Functional foods, foods with extra 'healthy' ingredients added, are being touted as the answer to a range of conditions from high cholesterol to iodine deficiency. But are they real health food or just hype?

For much of human existence, food has been a source of nourishment, nutrients and, if you're lucky, some enjoyable flavours.

But in a quest for better health, scientists are now stripping food back to its bare essentials to identify what it is about certain foods that make them so good for you.

These discoveries have led to the rise of so-called 'functional foods' – processed foods that have additional ingredients added to them to enhance their health benefits.

As you walk around the supermarket, you will find plenty of examples of functional foods: orange juice with added calcium, pasta fortified with iron, bread fortified with iodine and folate, margarine that helps lower cholesterol, and yoghurt cultivated with specific bacterial strains.

There is plenty of health hype around functional foods, and their price often reflects this, but how much of a health kick do functional foods really give?

Nutritionist Dr Rosemary Stanton believes functional foods are overwhelmingly a marketing exercise, and have no place in a healthy, balanced diet.

"Many functional foods are designed to replace something that … you would normally get in fruits and vegetables," says Stanton, citing one example of a cracker enriched with lycopene – a chemical found naturally in tomatoes – that can reduce the risk of some cancers.

"They often try to produce something as good as fruit and vegetables, which I think is crazy when we've already got fruit and vegetables."

 

 

Medicine in a tub

But functional foods can provide a condensed 'hit' of what's good for you, in a much more potent form or concentration than might normally be consumed in a healthy diet.

One example is the addition of plant sterols to margarines, which can lower LDL or 'bad' cholesterol. Sterols are a type of lipid, or fat, which is an essential component of cell walls in both plants and animals. The secret to plant sterols' success in lowering cholesterol in humans is the close chemical similarity of the two molecules, says Dr Peter Clifton, director of CSIRO's Nutrition Clinic.

"When you eat them, plant sterols compete with cholesterol and throw it out so there's less cholesterol available to be absorbed," says Clifton, who has been involved in studies of the effectiveness of plant-sterol-enriched margarine.

Clifton says there is very strong evidence of the benefits of plant sterols; more than 80 studies have been conducted. An analysis of the results from many of these showed an average drop in LDL cholesterol of 11 per cent.

While plant sterols are found naturally in vegetables, nuts and grains, Clifton says you would need to eat a huge amount of these foods to achieve the same cholesterol-lowering effects as the enriched margarine.

"If you're vegetarian and have broad range of foods in your diet, you can get 400 to 800 milligrams a day of plant sterols," he says. "The sort of doses that are required to get a convincingly measurable effect, you need 2 to 2.5 grams."

While the health benefits of these margarines aren't on par with cholesterol-lowering drugs such as statins, they have the benefit of being available on the supermarket shelf.

But it's this availability that worries Stanton. She's concerned children and others who don't need to lower their cholesterol will eat these products.

"We need to be careful when you use these things because they may not be suitable for everybody," Stanton says. There is evidence that some fat-soluble vitamins, such as A and D, are excreted with the cholesterol, so some products are topped up with extra vitamin A and D to compensate.

Probiotics are another popular functional food. These are usually found in dairy products such as yoghurt and yoghurt drinks. Probiotics are enriched with live cultures of beneficial bacteria such as lactobacillus and bifidobacterium.

Clifton says there is actually limited evidence to support many of the health claims made about probiotics. But there is some research to suggest probiotics can have real health benefits, particularly for the gut.

"There is certainly some proof that they do modulate the environment of the gut and may actually prevent you getting gastrointestinal infections," he says.

Filling dietary gaps

One area where functional foods can clearly be of benefit is filling a dietary gap caused by allergies.

"For example, if you've got someone who has an allergic reaction to milk protein, if you put calcium into something else it might help them," Stanton says. Calcium, which is essential for bone health, is the basis of a range of functional food products including fortified orange juice and soy milk.

Another group of people who could benefit from a functional food in an otherwise healthy diet are those allergic to seafood, which is a rich source of long-chain omega-3 fatty acids.

Long-chain omega-3 fatty acids are a type of polyunsaturated fat – the 'good' fats – linked with health benefits such as reducing the risk of heart disease and lowering blood pressure. The most common omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are found in fish – such as salmon, sardines and mackerel.

While there are also slightly different omega-3 fatty acids found in plants and red meat, the most important source is fish. This is where functional foods, such as fortified bread, milk and eggs, come in.

"You may get people who have a seafood allergy but don't react if omega-3 fatty acids are added to eggs," Stanton says.

There is another potential benefit to fortification with long-chain omega-3 fatty acids that has nothing to do with human health and everything to do with the environment.

"There's not enough fish in the world to feed everybody … so if we can't keep telling people to eat two fish meals a week, we do need some other sources of omega-3," says Stanton.

The whole food

But there are many unanswered questions about how effective it is to isolate ingredients from whole foods and consume them in another form, says dietitian Dr Alan Barclay.

"Functional foods seem to overlook the fact that there are many ingredients in a particular food, and by only consuming certain ingredients in isolation you are possibly missing out on other essential ingredients," says Barclay.

In general, nutrition experts such as Barclay, from the Dietitians Association of Australia, believe functional foods have only a limited place.

"They wouldn't be necessary if people ate according to the dietary guidelines for Australia," says Barclay.

Barclay says there are rare cases where functional foods might help address a nutritional deficiency. However, there are still many questions about how well we can absorb the nutrients from functional foods and whether there are nutrient interactions.

"There are a whole range of nutrient interactions and the simple addition of a vitamin or mineral or other nutritional factor to a food doesn't mean that your body will be able to absorb it and metabolise it in the same way that perhaps if it was found in a food naturally," Barclay says.

"The classic example is the calcium in milk – the lactose and the milk proteins aid the uptake and metabolism of the calcium so it's more bioavailable [able to be absorbed and used by the body] than simply the calcium in a supplement."