How much iron do children need and how do we get it into them?
Auckland University research suggests that up to 8 out of 10 toddlers are not meeting the recommended daily intake of dietary iron and 14% of children under 2 are deficient. In the last national Nutrition Survey, low iron levels were evident in 1 in 14 adult women over 15 years old, with over a third of teenage girls aged 15-18 years not meeting their daily iron requirements.
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How do we obtain enough iron and food and also process enough, because there's types of iron – for example heme and nonheme – that you get from different food sources. So what is the most easily accessed by the human body?
The heme iron, which comes from animal products – meat, fish and poultry – is the form that's most easily absorbed. And of the heme iron that we consume we absorb about 25%. It's little affected by other factors in the diet, so that absorption rate is fairly constant. But non-heme iron, which is found in a whole range of plant sources, and quite a wide range, is actually quite difficult for us to absorb. And the absorption rate from heme iron can vary from 2% to 20% just really depending on what the other factors are in the diet and also some physiological factors.
With the nonheme, say something like spinach which is very iron-rich... If you wanted to make the most of your spinach consumption and try and absorb as much as you can from spinach or a similar leafy green vegetable, are you telling me that what you eat along with it or the other aspects of your diet might affect how much you uptake?
Yes, very much so. Absorption can vary from 2% to 20%. One of the unfortunate things about foods like spinach and other high-iron containing vegetables – and legumes are also very high – they also contain a lot of what we call the things that inhibit, the inhibitors of iron absorption. So we need to overcome that inhibition of iron absorption and then add something that increases iron absorption.
One of the best contenders for that is Vitamin C. So foods that are high in Vitamin C as part of the meal can make a really big difference. And then also avoiding some of the other things that are also inhibitors. so phytates, which we find in things like tea and coffee and chocolate and, somewhat disturbing to me, red wine, can also inhibit the absorption of nonheme iron.
Is this a question of timing when you're consuming different things? Does the body have an hour or two's grace where if you make sure there's Vitamin C with your spinach... Is there a certain time between having your spinach and your afternoon tea or coffee?
Yeah, you're bang on with that. That's exactly what you need to do. Another important thing to consider there is milk, because calcium in milk also inhibits nonheme iron absorption. But the last thing we want to do is stop people drinking milk because that's so important for calcium for your bones.
An hour before, two hours after a meal – [avoid] the tea and coffee and milk. I think with children that can be quite a problem because of course it's natural for children often to have a large glass of milk with their meal. So perhaps save that for afterwards and maybe have something with some more Vitamin C in it as part of the meal.
If you want to reduce how much red meat you're having or the regularity you're having it, that's not necessarily going to be a problem. You might have the two things working together – perhaps less red meat, but also having some nonheme iron sources that can work in combination.
Yeah, exactly. So a meal, say, that has a lot of lentils or beans and a small amount of beef mince in it served with fresh tomatoes, which are really high in Vitamin C or a salsa with tomatoes and capsicum – also high in Vitamin C. That will mean you'll absorb a good amount – perhaps an optimum amount – of iron from that meal.
It’s getting those food combinations right, making sure that with every meal you have some good form of Vitamin C. So really high Vitamin C-containing foods – tomatoes and capsciums, all citrus fruit... Even squeezing fresh lime or lemon juice into a meal will help. Kiwifruit are really high in Vitamin C, as well.