I eat about 2bs of cucumbers per day in my fruit smoothies. However very often I get tartness/bitter taste and "numb" tongue from my smoothies. I am wondering what could cause such reactions-cucumbers, iceberg lettuce or squashes that I blend in large amounts with their skins on. So, is it ok to blend cucumbers and summer squashes with their skins on? The taste of skins is really bitter for these fruits.