ZOE Science & Nutrition - Everything you've heard about lactose is wrong
Episode Date: March 9, 2023Lactose is usually only discussed in the context of intolerance. This intolerance can make us feel bloated, gassy and uncomfortable. But from cow’s milk to yoghurt and even breast milk, lactose is e...verywhere! So, can it really be that bad for us? In today’s short episode of ZOE Science & Nutrition, we’re joined by Dr Will B. to find out. Follow ZOE on Instagram: https://www.instagram.com/zoe/ Download our FREE guide — Top 10 Tips to Live Healthier: https://zoe.com/freeguide Studies referenced in the episode: Nature: How humans’ ability to digest milk evolved from famine and disease PubMed Central (PMC) Effects of Prebiotic and Probiotic Supplementation on Lactase Deficiency and Lactose Intolerance: A Systematic Review of Controlled Trials PubMed Central (PMC) Improving lactose digestion and symptoms of lactose intolerance with a novel galacto-oligosaccharide (RP-G28): a randomized, double-blind clinical trial PubMed Central (PMC) Impact of short-chain galactooligosaccharides on the gut microbiome of lactose-intolerant individuals https://www.hopkinsmedicine.org/health/conditions-and-diseases/lactose-intolerance The Importance of Lactose in the Human Diet: Outcomes of a Mexican Consensus Meeting: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893676/ Episode transcripts are available here. Want to create your own podcast? Contact Fascinate Productions to bring it to life.
Transcript
Discussion (0)
Hello, and welcome to Zoe Shorts, the Bite Size podcast, where we discuss one topic around
science and nutrition. I'm Jonathan Wolff, and today I'm joined by Dr. Will Bulsiewicz.
And today we're talking about lactose.
Lactose is a very vilified substance. In fact, you've probably only heard the word lactose
said next to intolerance.
It's actually very true, Will.
And this is a topic, actually, you know, lactose intolerance, that I'm personally very interested in.
As it turns out, for 20 years, everything that I understood about lactose was wrong.
So, Will, let's start at the beginning.
What is lactose intolerance?
And is it as dangerous as we've been led to believe? Jonathan, like most of the topics we cover on the show, the truth is a lot more complicated.
Well, let's hear the truth about lactose then.
So, Will, can we start with the basics of what lactose is?
It's a special sort of sugar found in milk and milk products, right? Yeah, so lactose is actually two types of sugars, galactose and glucose, and they've
been linked together.
And what we would call this, and not to be a nerdy biochemistry guy, but we would call
this a disaccharide.
So in order for this disaccharide to be absorbed, our body needs to actually break this bond
that's holding the two sugars together. And without that, they're malabsorbed. So how do our bodies break this
lactose apart then, Will, to get at these two sugars that we can digest? So Jonathan, our body
produces an enzyme called lactase that basically is able to break this bond between the two sugars.
And in breaking that bond, it breaks down the lactose,
it frees these sugars. So help me and all the listeners to sort of imagine this. What happens,
you know, help me to understand the path of lactose as it goes through this digestive process.
Okay, so after you trigger a swallow, the milk is going to pass through your esophagus,
into your stomach, and then ultimately it's going to descend down into your small intestine. And when it enters into the small intestine, this is where we expect
the milk to come into contact with this enzyme. Lactase is in the cells that are lining the
intestine. But let's imagine for a moment that you don't have enough lactase there. In that case,
the lactose from the milk will continue to pass through the intestine. And as it moves through,
it's drawing water in, it's drawing electrolytes in. And then eventually, if it moves far enough
along, it's going to come into contact with your gut microbes and they will do what they're known
to do, which is ferment the lactose. And that produces gas. There's almost always a bacteria
that has the ability, that has the enzymes to break down the chemicals in the food that we eat.
So even when your own
body can't digest something, many times our gut microbes can do that for us. And we see this with
fiber and we're seeing it here with lactose. Sometimes though, our body will struggle with
what these bacteria or these microbes are producing. So now this explains lactose intolerance
because basically what we've created here is we've created more water in the intestines. We've created more gas, gas, diarrhea, bloating.
This is the picture of lactose intolerance.
Got it.
So sort of lactose intolerance in a nutshell is your body can't make enough of this lactase
to break down the lactose.
So your bacteria are having this feast and the sort of byproducts from these bacteria
can lead to nasty symptoms for people who aren't very tolerant of those byproducts.
Yeah, that's right.
And symptoms usually will begin about an hour after drinking milk, or it could be that you're consuming a soft cheese or something that's cream-based.
It's one of the most common causes of food intolerance out there.
And I think I've heard you say that amazingly, like most of the world's population is lactose intolerant, like 70% or something.
Yeah, this may be due to the loss of the intestinal lactase, the enzyme in adulthood.
And this is a condition which is transmitted by an autosomal recessive gene. So, you know,
for example, people with European ancestors, lactose intolerance is rather low. It's as
little as 5% in countries such as Switzerland or Denmark.
But in the rest of the world, it's extremely common. So it's estimated that over 90% of the
Asian population is lactose intolerant, 66% of people in Northern Africa, and 70% of the people
in the Middle East. That's amazing. So these are huge numbers. So actually, it's not that being
lactose intolerant is strange. It's actually being tolerant of the lactose is really the unusual situation, Will.
Are there any theories for why Europeans ended up with this ability to tolerate
milk sort of so much more than anybody else?
In essence, the ability to tolerate the lactose, it eventually emerged as a beneficial trait
when there would be a famine or there would be an infectious epidemic across Europe.
So for example, it's well studied that countries like Scandinavia have very heavily dairy-based
diets compared to the Mediterranean diet, which is more focused on olive oil and a wide variety
of plants and fish and a little bit of meat. So interestingly, tolerance for lactose only
became common in Europe in 4,000 or 5,000 years ago.
So is lactose intolerance dangerous, Will?
It's uncomfortable. It can affect your quality of life, but it's not dangerous.
And it's important to make sure that when you suspect that it could be lactose intolerance,
you have to make sure that it's not a cow's milk allergy.
And Will, you've sort of talked about allergies at length on a previous podcast.
And my simple takeaway was that an intolerance
doesn't involve the immune system. And often you can reduce it actually by exposure. Whereas an
allergy is when the immune system responds to a trigger, it responds to a really tiny amount of
whatever this food is, and it can be really dangerous. Did I summarize that okay?
Yes, yes. You nailed that. Exactly. And it's important for people to understand how dangerous these allergies can be.
They can lead to rashes, hives, difficulty breathing, and that's where it can be life
threatening.
So cow's milk allergy is usually to a protein in the cow's milk.
It's not actually to the lactose at all.
If you have a cow's milk allergy, you need to avoid cow's milk altogether because that's
the only way to really be safe.
And Will, I'd love to talk about that point for a minute because I think most people do not
understand this difference between intolerance and allergy. And I was diagnosed as lactose
intolerant more than 20 years ago when I had these food intolerances in my early 20s. And my
understanding was that I therefore had to give up all dairy. And one of the things I realized was I
didn't need to give up dairy. You know, if I was allergic to dairy, you know, you have to give up all of it because
even a tiny amount is going to trigger this immune system response, right? Well, but actually
intolerances are normally triggered by volume. But my big discovery, which I had no idea about,
was there's loads of dairy products that contain very little lactose at all. And so, for example,
you know, if you're eating a hard cheese or even quite a lot of yogurt, these have much lower levels of lactose. And so, in my
case, and I think for many people who might be listening to this, you'll find, wow, I can eat a
hard cheese. And in my case, I can also eat plenty of yogurt and I don't have any issues, even if I
were to drink half a liter pint of milk,
then I'm probably still going to feel uncomfortable even today.
Yeah, Jonathan, just to kind of riff off of that or to comment on this from a medical perspective,
you know, the last thing that I would ever want a person to do is to feel like they have to
eliminate foods from their diet because they're causing digestive symptoms when in many cases there's
a path towards healing that will allow you to tolerate and enjoy those foods and also receive
the nutritional benefits. Restrictive diets really don't turn out to be the solution to these
problems. At the end of the day, they're in many cases going to make your gut health worse. So what
we want is we want a way in which we can lean into these foods, overcome the food intolerance, and actually restore our gut and restore our ability to tolerate these foods.
And I do think that's possible.
It's possible with the types of foods that we're talking about today, lactose-containing foods.
And it's also possible with other types of foods such as high FODMAP foods that people may struggle with.
And I love this message, and it's definitely been my own personal experience. And obviously, people have different experiences. But trying to just exclude all of these things is,
I think, a very natural response. And then in my case, I think you only realize much later,
you've basically been cutting out all of these things that look after you for a long time.
Now, all of this said, I think I'm jumping ahead of the story, because I guess the first question
is, you know, if you do have some digestive
symptoms like gas or bloating or diarrhea, how do you know if lactose intolerance is the culprit,
Will? So the first thing that you can do, and this is honestly probably the most reliable
way to approach this, is to stop consuming these products. So stop eating and drinking any dairy
products and see if your symptoms improve. And if the symptoms go away when you stop and then they come back when you restart, then that's a extremely reliable way
to identify a food intolerance. I mean, these are sort of the tenets of an elimination diet,
temporary elimination, by the way. Genetic testing and breath testing are also options
and they can be helpful, but they're just not as reliable as the sort of gold standard approach,
which is eliminate, see how you feel, bring it back in, see how you feel. And let's say you've done this
elimination. Is there anything that a listener can do to improve their lactose intolerance symptoms
if they have discovered that it's clearly associated with eating this dairy? The first
option is pretty obvious, which is that you can cut down the amount of dairy that
you're consuming. This does not require you to make an absolute elimination or a permanent
elimination. Another thing that you mentioned, Jonathan, that I want to touch on real quick,
fermented dairy tends to be tolerated much better by people who have lactose intolerance. So you
will find that if you take a glass of milk and you turn it into kefir, the kefir doesn't seem
to trigger symptoms in people.
They tolerate it really well.
And the same would be true with hard cheeses as opposed to soft cheeses.
So consider fermented dairy as an option.
By the way, I would argue that's also a more healthy version of dairy.
And I think, you know, if Tim and Sarah were here, they would talk a lot about both of those things and sort of the magic way in which these bacteria can ferment this quite simple
chemical product like the milk into this incredibly complex product like the cheese or the yogurt.
And there's a lot of scientific evidence, apparently, that these are significantly
healthier for you than the milk. And I think, again, down to this magic of these tiny bacteria,
which I always love the idea of. What's kind of exciting about this is that when you consume the fermented
dairy product, I would argue this is a healthier version. It's also fermented. So in many cases,
it will have live bacteria, which is actually to our gut benefit. Now, all of that said,
when I'm on holiday in Italy in the summer, I'm definitely eating gelato. There is no chance I
could be like, no, I'm only going to have cheese. So, you know, I think this idea you should just give it all up is also unreasonable. So tell us about how else
you can manage the lactose intolerance symptoms, Will. You could take lactase supplements. They're
highly effective. You simply take them with the meal. It's actually possible, believe it or not,
Jonathan, to boost your own ability to digest lactose. As you slowly increase the amount of
lactose in your diet, your body will adjust and
accommodate it. There was a 2020 study that I thought was very interesting, and they found that
people actually get a benefit from probiotics. Now, there were a number of different ones because
one of the big things with probiotics is we want to identify the strain that provides the benefit.
So for the listeners, I would look at lactobacillus acidophilus, 10 billion CFUs per day. Finally, there's actually a good
bit of research that prebiotics can help. So specifically one called galactooligosaccharide
actually has been shown to improve the symptoms of lactose intolerance. And so in essence,
what you're doing is you're building up the microbiome, you're building up the gut,
and this allows you to tolerate food better. And I think these are all specific examples of a broader trend,
which is if you can improve your gut health,
you're eating a diet which is much more supportive of a healthy microbiome,
then actually just in general your ability to tolerate food improves.
And prebiotics is just basically food, isn't it,
of particular types that supports your bacteria.
So I think that's an exciting message as well,
that there have been these studies that have shown in these particular, you know, quite focused
interventions, real benefit. And I guess one would hope that a sort of full shift your diet could do
even more than that. Well, it's just at the end of the day, what we're showing here is the proof
of principle. You are not stuck. Your body is not rigid and you are not sort of cursed to be lactose intolerant for the rest of your life.
That in fact, your body is adaptable, that it can grow stronger and that you are capable of actually overcoming this issue, which is causing these symptoms.
So we've been making lactose sound pretty bad. Are there any advantages to lactose?
Well, actually, really surprising, Jonathan, there are. Lactose is a conditional prebiotic.
So what this means is that because it's fermented by the gut microbiota, it actually can contribute
to a healthier gut. The other thing that really surprised me, Jonathan, is that this is actually
the preferred carbohydrate for infants. There's a couple of reasons for this. It's a slow release
energy source. It has a low likelihood of causing damage to the teeth. And also it helps to shape the gut microbiota.
And I was quite surprised to discover that you will find more lactose in human breast
milk than you will find in cow's milk.
So there is an element that nature is saying this is good for our kids.
That's amazing.
So basically, we might have all those people who aren't dealing with it very well when
they're grown up.
But actually, when you're six months old, this is what you're sort of programmed to eat. It goes to show
that as often, we should all be careful about very simple answers about anything to do with human
health. So Will, what do we think? Is lactose as bad as it's made out? To me, the answer when it comes to lactose is clearly
no. We are building this up as this negative thing. And the reason why we're doing that is
because it's causing digestive symptoms for a large number of people. But what we learned here
today is that lactose is a prebiotic. It's good for our gut microbes. That human breast milk
contains a significant amount of lactose intended to feed our children. And there are strategies that we can use that will
allow us to overcome the lactose intolerance, whether that be modifying our food, modifying
the quantity of the food, or doing other things to support our gut biome in our ability to process
the lactose. So I think lactose has been inappropriately vilified.
Brilliant, Will. Thank you for guiding us through this complexity.
I think I've definitely gone away thinking, well, maybe I probably don't need a lot of
lactose in my diet right now, but that we shouldn't be so worried about it.
And that, as always with these things, often there's sort of two sides to the tale.
A hundred percent.
And I think that you have to find what works for you and what really guides you to better health and makes you feel great.
Brilliant. Well, I hope you enjoyed this week's episode.
If you'd like to try Zoe's personalized nutrition program to learn how to eat for your body and improve your health, you can get 10% off by going to joinzoe.com slash podcast.
I'm Jonathan Wolfe.
And I'm Dr. Will B.
Join us next week for another Zoe podcast. I'm Jonathan Wolfe. And I'm Dr. Will B. Join us next week for another Zoe podcast.