EVERY time you throw away a prawn head or discard that banana peel, you're missing out on a whole host of super-healthy nutrients.

For centuries, civilisations have enjoyed the myriad health benefits of the kinds of foods we throw out every day. While prawn heads, tripe and the skin from kiwifruit may sound like the diet from hell, these powerhouse ingredients actually contain many hidden nutrients which will boost how you look and feel - they just might take a bit of getting used to!

Here's how to incorporate them into your diet:

+ Kiwi fruit skin fights cancer cells

This high-fibre fruit boasts more vitamin C than oranges and can protect against DNA damage that can trigger cancer. The flavonoid compounds in the skin attack free radicals and ward off bugs that cause food poisoning. (Buy organic and thoroughly wash the skin with water.) US studies have shown these compounds help protect against heart disease.

How to have it: eat raw or blend in a homemade chutney.

+ Banana skin to beat depression

Bananas are packed with potassium, and a diet high in this mineral helps keep blood pressure at normal levels, which studies show reduces the risk of stroke. Researchers in Taiwan found banana peel extract is rich in the mood-boosting chemical serotonin.

How to have it: boil the skin for 10 minutes then drink the liquid once cooled, or put through a juicer.

+ Boiled vegetable water for a vitamin boost

Steaming is the preferred method for cooking vegetables as it helps lock in nutrients. However, if you choose to boil your vegies, you can still benefit by salvaging the nutrient-rich water.

How to have it: once cooled, drink it straight as the nutrients can degrade quickly.

+ Tripe a treat for the male reproductive system

The thought of eating the lining of a cow's stomach (tripe) is enough to turn your gut. But it is eaten by people all over the world and contains a host of healthy nutrients including calcium, zinc and selenium, which is a strong free-radical fighter. If you can handle the texture, tripe will bestow protective benefits for teeth, bones and the male reproductive system.

How to have it: enjoy in a variety of soup dishes.

+ Celery tops trump free radicals

Don't throw away celery leaves - you'll miss out on a rich source of vitamins C and A, fibre and antioxidants. The leaves have five times more magnesium and calcium than the stalks.

How to have it: chopped and served with parsley in salsa or served with fish.

+ Healthy all-rounder: Orange peel

Orange peel is an excellent source of vitamins and minerals including calcium, magnesium, zinc, copper, potassium and phosphorous. It is thought to be effective in treating many conditions including constipation, high blood pressure and may even lower LDL or "bad" cholesterol and the risk of stomach cancer.

How to have it: use organic oranges and grate zest on green beans and asparagus.

+ Prawn heads are rich in antioxidants

Do you bin prawn heads at barbecues? Consider this: they contain the powerful antioxidant astaxanthin, which is 10 times more effective than those commonly found in fruit and vegetables.

How to have them: barbecued, deep-fried, or added to risottos and soups.

+ Broccoli leaves boost vitamin A

The nutritional value of broccoli leaves far outweigh the benefit of the florets when it comes to beta-carotene. Just 28 grams of broccoli leaf will deliver 90 per cent of the daily requirement of vitamin A, compared to three per cent in the floret.

How to have them: sauté leaves with garlic and salt.

> Waiter, there's a bug in my soup

To most of us, bugs are seen as a pest. But in Asia, insects are actually considered a delicacy. Edible bugs such as grasshoppers and water beetles contain many vitamins and minerals, are low-fat and have twice the amount of protein as raw meat. How to have them: deep-fried or barbecued and in stir-fries.

Why don't we eat it?

Alisa de Torres, clinical psychologist and director at mypsych.com, says appetite is controlled by brain function in many ways. Not surprisingly, visual cues play a strong role in predetermining what we eat.

Food that looks appealing triggers a brain response to increase appetite. "It heightens our sensation of pleasure," de Torres says. "Things that don't taste so pleasant are also going to be aversive for us, making us not want to eat them. The brain is programmed to avoid things that might be toxic. So if foods have off flavours and are not familiar to us, we might be prone to avoid them."

Considering we're likely to experience food shortages in the future on a global scale, we face an ethical dilemma, de Torres says. And it is societal norms that prevent people from seeking out other healthy options in unusual places.

"You have to encourage people to be more exploratory," she says. "One of the things they're saying, with regards to food shortages around the world, is we should learn to eat insects. And in many parts of the planet people do indeed eat them. We have to encourage it."

Society can shape what people eat, de Torres says. People's perception of food - what we should and shouldn't eat - is largely driven by marketing.

"We are very heavily marketed to, and those foods become normalised," she adds. "Not being consumed by clever marketing is difficult."

The solution may be in your backyard. "We're going to have to get used to eating insects," de Torres says. "In Asia, traditionally many people eat insects and find them quite delicious."