Fructooligosaccharide also called FOS is a slightly sweet carbohydrate found in the root of certain plants. 

It has certain beneficial properties similar to Oligofructose and Inulin. Of these three natural prebiotics FOS is the sweetest and has the shortest molecular chain.

It is classified as a fiber because it passes through the digestive tract without being metabolized until it reaches the colon. Unlike cellulose fiber (bran etc) it is a soluble fiber. It is found in many vegetables including Yacon. a root tuber grown in peru.

It has a good taste and about half the sweetness of sugar.

In the food industry it is used to bulk up products, while keeping the calorie count low. Inulin, having a longer polymer chain, is less sweet, and is usually used to replace fat in low calorie products. Fructooligosaccharide, having a shorter chain, is sweeter, and are usually used to replace sugar. Also used to provide fiber in health bars and snacks. 

It has less than one third the calories of sugar. It has a zero glycemic index and is suitable for diabetics. It adds fiber to the diet. It is prebiotic and has been shown to promote the growth of beneficial bacteria in the colon. It has also been show to assist the body's ability to absorb minerals from food. It adds bulk and texture to processed foods.

See: NCIB potential benefits of FOS

Although it is not a sugar alcohol it has a laxative effect. It is a fiber and this can have beneficial effects but can cause cramps etc if consumed to excess. Probably best not to consume more than 10 gm per day. For this reason it is a good idea to be aware of its presence in processed foods and 'health foods'.

Certain people suffer from a mild form of Fructose Intolerance. Because Fructooligosaccharide is composed of Fructose, it also falls into this category. Symptoms are not too severe, but can be similar to those suffering from IBS (Irritable Bowel Syndrome)

Safety Guidelines:
For most people an upper guideline would be 10 to 15gm per day, though over time the body habituates to use and the amount can be safely increased.

CSPI (US) Recommendation

The recommendation issued by the Center for Science in the Public Interest (US) for this substance is - SAFE

The CSPI give SAFE for Inulin and Oligofructose, though they do not specifically mention FOS, it is almost identical in it's effects.

It is an natural product found in root vegetables. Inulin can be broken down by partial hydrolysis into Oligofructose or FOS.

Sold As:
Not usually sold on its own but added to sweeteners, processed foods or health foods. FOS tablets are sold as a supplement on Amazon.

Interesting facts:
Inulin, oligofructose, and fructooligosaccharide are fructans. They are carbohydrates made up of fructose molecules joined in a particular type of glycosidic linkage which cannot be broken down by saliva or digestive enzymes.

So although they are made up of fructose molecules, these cannot be used by the body, and do not cause the problems associated with this sugar. 

Of the three inulin is the most complex, has the longest chain and it is the least sweet. Oligofructose comes next, having up to 10 fructose molecules. Fructooligosaccharide is the shortest having 2 to 4 molecules, the last in the chain being a glucose molecule. It is the sweetest of the three.

All of these carbohydrates are soluble fibers meaning that they dissolve in water. They travel through the body undigested until they reach the colon. Here they undergo fermentation and this has a major effect on bacteria in the gut. It tends to promote beneficial bacteria but it also produces gas and can lead to flatulence. However, the body gradually adapts, and with long term use the benefits persist, but the undesirable side effects are reduced.

Good sources are Chicory root, Jerusalem artichoke, Leek, Asparagus, Wheat bran and also Bananas. Agave, but not Agave Syrup is a rich source.

Approved by the FDA as GRAS. Approved in most countries.


Conclusions for Fructooligosaccharide

About half as sweet as sugar, it has many beneficial effects. Excessive consumption can lead to problems. Best to limit consumption to 10gm per day. Has medicinal uses and is said to boost the immune system. Is also believed to assist with weight loss.

Name Calories / Gram Sweetness Index Glycemic Index Calories / Spoon-Equiv
FOS 1.4 0.5 0 11

Taste: -------- Good
Aftertaste: ---- No.
Concerns: ----- Only in excess.

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