Why eating nuts makes you healthier, according to science

[Music] hello and welcome to Zoe's shorts the bite size podcast where we discuss one topic around science and nutrition I'm Jonathan Wolfe and today I'm joined by Dr Sarah Berry and today's subject is nuts and Jonathan this is a subject I absolutely love I've done loads of Interventional human studies measuring the effects of eating nuts on people's Health well the good news is we had lots of listeners worried that nuts are full of fat and therefore are bad for you well I hope that they'll be very surprised by what we're about to discuss then good Let's Go Nuts sorry about that right so it's important before we get into the nutritional value of nuts to point out that there's lots of different ways of consuming nuts on average our consumption of nuts and seeds in the UK is about six grams per day which doesn't sound like lots but that's because we have a lot of people don't consume nuts um at all and that also includes nut Butters so to put that in perspective one portion of nuts is around 30 grams and that's roughly a small handful of nuts so six grams is literally just a couple of nuts a day then Sarah yeah that's right Jonathan which is a shame because I know they're packed full of nutrients in fact I've heard Tim describe the nut as a tree egg and Sarah you know how much you like the nutrients in eggs yeah absolutely and mixed nuts contain so many great nutrients they contain fiber they contain vitamin E magnesium selenium and nuts are also very high in fat but they're particularly high in monounsaturated fats which we know are the healthy type of fats so Sarah let's get into the nuts and bolts of things shall we oh my gosh I've got I've got loads more of these today it's a great one um how do nuts affect our health then in particular I've read that nuts might be good for our hearts yeah nuts do lots of great things that help our heart health so in particular nuts can decrease our bad LDL cholesterol and they can also decrease our blood triglyceride concentrations and this means that nuts might help to lower the risk of both heart disease and stroke now in addition nuts also contain bioactives and these are tiny molecules that have lots of really special roles to play in the body for example some have antioxidant and anti-inflammatory properties and a great example is polyphenols and these are thought to protect your cells from damage that are caused by free radicals and polyphenol chemicals from nuts can help to reduce bad cholesterol from being oxidized which happens when LDL cholesterol reacts with free radicals this is great because we know that oxidized LDL cholesterol can build up in the walls of your arteries it can cause them to become thicker and to stiffen reducing just how much blood can actually get through these arteries which can lead to atherosclerosis which is the first step towards heart disease and strokes and there's lots of different studies that have measured this and there's a number of different ones that have found that people who eat various types of nuts see a drop in the levels of these oxidized bad LDL by up to about 30 percent so now on top of that there's also impact on inflammation isn't there and inflammation is something that we're very interested in at Zoe because of the way that it seems to be linked to sort of almost every long-term disease that scientists are investigating it just comes up over and over again on on this podcasts and and elsewhere um now my understanding looking at some of the research there is that there are also studies where people whose diets were supplemented with nuts saw a real decrease in inflammation what they call like inflammatory markers in those papers yeah that's right Jonathan we see with lots of different types of nuts like walnuts almonds pistachios if you eat over a long period of time a portion of these nuts a day you have a reduction in many of these different types of inflammatory measures we also know that there's an impact of eating nuts for people that have metabolic syndrome and type 2 diabetes we know that they improve insulin sensitivity we know that they reduce your fasting blood glucose but interestingly they also improve your blood vessel function and this is something I've looked at in my own research and I think it's important to say at this point that I have received a lot of funding from the alma board of California to research the impact of almonds on cardiovascular health so I do always like to put any conflict of interest out there and we ran a study where we supplemented people with nuts for six weeks compared to a control and we found an improvement in the functioning of people's blood vessels when they had almonds so almost like how elastic they they are and finally there's some evidence as well just emerging that nuts might even prevent memory loss as we age although this is still at quite early stages of research much so it's all pretty amazing these like tiny nuts are definitely punching well above their weight oh how many more of these jokes are we gonna have Jonathan okay Jonathan we haven't even mentioned the fiber that's in nuts which is another great property of nuts and fiber simply put is the nut cell walls and in one 30 gram portion of peanuts um there's about two and a half grams of fiber and this is in comparison to a pack of uh salted crisps or potato chips which has less than one grams of fiber and there's really compelling evidence linking high fiber intake to reducing the risk of many chronic diseases and and even death which I'm particularly keen on so you know as you increase your dosage of fiber actually your life expectancy increases which is pretty cool I think most listeners here will be like oh we're in favor of the longer life expectancy um and this is rare right there's very few things actually where you see really clear impact not just on some sort of disease but actually whether or not you're going to to live longer yeah and fiber's the one nutrient that every nutritional scientist in the world agrees we that we're not getting enough of you know in the UK in the US we consume less than 20 grams we should be getting at least 30 grams a day of fiber so what's great is these nuts are packed full uh fiber and this fiber basically Works to feed your Healthy gut bacteria so Sarah it seems pretty clear nuts have lots of benefits they're also surprisingly well studied um in terms of sort of the research that you're talking about compared to a lot of the the topics um where we say you know there's like three studies in the whole world ever and it seems like particularly clear to do with cardiovascular health so you know sort of heart disease and strows I think the elephant in the room is really white um if nuts are high in calories um won't they contribute to weight gain so this is what I think it gets really interesting and obviously I'm biased because this has been the focus of my research with nuts which is their food Matrix so what makes the humble nut even more special is their structure and this is what I call the food Matrix so Sarah most people only know the Matrix as like a hit film 30 years ago so could you explain a bit more what the food Matrix is yeah so we're not talking about Keanu Reeves here uh Jonathan we're talking about the food structure and really simply put it just refers to the structure of a food so I think a really good way to illustrate this is using almonds and let's say you had a packet of whole almonds and a packet of ground almonds according to the backup pack labeling information they're not nutritionally identical but actually how they behave in our body is really different nuts consists of millions of tiny cells and these have cell walls which we've already mentioned is the fiber and they have a really important structural role and Within These cell walls a tiny fat globules now if I very very finely grind the nuts I break down the cell walls and the fat bursts out but when you eat whole nuts The Matrix so the structure of these cell walls remains intact so their fat is remaining within the cell walls and it's therefore not easily digestible and so research has shown that about 30 fewer calories are absorbed from these whole nuts compared to what's predicted based on the ingredients listed on the back of pack labeling and Jonathan from the studies that I've done where we collect poo after people have eaten whole nuts you actually see these whole big nut particles and if you slice through them which fort actually my researchers do rather than than I do and then put them under a microscope you can actually see these hundreds of intact cells still Within These chewed nut particles that we've collected from the poo and you can see within those all of these fat globules which is why it has 30 less calories that are being absorbed and Sarah is this true of like any plant that we eat or is this because like most plants you know we cook for ages first or ha you know is there something special and magical about nuts how do we understand that so lots of different types of nuts and we find consistently that the backer pack labeling information would overestimate the calorie amount by about 30 percent the impact of the cell wall structure within other plants varies depending on the plants so for example in more carbohydrate-rich foods such as oats you will still get full absorption of all of the nutrients so you will still absorb all of the calories but you'll change the rate at which you absorb them so you will lower your blood sugar response which is beneficial if you're having really large oats versus having really finely ground oats got it and so if I meet Team I don't know lentils for example which are quite a high fiber um food I know but they do have lots of carbohydrate I'm it's not the same as nuts I am probably going to end up extracting all of that but it's just going to take it's going to take a while but you know I'm going to get to it including my bacteria they're going to get their way through whereas these nuts it's sort of really unusual basically we're sort of struggling it's sort of very inefficient I guess you're saying we're sort of struggling to get all the calories out before actually it's coming out the other end yeah absolutely and we've done uh what we call mastication studies Jonathan where these are even more glamorous than the poop Stoke we do um these studies involve people chewing nuts and at the point at which they're about to swallow they spit them out we collect them and we analyze them we analyze them for how much fat is released at that point and what's interesting is at the point at which you're about to swallow an almond the amount of fat that's released from the chewing action bursting the cells is only about 10 at that point and this is because the cells of almonds and it's the same with other nuts are so so tiny they're 35 micrometers which is Tiny yet the point at which you swallow nuts is normally around nearly one millimeter particle size and so that's why so much is entering your stomach and your intestine intact and so that explains why actually you know the amount of calories you actually consume might be much less than than sort of on the packet presumably that does mean the more that you process nuts the more that the fat will be released and the more energy you'll be able to absorb yeah and this is another really interesting area of research is looking at the effect of consuming whole nuts versus um nut buttered and really finely ground nut powders and what we know is if you commercially grind the nuts to break all of the cell walls and release all of the fat then a lot more of that fat is accessible and therefore you do absorb a large proportion of the calories however using the kind of techniques that you might use at home to grind nuts or to make your own nut Butters you're unlikely to be able to grind the nuts to an extent that you break all of the cell walls so you're still likely to actually have a nut that has a lot lower energy density so lower calorie amount that's absorbed compared to if it was fully ground so I guess one question follows from this you know you might think it's a good idea that your body isn't absorbing all um all the fat but on the other hand does it mean that all these other nutrients that you were talking about like you know vitamin E and whatever else are also not going to be absorbed as much yeah yeah I've actually published research showing that the vitamini in the blood after eating whole almonds is Lots lower than the vitamin E after eating industrially ground almonds where all of the cell walls are broken down and Sarah I remember you telling me something really extraordinary that there's a study about how many calories different individuals extract from the same nuts and sort of showing this huge variation is that right yeah absolutely so there is a study carried out a number of years ago by David bear in the U.S where they fed individuals not so for a period of time collected their poo and had a look how much energy was excreted from consuming nuts and what this meant in real terms is that for some people a 30 gram portion of almonds resulted in them eating about 56 calories and yet for other people eating a 30 gram portion of almonds resulted in them eating about 168 calories so that's a huge difference and if you extract that over a week that's a large amount I can't do the mat off the top of my head but I think that's about 750 calorie difference so Jonathan I think all of this taken together goes some way to explain why despite what a lot of people fear research has shown that nuts simply do not cause you to put on weight and whilst the nutritional makeup of each nut very slightly broadly speaking one nut is not necessarily better than another and any type of nut as long as they're not coated in chocolate salt or sugar will make a really great addition to your diet foreign well I was going to tell you Mike can I tell you my Brazil nut story just to finish I haven't heard this one so yes please do so um because I always think about almonds and there's you know there's uh almonds are grown now commercially in uh um in a lot of places but Brazil nuts can't be grown like in a um in a plantation they haven't figured out how to do this and I once went to uh the Amazon many years ago amazing um trip just after I left my last um company and you know I we sort of went deep into uh into the Amazon and the Brazil nut tree it turns out is one of the biggest trees in the world and so it's one of the biggest trees in the Amazon it sort of sticks out this huge tree and apparently they're one of like the key trees in the ecosystem of uh of Amazon and these little nuts are actually coming this massive sort of Cannonball sized thing um the the Brazil nut tree uh grows and then it falls from a height of I'm making this up now like 30 meters so the huge thing that collapses to the ground and people who live locally or a lot of um sort of indigenous people who've been there you know before Europeans even um came to America has come at a particular the right season to harvest these sort of in the Amazon and take them to sell us and they have to mare massive hard hats because actually if this thing falls on your head it could kill you so I love this idea that you get this sort of Brazil nut that's sort of in the supermarket just seems like nothing at all but actually it's sort of this king of nuts that's come from the Amazon so I always think about that when I have it and also of course it's very ecological because um the Brazil nut tree can only survive because the whole Amazon around it is still being supported they haven't figured out a way to for it to grow so I feel I always feel quite quite good as well that somehow you're you're supporting some of the sustainability which we know is a is a big issue so that is my Brazil nut story so Jonathan I've been Googling Brazil nut tree while you've been telling me that and this is a total eye-opener to me so it looks like a coconut shell and when you cut it in half it's got like 50 60 Brazil nuts inside it again in case within their own shell never knew amazing right wow and apparently so all of this is what I was told that I thought you're gonna have to tell me that all of this was a total lie that they just tell to these visiting Western tourists apparently there is a particular animal I think it's like uh something a bit like a chipmunk which is the only animal which can actually crack open the outer shell of this so again this is like this whole amazing ecosystem where you you can only have a new Brazil nut tree because of this animal that can break open this massive um thing and I guess it like drags it off somewhere else or something as a way to move it around but um I I love this there's something really nice about the idea that you're connected to this uh this tree thousands of miles away I'm now Googling what animal I think it might be in agouti but um I'm not sure Google's not quite quick enough we'll put this in the show notes um so what's your final conclusion so my final thoughts are that nuts are a great addition to anyone's diet that having different types of nuts is great because whilst nearly all nuts contain fantastic uh combination of healthy fats and these magic polyphenols they do also differ slightly in some of their other attributes so having mixed nuts is great and my other top tip is to actually try substituting your normal snacks for nuts we know that about 20 of our energy intake comes from snacks if you can change your typical snacks to nuts you'll really see big improvements in your health uh I think the short summary is we think nuts are great we do we agree on this one Jonathan as we do on so many well if you'd like to discover how nuts can best fit into your life you may want to try Zoe's personalized nutrition program to improve your health and manage your weight you can get 10 off by going to join zoe.com podcast I'm Jonathan wolf and I'm Sarah Berry join us next week for another Zoe podcast thank you [Music] foreign [Music]

Channel: ZOE

Views: 257,199

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Id: Jmh_A-XJic4

Length: 19min 36sec (1176 seconds)

Published: Mon Apr 24 2023