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Here’s what you need to know about lactose intolerance.
Why do people become lactose intolerant?
First off, lactose intolerance is not a proper food allergy. It’s a digestive issue that results in the body being unable to break down a substance called lactose found in dairy products.
“Lactose intolerance occurs as a result of an enzymatic deficiency and is quite different to a milk allergy which is driven by the immune system,” said Anna Richards, an Auckland dietitian who specialises in allergy, intolerance and gastrointestinal disorders.
Some people, particularly children, do have actual milk allergies which can cause serious medical issues including anaphylaxis, a life-threatening reaction that narrows the airways.
But lactose intolerance is more about the tricky interaction between lactose in milk and something called lactase that the body makes.
Wait, those are pretty similar names…
Yep, it’s a little confusing. To keep it simple, just realise that lactose is a complex sugar that is found in dairy products.
Lactase , on the other hand, is a digestive enzyme the body makes to break down that lactose. And the older we get, the less of it our bodies make.
“It reaches its peak in infancy and declines after that but the rate of decline is genetically determined – that’s why there are such regional and ethnic differences in lactose intolerance,” said Clare Wall, a dietary expert and head of the School of Medical Sciences at the University of Auckland.
Being able to digest lactose is actually kind of a genetic mutation, prevalent in parts of the world where dairy farming evolved such as Europe. It’s called lactase persistence.
“It tends to be predominant in ethnicities that have historically not consumed lactose after infancy such as Asian, African, South American and tends to be less of an issue among Caucasian ethnicities whose ancestors have continued to consume lactose-containing foods lifelong,” Richards said.
“Around 85 percent of the world’s adult population are lactose intolerant.”
There isn’t a lot of firm data on how prevalent that intolerance is in New Zealand, but some research has shown that it’s also far more common among Māori and Pacific populations.
Lactose is the main carbohydrate in cows’ milk.
123rf
How can you tell for sure you’re becoming lactose intolerant?
Go with your gut, to be honest. The first symptoms of lactose intolerance usually occur 30 minutes to two hours after having food or drinks with lactose.
Those symptoms “can range from mild to severe depending on the amount consumed and a person’s individual tolerance level,” Richards said.
They can include abdominal pain and cramps, bloating and flatulence, diarrhoea, nausea, and sometimes vomiting or stomach rumbling.
The best at-home test a person can make is to simply stop having dairy products for a couple of weeks, and then slowly try having them again.
“If the symptoms improve on a lactose-free diet but return on introduction of lactose then this can confirm the diagnosis,” Wall said.
There are more diagnostic tests that can be made by a professional to confirm the condition, but some are not easily available in New Zealand, Wall said.
One is a breath hydrogen test which measures the level of hydrogen in exhaled air after ingestion of lactose following overnight fasting.
Could it be something else that’s bothering my digestion?
It’s always possible – issues such as gastroesophageal reflux disease or GERD and irritable bowel syndrome can also cause unpleasant symptoms.
A consultation with your GP can be useful, Richards said.
“It is important to see a healthcare professional for a diagnosis before making significant dietary changes, as symptoms can be similar to other conditions or there may be an underlying medical cause.”
There are also other, rarer kinds of lactose intolerance, including secondary lactase deficiency which results from injury to the gut, developmental lactase deficiency which can occur in premature infants and the rare genetic disorder congenital lactase deficiency where the body produces little or no lactase from birth and requires a lifelong lactose-free diet.
Okay, I guess I’m lactose intolerant. So can I just never eat dairy again?
There’s no “cure” for lactose tolerance, but it isn’t a complete dairy death sentence for your diet for many people.
“It’s about finding your individual tolerance level,” Wall said.
“Eating small amounts of lactose-containing foods with other foods rather than on an empty stomach also reduces gastric symptoms. And spreading the lactose-containing foods throughout the day.”
“It is a common misconception that lactose intolerance requires the complete exclusion of dairy from the diet,” Richards said.
“With the increase in the range of lactose-free and low-lactose dairy products on the market, dairy products can continue to be enjoyed in the diet.
“Experimenting with different products and portion sizes can help you find your personal tolerance level.”
She said that milk and products like custard and ice cream contain the most, while regular yoghurt contains a bit less and Greek yoghurt even less.
Different cheeses have different amounts of lactose.
RNZ
And what about cheese?
It depends on the kind of cheese.
Cottage cheese and soft cheese may be tolerated in small amounts, and the rule of thumb is generally the harder a cheese is, the less bothersome it might be for the lactose intolerant.
“A hard cheese such as a cheddar is low in lactose and can typically be freely included,” Richards said. “Very hard cheeses such as parmesan, Romano or butter have negligible lactose.”
Lactose intolerant people who drop dairy entirely may also need to look at supplementing their calcium intake.
“Cows’ milk and all mammal milks are nutritionally valuable foods providing protein, calcium, vitamin D and for children, fat,” Richards said.
“Soy is the only plant-based milk that is a nutritional equivalent. All other plant-based milks have negligible protein and fat and although they may be calcium-fortified the bioavailability (the way we absorb and use the calcium) is poor compared to dairy.”
Coconut milk also lacks protein and is high in saturated fat, she said.
A2 Milk has been studied for use by the lactose intolerant.
Getty Images
Are there supplements you can take to ease discomfort, or better milk products?
“The range of lactose-free products in the supermarkets including lactose-free milk and lactose-free yoghurt is increasing,” Richards noted.
There’s also been a fair amount of research done in New Zealand into whether A2 Milk, which has a different kind of protein type, may be better for those suffering lactose intolerance issues.
There are products that supplement lactase with names like “Lacteeze,” which may work for some people.
“They will moderate symptoms with a moderate dose of lactose but are not a ‘get out of jail free’ card for a giraffe-size milkshake,” Richards said.
“Tolerance will vary from person to person.”
