Vitamin D has been making headlines of late as an immunity booster. Vitamin D deficiency has also been reported to play a significant role in the ‘cytokine storm’ associated with people who are getting really ill from COVID-19 infection.
Vitamin D is produced when sunlight hits our skin and is crucial for health in many ways. It is one of the most common Vitamin deficiencies globally.
Here’s what you need to know about the role of vitamin D in your health.
We instinctively feel better on sunny days. And despite fears of melanoma, the fact is that being out in the sun, in moderation, is good for us.
Our skin converts sunlight into Vitamin D, a hormone essential for human health. This amazing compound, whilst referred to as Vitamin D, is actually a steroid hormone known as calcitriol. Vitamin D or calcitriol cannot be synthesized by the body in sufficient quantities to maintain health.
Vitamin D, also known as “the sunshine vitamin,” has a number of health benefits, most famously our bone health. And it has come into the spotlight recently, in the context of COVID-19, as a potential immune booster.
Vitamin D has recently been highlighted as a key player in the strength of our immune systems, especially when it comes to fighting off viral infections.
In a 2020 study, researchers examined the mean vitamin D levels among populations from 20 European countries as well as the documented cases of COVID-19 and the subsequent mortality rates from the virus. They found a potential correlation between lower vitamin D levels and higher incidence of COVID-19 risk and mortality.
An additional Spanish study on COVID-19 outcomes used vitamin D to treat patients already hospitalized for the disease. A total of 76 patients in the study were given the immunosuppressant hydroxychloroquine and the antibiotic azithromycin. Fifty of them were also given oral calcifediol (a vitamin D3 analog) daily, while 26 were not.
Of the 50 patients treated with calcifediol, only one required admission to the ICU (2%), while of 26 untreated patients, 13 required ICU admission (50%), and two died (8%). Although this was a small sampling of participants, the results were statistically significant when it came to reducing the severity of the disease.
These studies suggest that both screening for vitamin D deficiency and possibly using it as a supplementary treatment could play an important role in pandemic-related public health.
Other studies tell us that addressing vitamin D deficiency could also help protect against other viral illnesses, like seasonal influenza.
Even though the evidence is clear that having enough vitamin D is critically important, some 60-80% of the global population has some degree of Vitamin D deficiency.
Checking for vitamin D deficiency isn’t usually a part of standard blood tests in every physician’s office, so it’s often missed. And if you are deficient, you might not know it.
So what exactly is vitamin D? How much do you need? And do you need to supplement it
Vitamin D (calcitriol) is sometimes called cholecalciferol (vitamin D3), because it is calciferous (“carrying calcium around”) and a sterol (a type of steroid hormone).
Vitamin D is primarily obtained from our body’s response to the sun’s UV rays when they penetrate the skin. In addition to direct sun exposure, we can also get vitamin D from a few foods, as well as dietary supplements. It’s a fat-soluble vitamin, which means that if we take it orally, we’ll need to accompany it with at least some fat for the best absorption. Furthermore, while water-soluble vitamins are excreted and not stored in the body, vitamin D and other fat-soluble vitamins (like A, E, and K) accumulate in fatty tissues throughout your body.
Vitamin D promotes calcium absorption in our gut and helps our bodies to maintain adequate serum calcium and phosphate concentrations. Vitamin D also works together with vitamin K to regulate calcium metabolism which is essential for heart health. And it also plays a key role in skeletal health and bone strength. It also controls the reduction of inflammation, as well as modulation of processes like cell growth, neuromuscular and immune function, as well as glucose metabolism.
Our bodies need enough vitamin D to run properly. In fact, vitamin D offers a number of health benefits both on its own and through working together with other compounds in the body. Here are six great reasons to “Let the sunshine in” on a regular basis.
We need vitamin D in order to absorb calcium, which is necessary to grow and maintain strong bones. Research shows that when people are vitamin D deficient, they have worsened skeletal integrity.
In addition to bone health, vitamin D is also needed for the normal development and growth of muscle fibers — the thousands of muscle cells that are tightly wrapped together to form our muscles. As such, having inadequate levels of vitamin D in the body can lead to muscle weakness and pain.
Research has shown that having higher serum levels of vitamin D is associated with a lower cancer incidence. In fact, a 2019 meta-analysis of prospective cohort studies published in Nutrients looked at 16 studies involving 101,794 participants to determine the relationship between serum vitamin D levels and risk of cancer diagnosis and mortality. The researchers concluded that with each 20 nmol/L (that’s pronounced “nanomoles per liter,” in case you’re reading this article out loud as a bedtime story) increment increase of 25-hydroxyvitamin D (another name for calcidiol) concentration, the risk of developing cancer dropped by seven percent.
This relationship remains when looking at specific types of cancer, too. Another 2019 study found that higher serum vitamin D levels were associated with statistically significant, substantially lower risk of colorectal cancer among women. While not as significant, the same association was also seen among men. And in a 2020 review, researchers concluded that epidemiological evidence suggests there is a link between higher vitamin D levels and a lower risk for ovarian cancer as well.
Another health benefit of having adequate vitamin D levels in our body is heart health protection. A 2017 meta-analysis of 32 studies published in the American Journal of Clinical Nutrition found that higher serum vitamin D levels were inversely associated with total cardiovascular disease events, like heart attacks and strokes, and, ultimately, mortality from them.
A 2018 review and meta-analysis published in Nutrients also examined the relationship between vitamin D levels and ischemic stroke risk. The authors found that having lower vitamin D status was associated with a higher risk for ischemic stroke.
An autoimmune disease is a condition in which your immune system mistakenly attacks your body. A 2017 study published in Neurology found that vitamin D deficiency is a risk factor for multiple sclerosis, a physically and mentally progressive autoimmune disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. In a broader review from 2018, researchers concluded that vitamin D deficiency is prevalent in a number of autoimmune diseases. As such, vitamin D supplementation has been linked to the prevention of autoimmune diseases.
Having adequate vitamin D levels appears to be helpful in the management of type 2 diabetes as well. In a 2018 review published in Nutrients, researchers found that when serum vitamin D levels among people with type 2 diabetes were increased, their insulin resistance was reduced.
In another 2018 meta-analysis, researchers found that low vitamin D levels were associated with an increased risk for hyperglycemia — or uncontrolled high blood sugar — in both people who did and did not have diabetes.
Vitamin D deficiency — or not having enough vitamin D circulating in our blood — is a very common condition. Subclinical vitamin D deficiency is widely prevalent in almost every nation, impacting up to a billion people worldwide.
With chronic and/or severe vitamin D deficiency, a decline in intestinal absorption of calcium and phosphorus leads to hypocalcemia or a deficiency of calcium in the blood. Inadequate calcium can lead to secondary hyperparathyroidism, a condition in which your parathyroid glands make too much parathyroid hormone. This can result in accelerated bone demineralization, which can eventually turn into osteomalacia (softened bones) and osteoporosis (porous bones) in adults as well as rickets (softened and weakened bones) in children.
Vitamin D deficiency is diagnosed when the amount of vitamin D circulating in the bloodstream is lower than recommended levels for optimal health. So what should your levels be?… it turns out there are many credible researchers coming to very different conclusions.
In 2011, the widely respected Endocrine Society issued a report which concluded: “Based on all the evidence, at a minimum, we recommend vitamin D levels of 30 ng/mL, and because of the vagaries of some of the assays, to guarantee sufficiency, we recommend between 40 and 60 ng/mL (nanograms per millilitre) for both children and adults.”
However, writing for the New England Journal of Medicine in 2016, several leading epidemiologists and endocrinologists stated that in their opinion, we are over-screening for vitamin D deficiency and unnecessarily treating individuals who are actually fine. Based on their analysis, a more appropriate cutoff for vitamin D deficiency would be much lower — 12.5 ng/mL.
This leads to another question, which is maybe what we should have been asking all along. What is optimal? Apparently, most people can survive with blood levels as low as 12.5 ng/mL. But is that what’s best?
Here too, there is controversy. But a growing body of research is finding that the optimal blood levels of vitamin D are above 30 ng/mL, while other studies concluded that 40-60 ng/mL is the preferred range.
The short answer is, yes. Remember that vitamin D is a fat-soluble vitamin, which means that it accumulates in the body and is stored over time — unlike water-soluble vitamins that are just peed away if we consume more than we need. So vitamin D can build up in our body, and side effects and toxicity are possible if blood levels get too high.
Vitamin D helps the body absorb calcium from the food we eat. But too much of it can cause the body to store up excess calcium in your blood. Symptoms of hypercalcemia, or high blood calcium levels, include digestive distress, fatigue, and bone loss. A 2019 study concluded that excessive use of vitamin D could cause kidney damage in people who are not deficient in the vitamin.
It’s important to clarify that excess vitamin D levels result from oral intake only; we can’t overdose on the vitamin D our body makes from sunlight. The body is remarkably good at regulating how much naturally produced vitamin D is made and stored.
Blood levels of 100 ng/mL are considered to be the upper limit of a normal or healthy range by the Institute of Medicine, the Endocrine Society, and many reference laboratories. As it turns out, it’s not easy to get our vitamin D levels that high. In one major study involving more than 17,000 healthy adult volunteers, vitamin D supplements as high as 20,000 international units (IU) per day didn’t get participant’s blood levels above 100 ng/mL and also didn’t lead to any evident toxic effects.
A 2015 study looked at data from more than 20,000 people over the course of 10 years. The researchers found that only 37 people had levels above 100 ng/ml.
However, while 100 ng/mL might be a rarely reached upper limit, there are studies that have shown a small level of increased mortality with blood levels of 50 ng/mL or higher. While the evidence is a bit murky, it does seem that vitamin D toxicity is rare, and that somewhere in the 30-60 ng/mL range could be the “sweet spot” for most people.
There are certain lifestyle factors that can increase our risk of being vitamin D deficient. Some of these include:
Falling into any of these categories means checking vitamin D levels is especially important.
Checking Vitamin D levels isn’t difficult.
The test can be done with a pinprick of blood. If you decide to take a significant dose of supplemental vitamin D (over 2,000 IUs per day), you may want to check your blood levels again after a few months to see if or how things have changed.
Studies have shown that each additional 100 IU of vitamin D3 you consume per day will raise your blood vitamin D levels by 1 ng/ml (2.5 nmol/l), on average.
There are three main sources of vitamin D:
sunshine, certain foods, and dietary supplements.
When your skin is exposed to sunlight, it manufactures vitamin D. The sun’s ultraviolet B (UVB) rays interact with a protein called 7-DHC in your skin, converting it into vitamin D3 — the active form of vitamin D. This is the best way to get vitamin D. Recommendations for time in the sun vary and depend on individual factors like skin pigmentation, age, the latitude of where you live (there is less direct sunlight further from the equator), skin cancer risk, and the season. But you don’t need to devote hours a day to sun-worship; recommendations range from 7-30 minutes per day over a large portion of your body. Studies have found that people with dark skin pigmentation may need up to six times more sun exposure than people with light skin to get the same vitamin D3 production in their skin.
While there are some dietary sources of vitamin D, very few foods naturally contain it. Vitamin D is found in certain types of fatty fish (e.g., halibut, salmon, and mackerel), animal organ meats like liver, and in very small amounts in eggs and dairy products. Most foods containing vitamin D, including dairy milk, are fortified with it, meaning that the nutrient is added to them as a supplement. Vitamin D can also be found in fortified cereals, orange juice, and many plant-based milks (it will be noted on the ingredients list)
The only plant-based foods that naturally contain vitamin D are some types of mushrooms which contain it in the form of vitamin D2. Mushrooms produce Vitamin D similarly to how humans do when our skin is exposed to sunlight.
The most reliable way to raise vitamin D levels is to take it as a supplement. There are two main forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). These two types of vitamin D are not equal when it comes to raising serum vitamin D status. Both are effectively absorbed into the bloodstream, but the liver metabolizes them differently. Vitamin D3 appears to be much more effective in raising blood vitamin D levels than vitamin D2.
Vitamin D can be found as a supplement on its own or as part of a multivitamin. It’s also added to a number of omega-3 fatty acid supplements.
Note that the American Academy of Pediatrics recommends all breastfed babies receive a daily dosage of 400IU of vitamin D soon after birth to maintain their levels. This is because vitamin D is not transferred well through breastmilk. And babies generally shouldn’t be exposed to much sunlight. Formula-fed babies don’t typically need this supplementation because infant formula is fortified with the vitamin D they need.
Most supplements come in the form of vitamin D3, or cholecalciferol. However, most D3 supplements are not manufactured from vegan sources. Instead, many come from animal products such as lanolin, which is a greasy substance produced by sebaceous glands of sheep and found in their wool. Still, vegan vitamin D3 supplements are becoming increasingly widespread. These are usually made from lichen, an organism that arises from algae or cyanobacteria.
While many vitamin D supplements come in gel, oil, or capsule form, there are also liquid dropper options called micellized vitamin D3. Micellization of vitamin D3 appears to improve its solubility, absorption, and bioavailability. Which explains why a miscible form of vitamin D3 may actually be more effective in raising serum vitamin D levels than a fat-soluble version.
Research also indicates that vitamin D3 is best absorbed when paired with the nutrient vitamin K2. High blood levels of vitamin D — a potential problem for anyone taking D3 supplementation — can lead to excessive calcium accumulation in the blood, contributing to calcification of the blood vessels. Vitamin K2 helps make sure that calcium is used in the bones instead of ending up in the arteries where it doesn’t belong.
Once the vitamin D has done the job of making sure the calcium you consume hits your bloodstream, the vitamin K activates a protein called osteocalcin. This protein makes sure that the calcium that’s in the bloodstream winds up where you want it to go — into bones and teeth.
Bottom line: You don’t want to be deficient in vitamin K if you’re taking vitamin D. For this reason, many people take their vitamin D and K together.
BIO: Chantal is a B.Sc.Hons Allied Health with an international diploma in Nutrition and Sports Nutrition. Chantal is a passionate Gut Health advocate & holistic Lifestyle Coach, specialising in the improvement and management of the chronic diseases of lifestyle, the illnesses and diseases associated with dietary excess and their relationship to leaky gut and dysbiosis (imbalance) of the gut microbiome. These conditions include IBS, high cholesterol, high blood pressure, overweight, obesity, acne, eczema, depression, anxiety, auto-immune, hormone imbalance, cognitive decline etc.
Over her 25 year career, Chantal has held various positions within the health and wellness industry – including 10 years as the Executive Head of Vodacom’s corporate wellness & mobile health programs. Chantal is the owner/ founder of the DripBar which offers vitamin and mineral drip therapy in improving micronutrient deficiencies. She is also the founder/owner of a Kombucha brewery which produces the brand of organic green tea ‘booch’ called theFarmacy.
Chantal is a competitive cyclist, a plant strong vegan and mom to two grown up girls.
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