A functional food contains an added ingredient which is supposed to decrease risk of disease as well as promoting our well-being (health). Examples of functional foods are prebiotics and probiotics.
We carry a lot of bacteria in our guts (approximately 1kg). Although the number of bacteria in our gut is usually in balance; this balance can sometimes be disturbed due to poor diet, stre**, food poisoning etc.
The number of bacteria can grow at the expense of other (bad bacteria increases) and this could cause diseases in the gut.
Prebiotics can boost the number of 'good' bacteria over 'bad' bacteria.
They contain added sugars called Oligosaccharides which when eaten aren't digested by the body. Instead they are needed as food for the 'good' bacteria. With this 'food', the number of 'good' bacteria multiplies and therefore you have more 'good' bacteria. The 'bad' bacteria then decreases which makes you feel better.
Prebiotics are NOT produced by fermentation unlike probiotics. They are already present in foods such as Onions.
Probiotics already contain the 'good' bacteria themselves. And when taken, they just top up the levels of 'good' bacteria. They replace the bacteria which have been lost due to stress etc. You have more 'good' bacteria and therefore you feel better.
Probiotics are produced by fermentation
Plant Stanol Esters
Bencol (margerine spread) is a functional food. It contains stanol ester which is added to this spread. Stanol Esters occur naturally in plants, but only in small quantities.
Plant Stanol Esters are known to lower the high cholestrol levels in the blood which then lessens the risk of heart disease.
Plant Stanol Esters work by blocking the absorption of cholestrol (from the gut)