Everyone loves Paris but not because she’s the Grande Dame of good weather. With an average of 162 days a year of rain, it’s no wonder urbanites flock to the parks to picnic when the sun makes an appearance. Catching rays to soak up Vitamin D is not only good for your mood and the state of your tan, it’s important for your body all across the board.
We absorb it from the skin, but we also synthesize Vitamin D in the liver and the kidneys. From the Chinese medicine perspective, the liver and the kidney systems regulate growth overall and bone growth specifically, as well as mood, energy, vitality, immunity and reproductive ability. They have a lot to do with making sure the menstrual cycle is balanced.
It may sound strange that the liver and kidneys manage such diverse phenomena, but if you think about it, the body is a tightly knit network of chemical and physical reactions. Like employees working in a group setting, everything happens in an open environment and information is constantly shared back and forth. If it weren’t, how would your muscles know when your brain signals them to move? Or your heart knows to speed up and circulate more oxygen when you exercise?

What Does Vitamin D Do?
It’s linked to all of the activities that the liver and kidneys regulate, and more. It regulates the expression of hundreds of genes. It’s a key co-factor in calcium metabolism (along with magnesium), which means it promotes bone health by making sure you keep and absorb enough calcium and phosphorus to maintain strong bones. Older women in menopause should make sure they have enough D to protect themselves from bone loss and fractures.
In immune health, it plays a big role. Studies show low values are related to cancers, type 1 diabetes and autoimmune disorders like multiple sclerosis and rheumatoid arthritis. People with Crohn’s disease benefit from supplementation because the inflammation in the bowels may prevent proper absorption of D through food. Even the ability to ward off the common cold may depend on adequate D values.
It’s linked to cell differentiation (growth) and muscle health (energy). It protects the cardiovascular system (vitality) by maintaining blood pressure and helping avoid coronary artery disease, heart failure and stroke. D has been shown to reduce the progression of neurological disorders like Parkinson’s. Low D values have been liked to reproductive issues like preeclampsia and gestational diabetes.

How Does D Do All That?
How does one little fat-soluble vitamin get such airtime? It may be the fact that it’s fat-soluble. Fat is a vital component for us — it’s part of what makes up the brain as well as cell membranes; it provides energy and regulates temperature and hormones; and it’s key for reproduction, immune function and basic growth.
Without it, we wouldn’t survive.
Vitamin D is like a key that fits into these fat-regulated doors all over the body.
Chinese medicine sees fat as a Yin substance. It’s moist, nourishing, and helps build the components of our bodies. It gives us insulation, holds organs in place and because it digests more slowly, supplies longer-lasting energy. That’s why we eat it and feel secure, grounded, and slow. The warmth and energy actually come from the way we break down fats — they turn into a Yang substance and help drive metabolism. The combination of the Yin and Yang qualities is what makes us love fat — who doesn’t want to feel secure, warm, slow, yet energized?

Who needs Vitamin D?
Everyone does! But certain groups do well with supplementation. Because we get so much D from the sun, people with dark skin (melatonin reduces the skin’s ability to produce D), people who don’t go outside much, and the elderly (whose skin doesn’t synthesize D as efficiently, or are more likely to stay inside) should consider testing their levels. People who have fat malabsorption issues (like Crohn’s, ulcerative colitis, celiac disease and some autoimmune disorders) should also check into it since we use fat to break down D for our needs.
Obese people may also have reduced D because extra subcutaneous fat can store it, taking it out of circulation. Gastric bypass surgery reduces D because some of the upper small intestines where absorption takes places is bypassed. Breastfed infants might need it as well because breast milk doesn’t contain enough in itself. But if the mother provides supplements then adequate levels can be found in the milk.

How Much D Should You Have?
Next time you get a blood test, check to see if your serum 25-hydroxyvitamin D concentration is at least 30 ng/mL (75 nmol/L). The best way to get Vitamin D is from sunshine. At sea level, spend 30 minutes outdoors daily with at least 20% of the skin exposed. Eat chlorophyll-rich greens (they act like stored sunshine) such as kale, collards, parsley, wheat grass, spirulina, and also mushrooms. Fish and eggs are good sources. If you supplement, check with your doctor to be sure it won’t interact with medications. Adults can take 2,000 IU (50 μg) per day. Family doctors in France regularly prescribe a few maintenance doses a year in the form of liquid vials, best taken with a little bit (not a large meal) of fatty food such as eggs or avocados.