Food components and extracts Herbal
The dietary fibre (DF) hypothesis suggested
that DF, as plant cell walls, protected against colorectal cancer. The implicit
assumption in much historic literature was that the readily analyzed and quantified
nonstarch polysaccharide (NSP) component was critical in cancer protection. However,
the presence of polymeric phenolic components such as lignin or suberin has profound
effects on the physicochemical properties of the cell walls and largely determines
their physiological properties in humans. In certain groups of food plants, degradation of
cell walls that contain neither lignin nor suberin releases ferulic acid and other
hydroxycinnamic acids. These acids have antioxidant, antimutagenic, and other anticancer
effects, including modulation of gene expression and immune response.
Dietary fibres can also increase the population size and activity of beneficial
gut bacteria following pre-biotic ingestion.
Vitamins and minerals
New Zealand National Nutrition Survey (1999) shows that our population is not reaching
the current RDA’s of certain required micronutrients. Our goal is to study the effects
of deficient/sufficient levels to make recommendations for the benefit
These deficient nutrients can cause DNA instability through many mechanisms including
defects in DNA methylation.
Gene nutrient interaction
We know that low levels of micronutrients such as selenium (Se) enhance the risk
of cancer, and may be a particular problem in New Zealand, which has low Se in its
soils. Recent work suggests that small changes in genes, called single nucleotide
polymorphisms or SNPs, may affect the amount of Se required by individuals. There
is reason to believe that there are a small number of individuals in New Zealand
and other countries, who are cancer prone because they require a higher than normal
intake of Se.
Currently we are screening a sample of the population (>500 healthy men) to establish
how commonly these genotypes occurs, and consider whether supplementation with 200µg
Se per day, in the form of selenised yeast, can help to overcome the associated
deficiencies. The supplementation benefits are being measured through various biomarkers
including DNA stability (through Comet Assay), activity of seleno enzymes, effects
on DNA methylation and effects on androgen metabolism. Genotyping of our study group
has been accomplished through Applied Biosystems TaqMan SNP genotyping procedure
and Sequenome MassArray platform. Our nutregenomics approach in this assessment
is aligned with similar approaches being carried out through our work in the
Discipline of Nutrition.