For DEEP IMMUNE SUPPORT, strong evidence shows that vitamin D3 boosts many aspects of immunity, short and long-term. Vitamin D3 activates white blood cells to efficiently clear unwanted cells or invading microbes, and it helps to reduce viral or bacterial invasion by maintaining tight junctions between cells. Vitamin D3 decreases autoimmune activity, and cuts the long-term risks of developing multiple sclerosis, diabetes, asthma, and heart disease, as well as colon, breast, or prostate cancer. It also enhances hemoglobin levels, so that red blood cells can transport more oxygen to tissues.

Unlike other vitamins, vitamin D3 is technically a hormone defined as a substance made by a gland or organ in the body that travels in the blood to regulate its target tissues. Vitamin D may be one of the oldest hormones that exists on earth.

The immune system defends the body from foreign, invading organisms, promoting protective immunity. The risks from vitamin D deficiency and compromised immune function have become clearer in recent years. Low D3 levels are associated with increased autoimmunity and susceptibility to infection. Evidence supports the many roles of this crucial vitamin in addition to its classic effects on calcium and bone health. Vitamin D3 also eases joint and connective tissue inflammation, and it is needed for cell growth and neuromuscular function. It achieves all this because it has key roles in many metabolic processes, not because it is a panacea.

Vitamin D3 works by entering cells and attaching to vitamin D receptors located within the cell nuclei. The human genome has more than 2,700 binding sites for active D3; these receptors are located near genes that are involved in virtually every known major disease of humans. Once vitamin D3 locks into its receptor, the combination stimulates the cell’s DNA to produce proteins that have specific jobs in optimal immune function, as well as cell proliferation and maturation. Vitamin D is a powerful immune booster: it activates macrophage white blood cells and other key immune cells when it binds to its immune system receptors.

Sunlight absorbed through the skin triggers vitamin D synthesis, although in many climates there simply is not enough ultraviolet light, because of the sun’s angle. We make only tiny amounts of vitamin D in our skin in the summer, and virtually nothing in fall, winter, or spring.

As early as 1840, well before the discovery of antibiotics, patients with tuberculosis went to sanatoriums: There, treatment included exposure to sunlight which was thought to directly kill the tuberculosis. They were truly onto something! Although vitamin D levels fluctuate over the year, rates of respiratory infections consistently trend lowest in the summer and highest in the winter.¹

Most people need sufficient vitamin D3, either from a supplement or sun exposure, to achieve healthy blood levels of 60-100 ng/mL. Even in a temperate climate, blood levels may only increase by 5 points during the summer, so people generally need to continue supplementation all year. It is nearly impossible for us to receive enough vitamin D3 from foods as it is naturally present in only tiny amounts in very few foods, such as oily fish like salmon, mackerel and trout, or mushrooms. Because vitamin D3 is transported in fats, the absorption of vitamin D is greatly enhanced in the presence of an oil base or fatty carrier.

Scientists are actively studying the immunological actions of vitamin D3, as well as its effects upon cell growth and development. The infection-fighting T and B white blood cells are equipped to respond to vitamin D. They may act in a receptor-signaling manner either within the cell or by secreting substances to influence cells in the surrounding immune environment. Being fat-soluble, vitamin D easily crosses phospholipid cell membranes, and migrates to the nucleus. There it binds with vitamin D receptors, or with proteins that can respond to steroid hormones. This binding process regulates genes that turn immune and other cell functions on or off.

Vitamin D3 helps reduce the risk of respiratory infections through cellular and adaptive immunity as well as providing a physical barrier. Also, vitamin D helps maintain tight junctions and gap junctions between cells to keep microbes out. We know from studies that viruses can disrupt cell junction integrity which worsens the severity of infection. Vitamin D3 also enhances cellular immunity by calming the cytokine storm triggered by the body’s innate immune system. It helps support a healthy and balanced inflammatory response by reducing tumor necrosis factor and interferon, as well as by boosting T regulatory cells.

Vitamin D is made in our skin when UVB ultraviolet light from sunshine converts 7-dehydro-cholesterol, a cholesterol derivative, into cholecalciferol. This can occur after minutes of sun exposure, but the cholecalciferol may only last for hours or a few days at most. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. After it is made, cholecalciferol is first transported to the liver where it is converted into 25-hydroxycholecalciferol, a prohormone which is five times more active than cholecalciferol. This, in turn, is metabolized in the kidneys into 1,25-dihydroxycholecalciferol. The 1,25 form is the most potent form of vitamin D3, which is ten times more effective than cholecalciferol for immune boosting and creating healthy cells.

Vitamin D deficiency is very prevalent. In a 2011 estimate by the Centers for Disease Control, 25% of Americans were at risk for vitamin D inadequacy, with 8% probably suffering overt vitamin D deficiency. Increasing research reveals that vitamin D3 deficiency may affect half of the North American population. This may underlie many chronic degenerative disorders, and accurate supplementation is a highly cost-effective way to reduce common and life-threatening infections and diseases.

Very importantly, there is no standard vitamin D3 dose: Each of us has an individual dose requirement that depends on absorption and how fast our body clears vitamin D. With our patients, our aim for deep immune support is to reach a blood level between 60 to 100 ng/mL. Recent research indicates that 70 to 85 may be ideal. The Vitamin D Council (VDC) is a non-profit organization of medical professionals and vitamin D researchers whose goal is to educate professionals and the public on the benefits of vitamin D and the risks associated with deficiency. The VDC recommends blood testing and dosing to achieve an optimal level. Each person’s required daily dose is the amount that is needed to reach the standard target blood level after 4 to 6 weeks.

A landmark April 2014 study published in the British Medical Journal analyzed the results of double-blind trials with more than a million people conducted through Harvard, Oxford, and other leading universities. They found that low vitamin D3 blood levels were linked with a 35% increased risk of death from heart disease, and a 14% greater likelihood of death from cancer. For people with poor vitamin D levels, the risk of developing cancer, cardiovascular disease, diabetes, asthma, autoimmune diseases, or multiple sclerosis was doubled. The researchers estimated that roughly 13% of all deaths in the United States could be attributed to low vitamin D levels.²

Research in 2011 determined that higher vitamin D3 levels may cut the risk of getting colon or prostate cancer by 50%. In addition, a stunning 25% of breast cancer deaths in northern European women may be attributed to inadequate vitamin D levels. Adults who took D3 for three years or longer had an 11% reduction in mortality from all causes. Only vitamin D3 had these benefits, the D2 form had no effect.⁷

A number of important cross-sectional studies have looked at vitamin D levels and rates of infectious illnesses such as influenza, bacterial vaginosis, and HIV. All have reported an association between of lower vitamin D levels and increased infections. One such study followed 800 military personnel in Finland for six months. The results documented that recruits with lower vitamin D levels lost significantly more days from active duty due to upper respiratory infections than individuals with higher vitamin D levels.³

A well-designed, double-blind study in 2010 found that a therapeutic dose of vitamin D3 reduced influenza in children. Using an objective nasopharyngeal swab culture for diagnosis, 167 Japanese schoolchildren received either a therapeutic dose of vitamin D or placebo, and they were followed over four months. The children who received vitamin D therapy enjoyed a statistically significant 42% decrease in the incidence of influenza infection. The reduction in influenza A was more prominent in children who had not been taking other vitamin D supplements prior to the study. Very significantly, asthma attacks were also less frequent in children with a previous diagnosis of asthma.⁴

A new April 2020 clinical report emphasized the role of vitamin D3 in reducing respiratory tract infections that could include COVID-19. This review found that vitamin D deficiency is linked with an increased risk of acute respiratory distress syndrome as well as chronic airways disease.

Several batches of data were used: One observational study in Connecticut included 198 healthy adults in the fall and winter of 2009 through 2010. People with sufficient vitamin D experienced a reduced risk of acute respiratory tract infections. Over the winter, only 17% of individuals who had adequate vitamin D3 levels developed an acute upper respiratory tract infection, compared to 45% of those with poor D3 blood levels below 38 ng/mL.

Another study in Georgia was conducted with intensive care unit patients who needed ventilators. These patients had an average vitamin D level of only 21 ng/mL. When they received a one-time dose of 250,000 IU or 500,000 IU of vitamin D3, their hospital stays dropped from 36 days to 18 days. This study also confirmed that vitamin D boosted red blood cell hemoglobin concentration, allowing for better oxygen delivery to all tissues.⁸ 

Increasing epidemiologic evidence links vitamin D deficiency with increased risk of autoimmune diseases. Multiple sclerosis, rheumatoid arthritis, diabetes mellitus, inflammatory bowel disease, and systemic lupus occur much more frequently in people with low vitamin D3 blood levels.⁵ Of great concern is data showing that pregnant women with D3 deficiency have a higher risk of having babies who later develop diabetes. A lower maternal intake of vitamin D during pregnancy is linked with giving birth to children who are much more likely to have autoimmune diabetes mellitus.⁶

 Because of its wide-ranging effects on many tissues and its actions as a prohormone building block for numerous critical metabolic functions, the list of clinical benefits for Vitamin D3 is long.

The quality of a vitamin D3 formula matters a great deal as vitamin D is a fat-soluble nutrient, its absorption is enhanced in an oil base. In our clinic, we see consistently excellent results for vitamin D3 uptake in a formula incorporating either vegan medium chain triglycerides, or fish oil with omega-3 fatty acids. To maintain freshness and stability, we also like to include vitamin E, as natural d-alpha tocopherol or mixed tocopherols.

We recommend a blood level of 60-100 ng/mL all year. With this, our patients enjoy fewer colds and flu symptoms which clear up faster, less ‘winter blues,’ less joint pain, and increased energy. Our patients are glad to know that they are reducing their long-term risks of developing multiple sclerosis, which around 2008 was one of the first disorders found to be reduced by vitamin D3. They are also reducing the risks of autoimmune and inflammatory disorders, diabetes, asthma, and heart disease, as well as colon, breast, or prostate cancer.

 Recommendation: Vitamin D3 as cholecalciferol, in an oily or fatty base with either vegan medium chain triglycerides, or fish oil omega-3 fatty acids including DHA and EPA, also with vitamin E as d-alpha or mixed natural tocopherols to preserve freshness. Vitamin D3 should be taken with any meal that includes fat or oil, for peak absorption. The dose required is that which is needed to attain a blood level of 60-100 ng/mL after 4 to 6 weeks of taking it daily. For most people that daily dose may be in the 4,000 to 8,000 IU range, but it could be higher or lower. Checking your blood level is essential to confirm the correct dose: follow the directions of your healthcare provider.

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