Vitamin: a substance required by the body for normal, healthy, physiological function that we either do not make at all, or that we do not make in sufficient quantity and therefore must be obtained in the diet.
Vitamin D3 (cholecalciferol): this is one form of Vitamin D which is made in the skin when exposed to sunlight. Cholecalciferol can also be obtained in the diet from foods such as: salmon, sardines, tuna, cod liver, eggs and mushrooms. Many types of cheeses, yogurts, milk (both plant-based and cow's milk) fruit juices, cereals and butter and margarines are fortified with Vitamin D3.
See page 270 in Dr. Holick's research (1) below, published in the New England Journal of Medicine, for a detailed list of amounts of Vit D2 and D3 found in different types of foods.
25, hydroxy-vitamin D (25OH Vit D): when we synthesize cholecalciferol in the skin (in response to sunlight) and/or when we take cholecalciferol in via our diet, it will travel through the blood stream and when it arrives at the liver, it will be converted to 25OH Vit D. Whereas, 25OH Vit D will be the "primary form of Vitamin D circulating in the blood. For this reason, this is the specific metabolite that I will measure to evaluate if you are Vitamin D Deficient.
1,25-dihydroxy-vitamin D (1,25 Vit D): this is the "active form" of Vitamin D. The 25OH Vit D, which is made in the liver, will travel through the blood and when it arrives at the kidneys, 25OH Vit D will be converted to 1,25 Vit D. Although, the primary role of 1,25, Vit D is to help bring calcium across the GI track and into the blood, this is by far not its only role. Research has shown that Vitamin D Deficiency will exacerbate many disease conditions, including but not limited to osteoporosis, respiratory diseases, auto-immune diseases and infectious diseases. (1, 2, 4) Vitamin D deficiency has also been found to be intimately associated with infertility and poor pregnancy outcomes. (8, 9).
Parathyroid Hormone (PTH): as mentioned, if you are deficient in 1, 25 Vit D, you will not bring the calcium that you ingest across the GI tract and into the blood. Most of it will just be eliminated in your stool. Your body will try to compensate by secreting a hormone called PTH. You have small parathyroid glands (usually about 4) which are embedded in your thyroid gland. The parathyroid glands will sense low blood calcium and secrete PTH. The PTH will travel through your blood and target: a) your bone cells and break down the bone to release calcium into the blood, and b) your kidneys where it will increase reabsorption of calcium (move calcium back into the blood) and increase kidney-production of 1,25 Vit D.
As you can see, you body will work synergistically to ensure your blood calcium levels remain adequate. Calcium serves many important functions, such as to regulate your heart and to assist with vital neurological processes.
Vitamin D3 (cholecalciferol) is made in the skin following your exposure to natural sunlight and/or obtained in your diet. Cholecalciferol will travel through the bloodstream and enter into the liver, where it will be converted in 25OH Vit D. Next, 25OH Vit D will travel through the bloodstream and arrive at the kidney, where it will be converted to 1,25 Vit D, which is the active form of Vitamin D.
Interestingly, research over many years has demonstrated that most tissues and cells in the body have Vitamin D-receptors, and several types tissues possess the necessary enzymes to convert the 25OH Vit D to 1,25-dihydroxy-Vit D. (1)
Most people are aware that inadequate levels of Vitamin D are highly associated with osteopenia and osteoporosis. For more information about this please see my Osteoporosis webpage here. However, Vitamin D has many, many other functions to help maintain your overall health.
Vitamin D helps to regulate your immune system, and adequate levels are needed to ensure proper proliferation (formation) and differentiation (maturation) of numerous types of immune cells and chemical mediators that are involved in fighting infection. (5)
Many studies over many years have also demonstrated that Vitamin D Deficiency is associated with worsening of a variety of disease conditions, such as: asthma and other respiratory illnesses, Diabetes, cardiovascular disease and infertility (1, 2, 4, 8, 9).
Additionally, it has been well demonstrated in clinical trials that critically ill patients in hospital ICUs have had much worse outcomes when they were found to be Vitamin D Deficient. This was more recently unequivocally re-demonstrated in ICUs around the world in patients with COVID-19 infections. (4)
Therefore, as your Napro provider, I highly advocate optimal Vitamin D status for all of my patients, regardless of what condition you are seeing me for and even if you are presenting for just a routine annual well-woman visit.
Vitamin D status is effectively evaluated by checking 25OH Vit D levels.
Recall, 25OH Vit D is the "primary form" of Vitamin D circulating in the blood. There have been numerous reputable, reproducible studies published for more than thirty years confirming this recommendation.
A "reputable study" is generally a research trial that has been "double-blinded", "randomized" and "controlled", and for which the results are "reproducible". Studies that have large number of participants enrolled and studies that were conducted over longer periods of time are generally considered more reputable. The word "reproducible" means that many different trials have been conducted, over long periods of time, at different locations around the world, and the same results are being produced.
Why not also check for 1,25 Vitamin D?
Checking for the active form of vitamin D is not necessary (and actually quite inappropriate) for a number of reasons:
Well.. treating low levels of Vitamin D is super easy!
***** Do not take unless under medical supervision *****
I will recommend Vitamin D 3 supplementation, which can be purchased over the counter. I do encourage you to purchase your supplements form a reliable source such as Full Scripts since we know that many times unethical companies manufacture products that claim to contain ingredients, which are simply not there and/or not present in the doses advertised on the label.
If your 25OH Vit D levels are < 50 ng/ml, I will start you off at 5,000 IU daily.
I will then monitor your levels every 3 mos. Once we attain our goal of 25OH Vit D between 50-75 ng/ml, I will decrease your dose to a maintenance dose of 2,000 IU daily. I will continue to monitor your levels every 6 mos, thereafter.
Remember, Vit D is a one of the four "fat soluble" vitamins (A, E, and K are the other three). Unlike the "water-soluble" vitamins (the Bs and C), Vit D will NOT be eliminated via the urine if you take too much. Taking too much Vitamin D over a long period of time can result in Vitamin D Toxicity, since the excess will be stored in your fat cells.
Please read Dr. Holick's research article below (1). On page 278 , you will see how difficult it is to reach toxic levels. Vitamin D Toxicity is very rare, and it almost always occurs when an uneducated patient it supplementing themself and not having blood levels monitored. Dr. Holick's research shows that pts can take Vit D3 10,000 IU daily for up to 5 mos and this very high dose will not likely result in Vitamin D Toxicity.
There are no studies, of which I am aware, that indicate a young, healthy woman is at any risk of building up calcium in her blood vessels.
There are no studies to date, that I am aware of, that demonstrate any benefit of adding Vitamin K2 in younger women. I would very much like to see trials published to address this question. However, f you are post-menopausal and/or if u have any of the conditions mentioned abe ave will have a discussion.
Therefore, I have looked into the clinical trials that have addressed this question. There have been many studies done over the last several decades. The overall consensus is that the data is contradictory and inconclusive.
However, that being said, there do seem to be some quality studies that indicate elderly patients who have underlying comorbid conditions such as: Chronic Kidney Disease, Diabetes, Cardiovascular disease and/or post-menopausal Osteoporosis may benefit from adding K2 to their Vitamin D supplementation to prevent intravascular calcification (build up of calcium in the blood vessels). It appears this outcome has been demonstrated namely for two reasons:
Below I have posted several research articles. Numbers 5, 6, and 7 address Vitamin K2 supplementation and intravascular calcification.
As always, when reading research articles, be sure to look at "Methods" and "Data Analyses" sections. Many readers are fooled when they limit their reading to the "Introductions" and then skip to the "Discussions". The Introduction and Discussion sections offer the researchers' opinions and their views of the data interoperation. Whereas, the Methods and Data Analysis give the true story.
You will see ALL of the studies looking at the benefit of adding Vit K2 to Vit D3 supplementation enrolled participants who were elderly, or who had the concomitent comorbid condition(s) I mentioned above. The articles I posted below are "Systematic Review" articles where "meta-analyses" are done. These studies are the most reputable because an independent reviewer looks at hundreds of studies and give you an overall analysis of the data. The publications (#s 5, 6, and 7) below collectively reviewed over reputable 100 studies.
There are no studies to date, that I am aware of, that demonstrate any benefit of adding Vitamin K2 in younger women. I would very much like to see trials published to address this question. However, f you are post-menopausal and/or if u have any of the conditions mentioned ab,
My job as your provider is to empower you with quality medical education and then allow you to make the decision regarding your healthcare.
As far as I know there are no studies indicating that adding daily Vitamin K2 to your Vitamin D supplementation can increase your risk of forming a clot.
That being said, the belief that Vitamin K is needed for adequate absorption of Vitamin D has recently become a very popular practice, so I do wonder if we will see deleterious effects of patients taking too much Vitamin K in the literature a decade or so into the future. Thus, it seems important to discuss that Vitamin K is intimately involved in a series of normal, healthy biochemical reactions known as the clotting cascade, which is the body's way to make blood clots in order to stop you from bleeding out when you have an injury or a surgery.
Recall, Vitamin K is one of the four fat-soluble vitamins, which means you will not be able to excrete this in your urine if you take too much, rather it will be stored in your fat cells. Therefore, it seems logical to be concerned that taking too much Vitamin K (if you are not deficient to begin with) may put you at a higher risk of forming a blood clot. Also, many women are on hormonal birth control, which we know increases clot formation. We have also known for many years that women who are pregnant are at risk of forming clots.
Blood clots will most often form in the lower leg, less often in the upper thigh. A piece of the clot can break off and flow through the blood stream to the heart (causing a heart attack), to the lungs (causing a pulmonary embolism) or to the brain (causing a stroke).