The following study shows that green tea has the potential to reduce / inhibit the digestion of starch in food. Less than 2 cubs per meal can reduce the spike in blood glucose by 50%. This will work for starchy food like noodles, potatoes and crop.
US study "Inhibition of starch digestion by the green tea polyphenol, (−)-epigallocatechin-3-gallate" by Sarah C. Forester, Yeyi Gu, Joshua D. Lambert