Vitamin D is the most studied supplement as it relates to COVID-19.
Because the research process is rigorous, it requires a great deal of time for new information to become available. We do have more data now than we did in 2020 when we first reviewed the available evidence regarding COVID and vitamin D.
Today we’re reviewing the latest research on Vitamin D, the immune system, and COVID (along with other viruses) and how you can use this information in real life.
Table of Contents
Vitamin D and COVID-19 Research
At this time there are two published randomized controlled trials (the gold standard for research) looking at the effectiveness of vitamin D as a treatment for COVID.
A daily dose of 60,000IU administered to hospitalized patients for 8-10 days improved all inflammatory biomarkers and the duration of symptoms was lessened (1).
A single high dose of vitamin D (200,000IU in this study) taken 1-2 days after hospitalization did NOT have the same beneficial impacts (2).
In another ongoing study, a daily dose of 5,000IU for 7 days did reduce the severity of symptoms and time in the ICU.
Vitamin D deficiency or insufficiency is correlated with:
- A higher risk of getting COVID
- More severe symptoms and/or longer duration of symptoms
- Higher rates of admittance to the ICU and an increased need for a ventilator
- An increased risk of death from COVID (and related complications) (4, 5)
Through its role in supporting respiratory health, there is reason to believe vitamin D may also reduce lung damage in COVID-19 patients.
It’s thought that COVID enters the body and then attacks cells by landing on a receptor called ACE2 (or angiotensin-converting enzyme 2).
Once inside the cells, the virus begins to replicate and dysregulates the renin-angiotensin system (RAS) found in the respiratory system, specifically the lungs. Research shows that vitamin D plays a role in supporting the RAS and can, therefore, reduce lung damage (6).
Another study measured vitamin D levels in individuals getting tested for the coronavirus. This research found that patients testing positive for the virus had significantly lower vitamin D levels than those patients that tested negative (7).
Vitamin D and the Respiratory System
We also have other studies suggesting that vitamin D supports respiratory health.
A study by Queen Mary University in London found that daily vitamin D supplementation in individuals with vitamin D deficiency cut their risk of other respiratory infections in half (9).
Other studies have replicated these results showing that vitamin D supplementation can prevent upper respiratory infections (10).
Anti-viral effects of Vitamin D
Vitamin D status has been shown in numerous studies to be correlated with inhibiting other forms of viruses that we’re more familiar with such as Epstein-Barr.
Studies have shown that people may be more susceptible to winter illnesses due to the lack of sufficient sun exposure, and therefore inadequate vitamin D levels.
Additional Functions of Vitamin D
Every cell and tissue in your body has vitamin D receptors, and the latest thinking is that Vitamin D may function more like a hormone than a vitamin, essentially elevating its importance.
In addition to supporting immune health, Vitamin D also:
- Maintains normal blood levels of calcium and phosphorus, which help build bones.
- Affects your skin, brain health, blood sugar, cholesterol, hormone balance, and more.
Research shows reversing a vitamin D deficiency through supplementation can:
- Improve insulin production and sensitivity (13)
- Alleviate fibromyalgia symptoms (14)
- Boost testosterone in men (15)
- Reduce the risk of colorectal cancer (16)
- Decrease body fat (17)
- Reduce PMS symptoms (18)
- Improve inflammatory markers (18)
What Should My Vitamin D Level Be?
The Endocrine Society defines Vitamin D deficiency as a serum 25-OH vitamin D level below 20 ng/ml and insufficiency between 20 ng/ml and 30 ng/ml.
The range of what’s considered acceptable for vitamin D is really quite broad, in conventional medicine typically anywhere from 30 ng/ml – 100 ng/ml is considered okay.
From a functional nutrition perspective (read: for optimal health and immune support), we recommend vitamin D levels of 50-80 ng/ml.
How Much Vitamin D Do I Need?
Well, that depends on your current vitamin D status.
All of the benefits of vitamin D supplementation are only found in individuals with suboptimal vitamin D levels.
Because vitamin D is a fat-soluble vitamin, we will store it rather than excreting it if we consume too much. Too much vitamin D can negatively impact the balance of other minerals specifically calcium.
In women taking 4,000IU to 10,000IU daily for 3 years, their bone mineral density actually decreased (19).
Among functional practitioners, it is generally accepted that 2,000 IU per day will maintain current vitamin D levels, and around 5,000 IU daily will increase vitamin D levels.
Doses should not exceed 10,000IU per day unless being followed closely by a medical professional.
We recommend checking vitamin D levels at least once a year and adjusting supplementation accordingly.
It’s also worth noting that the recommendation from the Institute of Medicine is only 400 IU per day. There is much controversy around this, including some juicy drama around miscalculations.
Hopefully, we will see an increase in their recommendations in the near future.
How Do I Increase My Vitamin D Levels?
Food Sources of Vitamin D
The amount of vitamin D to maintain and increase levels is significant, and it’s really hard to get enough from food alone. The graph below is from the National Institute of Health (NIH) and shows the top five food sources of vitamin D.
|IUs* per serving
|Cod liver oil, 1 tablespoon
|Trout (rainbow), cooked, 3 ounces
|Salmon (sockeye), cooked, 3 ounces
|Mushrooms, white, raw, sliced, exposed to UV light, 1/2 cup
|Milk, 2% milkfat, vitamin D fortified, 1 cup
Vitamin D and the Sun
- Modest sun exposure ( 30 minutes outside in shorts and a tee) midday or between 11 – 3 at least 3 days per week produces enough vitamin D to keep from being deficient (20). Not to mention the added health benefits of being in nature…
- To protect your skin and get your vitamin D, our recommendation is to get 30 minutes of sun exposure daily and then apply sunscreen because sunscreen will reduce your vitamin D production from the sun’s rays.
The Best Vitamin D3 Supplement
When it comes to selecting a supplement, always choose D3 over D2. Vitamin D3 is easier for the body to absorb so it’s more effective in raising vitamin D levels.
It is also important to understand that nutrients do not work in isolation. Additionally, the intake of a nutrient does not always guarantee absorption.
Since there is an intricate relationship between fat-soluble vitamins, it is important to take vitamin D with vitamin K for optimal absorption.
Also, if magnesium levels are inadequate, vitamin D will likely be as well. This is because magnesium is involved in transporting and activating vitamin D for use by the body.
Liquid Vitamin D3
There are genetic mutations that can predispose some people to lower levels of circulating vitamin D due to an inability to activate the vitamin.
This can be tested for, but the easiest and most cost-effective workaround is to take the liquid form of D3.
This is what we recommend to our clients because it covers everyone’s needs. Our recommended supplement and instructions on how to order can be found below.
We believe testing is best and that everyone should know their vitamin D status!
- If you haven’t had your vitamin D levels tested within the last year, ask your physician at your next physical.
- For a more comprehensive assessment, we offer the NutrEval panel to assess your status of several nutrients allowing for even more personalized recommendations for diet and supplementation.
Vitamin D Supplement Tips
- Vitamin D should always be taken with a source of fat because fat is required for the absorption of this nutrient.
- If you have an issue digesting and absorbing FAT itself you may not be able to achieve adequate vitamin D levels.
- How would you know? Check your stool! If it is greasy, or you ever see oil floating on top of the toilet water after you have a bowel movement, you may need some nutritional support to improve fat absorption.
- Making sure you cover the above nuances may sound complicated, but these issues are easily covered by:
- Taking vitamin D/vitamin K combination supplement
- Supplementing your vitamin D after a meal (all meals should include a source of fat for nutritional balance)
- Including a multivitamin when taking your vitamin D
Thorne Vitamin D K2
We love Thorne’s D/K2 for vitamin D drops.
Clients often ask us how to take it – after your meal, simply invert the bottle over a spoon allowing the drops to drip onto the spoon until you reach the desired dose, and then drink off the spoon.
It pairs really well with their Basic Nutrients 2/day multivitamin for enhanced absorption.
You can order directly from Thorne using this patient code HCP1039686. Both are also available for order through our Wellevate Store. You can create an account using this link.
- We’re not advocating for the use of supplements alone to treat or prevent COVID 19.
- Adequate hygiene through proper handwashing specifically with soap and water along with reducing touching your face, nose, and eyes have been shown to slow the spread of this disease and we strongly encourage continuing with those practices.
- Don’t forget about stress management, healthy relationships, time in nature, having fun, and sleep for immune system support.
- Vitamin D doesn’t make you immune to COVID-19, and believing so could be dangerous.
- It’s also very important to keep in mind that one nutrient is never a panacea.
We’ve concluded that a daily vitamin D supplement (especially if deficient) is a great way to support your immune system.
There are more clinical trials underway to assess the use of vitamin D in patients diagnosed with COVID-19, and we’ll have more detailed information from future research.
Check out our other blog post for our favorite supplements to keep your immune system functioning optimally!
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