Winter is the season of the Kidneys. That growth and development, as well as reproduction and the immunity that is deep within us are ruled by the Kidneys is no surprise when you consider that they also rule the uterus and the brain (the two extraordinary organs in Chinese Medicine). The Kidneys are classified as the most Yin organ, so Yin it is the source for Yang.
Think of Yin as blood and moisture, cool and fluid. It flows, passive and receptive, to nourish the substances of the body. To know Yin we must also know Yang–as they are interdependent. Yang is the energy and warmth that is circulates stuff in the body. Yang is the processes, the things that happen like digestion, assimilation, homeostasis, libido, appetite.
Indeed the Kidneys are full of moisture, they maintain the correct water balance of the body and the correct composition of extrecellular fluids. They concentrate urine, pass it to the bladder for storage until it is released through the urethra. To do this, the Kidneys have about 1 million nephrons and receives 1 liter of blood every minute. The nephrons are lined with many mitochondria, which are helpful since almost all of the glucose and amino acid molecules filtered from the blood are reabsorbed. Someone mentioned to me that it seems like the Kidneys do a ton of work, so does that make them more Yang? The kidneys do a lot of work, yes, but they do it in a very energy efficient way. The work in the Kidneys are done with the help of concentration gradients, which employes movement from a region of greater concentration to a region of lower concentration. This is also known as diffusion, which is the process of random motion to form a state of equilibrium. It uses no energy. That certainly sounds Yin to me!
In the “Chih” entry, I mentioned that the Kidneys rule over the bones and marrow, joints, sexual-urinary organs. Here are some typical Kidney imbalance symptoms. Note if any of these issues happen to you only in damp, cold environments or seasons.
- Joint problems and pain
- Weak knees, wobbly legs, weak ankels
- Fertility, sexuality, hormonal issues,
- Urinary and kidney problems, night time urination
- Morning loose/watery stool
- Teeth problems
- Brittle bone
- Fear, paranoia, lack of will power
- Poor memory especially short-term, senility
- Thinning, loss, or premature graying of hair (including body hair)
- Premature aging
- Hearing and ear problems
- Leg edema
- Low-back pain and weakness
Kidney imbalances are not just some esoteric things that only apply in a Chinese Medicine context. Western medicine gives diuretics for swollen ankles. A friend of mine had some sort of kidney failure as a child, and has since had teeth problems. People with anxiety problems tend to also have loose stools. And now we know why sometimes too much sex can make your legs wobbly (it’s not just the straddling ;). Honestly though, touch the small of your back or your partners after sex and see if it feels cool to the touch. If it does momentarily it is not a concern, but if it stays that way some warming Kidney Yang tonics could be of help (with a little break from hitting the sheets).
Some of the signs of Kidney imbalance mentioned above overlap with the principle of Cold, like achy joints, loose stools, and urinary and menstrual problems. If the lower back is sore, I think Kidney. If not, I lean towards Cold. This is not be a catch-all way to differentiate as there are many exceptions, but it helps me to begin somewhere.
Here is a link to a wonderful Yin yoga sequence, to restore and revitalize. http://www.yogajournal.com/practice/2545
Tierra, Lesley. Healing With the Herbs of Life. 150-160.
Purves, et. al. Life: The Science of Biology. 105, 1079-1082.