Transcript
A (0:01)
Hello and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today, we're taking a closer look at one of the world's favourite breakfasts, oats. Depending on who you ask, oats are either a superfood or a source for concern. Either a great way to get fiber or a worrying blood sugar spiker. So what's the truth? Are oats a smart start to your day or something to be cautious about? Professor Sarah Berry joins me to dig into the science. What does it really say about oats? What are oats and, like, what happens to them before they arrived in my bowl?
B (0:44)
Yeah, so oats are a type of seed or a whole grain that comes from the oat grass, and this is called the avena sativa plant, and I hope I pronounced that correctly. They're very much like a wheat kind of plant. And the seed is encapsulated within this hull, which is like the kind of shell, and what happens is that is removed because you wouldn't be able to eat that shell. And what you're left behind is with the oat grain or the oat seed, and that consists of this outer bran layer, which is slightly brown, orangey, which is what you sometimes see in your oat flakes. You see a little specks, don't you, of this kind of brown and orange, and that's from this outer skin. And then within that outer skin is the main part of the oat, which we call the endosperm. And it's within that endosperm that contains all of the starch, so all of the carbohydrate, as well as some fibre and as well as some protein. And then in the outer layer, that skin, we often call it the bran, that contains a lot of fibre. And so an oat seed typically contains about 60 to 70% carbohydrates. It contains about 10% of protein, which is quite high for a whole grain. And it contains a very special type of fibre called beta glucan. It also contains lots of vitamins, so particularly B vitamins. And it contains lots of minerals, so magnesium, zinc, iron, manganese. And it contains some bioactives, which we call polyphenols. And it contains a particular type of bioactive. Is there evidence to show in populations that eating oats are even healthy for us? And there's some fantastic data that's come from what we call the epidemiological studies, which are studies in large populations where they've followed people for a long period of time and looked at, depending on whether people are oat eaters or not oat eaters, whether that affects their risk of disease. And in one such study, where they followed more than 500,000 individuals over many years, they found that people who were oat eaters versus those who didn't eat any oats actually had lower rates of type 2 diabetes by about 15% and lower all cause mortality, which basically means risk of dying, and that was by about 20%. Now, obviously, there's lots of other things that might explain some of this. You know, people who eat oats tend to smoke less, et cetera, but you can actually adjust for that in the analysis. You can never fully disentangle it. So it's not kind of the strongest evidence to pull on. But that gives us an idea that there's something going on there, that there's something about eating oats that might be beneficial for our health. And so the next thing we need to look at is clinical trials. And also, is there a mechanism, is there some kind of rationale why we might be seeing this? And what we know is that oats contain a very special fibre called beta glucan. And this fibre is well known to reduce circulating cholesterol levels, so to reduce total cholesterol, but also reduce ldl, which is our bad cholesterol that we know is linked to heart disease. And there's been lots of clinical trials that have been published showing that if you add oats to a meal or the beta glucan to a meal, that you can significantly reduce people's cholesterol levels. It needs to be about a certain dose. So we know that you need to be having about 3 grams of the beta glucan a day in order to lower your cholesterol. And so the FDA in the US and the efsa, the European Food Standards Agency in the uk, actually have an approved health claim that beta glucan, this fibre that's in oats at 3 grams a day, can reduce your cholesterol and hence is associated with improved heart health. And I think the evidence is quite consistent for that.
