manage symptoms while still enjoying a varied and nutritionally adequate diet.

What is lactose intolerance?

Lactose is a disaccharide (a type of sugar) found naturally in milk and many dairy products.

To digest lactose, our small intestine produces an enzyme called lactase. Lactase breaks lactose down into two smaller sugars — glucose and galactose — which can then be absorbed into the bloodstream.

When the body doesn't produce enough lactase, lactose isn't completely digested in the small intestine. Instead, it travels into the large intestine, where it is fermented by gut bacteria.

This fermentation can produce gas and draw water into the bowel, contributing to symptoms such as:

→ bloating
→ abdominal pain or cramping
→ increased gas
→ tummy rumbling or gurgling
→ diarrhoea
→ sometimes nausea

Symptoms can depend on several factors, including:

The amount of lactose consumed: A larger dose is more likely to cause symptoms.
Your individual tolerance: Lactose tolerance varies significantly from person to person.
The food it's consumed in: Foods like yoghurt containing live bacterial cultures may be better tolerated than milk, as the bacterial cultures can help with lactose digestion.
What else you're eating: Consuming lactose as part of a meal may be better tolerated than consuming a large amount on its own.

What causes lactose intolerance?

There isn't just one reason for lactose intolerance.

Primary lactose intolerance

For many people, lactase production naturally decreases after childhood and into adulthood. This is sometimes referred to as primary lactase deficiency or lactase non-persistence.

However, some people continue to produce lactase into adulthood — known as lactase persistence. This is more common in populations with a long history of dairy farming and milk consumption.

Lactose malabsorption is therefore more common among people with East Asian, Southeast Asian, African, Indigenous American, and some Middle Eastern or Mediterranean ancestries, while it is less common among people with Northern European ancestry (Deng Y et. al). However, there is substantial variation both within and between populations, so ancestry cannot determine whether an individual will experience lactose intolerance.

How much lactase someone continues to produce also varies between individuals. As a result, lactose tolerance can differ considerably from person to person. Some people can tolerate relatively large amounts of lactose, while others may experience symptoms after smaller amounts.

Secondary lactose intolerance

Lactose intolerance can also develop temporarily when the small intestine is damaged or inflamed.

For example, gastroenteritis or other infections can temporarily damage the cells lining the small intestine and reduce lactase activity. Other conditions affecting the small intestine, such as coeliac disease or inflammatory bowel disease, can also contribute.

This can mean someone who previously tolerated dairy suddenly develops symptoms after eating lactose-containing foods.

The good news is that secondary lactose intolerance can improve when the underlying cause is treated and the gut lining heals.

In these situations, reducing lactose temporarily may help manage symptoms while the gut recovers, followed by gradual reintroduction as tolerated.

So if you've recently had gastroenteritis and suddenly find that milk is upsetting your stomach, it doesn't necessarily mean you've developed permanent lactose intolerance.

Congenital lactase deficiency

Extremely rarely, babies are born with an inability to produce lactase. This is known as congenital lactase deficiency and is different from the more common forms of lactose intolerance that develop later in life.

For most people, lactose intolerance develops later in life or occurs temporarily following damage to the small intestine.

Where is lactose found?

Lactose is found naturally in milk and dairy products, but the amount can vary considerably between foods.

Foods that can contain more lactose include:

cow's milk
goat's milk
condensed milk
evaporated milk
ice cream
some yoghurts
custards
milk-based desserts
some fresh or soft cheeses

Naturally lower-lactose dairy options include:

hard or mature cheeses
butter
some yoghurts, depending on the product and your individual tolerance

Fermentation and processing can reduce the amount of lactose in some dairy foods, which is one reason yoghurt and mature cheeses may be better tolerated than milk by some people.

This is one reason why "I can't tolerate dairy" isn't always an accurate description.

Lactose-free dairy is still dairy. Lactose-free milk and other lactose-free dairy products have had the lactose broken down into simpler sugars, but they can still provide many of the same nutrients found in regular dairy.

So, if lactose is the problem, you may be able to continue enjoying dairy by choosing lactose-free alternatives rather than removing dairy altogether.

Do I need to avoid dairy?

For many people with lactose intolerance, completely eliminating dairy isn't required.

Instead, there are several strategies that may help you find your individual tolerance:

Reduce the portion size: You may tolerate a small amount of lactose but experience symptoms after a larger amount.
Spread lactose throughout the day: Rather than consuming a large amount of lactose in one sitting, smaller amounts across the day may be better tolerated.
Have lactose-containing foods with a meal: Some people find lactose easier to tolerate when consumed as part of a meal rather than on its own.
Choose naturally lower-lactose dairy: Hard cheeses and butter contain very little lactose, while yoghurt may be tolerated better than milk by some people.
Choose lactose-free dairy: Lactose-free milk, yoghurt and other dairy products can be an easy way to continue eating dairy without the same lactose load.
Consider lactase enzyme supplements: Lactase enzyme supplements can help some people digest lactose, particularly when eating away from home or when you want to enjoy a food that contains more lactose.

Many people with lactose intolerance can tolerate at least some lactose, although the amount varies between individuals. Research suggests that many people can tolerate around 12 g of lactose — approximately the amount found in a cup of milk — without symptoms or with only mild symptoms.

The right approach will depend on your individual symptoms, dietary preferences and nutritional needs.

Don't forget about calcium

One of the biggest concerns with unnecessarily eliminating dairy is missing out on important nutrients — particularly calcium.

The recommended number of serves from the milk, yoghurt, cheese and/or alternatives food group varies depending on your age, sex and life stage. For example, the Australian Dietary Guidelines recommend 2½ serves per day for women aged 19–50, while recommendations are higher for some older adults. Go to eatforhealth.gov.au for information about dairy foods and their alternatives.

Dairy foods can provide:

calcium
protein
iodine
vitamin B12
riboflavin
phosphorus
vitamin D in fortified products

Lactose-free dairy products can provide many of the same nutritional benefits as their regular counterparts.

If dairy isn't part of your diet, there are also plenty of other ways to meet your calcium needs.

Other sources of calcium include:

calcium-fortified soy milk and other calcium-fortified plant milks
calcium-set tofu
canned fish with edible bones, such as sardines and salmon
tahini and sesame seeds
almonds
bok choy and other calcium-containing vegetables
legumes

When choosing a plant-based milk as a replacement for cow's milk, check the nutrition panel for calcium fortification.

Calcium-fortified soy milk is also one of the plant-based options that is nutritionally similar to cow's milk in several important ways, including its protein content. The Australian Dietary Guidelines specifically include calcium-fortified soy beverages as an alternative within this food group.

Can probiotics help?

You may have heard that probiotics can help with lactose intolerance.

The evidence is promising, but it's important not to lump all probiotics together.

Research suggests that some specific probiotic strains may help improve lactose digestion and reduce symptoms in some people, but the effects appear to be strain-specific. In other words, evidence for one particular probiotic strain doesn't mean that every probiotic supplement will have the same effect.

Research has investigated probiotic strains from groups including Lactobacillus and Bifidobacterium, as well as some yeast strains such as Saccharomyces. However, the evidence varies considerably between strains, doses and formulations.

There has also been research into the specific strain Lactobacillus acidophilus DDS-1, with a randomised controlled trial finding improvements in some symptoms of lactose intolerance compared with placebo.

A 2023 meta-analysis of 12 studies in adults found that probiotic supplementation was associated with improvements in some symptoms of lactose intolerance, including abdominal pain, diarrhoea and flatulence (Anh SI et. al.) . However, the studies varied considerably, and the authors identified publication bias for several outcomes. More research is needed to determine which strains, doses and formulations are most useful.

So rather than thinking "probiotics cure lactose intolerance", it's more accurate to say that certain probiotic strains may help some people manage their symptoms.

If you decide to trial a probiotic and don't notice any meaningful improvement after a reasonable trial period, you can stop taking it or consider trying a different strain or formulation. Probiotic effects are strain-specific, so a lack of benefit from one product doesn't necessarily mean another won't be useful.

Can I improve my tolerance to lactose?

This is one of the most important things to know about lactose intolerance.

You may not need to avoid lactose forever.

If you've been avoiding dairy completely, it can be tempting to assume that every amount of lactose will cause symptoms. But many people with lactose intolerance can tolerate at least some lactose, particularly in smaller amounts.

Once symptoms are well controlled, gradually reintroducing lactose-containing foods can help you work out your individual tolerance. This might involve starting with a small portion and gradually increasing the amount as tolerated.

For example:

small amount → assess symptoms → gradually increase if comfortable → find your personal tolerance

This isn't about forcing yourself to eat foods that make you feel unwell.

It's about finding the maximum amount you can comfortably tolerate, rather than automatically restricting more foods than necessary.

And if your lactose intolerance is secondary to something like gastroenteritis, your tolerance may improve naturally as your gut recovers.

Because everyone's tolerance is different, there isn't one universal "safe amount" of lactose for everyone.

How do I know if lactose is actually the problem?

It's worth remembering that these symptoms aren't specific to lactose intolerance. Other gastrointestinal conditions like irritable bowel syndrome (IBS) can cause very similar symptoms, so experiencing bloating after dairy doesn't automatically mean you have lactose intolerance.

It's also important to distinguish lactose intolerance from cow's milk allergy.

Lactose intolerance relates to difficulty digesting lactose, the sugar in milk. Cow's milk allergy involves an immune response to proteins found in milk and is a different condition requiring different management.

If you regularly experience gastrointestinal symptoms after eating dairy, it's worth speaking with your GP or an Accredited Practising Dietitian rather than assuming lactose is the cause. Depending on your symptoms and medical history, a healthcare professional may recommend a structured dietary trial or further testing.

The takeaway

Lactose intolerance doesn't have to mean giving up all dairy.

For many people, managing lactose intolerance is less about "what foods can I never eat again?" and more about "how much can I tolerate, and what strategies help me enjoy these foods comfortably?"

You may be able to tolerate more lactose than you think — particularly when you adjust portion sizes, consume lactose with meals and spread lactose-containing foods throughout the day.

And if you've been avoiding dairy for a while, working with a dietitian can help you assess your tolerance, support adequate calcium and nutrient intake, and gradually expand your food choices where appropriate.

You can find an Accredited Practising Dietitian on the Dietitians Australia website or book an appointment here.

References

Ahn SI, Kim MS, Park DG, Han BK, Kim YJ. Effects of probiotics administration on lactose intolerance in adulthood: A meta-analysis. Journal of Dairy Science. 2023;106(7):4489–4501. doi:10.3168/jds.2022-22762.

Dietitians Australia. Lactose intolerance. Dietitians Australia; 2022. https://dietitiansaustralia.org.au/health-advice/lactose-intolerance

National Health and Medical Research Council. Australian Dietary Guidelines. Canberra: National Health and Medical Research Council; 2013.

Deng Y, Misselwitz B, Dai N, Fox M. Lactose intolerance in adults: Biological mechanism and dietary management. Nutrients. 2015;7(9):5380–5397. doi:10.3390/nu7095380.

Ingrid Kotzee