The bite-size podcast, where we discuss one topic around science and nutrition.

I'm Jonathan Wolf.

And as always, I'm joined by Dr Sarah Barry today, we're asking, can you reverse the damage

from a bad diet?

So Jonathan, everyone wants to live a long and healthy life and we know that a lifetime

of healthy food choices can increase your life expectancy, but some research has attempted

to assign a set amount of time to certain foods that could help hack your diet and prolong

your life.

Well, that sounds very cool.

So you're saying there is a definitive list of how to get rid of all those terrible dietary

choices in the past.

And I will be able to figure out exactly how many years I would live longer as a result.

It sounds a bit too good to be true.

It does.

And whilst I'm actually really sceptical of this kind of approach to defining the healthfulness

of our diet, based on just single foods, given that our diet is so much more complex than

this, some of the data produced could help people make smarter choices when it comes

to their diet.

Sounds brilliant.

Let's dive into it.

So first of all, Sarah, this idea that some foods can extend your life expectancy goes

back millennia.

We did a bit of research and the ancient Greeks wrote about the life-extending power of Ambrosia,

which I've yet to try, but I'm definitely up for.

Apparently, explorers in the 16th century spent their lives searching for the fountain

of youth.

We're no longer praying to the gods or searching the world for magical water sources, but we

are still obsessed with finding foods with these mythical properties that will extend

our lives.

So does science support any of this magical thinking that we've been going after for thousands

of years?

No, simply, as disappointing as it is there's just no silver bullet.

When it comes to our diet, our diet's far more complex than single foods.

It's a combination of, you know, many different foods, each of which has thousands of chemicals

in each food, which interact with the other foods and other chemicals in the meal to modulate

their health effects.

Plus we have to consider our dietary habits such as the timing that we eat, our food,

the order that we eat, our meals, how much sleep or exercise we've had and so forth.

Because all of this can also modulate the health impact of any given food on our body.

However, Jonathan, having said this.

There is some interesting research that was published by Michigan University that analyzed

almost 6,000 foods found in the diet of typical Americans and compared how healthy or unhealthy

they were using the idea of how much time they added or removed from our life expectancy.

I like the idea of that.

It is very simple.

So let's start maybe with bad news.

Sarah, what's the biggest offender in terms of shaving those precious moments off of my

life.

So if we look at some of the individual items that they reported on the study found that

due to its high content to process meat and sodium, which is a measure of salt, in the

food that a standard hot dog takes an entire 36 minutes off your life expectancy.

So imagine that in the context of someone consuming a hot dog maybe every other day.

36 minutes, that doesn't sound good.

Bad for all the professional hot dog eating contestants who are listening to this podcast

for the rest of us, what other foods are considered to be the most harmful to my lifespan

Well, I don't think many of these will come as a surprise.

So it's mainly other highly processed foods like bacon, pizza cheeseburgers, which will

also take several minutes from your life expectancy with every serving.

So every portion of these that you have.

Okay.

So, that doesn't sound good, but it can't all be bad.

You mentioned that they'd also looked at some foods that were on the other end of the spectrum

and can add to my life expectancy.

So what can I eat and add minutes to how long I'm going to live.

Yeah.

So the foods that add to your lifespan include seafood,

which can range from anywhere between 10 minutes to 70 minutes.

Depending on the type of seafood that you're having.

And this is largely due to these healthy omega3 fats that are found here in some fish.

Nut butter, actually ranked high as well, largely due to the healthy fats, protein and

fibre, and what may surprise some people is, really interestingly, the researchers found

that there was no association between the food scores and the calorie amount in each

of the food.

And this adds just more strength to this whole argument that we must focus on food quality

and not calories.

When we consider the health effects of foods.

Got it.

So what you're saying is that if I eat a certain fish every hour I can live forever.

Sarah, is that right?

No, the diet's far more complicated than that.

We may have found a small flaw in this research approach, but given that we can, we rarely

in fact eat single ingredients or foods in a meal.

So can I offset the bad foods with the good foods and make sure that my life expectancy

is still as high at the end as at the beginning?

Okay.

So according to the researchers who undertook this analysis, they do say yes, you can offset.

So if we take a vegetable pizza, as an example, vegetable pizza has a near neutral effect

on the minutes lost.

And this is due to the vegetables on the pizza.

Offsetting the unfavourable effect of the salt and the fats in the pizza.

I'm pretty surprised to hear this, Sarah and I, I want to listen to your views shortly.

So imagine I have eaten a lifetime of these life expectancy-reducing foods, and I think

this was a good description of the first half of my life. is there a way to reverse the

negative impact of this bad diet?

Or is it just too late?

So I think it's firstly important that we look at what we mean by a bad diet outside

of these individual foods that we've just talked about.

And overall, when we talk about a bad diet, we're talking about a diet that contains high

amounts of processed foods, red meats, high sugar foods, low pulse, fruit and vegetable

intake.

And sadly, this is a typical Western diet that most of us consume.

So I think everyone who's been listening to these podcasts for a while is not gonna be

surprised to hear that a typical Western diet is bad for this sort of research.

How do they define a good diet?

So there was another really interesting research study, which took a slightly different approach

to the one that we've just discussed, which was looking at these.

Individual foods.

And what they did is they looked at the whole diet and we know that it's really important

to consider a whole dietary approach rather than demonizing individual foods or putting

individual foods on a pedestal.

And they devised something called an optimized diet.

And this is based on research from thousands of studies, which then estimated how many

life years we would gain if we followed an Optimized diet.

An optimal diet included more legumes, pulses, whole grains, and nuts, particularly less

meat and particularly less red or processed meat.

So we've got this researcher saying here is this sort of generic, optimal diet.

We have to eat that completely.

And we've also described the bad Western diet.

Most people aren't going to be doing either of these two things.

Is there a middle ground?

Yeah.

So I think you're right.

That it's all very well telling someone to follow an optimal diet, but it's often actually

really prohibited to people based on cost, taste and cultural preferences.

So what I like about this research is that the researchers also calculated what would

happen if people followed a diet, which was halfway between the typical Western diet and

the optimal diet, and they called this the ‘feasibility approach diet’.

And this takes into account.

Like I said, the fact everyone is able to completely change their diet or have access

to the foods or resources required for the optimal diet.

So it's great that we have a third option here for a pretty decent diet, and that's

still significantly better than the Western diet.

So let's say I've lived the majority of my life eating the typical Western diet.

And I decide, you know, I wake up one morning and I'm like, you know what?

I need to make a change.

I want to embrace this sort of optimal diet from these researchers.

Will that be enough to undo the damage that I've done to my body over the last 45 years?

Okay.

So according to this research, it depends on how old you are, and I'm not gonna ask

you, in front of a big audience, how old you are, Jonathan.

So I'm 47, Sarah.

Okay.

I've got a few years on you then, Jonathan.

So, according to this evidence, it depends upon when you adopt this healthy diet.

And what I think is really, really positive is that even up to adopting this age 60 or,

or 80, there's an improvement.

So if you swap to an optimum diet, you can significantly improve your life expectancy

at a whole range of ages.

So for example, if you switch from a Western to an optimal diet at the age of 20, you could

gain a whole extra 10 years.

And even those who switched at the age of 60 would see an increase in their life expectancy

on average, by about eight years.

I think what's important to note is the benefits of the feasible diet.

So this kind of midway diet was also substantial.

So we had a gain of about seven years.

If you adopted it at 20 years of age and nearly five years if you adopted it at 60 years of

age,

That's a pretty strong message.

Right?

So that suggests that it's not too late to say, you know, I could make a change to my

diet, even if you might have been causing a lot of damage for many, many decades.

Yeah.

And I think this applies across many areas of our lifestyle.

If we think about exercise, if we think about smoking, there's really clear evidence at

whatever age you take up exercise or whatever age you give up smoking, there is a benefit

to your quality and your quantity of life, and the same we see with diet.

And so for people who are listening, that might be 40, 50, 60, 70, and think