Antioxidants

The process of oxidation in the human body damages cell membranes and other structures, including cellular proteins, lipids and DNA.

When oxygen is metabolised, it creates unstable molecules called ‘free radicals’, which steal electrons from other molecules, causing damage to DNA and other cells. The body can cope with some free radicals and needs them to function effectively.

However, the damage caused by an overload of free radicals over time may become irreversible and lead to certain diseases (including cancers). Oxidation can be accelerated by: other factors. Antioxidants are found in certain foods and may prevent some of the damage caused by free radicals by neutralising them.

These include the nutrient antioxidants, vitamins A, C and E, and the minerals copper, zinc and selenium. Other dietary food compounds, such as the phytochemicals in plants, are believed to have greater antioxidant effects than. These are called the non-nutrient antioxidants and include phytochemicals, (such as lycopenes in tomatoes and anthocyanins found in cranberries).

Some conditions caused by free radicals include:

• triggered by damaged cell DNA. A diet high in antioxidants may reduce the risk of many diseases (including heart disease
• certain cancers). Antioxidants scavenge free radicals from the body cells
• prevent or reduce the damage caused by oxidation

The protective effect of antioxidants continues to be studied around the world.

For instance, men who eat plenty of the antioxidant lycopene (found in red fruits and vegetables such as tomatoes, apricots, pink grapefruit and watermelon) may be less likely than other men to develop Lutein, found in spinach and corn, has been linked to a lower incidence of eye lens degeneration and associated vision loss in the elderly.

Research also suggests that dietary lutein may improve memory and prevent cognitive decline.

Studies show that flavonoid-rich foods prevent some diseases, including metabolic-related diseases and cancer. Apples, grapes, citrus fruits, berries, tea, onions, olive oil and red wine are the most common sources of flavonoids.

Plant foods are rich sources of antioxidants

They are most abundant in fruits and vegetables, as well as other foods including nuts, wholegrains and some meats, poultry and fish. include:

• – red meat offal

Also derived from the plants that animals eat

There is increasing evidence that antioxidants are more effective when obtained from whole foods, rather than isolated from a food and presented in tablet form. can increase our cancer risk.

For example, vitamin A (beta-carotene) has been associated with a reduced risk of certain cancers, but an increase in others – such as in smokers (if vitamin A is purified from foodstuffs).

A study examining the effects of vitamin E found that it did not offer the same benefits when taken as a supplement. Also, antioxidant minerals or vitamins can act as pro-oxidants or damaging ‘oxidants’ if they are consumed at levels significantly above the recommended amounts for dietary intake. A well-balanced diet, which includes consuming antioxidants from whole foods, is best.

If you need to take a supplement, seek advice from your doctor or dietitian and choose supplements that contain all nutrients at the recommended levels. Research is divided over whether antioxidant supplements offer the same health benefits as antioxidants in foods. , it is recommended we eat a wide variety from the main 5 food groups every day: – mostly reduced fat (reduced fat milk is not recommended for children under 2 years).

To meet your nutritional needs, as a minimum try to consume a serve of fruit and vegetables daily. Although serving sizes vary depending on gender, age and stage of life, this is roughly a medium-sized piece of fruit or a half-cup of cooked vegetables. has more information on recommended servings and portions for specific ages, life stage and gender.

It is also thought antioxidants and other protective constituents from vegetables, legumes and fruit need to be consumed regularly from early life to be effective.

See your doctor or dietitian for advice

About oxidation heart and liver disease ) and some cancers (such as oral , oesophageal, stomach and bowel stress cigarette smoking alcohol sunlight pollution Antioxidants and free radicals vitamins or minerals The effect of free radicals deterioration of the eye lens, which contributes to vision loss inflammation of the joints ( arthritis ) damage to nerve cells in the brain, which contributes to conditions (such as Parkinson’s or Alzheimer’s disease ) acceleration of the ageing process increased risk of coronary heart disease , since free radicals encourage low-density lipoprotein (LDL) cholesterol to stick to artery walls certain cancers Disease-fighting antioxidants prostate cancer.

Lycopene has also been linked to reduced risk of developing type 2 diabetes Sources of antioxidants Good sources of specific antioxidants allium sulphur compounds – leeks, onions and garlic anthocyanins – eggplant, grapes and berries beta-carotene – pumpkin, mangoes, apricots, carrots, spinach and parsley catechins – red wine and tea copper – seafood, lean meat, milk and nuts cryptoxanthins – red capsicum, pumpkin and mangoes flavonoids – tea, green tea, citrus fruits, red wine, onion and apples indoles – cruciferous vegetables such as broccoli, cabbage and cauliflower isoflavonoids – soybeans, tofu, lentils, peas and milk lignans – sesame seeds, bran, whole grains and vegetables lutein – green, leafy vegetables like spinach, and corn lycopene – tomatoes, apricots, pink grapefruit and watermelon manganese – seafood, lean meat, milk and nuts polyphenols – herbs selenium – seafood, offal, lean meat and whole grains vitamin A – liver, sweet potatoes, carrots, milk, and egg yolks vitamin C – oranges, blackcurrants, kiwifruit, mangoes, broccoli, spinach, capsicum and strawberries vitamin E – vegetable oils (such as wheatgerm oil), avocados, nuts, seeds and whole grains zinc – seafood, lean meat, milk and nuts zoochemicals Vitamin supplements and antioxidants Research shows that some vitamin supplements lung cancer Dietary recommendations for antioxidants To achieve a healthy and well-balanced diet vegetables and legumes or beans fruit grain foods and cereals (mostly wholegrain) lean meat, poultry or alternatives such as fish , eggs, tofu , legumes and beans, nuts and seeds dairy and dairy alternatives The American Dietary Guidelines Where to get help Your GP (doctor) Dietitians United States 1800 812 942 American guide to healthy eating .

Key Points

• Antioxidants are found in certain foods and may prevent some of the damage caused by free radicals by neutralising them
• Some conditions caused by free radicals include: triggered by damaged cell DNA
• diet high in antioxidants may reduce the risk of many diseases (including heart disease and certain cancers)
• Antioxidants scavenge free radicals from the body cells and prevent or reduce the damage caused by oxidation
• Research also suggests that dietary lutein may improve memory and prevent cognitive decline