An apple a day keeps the doctor away, spinach will make you strong and carrots will give you night vision. These are among the silly sayings people have been throwing around for ages in a bid to get kids to eat well. But where do they come from and is there any truth to them? I talk to NZ Healthy Food Guide nutritionist Claire Turnbull to find out more.

An apple a day keeps the doctor away

There's no doubt that fruits and vegetables play an important part in keeping us healthy and well. Turnbull, author of Lose Weight for Life, says two servings of fruit a day is best (and follow the 5+ a day rule - making it up with at least three servings of veg). However, your daily fruit dose does not have to contain an apple. Turnbull's not sure where this old rhyme comes from, and it's certainly not harmful, but variety is great for your body. Sticking with seasonal produce will help you mix it up, plus if you are lucky enough to eat the delicious pickings straight from the tree, you'll know how much better seasonal goodies taste. (FYI: I love a handful of blueberries in my breakfast smoothie, some raisins for an afternoon pick-me-up or an orange to sweeten up a vegetable juice.) The World Health Organisation says getting your daily dose of fruit and veg reduces the risk of heart disease and certain types of cancers.

Spinach makes you strong


Sure, this green leafy vegetable has some iron in it. But the myth - perpetuated by the cartoon muscle man Popeye and his inhalation of cans of the stuff - is actually based on a bit of a stuff up. "They made a mistake with the nutritional analysis back in the day and put the decimal point in the wrong place with spinach, making it look like it had a huge amount more iron that in really did!" Turnbull says.

If you want to get some tone in your muscles you'll need to make time for resistance training in your exercise regime (a couple of pump classes a week will get you on your way to enviable Michelle Obama guns, with the benefit of a boost to your metabolism if you keep it up.) And for a well-balanced temple, you need some protein - which will also help with muscle recovery, Turnbull says. (I like a post-gym omelet).

Iron alone won't make you strong. What it will do is help your body make red blood cells, which will give you lots of energy, keep your brain working at its best and improve immunity. Meat is full of it, but one of my other favourite iron-packed goodies is parsley - I add the herb to my eggs and in green juices.

Carrots improve night vision

There's a good little yarn about how carrots got to be praised for seeing in the dark. You can read the full story here. But in a nut shell, yellow fruits and veggies contain beta-carotene. The liver converts these in to to vitamin A which helps keep your skin healthy, your immunity in check and your vision at its best. This was the basis of the myth started by the Royal Air Force in WWII - they didn't want to give away their new radar technology, so said their super-human accuracy was because of all the carrots. Turnbull says Vitamin A deficiency is the greatest cause of blindness in the developing world. However, if you aren't lacking in it, then eating more carrots won't give you special vision.

Fish makes you smart

Oily fish (like salmon and whitebait) provide the body with long chain Omega-3 fatty acids. These guys are very good for brain (both in its development in the womb and throughout life). Our bodies aren't able to make these by themselves, Turnbull explains, so you need to help it out by eating enough foods filled with them. "They do play a part in brain health but I don't think we can say categorically that people who eat fish are always going to be more clever than those who don't," Turnbull says. She recommends eating fish eat least twice a week, and try to make one of those an oily one.

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* What food sayings have you heard of? Any that you'd like me to find out more about? Are there any you use to encourage healthy eating?