Adding cancer-fighters to increase protection
in fruits like apples and cherries as well as tea, appear to work
together against cancer cells, according a new research to be
published next month.
The in vitro study is part of a growing investigation into the potential synergy between different natural compounds to acheve greater protection against cancer than from one nutrient alone.
Dr Yongping Bao from the UK-based Institute of Food Research reported last year on an interaction between sulphoraphane and the antioxidant mineral selenium in inducing anticancer enzymes and inhibiting cancerous cell growth and tumour formation. The two food components were reported to be up to 13 times more powerful when put to work together than when used alone.
In the new study, Dr Bao reports that sulphoraphane, found in all brassica vegetables, also works in synergy with the polyphenol apigenin.
Apigenin is natural flavonoid present in fruits and vegetables such as apples, beans, broccoli, celery, cherries, grapes, leeks, onions, parsley and tomatoes, as well as plant-derived beverages like tea and wine.
Writing in the 9 September issue of Carcinogenesis (vol 25), Dr Bao and colleagues note that flavonoids have a number of different properties in vitro, including the induction of phase II enzymes, such as UDP-glucuronosyl transferases (UGT) and glutathione transferases (GST), two major phase II detoxifying enzymes. These enzymes delete genetically damaged cells before they become cancerous and detoxify carcinogens making them readily excretable.
Investigating the anticancer activity of sulphoraphane and apigenin in human intestinal cells, they found that apigenin induces UGT1A1 transcription four-fold. Sulphoraphane induced both UGT1A1, by almost four times, as well as GSTA1 (2.5-fold) in both dose- and time-dependent manners.
The combination of sulphoraphane and apigenin resulted in a synergistic induction of UGT1A1 mRNA up to 12-fold, they write.
But both compounds acted through different signaling pathways, reveals the study, allowing for the synergistic effect.
More research is needed to better understand the mechanisms of compounds such as sulphoraphane in regulating gene expression during cancer formation. The IFR researchers are applying to carry out a human study.
US researchers have also studied how broccoli's glucosinolates and the lycopene found in tomatoes could work together to boost the cancer protection already known to be offered by each of the foods alone. This increasingly used approach aims to measure the complex interactions that take place in the overall diet rather than singling out specific nutrients.
In their study on rats, those fed a combination of tomatoes and broccoli had markedly less prostate tumour growth than rats who ate diets containing either food alone - and also less tumour growth than rats who ate diets containing specific cancer-fighting substances isolated from tomatoes and broccoli.
There may be many other compounds that act synergistically when combined in the human diet.