Roasted walnuts found to reduce the risk of colon cancer

Researchers at Friedrich Schiller University Jena in Germany report that roasted walnuts can reduce the risk of colon cancer. In their study, which was published in the journal Nutrition Research, they aimed to determine whether roasting walnuts would affect the anticancer effects of walnuts.

  • Walnuts are loaded with bioactive compounds such as polyunsaturated fatty acids, polyphenols, and dietary fiber — all of which contribute to a healthy diet and may cut the risk of developing colon cancer.
  • However, the researchers thought that heat treatment like roasting may alter the chemical composition of walnuts as well as their cancer-fighting properties. They hypothesized that different roasting conditions change the anticancer effects of walnuts.
  • To test this hypothesis, the researchers investigated whether different roasting conditions would change the cancer-fighting effects of walnuts. They subjected raw and roasted walnuts to in vitro digestion and fermentation.
  • They treated colon adenoma cells with fermentation supernatants and examined the expression of catalase, superoxide dismutase 2, glutathione peroxidase 1 (GPx1), glutathione S-transferase P1, glutathione S-transferase T2 (GSTT2) genes. They also examined cell growth and apoptosis, or programmed cell death.
  • Walnut fermentation supernatants increased mRNA levels of catalase and GSTT2 – which are involved in detoxification – and significantly decreased GPx1 levels.
  • In addition, walnuts reduced the growth of colon adenoma cells in a time- and dose-dependent manner. Higher concentrations of walnut fermentation supernatants significantly increased the number of early apoptotic cells and induced caspase-3 activity. Moreover, the roasting process did not directly affect the observed outcomes.
  • These results suggested that walnuts lower the risk of colon cancer by inducing expression of genes involved in detoxification and by inducing growth inhibition and apoptosis in colon adenoma cells.

In conclusion, these findings indicated that roasting walnuts did not affect the nuts’ anticancer effects on colon cancer development.

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Journal Reference:

Schlörmann W, Lamberty J, Ludwig D, Lorkowski S, Glei M. IN VITRO–FERMENTED RAW AND ROASTED WALNUTS INDUCE EXPRESSION OF CAT AND GSTT2 GENES, GROWTH INHIBITION, AND APOPTOSIS IN LT97 COLON ADENOMA CELLS. Nutrition Research. November 2017; 47: 72-80. DOI: 10.1016/j.nutres.2017.09.004

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