Got vitamin D from sunshine and diet? If not, are you taking the proper dose of a vitamin D supplement?
These are good questions to ask given the emerging role vitamin D potentially plays in health maintenance, and disease prevention. This includes improving bone mass density, enhancing immunity against respiratory infection; decreasing the risk for diabetes, certain cancers, and cardiovascular disease; preventing bone spurs in osteoarthritis. Vitamin D is actually a hormone [cholecalciferol], but will be referred to as a vitamin throughout this article.
The Sunshine Vitamin
Sunshine is the main source of vitamin D. Skin converts UV rays to cholecalciferol, a preliminary form of vitamin D (most efficiently when sweating). The liver and kidneys convert cholecalciferol to 25‐hydroxy- cholecalciferol [25(OH)D], and ultimately to the active form of vitamin D. The skin starts this cascade of events by producing anywhere form 6,100 to 25,000 IU of cholecalciferol after only a few minutes of sun exposure.
When to Supplement
However, many other factors come into play such as skin pigmentation, skin integrity and age; as well as the amount of skin exposed to the sun. Such things as sunscreen use, strength of UV rays, and topography are considerations. In general, there is likely-hood of suboptimal vitamin D levels if you are darker skinned, and/or do not spend much time in the sun. The risk for clinical vitamin D deficiency increases with kidney disease; alcoholic or non alcoholic liver disease; gall-bladder or bile-duct disease; gastric bypass, malaborption, or inflammatory bowel diseases. In all these instances, supplementation may be advised.
Average to optimal vitamin D status is based upon a blood 25(OH)D level ranging from 20 to 100 ng/mL depending on whom you ask. And different sources suggest that adults supplement with anywhere from 400 to 10,000 IU of vitamin D daily. To make things a bit clearer, healthcare providers consider the 25(OH)D blood level, plus environmental and lifestyle factors, health status, and contraindications to supplementation. Then recommend dietary sources of vitamin D, or supplementation with standardized or calculated doses. (D3 is preferred to D2). Here are some doing guidelines:
Functional Medicine reference range & dosing [Grisanti & Weatherby, n.d).
...If deficient or insufficient:
... RDA vs. Food Sources
The Recommended Daily Allowance (RDA) of vitamin D is 600 to 800 IU, a standardized dose originally declared by the Institute of Medicine in 2010. Note that the RDA is currently under scrutiny as underestimated. Fatty fish (salmon, tuna, sardines etc.) are rich sources of the RDA, providing up to 560 IU per serving. According to the National Institute of Health (NIH), animal-based vitamin D is five times more potent than a D3 supplement in raising 25(OH)D levels.
... Weight-based Dosing
A maintenance-dose, based upon weight multiplied by a factor of 27, may be more reflective of individual needs. For example, a person weigh-ing 150 pounds starts with a baseline dose of 4,070 IU (150 x 27 = 4,070). Adjustments are then made for type of sunlight, duration of exposure, percent-age of skin exposed etc. There are Apps to calculate this.
... Deficiency-based Dosing
Another dosing regimen, for an established deficiency, is based upon the expected rise in 25(OH)D level for every 1000 IU of vitamin D3 taken. A pilot study found that the more deficient a person was, the greater the rise in 25(OH)D. The median dose to correct a moderate deficiency was 4000 IU of D3 daily; 9000 IU daily to correct a severe deficiency. In this study, the closer to optimal a person's blood 25(OH)D level became, the smaller the rise with each subsequent dose. Meaning, more was not better.
Too Much or Too Little Vitamin D3?
Excess amounts of vitamin D3 are believed to damage the heart, blood vessels, kidneys, and pancreas due to increased blood levels of calcium. Naturopathic and Functional medicine practitioners may prescribe the higher doses of D3 in combination with vitamin K2 in order to facilitate the transport of calcium from the blood into bones. It is recommended that serum calcium levels should be measured regularly in patients receiving greater than 4000 IUs of vitamin D because hypercalcemia is the best indicator of excess vitamin D [Grisanti & Weatherby, n.d).
How much D3 is excessive vs. toxic also varies. The Tolerable Upper Intakes range from 4,000 to 10,000 IU daily for adults. While toxicity thresholds range from 10,000 to 40,000 IU daily, and/or a serum 25(OH)D level ranging from >100 to >240 ng/mL. In general, the NIH reports that hazard is unlikely with daily intakes below 10,000 IU.
Signs of Deficiency & Contraindications
Classic signs of a clinical vitamin D deficiency are osteomalacia in adults, and rickets in children. Signs of chronic insufficiency may include weakness, decreased vitality, premature aging, muscles spasms etc. Of note is a 5-year study published in JAMA, which "demonstrated a significant association between vitamin D insufficiency and... significantly faster rates of decline in memory and executive function performance" (DeCarli, C. et al, 2015).
According to Functional Medicine experts, vitamin D is indispensable in helping maintain the health of the small intestine lining where micronutrients are assimilated; or to help prevent auto-toxicity, systemic inflammation, and auto-immune reactivities related to leaky gut syndromes (Carnahan, 2016). It preserves junction complexes and stimulates epithelial cell renewal. It modulates the immune function associated with mucosal barriers. and increases colonic epithelial cell resistance to injury (Burdett, 2016). It is well documented that raising serum vitamin D levels in deficient or insufficient patients will help reduce musculoskeletal pain, low-back pain and generally reduce inflammation [Grisanti & Weatherby, n.d). Vitamin D is essential for pancreatic health.
Contraindication to high-dose D3 supplementation [or at least D3 without K2] may include certain cardiovascular, renal or, parathyroid diseases. Vitamin D supplementation is contraindicated in patients taking thiazide diuretics [[Grisanti & Weatherby, n.d]. Some authorities say that it is imperative for those experiencing Herxheimer reaction [healing crisis] from treatment of e.g. spirochete infections such as Lyme, not take vitamin D considerations.
The Vitamin D Receptor Saga
It seems like low vitamin D level is endemic such that many physicians are now monitoring vitamin D levels, and prescribing vitamin D3 to their patients. However, the true problem may be with the vitamin D receptor (VDR), which when damaged by infection, inflammation & toxicities contributes to chronic disease, and autoimmune diseases. A person can have a genetic defect in the VDR leading to chronically low vitamin D levels.
The VDR is ubiquitous throughout the body. Since vitamin D is needed to regulate the immune system and enable the body to fight disease naturally, when the VDR is impaired this can not happen. In fact, active vitamin D precursors (measurable via blood labwork) can build up in the body and cause more harm than good. The way to revive the VDR is to slowly unburden the body of hidden toxicities, infections, inflammations with drugs, herbs, food medicines, and or supplements.
The medical way to do this is the Marshal Protocol (slowly pulsed doses of antibiotics) under the supervision of a medical doctor. In Functional Medicine, it is best to have a diet rich in phytonutrients that continuously prevent and/or eliminate the hold of bad bugs, toxins, and inflammatory reactions. And a supplement containing b-calcium fructoborate (a form of boron) plus co factors that support the VDR.
In Chinese medicine it is interesting to note that ox bile /Niu Huang contains lithotropic acid, a chemical that revives the VDR. This substance is traditionally considered a great detoxicant, used to "open the orifices & revive the shen" in emergency Chinese herbal medicine terminology. However, the use of bile products (even OTC ones) come with cautions & considerations.
Burdett, C. (2016). Triad of gut destruction. In Functional Medicine University.
Carnahan, J. (2016), Autoimmunity and the gut: A detailed examination of various triggers to immune system dysfunction and the development of autoimmunity. In Functional Medicine University.
DeCarli, C. et al. (2015). Vitamin D status and rates of cognitive decline in a multiethnic cohort of older adults. JAMA Neurology. DOI: 10.1001/jamaneurol.2015.2115.
Garland, C., French, C., Baggerly, L., Heaney, R. (2011). Vitamin D supplement doses and serum 25-hydroxyvitamin D in the range associated with cancer prevention. Anticancer Research 31, 607- 612.
Grisanti, R. & Weatherby, R. (n.d). Insider's guide special topic: The FDM approach to auto-immune disease. In Functional Medicine University's Functional Diagnostic Training Program. Sequoia Education Systems,
Institute of Medicine. (2010). Dietary reference intakes for calcium and vitamin D.
National Institute of Health. (2014). Vitamin D: Fact sheet for health professionals.
Veugelers, P., Ekwaru. J. (2014). A statistical error in the estimation of the recommended dietary allowance for vitamin D. Nutrients 6 (10), 4472.
World’s Healthiest Foods. (n.d.) Vitamin D.