Antioxidants to the rescue

by The WellBeing Team August 6, 2009

Antioxidants come in many forms, including vitamin C, beta-carotene, vitamin E, selenium, resveratrol, alpha-lipoic acid, zinc, vitamin A, lycopene and flavonoids. They’re also found in a wide variety of foods and even drinks. Tea, berries and other fruit, vegetables, legumes, olives, grains, herbs, spices and eggs all contain antioxidants. We know that antioxidants are very important to health, but what is it that makes them so special and how exactly do they interact with free radicals to protect you from disease? Plus, which ones do you need and are you getting enough of them?

The baddies: free radicals

Any article about antioxidants has to start with free radicals. Antioxidants are important, not for themselves but for the way they keep free radicals at bay and prevent these highly reactive chemicals from damaging your health. Free radicals have the potential to harm your health quite profoundly because of their instability.

All substances are made of atoms, which in turn are made up of protons, neutrons and electrons. In most substances, there’s an even number of electrons, which means the atoms are stable and don’t react very easily with other atoms. Free radicals, however, have an odd number of electrons, which makes them unstable and highly reactive. They are constantly trying to take another electron from somewhere to return them to a stable state. This is a problem because, inside your body, free radicals stabilise themselves by stealing electrons from the cells of your body. They can also take electrons from your DNA, or from any of the other chemicals that are driving your bodily processes. On stealing these electrons, the free radical changes and damages your cells, DNA or biochemicals and it’s this free radical damage that has been associated with many health problems, from dementia and heart disease through to cancer and diabetes.

Free radicals exist in our bodies all the time. They are not something we can steer clear of, but are instead a byproduct of normal metabolic processes, an unavoidable consequence of being alive. Our body can cope with some free radicals and has mechanisms for dealing with them. Indeed, some free radicals are actually needed — for example, the super oxide radical regulates many biochemical processes and is used by our immune systems to kill off invading micro-organisms.

While a certain amount of free radical activity is unavoidable, the lower the level of free radicals and the more quickly they are neutralised, the better. Some situations, however, increase their production above “normal” levels: for example, smoking, microbial infections, intensive exercise and exposure to pollution and industrial chemicals. These may increase free radical activity above the level that can be managed by the body, raising the risk of damage to cells, DNA and biochemical processes.

The heroes: antioxidants

It has been known for a long time that eating fruit and vegetables protects us from developing many chronic diseases, including those driven by free radical damage, and in the 1980s it was postulated this was due to a group of compounds called antioxidants.

It was believed that antioxidants acted like sponges, soaking up the free radicals’ unpaired electrons. Laboratory experiments gave a form and explanation to what was already known from population studies, as it was shown that antioxidants either quenched free radicals by donating one of their electrons, or they scavenged the unpaired electron away from the free radical. Both of these actions made the free radical stable, unreactive and therefore unable to inflict further damage on the body. Both of these actions protect our cells, DNA and biochemical processes.

It was also discovered that antioxidants come in all shapes and sizes. Some of the most studied include vitamins C, E (the tocopherols) and A, as well as beta-carotene. But as our knowledge of antioxidants has grown, so have the types and groups that have been studied. Other carotenes have been discovered, including lycopene, found in red fruit and vegetables. Flavonoids, such as quercetin, have been discovered in brightly coloured fruits and green vegetables. Seeds and legumes have been found to contain lignans, while another group called indoles are also present in green vegetables.

While most fruits and vegetables contain a complex mixture of several different types of antioxidant, there is also a number of other plants we ingest that contain antioxidants. These include wheatgerm, olives, eggs, linseeds, legumes such as soybeans and, of course, Camellia sinensis, the plant that gives us tea: black, green, white, jasmine and bancha.

Why do plants contain antioxidants?

Plants contain antioxidants for many reasons, and they perform a number of functions. While they are good for your health, antioxidants also have an important role in maintaining the wellbeing of the plant. Some, like the flavonoid group, are frequently concentrated in the leaves of plants, where they act as an ultraviolet filter and protect the plant from sun damage. Other brightly coloured flavonoids are found in the fruit and flowers of plants, such as berries, where the bright colours attract pollinators and seed dispersers.

Antioxidants can also protect the plant from attack by animals, insects and microbes. The antioxidants in tea discourage animals from eating the leaves, while the isothiocyanate antioxidants in mustard, horseradish and radishes are not only responsible for their pungent flavour but also provide a chemical defence against bacteria and fungi.

It has also been suggested that organically grown fruit and vegetables may contain more antioxidants, as they are subjected to more stressful conditions. Recent research by the US Department of Agriculture has shown that plants grown in more taxing conditions — for example, those exposed to regular insect attacks or difficult weather conditions — are forced to release greater amounts of these antioxidant compounds to protect themselves.

Therefore, food produced from organic or more traditional farming methods, where broad-spectrum herbicides and insecticides have not been used, are likely to contain more antioxidants than conventionally farmed produce.

Which ones do you need?

Antioxidants are important and you need them for good health, but which ones do you need? There are many, many different antioxidants and they are available from a wide variety of foods. Antioxidants in foods don’t exist in isolation — they are part of a complex range of compounds, created in different amounts and different ratios in the plant. It is believed it’s this complexity of antioxidants that creates the protective effect: they act synergistically with each other to reduce free radical damage.

The most important consideration with antioxidants is to make sure you are having a variety by eating a wide range of different foods. Variety is important because the antioxidants protect each other. As stated, free radicals have an uneven number of electrons; this is the cause of their instability. Antioxidants are thought to disarm free radicals by either taking away their extra electron, or donating one of their own to the free radical. However, this action leaves the antioxidant itself with an uneven number of electrons, meaning it’s now less stable, more reactive and can act like a free radical itself, with the ability to damage our cells, DNA and biochemistry.

In normal circumstances, these converted antioxidant radicals are much less reactive than the original free radical and they only stay in this state for a short period of time, thereby limiting their potential for harm. The presence of other antioxidants in your body also protects from further damage.

The complex nature of antioxidants

The digestion, absorption and transport of some antioxidants can also be influenced by other components of the food we eat. We humans are complex creatures, character-wise, as well as physically and biochemically, and it seems reasonable to think the way our bodies absorb, utilise and respond to antioxidants may also be a complex process. It has been found that some antioxidants compete with each other for absorption and transport and are also affected by other components of the food we eat.

It has also been suggested that fibre may play a role in increasing the activity of antioxidants by slowing the rate at which they are broken down and absorbed into the bloodstream. The presence of fibre may lead to antioxidant compounds hanging around in the stomach and colon for extended periods of time, where they can neutralise free radicals in the digestive system itself.

Some antioxidant compounds are big molecules that are difficult to digest and absorb through the wall of the digestive tract. It may be that the presence of other nutrients or fibre may cause more efficient absorption of the antioxidants. It’s also thought that some free radicals may actually be beneficial to our health. For example, green tea, a potent source of antioxidants, also contains the free radical hydrogen peroxide. It may be that these plant radicals are actually beneficial in small amounts, as they may kick-start our own body’s defensive processes and internal antioxidant production.

Are you getting enough?

Despite their presence in tea, grains and legumes, the primary source of antioxidants in our diet is fruit and vegetables. These are full of the variety and complexity we need to maintain good health. However, despite fruit and vegetables being antioxidant-complex, proven to work, high in fibre and still relatively cheap, in Australia we generally don’t eat anywhere near enough of them. In fact, in 2006, the Chief Health Officer of NSW reported that only 5 per cent of men and 10 per cent of women get their daily intake of five servings of vegetables. Despite being heavily promoted by all health authorities, the very foods that protect against long-term ill-health are the foods we are eating less and less of.

There are many reasons for this, from the increased consumption of processed foods and decline in cooking knowledge through to our growing reliance on carbohydrate-rich foods such as bread and pasta. Whatever the reason, throughout most of the developed world, people are eating fewer and fewer daily serves of fruit and vegetables. Then there’s the loss of antioxidants that occurs through crops being grown in depleted soils, being picked too early and cold-stored. The result is that most people in Australia are eating fewer and fewer of these lovely antioxidants that improve our health so much.

Your best food source of antioxidants is organic fruits and vegetables. How much fruit and vegetable do you eat? How often do you eat nuts and legumes? If the answer to either of those questions is rarely, you are almost certainly not getting enough antioxidants to protect your health long-term. To maximise your food intake of antioxidants, it helps to know the best sources.

Eat more antioxidants

It’s worth while including as many of the top 20 antioxidant-containing foods as possible in your diet. But the most important thing to remember when you’re aiming to include more antioxidants in your diet is to eat a wide variety of foods and make sure you’re having at least two fruits and five vegetable serves (about three cups) every day, as recommended by current Australian nutritional guidelines. This can sound like a lot, but if you spread it over three meals and a couple of snacks, you don’t have to feel like a rabbit. Add in some nuts and a few legume-containing meals and you’re sure to have a diet jam-packed with antioxidants.

Your antioxidant-rich diet could include:

Breakfast

Scatter some berries and ground linseed (available from healthfood shops) over your cereal.
Make a fruit salad and serve with yoghurt and a spoonful of nuts.
Have wholegrain toast with avocado, tomato and black pepper.
Make a smoothie with mixed fruit and yoghurt.

Lunch

Add some tomato, baby spinach and avocado to your normal sandwich.
Take a salad from home and include at least four different vegies, with some avocado, a few nuts and boiled eggs.
Make wraps, with handfuls of salad and some homous.
Buy something that includes at least three different-coloured vegetables.

Dinner

Add a handful of baby spinach to your pre-made pasta sauce and cook some broccoli florets in with the pasta.
Serve dinner with a big salad including rocket, tomato, avocado and capsicum.
Reduce the amount of starchy carbohydrate food (bread, pasta, potato, rice) you’re eating and replace with an extra cup of vegetables.
Add a tin of lentils or chickpeas to soups and stews.

Snacks