Cereals and grains, especially wholegrains, contain a range of dietary fibres important for health and in the prevention of disease. These include:

• Soluble fibres such as B-glucan (found in oats and barley), pentoses (found in rye) and arabinoxylans (found in barley, wheat and rye)

• Insoluble fibres such as lignins, cellulose and hemi-celuloses (found in most cereals, especially wheat bran, rice and maize);

• Resistant starch (found in some cereals like corn, cooled cooked rice and maize, high amylose starch varieties of maize and high amylase rice);

• Smaller oligosaccharides such as fructooligosaccharides and inulin (found in wheat, rye, oats and barley, with very young barley having high amounts).

As for the total amount of dietary fibre contained in the different wholegrains and pseudo-cereals, this varies, as can be seen in the table below:

The various roles that cereal fibres play in the promotion of human health are extensive, some of which include:

1. Cardiovascular Health

• Beta-glucan (a soluble fibre common in the cell wall of many grains, especially oats and barley) has cholesterol lowering properties. Soluble pentosans (e.g. arabinoxylans) have also been shown to also lower serum cholesterol.

• There is evidence that the potential health effects of cereal fibre may depend on whether it comes from wholegrain or refined grain and the relative proportion consumed of each. Nutrients contained in wholegrain fibre such as antioxidants and minerals are thought to be a major factor in the protection against chronic disease in addition to benefits from fibre itself.

• A study involving over 10,000 women found consumption of predominantly wholegrain fibre versus fibre from refined grains reduced the risk of heart disease. After adjusting for lifestyle factors, the predominantly wholegrain fibre group had a 17 per cent lower death rate and an 11 per cent lower coronary heart disease rate than the refined grain fibre group.

Predominantly wholegrain fibre group:

1.7  g wholegrain fibre per 2000 kcal/1.9g refined grain fibre per 2000 kcal

Predominantly refined fibre group:

1.3 g wholegrain fibre per 2000 kcal/4.5g refined grain fibre per 2000 kcal

The results support the idea that health benefits stem from more than fibre itself.

2. Bowel Health

Constipation:

• Wheat bran has most consistently been reported to manage constipation, especially in those most vulnerable to the problem, including pregnant women, the elderly and post-surgical patients.

Haemorrhoids:

• There is some evidence to support the addition of unprocessed bran to the diet to help manage haemorrhoids.

Colorectal Cancer:

• Evidence from case-control cancer studies suggests wholegrain cereal foods and cereal fibre rich foods may protect against colorectal cancers.
• Researchers have observed a reduction of colorectal cancer risk of about 30 per cent when fibre-rich wholegrain or wholemeal cereal foods are regularly included as part of a healthy diet as recommended in the Australian Dietary Guidelines.

3. Immune Function

• The grain fibre components thought to have an effect on immune function include inulin, beta-glucans and resistant starch.

• Results from a study conducted on 38 men who consumed 200g/d of bread containing a mixture of inulin, soy fibre and linseed showed that compared to a control rye bread, the test bread increased the percentage of activated T-cells and CD19 in lymphocytes.

• Evidence is starting to accumulate that beta-glucans act as immunomodulators, which possibly stimulate the immune system and provide an increased resistance to various infections, as well as provide an anti-tumor action.

• Resistant starch derived from cereals and grains, and its subsequent fermentation to produce butyrate, may potentially assist inflammatory bowel disease by modulating the immune and inflammatory response. Research to confirm this is yet to be carried out.

To View references click here