it is to our health. Vitamin D is unique in another way; mammals can manufacture it strictly from sun exposure.
What does Vitamin D do?
It has been established for many years that Vitamin D regulates calcium absorption, and calcium levels in the body. We have known for a long time that rickets in children, or osteomalacia in adults is primarily caused by a deficiency in Vitamin D.
But, the function of Vitamin D in the human body doesn't end at bones. Vitamin D also improves immune function, muscle function, cardiovascular function, respiratory function and brain development. Vitamin D also has anti-cancer effects. Vitamin D helps our immune cells fight off bacterial, fungal and viral pathogens. Having a sufficient amount can reduce our chances of catching a cold or the flu (1, 2, 3). Maybe cold and flu season is actually caused by dwindling sunshine, and less Vitamin D in our blood rather than an onslaught of germs.
Vitamin D deficiency has been associated with a wide variety health issues, including cardiovascular disease, high blood pressure, heart failure and ischemic heart disease (reduced blood supply to the heart). Vitamin D deficiency has also been associated with depression, which might partially or fully explain the “winter blues”, or Seasonal Affective Disorder (4, 5).
Vitamin D deficiency is also associated with cancer, especially of the prostate, colon and breast, chronic pain, autoimmune conditions such as rheumatoid arthritis, multiple sclerosis, and Crohn’s disease, infectious diseases such as tuberculosis, hepatitis B & C, HIV, all types of diabetes, and allergic conditions such as asthma, mental illness, and Alzheimer's disease (6, 7, 8, 9, 10).
Vitamin D and Sleep
disorders prevent our bodies from getting the deep healing rest at we need to stay healthy (11).
Vitamin D and the Gut
New emerging research is linking Vitamin D deficiency to increased susceptibility to digestive conditions such as irritable bowel syndrome, colorectal cancer, inflammatory bowel disease, and diverticulitis (12, 13).
Other new studies indicate human gut microbiome is modulated by Vitamin D. This is important because more and more research is pointing to the the gut as the source of health or disease. When Hippocrates stated that “all disease begins in the gut”, he was correct, and we are just finding this out now. It is possible that a deficiency in vitamin D could cause gut dysbiosis (more bad bacteria in the gut than good bacteria), which could lead to all the previous health conditions listed, and more. Of course, there is more than just vitamin D required to keep your gut microbiome happy, but I will devote a whole blog (or many) to the gut microbiome in the future (14, 15).
Vitamin D and Pregnancy
Unfortunately, many pregnant women and infants worldwide are deficient in Vitamin D. Vitamin D deficiency in pregnant women has been associated with an increased risk of pre-eclampsia, gestational diabetes mellitus, preterm birth and first trimester miscarriage (16, 17, 18, 19).
Where can we get Vitamin D?
supplement with Vitamin D during the winter months. But we may need to even supplement with Vitamin D during the summer months if we work indoors all day, live in a smoggy city full of tall buildings, or wear sunscreen or full body clothing each time we go into the sun. Older, obese or pregnant people will require a higher intake of Vitamin D (20).
We can obtain a small amount of Vitamin D from food, but it is very difficult to get enough strictly from diet. Cod liver oil, not only contains Vitamin D, but also preformed Vitamin A (retinol), which many people are also deficient in. Or, we can take a supplement with just Vitamin D.
Testing our Vitamin D Level
Now we have established how vital Vitamin D is to our health, how do you make sure you are getting enough? Testing our blood level is the only sure fire way to know if you have enough Vitamin D. You can ask your medical doctor to test your Vitamin D levels, but if he/she refuses to, you can get your Vitamin D blood level tested through a Functional Medicine practitioner. Another option is to order an in home Vitamin D blood test (21).
How much should we take?
Dr. Rhonda Patrick is a Vitamin D researcher. She states that the Vitamin D sweet spot is between 40 and 60 ng/ml (100 nmol/L to 150 nmol/L) (22). We don't want it too high, but we don't want it too low either. Therefore, what ever intake of Vitamin D it takes to keep our blood level in the sweet spot is the right amount.
The important thing to remember about supplementing with any fat soluble vitamin, is that we need to take Vitamins D, A and K2 in balance. Dr. Kate Rhéaume-Bleue suggests the ratio 1000IU:1000IU:100mcg - D:A:K2. Therefore, if you are taking 3000IU of Vitamin D, you would take 3000IU of Vitamin A and 300mcg of Vitamin K2 (23).
What about Vitamin D Toxicity?
Vitamin D is a fat soluble vitamin, meaning that if we take too much our bodies will have a difficult time excreting the excess. Vitamin D toxicity tends to express itself by causing hypercalcemia, which is too much calcium in your blood (23). Fortunately, Vitamin A, D and K2 (also fat soluble vitamins) work synergistically in order to protect each other from toxicity. One of Vitamin K2's job is to help calcium move from the blood into the bone, thus preventing hypercalcemia.
This means that if we have sufficient levels of Vitamin A and K2, we will have a difficult time overdosing on Vitamin D (24, 25). Unfortunately, many people are deficient in both Vitamin A and K2 as well.
My favorite Vitamin D supplement is this one. It not only contains Vitamin D, but also Vitamin K2.
What if you are taking Medication?
Most individuals can supplement Vitamin D with no problem. But there are a few cases in which you should talk to your doctor before supplementation:
Conversely, you may need more Vitamin D than normal if you are taking carbamazepine, phenytoin, primidone, barbiturates and some medicines used for the treatment of HIV infection (26).
**Please talk to your doctor**
I would like to hear from you.
Did you know how important Vitamin D is for health? Do you supplement with Vitamin D? Have you had your Vitamin D level tested? Did you noticed a difference in your health after supplementation?
Lindsay Rusk, R.Ac., fmp
Lindsay Is a Registered Acupuncturist, Functional Medicine Practitioner, Health Investigator, Paleo Enthusiast, and Blogger.
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