Welcome to Science with Sanjula where we talk about anything global health.
My name is Sanjula Singh, and I'm a researcher at the University of Oxford.
Join me as I speak to world leading scientists who tackle today's biggest challenges in health care.
Today, we're joined in the studio by Dr. Keren Papier, a senior nutritional epidemiologist at the University of Oxford.
We're going to talk meat, veganism, alcohol and much more.
Thank you so much for joining us today, Keren. First of all, can you please tell me what made you so interested in what we eat?
It started really as a child I was really interested in nutrition, and I was really fortunate.
I got to live in different countries across the world and I got to see what people ate and how different it was and how lifestyles went around food.
I just was really interested in it. I was really fortunate during my studies, so I studied public health, nutrition, and in my first year,
really in my first semester, I had the topic called epidemiology, which is about people and diseases and patterns.
And I just thought, this is amazing.
What a way to tie in interest in nutrition and people and different cultures around the world and understanding disease and patterns.
And I just fell in love with it. And through my degrees I got to do research over the world as well.
So I was able to go to the Philippines and investigate malnutrition in children and schistosomiasis.
So it really unfortunate worm that children are unfortunately dealing with.
Just from from the lifestyles, from from farming and being in the water and being there was really interesting
because I saw that there were a lot of children who were undernourished.
So we see malnourished as in poor nutrition, but really not getting enough.
But a lot of the adults actually had over nutrition.
So they were actually larger overweight or obese, but not necessarily eating what they should be eating.
And I found that really interesting. And that led me to doing my Ph.D. from Australia, but also through Thailand and looking at yeah,
looking at how the changing lifestyles were changing diseases and how diabetes was becoming
an issue that hadn't been an issue previously because of all the different changes going on.
Then how did you move to Oxford? So at the end of my PhD, I was of course looking for opportunities and thinking about what the next stage would be.
And having done a lot of work in global health and really in countries that were sort of becoming either upper middle income or not quite high income,
but seeing that some of the issues were quite similar with what's happening in high income countries,
I thought that I could easily translate that research and wanted to see, well, what else is happening in high income countries as well?
What happens when we eat meat, for instance? What happens when we don't eat meat?
What does that do to our health and our long term health? What are people that are eating meat doing?
What are their lifestyles? Are there differences between them?
And that's evolved into projects also on what happens to people who completely omit meat.
So what we call vegetarians, for instance.
Well, let's dive into a vegetarian diet and maybe could you maybe explain first what is a vegetarian diet and what is a vegan diet?
It's a great question because we know what they are not.
So we know that vegetarians do not eat meat and do not eat fish.
We know that vegans don't eat meat, don't eat fish, don't eat eggs, don't eat dairy.
But what they do eat could be completely different. So it's even a tough one to define, so to say.
Absolutely. And of course, what does that mean for health? Because if someone is having, say,
vegetables and fruit and legumes and pulses and nuts and really a variety diet versus someone who might just be having white pasta,
maybe tomato sauce soda the whole day. And both could be vegan diets.
Right. That's exactly right. So how do you go about and do research on that?
We're very fortunate that people are really kind and are happy to take part in research and help us answer interesting questions.
So a lot of the research we do is through cohort studies.
So what that means is we'll ask people to take part in a study and the people that we asked to take part,
they might have something interesting about them.
So in the case, for instance, of vegetarians and vegans, we really target people who are omitting meat,
are omitting fish, are omitting dairy, or eggs and say, can you please take part in our study?
And we've done this over the years. And for instance, we have a study that's been running since the mid 1990s called the Epic Oxford Study,
and it's got over 65,000 people who have said, Yep, I'll take part in your study.
So then we sent them surveys. These are questionnaires and they ask about their diet, their lifestyle habits.
So do you smoke? Do you drink alcohol? What do you eat?
And looking at these questions and information, we then know who's following a vegetarian diet,
who's eating a meat diet, for instance, and we can then follow them up over time.
So people are very kind to also allow us to access their records, their NHS records.
So National Health Service. So if someone's gone to hospital or had a cancer or passed away, we can see what's happened.
So we can see did someone follow a vegetarian diet, say, in 2000?
And then we could see over time we might ask them again repeatedly, Oh, what was your diet five years later?
What was your diet ten years later? And we can use this information to look at diet over time with different health outcomes.
So then what we're doing is really comparing. We see people who, say, developed ischaemic heart disease.
So for instance, heart disease, what's different to the people who developed heart disease compared to those who didn't develop heart disease?
Were they eating a different way? Did they smoke? Did they not smoke?
What was their weight, for instance? So then we can compare and see.
Right. Are the vegetarians and vegans having more or less of different disease outcomes, for instance, to people who are eating meat?
You just some very interesting points. I'm just going to kind of pinpoint those.
First of all, biomarkers.
What are those? The biomarkers, unlike, for instance, with a questionnaire where you're asking questions maybe on a survey or in paper,
biomarkers are actual measures of what's happening in the body.
So, for instance, blood biomarkers is something that we might use a fair bit in in nutrition.
We have different types of biomarkers. So we have what's called recovery biomarkers that are trying to reflect absolute intake.
So, for instance, energy, how much energy did somebody consume?
Now, this is great because it's very, very precise.
In theory, you should be able to find out how much energy someone ate.
But it's very expensive; you have to take it to a lab to process it.
It's not always the most feasible thing to do.
So we do have some other biomarkers in nutrition, but they need to be used in combination with dietary surveys.
So for instance, you might want to know if somebody had fruit and vegetable intake.
So you might ask them to tell you in a questionnaire.
We can have a biomarker that tells you, well, what, someone's vitamin C in their blood right now.
Now, that's helpful because you can try to compare them. And you can imagine that if I looked at your vitamin C in your blood,
that doesn't require you having to remember if you ate fruits or vegetables yesterday.
So it does get rid of that. But it's not always perfect because when I measure the biomarker might change completely.
So you might change during the day between days.
Also, your metabolism, your personality, the things that are about you
for instance, your body size, how you metabolise that might affect it.
So if you think of something like vitamin D, for instance, if we look at intake,
that information is not really good because most of our vitamin D actually comes from the sun.
So something like a biomarker might actually tell you that, whereas an intake might be a bit tricky.
But of course, your body size, whether you smoke all these different factors, might affect the levels in your blood.
Do you think in the future there may be more biomarkers that are going to adequately reflect our long term intake?
Or do you think that something that may just not be possible for diet? I think it's hard to have sort of a one stop shop.
I think the best we can do in research is really look at the evidence coming from different sources
and seeing how it lines up and really try to understand why is this telling us something different.
So for instance, with the vitamin D example, it makes sense that because it comes from the sun that looking at our intake might not be enough.
So this area is developing and we have a lot of really clever techniques now to measure all these different types of biomarkers,
and that is super informative and super helpful and it's a really exciting space.
So that area is still developing,
but I still think that it's best to do it in combination with the different types of data that are available, not the sort of the one solution.
All right. So we need cohort studies. We need very good questionnaires.
We need biomarkers. What else do we need? Well, genetics is an area that's of interest.
It's been particularly useful for some areas, maybe not for all aspects of nutrition, but it depends how you define nutrition.
So for instance, something like alcohol could be called a dietary factor, but it's really also a lifestyle factor.
We also have trials. So trials don't work for all aspects of nutrition because of course some diseases take so long to develop.
Some things trials are quite useful for nutrition. For some things, genetics might be.
For others, observational study biomarkers. So it's really this kind of mixed bag of where we're getting our evidence from.
If you open up pretty much any magazine these days in the UK or anywhere in the world,
you'll see a very large headline saying "this is a superfood, you should eat this" or "this is really bad for you".
What do you think about that when you read such statements? One - we're popular.
Everyone loves nutrition. Everybody eats all the time.
It's not a drug. It's not a for instance, smoking, for instance, food affects everyone from the day they are born to the day you die.
You're going to be eating. So people have a vested interest. It's going to catch headlines.
But then for somebody on the other end, reading the headline,
I guess a few things that would be amazing if people could consider is please don't hate the scientists right away.
Often the things we put out are not exactly what's being picked up in the headline.
And I think it's good to have like a toolkit of what do you do if you do read this headline that just says something,
you know, "butter is good", "butter is bad". What do you do?
Yeah. And I think that some things to sort of keep in mind are really what was the question?
What were they asking? So, for instance, if they're asking, is butter good or bad,
what are they comparing it to? Are they comparing eating butter versus just eating sugar all day?
Because in that case, butter might look a little bit better than if you're comparing butter to maybe whole grains and different oils, for instance.
So what's the actual question? Are you comparing something that makes sense?
It needs to sort of be plausible. And when we're thinking about that, things that can actually maybe lead to something.
So having more of this might lead to more of that, it's really does it make sense?
Is it biologically plausible? Is this something that could have just been an artefact?
We look at really large numbers. So sometimes you find things that you weren't looking for.
So to think about what was the question at hand to think about, does it make sense?
What does the evidence say overall? I am going to ask you to give a mini lecture on what you think,
given all the current evidence out there, is the best diet for any person living on the planet right now.
I think anybody who's got any sort of aunt or grandmother in their corner would have probably grown up with hearing.
"it's all about balance", and "don't have too much of those, don't have too much of that".
And I really think there's some really good advice there.
In the end of the day, that it's really about staying within some form of balance.
We have some good evidence around plant based foods so that consuming more fruits and vegetables and beans and legumes and
maybe trying to limit the amount of red and processed meat that were eating every day that it seems to be health promoting.
And this might be from various types of diets,
but these are the components that we know more about and that our guidelines are supporting. In terms of what we eat in our diet
it's so cultural and it's so personal and specific.
And for instance, when I was doing my research in the Philippines, rice was so important and it was really sort of the central meal of the day,
whereas in other parts of the world, maybe bread is the centre of the meal.
So what goes into your meal is going to be so dependent on what you like, what makes you feel good,
what you can afford, what you know how to cook, what you enjoy, what maybe you've been handed down from your family.
But I think also when we're thinking about diet, we do know that we have more evidence for consuming more plant based foods.
But it's not just about our health. There's other aspects.
So besides maybe religion and culture and also preference, taste time what
you know how to make- environment.
We have good evidence that reducing our red and processed meat, it is helpful and it does help reduce impact on the environment.
So I think when we think about our diet, there's so much to think about.
But in the end of the day, it's what's going to fit in with your lifestyle and you might be someone who doesn't consume meat at all.
So what you're eating in the day might be completely different.
And we've learned from looking at vegetarians and vegans, for instance, in our cohort in Epic Oxford,
that it's not just about removing the steak from the plate and putting tofu on there, but the whole day is different.
More vegetables, more grains, more cereal. Everything changes throughout the day.
So to answer your question, I think the day could be completely different within those sort of boundaries and guidelines
and really also thinking about not just health but our environment and other things that are
important to us and trying to limit some of the things that we think could be worth limiting,
like salt and sugar and saturated fat. But what can you tell us about alcohol?
Because some people would say, well, one glass of wine per day is actually good for you.
Other people, they would say you should not drink at all.
Other people may say, well, maybe a moderate amount of alcohol is actually good for your mental health, for example.
Is there any evidence on that or what is the evidence like?
Alcohol is so interesting.
Again, it's both could be considered diet, but it can also be considered lifestyle and and living in the UK seeing how embedded,
makes you think about well what happens if someone who's never having alcohol? They're probably going to be different,
right? What does that say about them? It's probably not random if you're not having alcohol, especially somewhere like the UK.
Maybe you're sick, maybe religious purposes, maybe for some different reason you're not having alcohol.
So it's good to keep in mind when we're thinking about alcohol that comparing anything,
any intake to someone who never drinks, the never drinkers are a little bit different.
They're not at random. There's probably something a bit special about them. Now in terms of the research about
what we know about consuming alcohol in different health outcomes when it comes to cancer,
more alcohol, pretty much more of many cancers.
So if you think about it, it makes sense through the mouth, the pharynx, this sort of area really through the GI.
that all going down to the liver, of course, right,
your breast, colorectal cancer, there are several cancers that more alcohol, more risk of these cancers.
So not drinking at all would mean the lowest risk of those cancers?
That's right. So it's really sort of this dose response where more alcohol is more of these cancers. With cardiovascular disease risk
there have been a bit of a mixed bag in the literature.
So we used to see, and we still see, this situation where some studies show what's called a j-shaped association,
which means that no alcohol looked like it had it looked worse than some alcohol.
Exactly. Actually, one or two glasses per wine is a for example. Exactly.
Now why that's happening. So again, if you keep in mind, if we're comparing to people who have no alcohol, they might be different.
So again, are they people who had an illness who are no longer drinking because of their illness?
It might not be the best comparison group. So more and more we're moving towards, instead of comparing it to non-drinkers,
to maybe people who drink a little bit because they might be a little bit more or less outstanding than the non-drinkers.
In terms of the evidence we do have, it's mostly observational.
Now, if you're trying to report alcohol, that is really tricky because it can come with judgement.
Also, if you're trying to remember if it's wine versus if it's beer, if, if you're say out,
you might not really know the differences or maybe you're having a drink that mix with them all together.
Now also, okay, let's say you remembered in your report and you put it in the survey and you know the amount and you're okay with all that.
The type of drink might just depend.
So people who are drinking beer might not be the same as people who are drinking wine and champagne in terms of maybe your ethnicity,
in terms of how much you can handle having different alcohol types or if you're a man versus a woman.
So there's trickiness around reporting how much we're consuming, what we're consuming,
the types we're consuming, who's drinking the different types of drink.
So all these factors muddle up a little bit when you're trying to then look at alcohol, which makes it so tricky.
So these associations we were seeing with cardiovascular disease risk,
we didn't know if to take them at face value or if this is really what's happening.
And more recently, we've been able to have some genetic evidence with regards to alcohol.
And in East Asians particularly is is a really interesting group to look at because they have a genetic variant.
So it means that they have something different about their genetic predisposition to how they metabolise alcohol and they don't do it as quickly,
which means that they're probably not going to feel very good if they drink too much.
So having this genetic predisposition to metabolising alcohol slowly is sort
of a predictor of the fact that you're probably not going to drink very much. So using that evidence, using genetic evidence,
there's been research showing that when you don't look at the observational, so when you're not looking at people self-reporting in questionnaires,
but rather looking with the genetic evidence, this j-shaped association not as clear.
So, for instance,
if some of the observational evidence showed that there might be this sort of protective effect of some alcohol for heart disease and for stroke,
some of the genetic evidence isn't actually showing this and is actually showing that more alcohol, more stroke.
What about red or processed meat? How far are we in figuring out how bad that actually is for you?
Because I think there are some people who still don't believe that eating meat is bad for you.
And they may use, I don't know, personal arguments that they just like eating meat, for example,
or they'll say that people have been eating meat for centuries now.
How do you feel about that? Great question. Something that takes up a lot of my thoughts during the day, I'll be honest with you.
Processed meat and red meat. Not the same thing. Can you please explain what is the difference?
By definition, processed meat should be something that has enhanced shelf life.
It's been cooked or smoked or cured. It's had something added to it preserved.
So like bacon that's been cured, for instance. So it's something a little bit different about it.
Things have been added to it. A lot of salt has been added to it potentially, right?
Which you then start thinking, right, a lot of salt, maybe blood pressure, maybe stroke and heart disease.
But processed meat is still a little bit of a grey area because in terms of risks.
In terms of the evidence,
for instance, processed meat in colorectal cancer is our best evidence when it comes to what we're most confident about for processed meat,
with higher processed meat intake, increasing risk of colorectal cancer.
And some of the reasons we think is maybe because of the additives or what's been added to the processed meat.
But processed meat could also be a burger.
And if you made the burger at home by mincing it, basically that's unprocessed red meat ground up,
whereas if you're getting it from an outlet, so a takeaway place where it's been processed differently, it comes a little bit different.
So processed meat is different to unprocessed red meat,
which in theory shouldn't have undergone the curing or the preservatives or the colours being added to it.
Finding people who eat just one is a little bit tricky. So if you're studying people in the population, these are real people.
If you're getting someone to fill in your questionnaire and say, Oh, do you eat bacon? Yes.
Do you eat steak? No, no, no. I'm bacon only, right?
Yeah. People tend to eat both of them. So then when we're studying it, sometimes it's tricky to pull apart.
So some things I think are a little clearer.
So I think if you think of maybe bacon or if you're thinking of salami, you might think of those as processed meat.
But maybe some of the foods in the middle, maybe some of the pies and the burgers, maybe kebab, those sort of things.
You might not know where you kind of sit. And then, of course, health implications.
So the evidence we have is with processed meat, with colorectal cancer.
That's our strongest evidence and probably for unprocessed red meat. With regards to heart disease,
we think there's some good evidence there as well that consuming more red and processed meat might increase the risk of heart disease.
And again, when we're thinking about diet or any risk factor, it needs to make sense and what could it be about it?
And red and processed meat often have a lot of saturated fat.
And saturated fat can increase LDL, which is your low cholesterol.
That's considered the less favourable cholesterol,
which has been associated with a higher risk of ischaemic heart disease or heart disease, for instance.
So it could make sense that there's something but again
I think it's interesting to really dive into separating out some of the different meats separately and getting
more information from people who are eating sort of just this or just that and also how much they're eating.
Are they eating just a rasher of bacon a day or are they eating really large amounts? because how much you eat might affect.
So we're still figuring it out as well. There's no definite answer, but there are some very strong trends.
Yeah. And so I would say for colorectal cancer and potentially for heart disease,
those are the outcomes that we are more confident about with regards to red and processed meat.
And you've mentioned salts already, but could you elaborate a little bit more on that, please?
Salt does make our food tastes great. And it's everywhere.
Like, how can we eliminate salt? I think it's almost impossible.
Yeah, it's a really interesting point and also how it's consumed.
So, for instance, in a place like the U.K., a lot of salt would be consumed in our pre-packaged foods where,
for instance, maybe in some other countries, a lot of salt would be from home making it.
So you're adding it yourself so that in terms of reducing it, if you're adding it when you're cooking at home,
it's going to be different to if it's already in our products. So here, because it's already in our products,
it kind of needs to be at the higher level in terms of reducing the amount of salt or maybe substituting the type of salt that's being used.
I think my last question is always what would your personal and professional advice be for young professionals?
I would say on a personal note, to stay curious, not to be afraid of asking questions,
to keep learning, to just keep getting better and to just keep growing.
And on a professional level? Do what you love.
That's not always possible.
Sometimes people can't afford to work in jobs that allow them to do exactly what they love, but just hang on to it in your mind.
And down the track, there might be an opportunity to be able to pursue that path.
Or if anyone asks for ideas, you're sort of ready to go. So you do what you enjoy and it'll make everything so much better.
It was wonderful to have you in the studio with us today, Keren. Thank you so much for joining.
Next week, we'll be joined by Professor Sir Rory Collins,
who is one of my mentors and who is the head of the Nuffield Department of Population Health at the University of Oxford.