Before the deepest part of winter sets in, it is a good idea to give your kidneys a boost as they are the organs most vulnerable during this season. This can be done through daily teaspoon of liquid chlorophyll in water or an herbal "kidney tonic". Parsley, kale, and dandelion greens are also very good. Avoid cold and raw foods in excess. A 4-day kidney cleanse is advisable for many people.