Auckland Cancer Society Research Centre

Optimising dietary strategies for cancer prevention

Food components and extracts


Herbal extracts

Herbal extracts

Plant fibre

Denaturing gel electrophoresis

The dietary fibre hypothesis suggested that dietary fibre, from plant cell walls, protected against colorectal cancer. The implicit assumption in historic literature was that the readily analysed 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, anti-mutagenic, and other anti-cancer effects, including modulation of gene expression and immune response.

Dietary fibre can also increase the population size and activity of beneficial gut bacteria as seen following pre-biotic ingestion.

Vitamins and minerals

The 2008-09 NZ Adult Nutrition Survey showed that our population is not reaching the current dietary reference intake (DRI) of certain required micronutrients. Our goal is to study the effects of deficient/sufficient levels of micronutrients to make recommendations for the benefit of public health.

Vitamin and mineral deficiency
Micronutrient intake in NZ men and women aged 31-50 years compared to DRI in 2008-09

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 enhance the risk of cancer and may be a particular problem in New Zealand, which has low selenium in its soils. Recent work suggests that small changes in genes, called single nucleotide polymorphisms or SNPs, may affect the amount of selenium required by individuals. Additionally, to reach maximum benefits of selenium nutrition for prostate health, other trace elements such as Zn should also be in balance.

Screening a sample of the population (>550 healthy men) has established how commonly these risk genotypes occur in our population. Men with such genotypes are especially vulnerable for prostate health implications if they are deficient in trace elements. The supplementation benefits of 200 μg/day selenised yeast for six months were measured through various biomarkers including DNA stability (Comet Assay), activity of seleno enzymes, effects on apoptosis (programmed cell death) and effects on androgen metabolism. Genotyping of our study group was accomplished through the Applied Biosystems TaqMan SNP genotyping procedure and Sequenome MassArray platform.