Fibre – NSP or AOAC? The answer is AOAC


 

July 2015
The new definition for fibre known as AOAC fibre includes all carbohydrates that are not digested nor absorbed, plus lignin.

This approach lets UK intakes be compared with other countries.

Recommendations from the Scientific Advisory Committee on Nutrition (SACN) on fibre

SACN recommends an increase in the population’s fibre intake to an average of 30g per day for adults.

For children, the recommended intakes are:

15g/day (age 2-5);

20g/day (age 5-11);

25g/day (age 11-16);

30g/day (age 16-18).

SACN has extended the definition of dietary fibre. This includes not only non-starch polysaccharides (NSP) but also non-digestible oligosaccharides, resistant starch and polydextrose.

The exact definition of dietary fibre has been subject to much controversy and discussion.

The EU has adopted the CODEX Alimentarius definition meaning that dietary fibre is one of three categories of carbohydrate polymers: Naturally occurring edible carbohydrate polymers, carbohydrate polymers obtained from food raw material by physical, enzymatic or chemical means, and synthetic carbohydrate polymers. Also, dietary fibres should contain at least three monomeric units. 2012

The Department of Health hope to include AOAC data within the Composition of Foods Integrated Dataset (CoF IDS).  As a temporary solution until AOAC data is available, fibre content can be estimated by multiplying NSP values by 1.33.  Please note that using this method will only give a rough approximation of AOAC content.  The conversion factor was an average derived from several different food groups, and so using it with specific products will give over- and under-estimates of AOAC content.

Nutrition Claims - a product that is high in fibre must have at least 6g fibre per 100g.

ANALYSIS OF DIETARY FIBRE 

A number of methods of analysis for Dietary Fibre has been used in the UK over the years for the purpose of food nutrition labelling and these methods have changed as the definition of Dietary fibre has evolved.

The Southgate method (1969) was used for many years and the results are included in standard works on nutrition information such as McCance and Widdowson. A method developed by Englyst et al (1992), which determined NSP only, was accepted by MAFF and it remained the recommended UK method for nutrition and labelling purposes until 1999.

Cereals are good sources of fibre

Cereals are good sources of fibre

In August 1999, the Joint Food Safety and Standards Group (JFSSG – the precursor of the Food Standards Agency) accepted the role of resistant starch and lignin in DF and recommended the adoption of AOAC method 991.43 as the official UK method for DF. The further method, AOAC 997.08, determines fructans since these are also accepted as DF components (Hignett, 1999). This was confirmed in 2000 by a Food Standards Agency Guidance note.

In November 2005 the Institute of Grocery Distribution published a new Table of Guideline Daily Amounts (GDAs) for nutrients, in which the GDA for dietary fibre was 24g, and this Table carried the endorsement of the FSA.

The UK is now in line with the United States and continental Europe in the methodology for the analysis of DF.

However, the methods previously in use in the UK gave rise to different results and the user of these results must be aware of the differences. For example, Englyst determines NSP and can be split into insoluble and soluble DF. Southgate figures are normally higher than Englyst, particularly in the case of starchy foods. The AOAC method,

Sources of dietary fibre include vegetables, wheat and most other grains.

Foods rich in soluble fibre include fruits, oats, barley and beans.

Source of Dietary Fibre (DF)
The food must contain at least 3g DF per 100g or per 100ml or ‘the reasonably expected daily intake of the food’.

Increased Dietary Fibre
The food must contain at least 25% more than similar food for which no claim is made and must meet the criterion for a source claim

High in Dietary Fibre
The food must contain at least 6g DF per 100g or per 100ml or ‘the reasonably expected daily intake of the food’.

This FSA Guidance Note gives no Dietary Reference Value (DRV) for DF determined by the AOAC method but states that the value of 18g (which is based on analysis by the Englyst method) should not be used. A DRV related to the AOAC method is not proposed but will form part of harmonised EC legislation for nutrient claims
In the case of some processed cereal products, the differences between DF (AOAC) and DF (Englyst) could be greater than those shown above, due to the presence of variable amounts of resistant starch.

This is an interesting report on dietary fibre comparing NSP and AOAC fibre measurement

LEVEL OF DIETARY FIBRE IN FOODS
A comparison of Dietary Fibre  found in food using the AOAC and the Englyst methods is given in the following table:
Product AOAC (g/100g)* Englyst (g/100g)
Apples (with skin)2.0 1.6
Bananas 1.9 1.1
Carrots (boiled) 3.1 2.5
Baked Beans 4.2 3.7
Cabbage 2.0 1.8
White Bread 2.0 1.5
Brown Bread 4.5 3.5
Wholemeal Bread 7.4 5.8

Dietary fibre BNF

In 2009-2011 the average daily intake of fibre was 14.8g for men and 12.8g for women. In the UK the main sources of dietary fibre are cereals, then vegetables and potatoes.
The recommended daily intake for fibre is 30g for AOAC (18g NSP) for adults. Young children should not eat too much fibre as it makes them too full.

The old measure for fibre on a food label used the Englyst method which measures plant cell wall components of dietary fibre.

In USA and EC countries they use American Association of Analytical Chemists (AOAC) method including lignin and resistant starches.

New UK food tables show AOAC and NSP.

Dietary fibre consists of one or more of:

  • Edible carbohydrate polymers naturally occurring in the food as consumed,
  • carbohydrate polymers, which have been obtained from food raw material by physical, enzymatic or chemical means,.
  • synthetic carbohydrate polymers.

Properties:

  • Dietary fibre generally has properties such as:
  • Decrease intestinal transit time and increase stools bulk fermentable by colonic microflora
  • Reduce blood total and/or LDL cholesterol levels

Reduce post-prandial blood glucose and /or insulin levels.

With the exception of non-digestible edible carbohydrate polymers naturally

occurring in foods as consumed where a declaration or claim is made with respect to

dietary fibre, a physiological effect should be scientifically demonstrated by clinical

studies and other studies as appropriate. The establishment of criteria to quantify

physiological effects is left to national authorities.

Is the BNF showing AOAC or NSP as Fibre on the analysis of recipes and diets?

If AOAC fibre then how has database calculated for the 1530 foods on McCance that don’t have AOAC data? Do they use a formula to convert from NSP to AOAC?

 The BNF website says 11-16 needs 25g fibre.
Explore food site just says Fibre and a lot of foods don’t have an AOAC measure.
On this link it says Banana has 1.5g fibre per 100g yet the McCance and Widdowson 2015 is 1.4g
They say an apple 100g contains 2.4g fibre but it has 1.2g AOAC fibre or 1.3g NSP fibre
They say baked beans 150g has 6.8g fibre but it has 7.35g AOAC fibre and 5.7 NSP fibre.

Fibre  in the Nutrition Program is presented as AOAC values. Where no AOAC measure is available, the NSP value has been multiplied by 1.33 to give an AOAC equivalent.

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