It is hardly a coincidence that sore throats, colds, flus, and related complications such as sinus infections and pneumonia typically circulate during the winter period. They are primarily a result of having low vitamin D levels. During the winter, the sun sits too low in the sky to enable vitamin D synthesis in our skin, and we only have a limited amount of the nutrient stored in the liver. Good hand hygiene, warm soup, garlic, echinacea and other immune-boosting herbs alone will not deal with the problem, as they can never compensate for our lack of essential vitamin D, which the white blood cells of our immune system need in order to silently kill of virus. But how much vitamin D do we need, is it possible to get too much, and which mineral is necessary for activating the vitamin?
Many people mistakenly believe that it is both natural and inevitable to catch influenza or colds, have a sore throat, or contract other virus infections during the cold season. What they do not realize is that infections require two things: Being infected and having a weakened immune system. Proper hygiene is relevant, of course. Still, the immune system requires a host of different nutrients in order to function optimally. Even if you stick with the official guidelines for healthy eating, you may be hard pressed to get enough vitamin D, according to leading experts. The risk of being chronically vitamin D-deficient is increased by such factors as spending too much time indoors, being old, having dark skin, being overweight, having type 2 diabetes, and using cholesterol-lowering medication. In beginning, a deficiency goes unnoticed, but it makes us more vulnerable to virus infections and sequela that may be potentially life-threatening, at least for older people or immunocompromised individuals.
Vitamin D activates the entire immune defense
The immune system consists of different proteins, antibodies, and white blood cells that work around the clock to protect the body against infection. All cells in the body have vitamin D receptors (VDR) that should be viewed as hormones because they are made from cholesterol, just like all other steroid hormones (sex hormones, stress hormones etc.).
In our airways, we have particularly many white blood cells (macrophages) that require vitamin D in order to attack germs. Vitamin D also boosts certain antibiotic peptides in the lungs.
Scientists from the University of Copenhagen have observed that vitamin D plays a crucial role in the activation of the immune system’s vanguard, the so-called T cells. When there are no imminent threats, billions of T cells circulate in the blood in “sleep mode”, but they are alert. As soon as an inactive T cell detects the slightest trace of a foreign body, it deploys its antennas and awaits activation.
This was when the scientists noticed that the first antennas, which the T cells deploy, are their vitamin D-binding receptors. This switches on a certain gene that enables the T cells to replicate and form an entire army, which can direct its swift attacks at virus and microbes. Vitamin D works like a battery in the T cells. Without vitamin D, the immune defense remains dormant and passive, leaving us susceptible to many different infections.
The Danish researchers’ groundbreaking discovery is published in Nature Immunology and sheds new light on the widespread vitamin D deficiency, which is a problem that needs to be addressed.
A vitamin D supplement can reduce your flu risk by 40-50 percent
Studies of vitamin D supplementation as a means of preventing influenza and other infections show conflicting results, which is due to the way these studies are designed. According to Professor Adrian Martineau, who conducted a large meta-analysis, it is only relevant to give vitamin D supplements to people who are in need of the nutrient, and the best effect is seen when the supplements are taken on a daily basis. In people that already have low blood levels of vitamin D, supplementation with the nutrient can reduce by 50 percent their risk of influenza and acute respiratory tract infections (RTI).
The daily supplementation dose is also important for the study result, as regular vitamin pills rarely contain enough vitamin D to optimize blood levels of the nutrient.
Scientists from the University of Colorado Anschultz Medical Campus studied older patients who were supplemented with different vitamin D doses for a year. They found that the participants that got the highest doses (82-107 micrograms) had the largest reduction of acute RTIs, including pneumonia. Their risk was reduced by 40 percent.
|Many older people, cancer patients, and people who are weak die of pneumonia caused by a virus infection. Therefore, high-dosed vitamin D supplements have the potential to save millions of lives.|
Vitamin D also protects against bronchitis and asthma
Bronchitis and asthma often follow in the wake of virus infections such as colds and influenza. Studies show that vitamin D has two mechanisms that protect against bronchitis and asthma. Firstly, it strengthens the immune defense. Secondly, it prevents undesirable, persistent inflammation.
It is vital that we humans can fight an infection swiftly and effectively. At the same time, it is important that the immune defense does not overreact, as this will cause chronic inflammation. That is why vitamin D is so crucial for preventing bronchitis, asthma, and other conditions where inflammation plays a key role. According to a study that was published in Nutrients in 2015, vitamin D is both directly and indirectly involved in the regulation of T cells and their production of various cytokines (inflammation markers).
The discomfort that we feel with an influenza is not caused by the virus but by the cytokines that the immune defense produces.
How much vitamin D can we humans produce?
It is relatively easy to produce between 20 and 100 micrograms of vitamin D if you spend time outdoors in light clothing on a hot summer’s day. Older people and individuals with dark skin have more difficulty with synthesizing the vitamin. Excess vitamin D is stored in the liver for later use, but these stores are easily depleted in the winter and early spring. If you do not get enough sunshine in the summer period and use too much factor cream, you risk a chronic deficiency.
RI levels and the actual need for vitamin D
In Denmark, normal vitamin pills only contain around five micrograms of vitamin D, which is the reference intake (RI) level for adults up to 70 years of age. Many scientists claim that we need much more in order to ensure optimal immune function.
High-dosed vitamin D supplements with as much as 20-80 micrograms are available. The actual need depends on your age, BMI, chronic diseases such as diabetes, and the use of cholesterol-lowering medication.
It should also be mentioned that magnesium is required in order to activate the form of vitamin D that we get from sun exposure or from supplements.
Vitamin D is lipid-soluble, which means that the best way to take the nutrient in supplement form is in capsules where it is bound to oil.
It takes a supplement to optimize your blood levels of vitamin D
Vitamin D in the blood is measured as 25-hydroxyvitamin D3. In Denmark, the lower threshold for vitamin D in the blood is 50 ng/ml. Leading scientists believe that we most aim as high as 60-100 ng/ml to obtain optimal disease prevention. At our latitudes, this would require taking a vitamin D supplement during the winter period.
Is it possible to get too much vitamin D?
You cannot produce too much vitamin D from sun exposure. When it comes to supplements, the European Food Safety Authority (EFSA) has set an upper safe daily limit for vitamin D intake, which is 25 micrograms for infants, 50 micrograms for children aged 1-10 years, and 100 micrograms for older children and adults, including pregnant and breastfeeding women.
Long-term intake of vitamin D doses that are more than 100 times the RI level may result in calcium precipitation within the kidneys and bladder, and there is a risk of kidney stones. Too much calcium in the blood may cause nausea, headaches, and constipation. In connection with pregnancy, elevated amounts in the blood may lead to fetal damage.
Don’t take vitamin D supplements, if you suffer from hypercalcemia (elevated blood levels of calcium) or have elevated phosphate levels in your blood, because it may worsen your condition. Magnesium and vitamin K2 help drain calcium from the blood and store it in bone tissue. People with sarcoidosis should be careful with vitamin D supplementation when their disease is active. If in doubt, ask your physician.
D-vitamin – hvad er det og kan man få for meget d-vitamin. Illustreret Videnskab 2019
Essen MR et al. Vitamin D controls T cell antigen receptor signaling and activation of human T cells. Nat Immunol 2010
University of Copenhagen. Vitamin D crucial to activating immune Defences. 2010
Martineau Adrian et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. The BMJ 2017
Urashima M, et al. Randomized trial of Vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr 2010
University of Colorado Anschultz Medical Campus. Vitamin D reduces respiratory infections. ScienceDaily November 2016
Cynthia Aranow. Vitamin D and the Immune system. J Investig Med. 2011
Qi Dai el al. Abstract CT093: Bimodal relationship between magnesium supplementation and vitamin D status and metabolism: Results from randomized trial. Cancer Research July 2018
Pernille Lund. Immunforsvarets nye ABC. Hovedland. 2012
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