Nuts, such as almonds or hazelnuts, can go rancid really quickly. Rancid nuts tend to contain a type of fungus which produces aflatoxin-1. Aflatoxin-1 is one of the most carcinogen chemicals known. So take care to solely enjoy the natural benefits, without suffering from storage-caused problems. Store nuts in a sealed container in a dry and dark place. Make sure to buy them at a nuts specialist to assure they were handled the right way before you bought them as well. They can hold up to two months when stored sealed, dry and dark.