I became intrigued with vitamin D when I heard Covid-19 patients who were deficient had increased mortality rates (1, 2, 3). This was enough to get my attention. I began researching the topic which took me down a rabbit hole that lasted many months.
Disclaimer: I am not a doctor or medical practitioner. These are my opinions and what I am doing for my own life. You should seek medical counsel before taking any medical advice, exercise suggestions, dietary advice, or before implementing any of my tips outlined in this post.
The more I read, the more I wondered why I had never been exposed to this information before. I had to go searching and scanned through more than 100 research papers looking for clues to better protect myself.
Why is it that we live in the greatest country in the world, but between 70 – 97 % of the population has insufficient vitamin D levels (4)?
Another study was done estimating the economic burden and premature deaths due to vitamin D deficiency in Canada. The researchers estimated that premature deaths could be reduced by 23,000 and the economic burden reduced by $12.5 billion due to disease reduction (5).
The reduction of diseases included cardiovascular disease, cancer, dementia, MS, osteoporosis, diabetes, and respiratory tract infections.
After saturating my brain with this information, I finally began to understand why I got so many colds every year. December would begin my yearly contraction of the cold virus which would usually last until the end of May. If I only knew that it may have only been vitamin D deficiency. It would have saved me a lot of discomfort.
While there are many benefits to having adequate vitamin D levels, the focus of this article is how it relates to the immune system for the aging adult.
What Is Vitamin D?
Vitamin D, commonly called the sunshine vitamin is a nutrient our bodies need for good health. It was first discovered as a cure for rickets, a debilitating bone disease in the early 1800’s.
For many years it was just recommended for good bone health, but recently, vitamin D is being recommended for many more health issues. Vitamin D receptors have been found in almost every cell of the human body.
There are three ways to obtain vitamin D: The body produces it by converting cholesterol in your skin when it absorbs the sun’s uvb rays, from supplements, and to a small extent from the absorption from foods.
Concern For Older Adults
In a study done on the role of vitamin D on the aging adult, the evidence indicates an association between low levels of vitamin D and diseases associated with aging. These diseases include cognitive decline, depression, osteoporosis, cardiovascular disease, hypertension, type 2 diabetes, and cancer (6).
Older adults don’t produce vitamin D as well due to a decrease in cholesterol in the skin. In fact, being greater than 50 years old is one of the risk factors for Vitamin D deficiency/ insufficiency (Table 1).
In a study on aging and vitamin D production from ultraviolet radiation, it was revealed that aging can decrease by greater than two-fold the capacity of the skin to produce vitamin D3 (7).
Vitamin D & The Immune System
Since vitamin D receptors are found on immune cells, they have the ability to regulate the immune response. Deficiency in vitamin D is associated with increased autoimmunity and an increased susceptibility to infection (8).
In a cohort study on 198 healthy adults over the fall and winter, it was found that people who had a vitamin D level of greater than 38 ng/ml (95 nmol/L) had a two-fold reduction in the risk of developing acute viral respiratory tract infections and with a marked reduction in the percentages of days ill (9).
Interesting to note, is that in Canada, the cut off for “normal” blood levels are > 50 nmol/L (10). This is almost half the levels found in the study above to reduce the risk of developing acute viral respiratory tract infections. Vitamin D recommendations in Canada are directed primarily at bone health, not immune health.
In another large study with 16,975 individuals, it was found that individuals had 56% higher odds of community-acquired pneumonia when vitamin D levels were less than 30 ng/ml (75nmol/L) (11).
Sources Of Vitamin D
Sun exposure
Sun exposure is by far the most important source of Vitamin D. Did you know that living at higher latitudes has an associated risk for many chronic diseases including autoimmune diseases, some cancers, cardiovascular disease, infectious disease, schizophrenia, and type 2 diabetes? This is all due to less vitamin D production in the skin (12).
Unfortunately, in Canada & Northern US, you absorb zero vitamin D from the sun in the winter (13).
A quick way to know if you’re getting any vitamin D from the sun is to look at your shadow. If your shadow is the same length as your height or shorter, you are absorbing vitamin D. If it’s longer, you’re not (14).
The other thing you should consider is sunscreen. It blocks the majority of UVB rays….. the rays needed for vitamin D synthesis in the skin (15).
An SPF 15 sunscreen filters out 93% of UVB rays, 97% from SPF 30, and 98% from SPF 50. The verdict is still out as to how much it blocks vitamin D production though and risk of developing skin cancer is also an important consideration (16).
The National Institute of Health recommends 5-30 minutes of sun between 10 a.m. and 4 p.m. at least twice a week on the face, arms, legs or back without sunscreen (17).
Food
The next source of vitamin D is from food.
However, there are only certain foods that contain a decent dose of vitamin D: cod liver oil (1,360 IU per tablespoon), fatty fish, eggs, fortified beverages and yogurts. Wild caught salmon is one of the best food sources of vitamin D and has a much higher concentration than the farmed variety.
Farmed salmon has only 25% of the vitamin D compared to wild caught. For comparison, a 3.5 oz serving of wild caught salmon has a mean concentration of vitamin D of 988 IU vs 240 IU from farmed salmon (18).
But really, how much salmon can you eat each week?
Eggs are another great source of vitamin D. Just like salmon, you get what you pay for. Free range and organic eggs have 42% higher concentration of vitamin D than conventional eggs (19).
For a complete list of food with vitamin D, see table 3 in the National Institute for Health fact sheet on vitamin D (NIH vitamin D fact sheet).
So, if you’re not getting enough vitamin D from your food or the sun, the next source is supplements.
Supplements
Just like wild salmon vs farmed salmon and organic eggs vs conventional eggs, you get what you pay for when it comes to supplements.
The costs of good quality foods and supplements is represented by the nutritional value of what you consume.
The challenge with buying supplements in North America is quality control and poor government regulations.
You may save money buying the cheapest vitamins, but if your body is not absorbing them or what’s written on the label is not what’s in the tablet, then in reality you could be paying more (20).
Why cheap out when it comes to your health and longevity? You have one body. Take good care of it.
I would recommend only buying supplements that are 3rd party certified to contain what’s listed on the ingredients label.
A typical multivitamin contains between 400 & 800 IU of vitamin D. How much of that is your body absorbing depends on the quality of the brand. Again, you get what you pay for.
Vitamin D Toxicity
The most common risk discussed when taking high levels of vitamin D is toxicity.
Vitamin D toxicity doesn’t happen from the sun or food, it happens from taking too many supplements.
Multiple studies have been done on patients with MS taking doses of vitamin D 20,000 IU per day for 12 weeks (21). None of the patients in this study suffered from side-effects.
Also another study published by the Dermato-Endocrinology journal evaluating D3 intakes up to 15,000 IU per day found no adverse side effects at this level (22).
Based on the above studies, the tolerable upper limit suggested by the current RDA’s seem a tad bit understated.
Nutrients To Take Along With Vitamin D
It would be great if you could just sit in the sun and all your problems would go a away. However, there is more to the vitamin D story.
If your trying to maximize the usage of stored vitamin D, make sure you are also monitoring your magnesium intake (23). Researchers found that low magnesium levels make vitamin D ineffective for 50% of Americans (24).
How much magnesium do you need? Current RDA for Magnesium is 420 mg for males and 320 for females.
You should easily be able to get this from your diet as there is ample magnesium in foods like bananas, spinach, dark chocolate, avocados, pumpkin seeds and tuna to name a few.
Vitamin K2 is another nutrient that should be taken with vitamin D (25). It’s important to be mindful of this nutrient especially if you are at the higher end vitamin D intake (26).
How much vitamin K2 do you need? If at least 32 mcg of vitamin K2 is present in the diet, then the risks for blood-vessel calcification and heart problems are significantly lowered (27).
Vitamin K2 can be found in foods like butter, lard, eggs, meat, fermented foods, natto or supplements.
How Much Should You Be Taking? RDA’s
And this is where it gets confusing.
The current recommended dietary allowance (RDA) in Canada for adults up to 70 years old is 600 IU per day up to a maximum of 4000 IU. (28)
However, In a study on vitamin D usage during the winter months, it was estimated healthy men use between 3000 – 5000 IU per day from stores from the sun obtained in the summer months (29).
So, how are your stores from the past summer? Did you get out much? If you did get out, was your body covered in sunscreen? If so, you may have stored very little of the sunshine vitamin.
The RDA in Canada has to do with minimum levels for bone health (blood level>_ 50 nmol/L is considered sufficient).
However, there is much debate on the clinical definition of vitamin D deficiency and what constitutes optimal levels.
The Canadian Government follows the recommendations from the US Institute of Medicine (IOM) at 600 IU per day up to a maximum of 4000 IU, but the Endocrine Society has the RDA set much higher at 1500 – 2000 IU per day for adults up to a maximum of 10,000 IU.
That’s crazy! A range of 600 IU per day to 10,000 IU per day (See table 1 from NCBI article on Vitamin D and MS).
In Canada, blood levels of vitamin D greater than 125 nmol/ L is “cause for concern”, but the endocrine society says levels between 100 – 150 nmol/ L is “ideal”.
So who should you listen to?
Apparently, the IOM sets their guideline focused on bone health only and the Endocrine Society RDA is based on skeletal and extra-skeletal effects of vitamin D.
Drug Interactions (Things that lower vitamin D absorption)
Another thing you should be aware of with vitamin D is certain prescription drugs and some herbs will adversely affect the metabolism of vitamin D.
Certain herbal medicines (St. John’s Wort & Kava Kava) and medications (Antibiotics, Anti-epileptics, Anti-neoplastic, Anti-Inflammatory agents, Anti-hypertensives, Anti-retroviral drugs, endocrine drugs) interfere with vitamin D metabolism and if you are taking them, you may need to monitor your vitamin D intake (30).
Recommended Course Of Action
I’ve covered a lot of information on vitamin D in this post. There seems to be much controversy as to the daily intake requirements.
One thing is certain. For most of the year in Canada and northern US, you should consider taking a vitamin D supplement as it is very challenging to get adequate levels of the nutrient from food alone.
Here is a great article from Consumer Reports on how to choose supplements wisely (consumerreports.org). If they are not certified by Consumer Labs, NSF International, UL or USP, you may not be getting what you paid for.
There are a lot of great brands that have certifications from the above institutions. If you want to know what brand I use, send me a message using the “contact me” form.
Summary And What’s Next
So, how much vitamin D do you really need? Well, there is much to consider in that question.
The purpose of this post was not to tell you how much you need, but to convey that you may need more than what you are currently taking. With some of the issues I uncovered, there are so many variables that will determine your needs.
You should seek medical counsel before going outside of the current guidelines.
For more information on vitamin D, watch the discussion below from Ivor Cummings “D is for Debacle”.
Further Study
D is for Debacle – Ivor Cummings
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