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  • Hello, and welcome to Zoe shorts.

  • 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 thefeasibility 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