Berry components, such as polyphenols, have been shown to have bioactivities in model in vitro screens relevant to cancer and cardiovascular disease. Although this information is indicative of effectiveness in vivo, it is important to understand if the components are sufficiently bioavailable from normal intake to have these effects in the body.

For example, for a berry component to be effective against cardiovascular disease or atherosclerosis, it has to be stable to gastrointestinal digestion and be taken up from the gut into the bloodstream in sufficient amounts to have its proposed effects. Similarly, any component effective against models of, for example, prostate cancer would have to reach that tissue.

SCRI is carrying out two main types of studies on the stability and bioavailability of berry components.

The first involves modelling gastrointestinal digestion in the laboratory. This gives information on the stability of key berry polyphenols in the digestive tract and gives an idea of the pool size available for uptake in to the bloodstream^1,2. In vitro gastrointestinal digestion has also been used to provide samples that mimic the polyphenol composition of material that would reach the colon for studies on colon cancer cells³.

The second assesses the bioavailability of polyphenol components in human studies. Samples of blood, faeces and urine are obtained from volunteers before and after ingestion of fixed amounts of berries and/or juices in intervention studies carried out by our collaborators at the University of Dundee.

We use state-of-the art liquid chromatography mass spectrometric (LC-MS) and gas chromatography mass spectrometric (GC-MS) methods to target the fate of individual components and their known metabolites in the bloodstream and as they are excreted in the urine and faeces. This provides data on the levels of components achievable in the bloodstream, the rate of excretion and length of residence in the body. We also use non-targeted metabolomic methods, which can identify patterns of serum metabolite changes caused by berry ingestion.

References

1. McDougall, G.J., Dobson, P., Smith, P., Blake, A. and Stewart, D. 2005. Bioavailability of raspberry anthocyanins in a model in vitro digestion system. Journal of Agricultural Food Chemistry 53, 5896-5904.

2. McDougall, G.J., Fyffe, S., Dobson, P. and Stewart, D. 2005. Anthocyanins from red wine – their stability under simulated gastrointestinal digestion. Phytochemistry 66, 2540-2548.

3. Coates, E.M., Popa, G., Gill, C.I.R., McCann, M.J., McDougall, G.J. Stewart, D. and Rowland, I. 2007. Colon-available raspberry polyphenols exhibit anti-cancer effects on in vitro models of colon cancer. Journal of Carcinogenesis 6, 1-13.