Secosteroid Hormone D (Vitamin D)
This article does NOT constitute medical advice. Consult with your physician before making any changes to your medical plan.
After decades of disinterest many doctors are now testing vitamin D levels and recommending supplemental treatment to those people showing deficiencies. But what does a vitamin D deficiency really look like? When is it necessary to supplement? How much do you need to take and at what frequency? And, how do we separate correlation from causation in epidemiological studies about vitamin D? These are all questions I have been asking for many years. Finally, I have a fundamental understanding.
Let's begin with a brief discussion about the basic vitamin D pathways. We can make vitamin D3 in our skin from sunlight, or we can ingest it in our food or from a supplement. The transportation pathways are different. The formation of vitamin D in the skin from sunlight begins with a photosensitive molecule called 7-dehydrocholesterol (7-DHC). This is the same molecule that makes the more well-known cholesterol molecule. If your shadow is shorter than your height then your bare skin is receiving UV-B rays from the sun that hit 7-DHC, and 7-DHC then gets converted to vitamin D3. That's the simple explanation. Since you are using up 7-DHC to make vitamin D3 there will be less 7-DHC left over to make cholesterol, so your cholesterol blood tests may be lower than otherwise. When you make vitamin D3 from the sun it gets transported to the liver by a molecule called vitamin D-binding protein. When you ingest vitamin D3 from food or supplements it takes a different path. In this case, vitamin D3 attaches to a low density lipoprotein cholesterol-carrying molecule (LDL-c) in the gut and gets transported to the liver. In this case, you need lots of LDL-c molecules to facilitate the transport, so your cholesterol blood tests may show higher levels of LDL-c as the liver makes a lot more of these molecules. The liver then converts the vitamin D3 into the storage form of vitamin D which is called 25-hydroxyvitamin D. We'll call this storage form "25D" to keep it simple. When needed, the liver releases 25D into the blood where it will travel to the kidneys to be converted to the active form called 1,25-dihydroxyvitamin D, which we will call "125D" in this article. Your doctor is measuring the 25D storage form in your blood as it travels from the liver to the kidney. Your doctor is not measuring the active 125D form unless you specifically request it. The liver is in control of how much 25D your doctor sees in your lab result. However, 125D is the form that works with the vitamin D receptors (VDR) and retinoid X receptors (RXR), to make your biological chemicals and immune response chemicals. RXR is a vitamin A receptor that is necessary to activate vitamin D. 25D is not indicative of the biological benefits of vitamin D. It is 125D that indicates the appropriate amount of vitamin D that your body has available for biological benefits like immune function. Your doctor is measuring the wrong number. The body is not going to release 25D into the blood if it is not needed, so it should be fairly low. Yet 25D is the only number that doctors and research studies are looking at. In most cases 25D should be on the low side when measured in the blood. You may have loads of 25D stored in the liver, fat cells, bone, and muscle cells, but it may not show up on a blood test because the body simply does not need it in the blood at that time.
Often doctors measure 25D in the blood, find that the number is below 30ng/mL, and immediately recommend a vitamin D supplement. This can be problematic. For example, it is a well-known fact that vitamin D is necessary for proper calcium management. Too much 25D in the blood will spike the need to pull calcium into the blood. If you are eating enough calcium then the body can pull calcium into the blood from the food. But if you are not eating enough calcium then the body will pull calcium from the bone causing osteoporosis. The doctor may tell you to eat or supplement with more calcium, but calcium deficiency is not the problem in this case. The problem in this case is too much 25D in the blood from consuming too much vitamin D supplement. By measuring the active 125D form you can see if the body truly has optimal vitamin D usage. If you pump your body full of unnecessary exogenous vitamin D you could be creating problems instead of solutions. First, get your 125D measured and check to see if it is in the guideline range that your lab provides. Then compare it to previous measurements of 125D that you have had in the past. Next, look to see how 125D relates to 25D. Generally, 125D should be 1-3 times higher than 25D. If 125D is much higher or lower than 1-3 times 25D then it could be a sign of disease, but that doesn't mean vitamin D supplementation is necessary or safe. Very low 25D is often a marker of disease, but that does NOT mean that the disease is caused by low vitamin D either, and it does NOT mean that supplementing with 25D will fix the disease even if 25D increases with supplementation. It is generally just a correlation, not a causation.
125D will generally stay around the same level year round. You will notice that 25D may be lower in the winter time, but 25D is NOT doing the biochemical work. 125D is doing the biochemical work. Lower 25D in the winter is not a bad thing. It is the natural cycle. If you get enough UV-B light during the summer then you will have more than enough stored 25D to last for several years. The body may put less into the blood in winter, and as a result you may see lower 25D numbers on a blood test in winter, but when the body needs more 25D in the blood it will put it in the blood from the vast storages. If you want to check a blood test number then check 125D. For most people our relationship with light and dark is the best regulator of vitamin D. This is described in detail in my article called Light, Electron, and Water As Nutrition For Quantum Health. Read it carefully. Study the research included in the links. Put it into practice daily. Live your life by it. It is the way we evolved to manufacture, consume, and utilize vitamin D. A quick fix approach, like a supplement or drug, is rarely the answer to biological impairments. It is usually misguided human adaptations that cause problems with our ancestrally evolved biology.
As you carefully read epidemiological studies on vitamin D you will notice that nearly all of those studies compare disease rates to 25D, not 125D. It usually shows a strong correlation between those diseases and levels of 25D. This is correlation, not causation. A low 25D level is usually the RESULT of the disease, NOT the CAUSE of the disease. Increasing the 25D does not fix the underlying disease, and it could make things a lot worse. Fix the disease first! How do you do that? Start with my article called Healing Chronic Disease.
This article does NOT constitute medical advice. Consult with your physician before making any changes to your medical plan.