Dear Readers,
This week’s question comes from my friend Midhun. He texted me to ask about Vitamin D and how much he should be taking. He then looked up the government of Canada’s recommended dietary allowance (RDA) and didn’t understand the dichotomy. He texted me back to confirm the amount I recommended. Then texted me an exacerbated, “Are you trying to kill me?!”
So, while I’ve written about Vitamin D in the past and it’s a nutrient that’s received a lot of press in recent years, it’s really important - especially this time of year in Canada - to understand what is optimal. In fact, health policy makers and researchers in Canada have been sounding the alarm about inadequate vitamin D levels for years.
Canadian Researchers Sound the Alarm
When I was a student at the Institute of Nutrition in 2010-2011, I recall stumbling on research from Reinhold Vieth , a professor at the University of Toronto’s Department of Nutritional Sciences, Department of Laboratory Medicine and Pathology, also with The Department of Pathology and Laboratory Medicine at Toronto’s Mount Sinai Hospital. Vieth is a global authority on the role of vitamin D on human health and ran a clinic out of the hospital that offered early blood testing for vitamin D levels. Even then, Vieth was calling for radically increased RDAs. In 2010 the University of Toronto Magazine published an article featuring Dr. Vieth warning of a health crisis for dark-skinned Canadians. In the article he said,
I think everybody would benefit from taking vitamin D supplements in the winter. There’s no harm in taking 2,000 units. For a dark-skinned person it’s appropriate to take more than that, but no one’s telling them to.
In light of the very well documented link between low serum vitamin D and poor Covid-19 outcomes1 and the racial disparity of poor Covid-19 outcomes in America2 (which I explore in another blog post), Vieth’s 2010 predictions seem eerily prophetic.
Another Canadian researcher has been calling for increases, too. In her April 2015 research paper titled D-FENCE AGAINST THE CANADIAN WINTER: MAKING INSUFFICIENT VITAMIN D LEVELS A HIGHER PRIORITY FOR PUBLIC HEALTH (doc attached), published in the University of Calgary’s The School of Public Policy Journal, Jennifer D. Zwicker writes:
Increasing vitamin D intake should be considered a public health priority. Vitamin D deficiency is known to be linked to rickets in children and osteomalacia in adults (bone softening and malformation) as well as osteoporosis (loss of bone density, increasing susceptibility to fractures). However, a growing body of evidence also suggests that vitamin D may have a role in the prevention of chronic diseases such as heart disease, high blood pressure, diabetes, cancer, cognitive decline, Parkinson’s disease, multiple sclerosis and arthritis.3
Why the Concern?
The reason she and others are concerned and why we’re so low in vitamin D is our latitude. Canada simply does not get enough sun in the winter months to provide sufficient vitamin D levels, even if the weather were such that we could suntan! We are too far from the equator. This is exacerbated in those with darker skin tones, because they need more UV rays to synthesize the same amount of vitamin D. The melanin in the skin (what creates skin colour) acts as a barrier to too much vitamin D synthesis. In those who natively live close to the equator, darker skin helps them withstand more sun. Fair skin tones in people who are native to northern latitudes help them more readily synthesize vitamin D from the sun. People native to northern latitudes have lighter skin, which synthesizes vitamin D more readily from the sun. It’s unknown to what degree that contributes to the increase in health issues in immigrant populations to northern latitudes. However, we know immigrants in Canada/ the U.S. are at particular risk of lower vitamin D.4
Policy Makers Don’t Want to Listen
In October 1999, Health Canada published a document titled Proposed Policy Recommendations: Addition of Vitamins and Minerals to Foods, which laid out the intentions to review nutrient recommendations in collaboration with researchers from the United States and to create united dietary recommendations going forward, as well as how to determine the guidelines for adding vitamins and minerals to foods. You can read the document here. The complete updated dietary reference intakes can be found here.
The revised recommendation for vitamin D for adults under the age of 70 is 15ug, which translates to 600 IU. If you’ve read anything about vitamin D for the last oh, say 15 years, you are probably scratching your head right now and looking for your bottle of vitamin D.
It’s not your memory. The recommendations are woefully inadequate according to independent researchers. The official justifications for this can be read here, with toxicity concerns cited as a limiting factor.
In 2006, in frustration over the official recommendations, Professor Vieth published a review of vitamin D research5 and concluded that studies show 10,000 IU a day are safe and there is a lack of evidence that amounts lower than 20,000 IU could be toxic. He points out that sunbathing for 20 minutes at noon raises levels equal to 10,000 IU. He gets to what I think is the heart of the issue:
Like it or not, boards that specify a UL (upper limit) should address the implications to stakeholders affected by it. My own interest relates to research, and the problem there is that the UL for vitamin D determines the allowable dosage to be used in clinical studies. There are several examples of this. In theory, the UL is based upon knowledge gained through research. However, there is something terribly wrong when the UL has determined, and continues to determine, dosages used in the very research the UL is supposed to be based upon.
What he’s saying is creating upper limits (UL) that are arbitrarily low, rather than based on the actual data that exists, creates barriers to researching therapeutic levels. Research funding committees don’t want to fund research above the UL and research ethics committees mandate additional monitoring for researching anything higher than the UL, which creates additional cost, further limiting research. The problem with vitamin D research right now is that while it clearly demonstrates that vitamin D deficiency / insufficiency correlates strongly to disease and mortality, studies on supplementation don’t show the expected reversal in disease prevalence. What’s going on here?
Well, first, by formally endorsing the notion that anything above 2000 IU per day is toxic when in fact 10 times that dose has to be taken to be toxic for the majority of the population, nobody is able to research higher levels to determine if they show promise in disease prevention. This seems to be Vieth’s frustration.
Another perspective - and I fall into this camp - is that it’s possible that supplementing with vitamin D does not do for us what sunlight exposure does. We know sunlight is responsible for far more than just vitamin D, including regulation of the circadian rhythm, signalling nitric oxide release (important for blood pressure and tone of the blood vessels), and expression of adrenocorticotropic hormone and other stress and hormone modulating factors6 . It’s possible that there are components or pathways in UV exposure that we don’t understand yet. I cover this in more depth in another article.
I suspect it may have something to do with conflicts of interest related to lobby and special interest groups. The process of dietary recommendations impacts agriculture and food companies, as well as pharmaceutical companies on the other end. It’s naive in today’s political climate to think otherwise.
Moreover, to increase the dietary RDI for vitamin D would be to endorse more fatty fish, organ meat, and eggs (yolk specifically).7 You can see why that’s problematic for policy makers in today’s political climate around meat. For more on this issue, you can follow the work of science journalist Nina Teicholz. A former vegetarian who decided to do a deep dive into nutrition policy around fat, which changed her diet and the trajectory of her career, she addresses the issue head on in her article “The scientific report guiding the US dietary guidelines: is it scientific?” The article was featured in the British Medical Journal and can be found online here. Teicholz has subsequently created a non-partisan, non-profit organization called The Nutrition Coalition to lobby the government to focus on research when revising their dietary guidelines.
What is vitamin D and how do you get it?
Well, for starters, it’s technically not even a vitamin. And it’s not singular. It’s a group of hormone precursors, very similar in structure to steroid molecules. The most important players in this group (as we currently understand it) are vitamins D2 (ergocalciferol) and D3 (cholecalciferol). So it’s more accurately called a hormone than a vitamin.
This hormone is so essential for our health that we have a built in mechanism to ensure we get enough, irrespective of dietary intake. It’s manufactured by our bodies when our skin is exposed to UV rays (specifically the UVB rays) from the sun. This synthesis requires our own cholesterol and activation by our liver and kidneys. (Yes, cholesterol is essential in this process!) It’s unique among vitamins, not only because we generate it from the sun, but also because every cell in our bodies has a vitamin D receptor, which has the ability to impact the expression of our genes. This is science we are just starting to understand, but it indicates this little hormone is essential in a way no other nutrient is.
I’m going to repeat that for emphasis:
This little hormone is essential in a way no other nutrient is.
Animal foods are the best source of vitamin D3, but dietary consumption alone is not enough to reach optimal levels and the animal’s diet impacts the amount of vitamin D it stores. However, the form of the vitamin in animal products may be more potent than previously realized. Consider this quote from the National Institutes of Health fact sheet on vitamin D:
The impact of this form on vitamin D status is an emerging area of research. Studies show that 25(OH)D appears to be approximately five times more potent than the parent vitamin for raising serum 25(OH)D concentrations [17,20,21]. One study found that when the 25(OH)D content of beef, pork, chicken, turkey, and eggs is taken into account, the total amount of vitamin D in the food is 2 to 18 times higher than the amount in the parent vitamin alone, depending on the food [20].
Vitamin D is present in certain fish, fish oils, liver, and quality egg yolks, quality butter, and - dare I speak it - raw, whole fat milk from grass fed cattle. I mention this because raw milk contains every known fat and water soluble vitamin, all 18 fatty acids, and multiple enzymes and probiotics to aid digestion - all of which are almost completely destroyed by pasteurization. But selling raw milk is illegal in Canada so let’s do forget I said that and keep moving along.
We can get vitamin D2 from mushrooms that have been exposed to UV rays, fortified foods, and supplements. But many supplements do not contain the desired form of this hormone group for therapeutic value. We want D3. Many foods are supplemented with D2. You can check the label of your dairy and baby formula products to see which form of vitamin D they contain, and then take that with a grain of salt. According to this study published in the New England Journal of Medicine, we don’t really know how much vitamin D - or which form - is being added to our fortified products. Note that most of the infant formula tested contained 200x or more vitamin D than was on the label. With fortified foods it’s hard to know what exactly you’re getting, not only because of manufacturing oversight, but because nutrition labels are difficult to implement and regulate.8
What does vitamin D do?
Vitamin D is best known for its role in bone and dental health. Without adequate vitamin D children can develop rickets, and adults are at risk of premature bone aging and resulting fractures, as adequate vitamin D is needed for calcium, phosphate, and magnesium absorption and regulation9. It’s also important for neuromuscular function10 and inflammation11. Low levels of vitamin D in the bloodstream have been associated with a significant increase in death from many diseases, including cancers and heart disease12. Additionally, some research supports a link between vitamin D and mood and sleep, although this benefit may be linked to sunlight exposure as much as vitamin D levels13.
Vitamin D also helps keep abnormal cells from multiplying in breast and colon tissues. Isn’t it interesting how these cancers have proliferated since the campaign to push sunscreen? Vitamin D synthesis can’t happen in the presence of sunscreens with SPF 15 or higher. There is additional data to support that vitamin D deficiency increases our overall risk of cancer and our risk of melanoma, the deadliest type of skin cancer.
And What About Mental Health?
Dr. Cannell, MD is both a practicing psychiatrist and founder of The Vitamin D Council, which was a long running non-profit devoted to vitamin D education. In an 2018 interview with Dr. Eeks of bloomingwellness.com, Dr. Cannell stated:
What the literature supports is that people with mental illness have low Vitamin D levels. It’s true for depression, schizophrenia, autism and others. There was one study conducted by Rinehold Vieth involving endocrinology outpatients who were given 4000 units of Vitamin D for 6 months, and their feelings of wellbeing improved significantly. There aren’t a lot of randomized, controlled studies on Vitamin D and mental illness, so this leaves you with an option: to treat or not to treat. I don’t think we can wait for randomized studies. Say you have a schizophrenic patient with low Vitamin D levels. What do you do? The ethical thing to do is to treat the Vitamin D deficiency. Given what we know now about Vitamin D, we have an obligation to treat it in any psychiatric patient who is deficient.
How do you know you need it?
If you live in Canada in the winter it’s safe to say you’re not getting enough from the sun. And if you have brown skin or are vegetarian, you very likely need to supplement with more. Serum 25-hydroxyvitamin D [25(OH)D] testing is the best way to know your vitamin D status.
This gets tricky because different countries use different units of measurement. In Canada we use nmol/L. In the U.S. they use ng/mL. To convert ng/ml to nmol/L multiply the ng/ml by 2.5 for example 50 ng/ml is equivalent to 125 nmol/L.
Most experts agree that below 25-30nmol/L is deficient. There is debate about the optimal range, because, as noted above, the science is inconsistent on what level best reduces the correlation to disease while protecting against toxicity. Experts generally suggest between 50-75nmol/L. Before it’s dissolution, The Vitamin D Council suggested a target of 125nmol/L. These are all well below what is known to be toxic.
Certain populations are known to be more likely to be deficient in vitamin D and should be supplementing with the guidance of a professional and annual testing to determine blood levels. At risk populations include:
those over 65 - older skin often doesn’t produce as much vitamin D as it used to and the elderly are at risk for falls and fractures
those with darker skin tones
those with psychiatric issues
those who work indoors, wear sunscreen all the time, or cover much of their skin when outside
those who live in places where the sun’s rays are weaker and/or they don’t get as much exposure to the sun for good parts of the year
those who have a gastrointestinal condition like Crohn’s disease or celiac disease or who have bile issues (both important for vitamin D synthesis and uptake)
those who are vegetarian or vegan (animal products are the best sources of the active form of vitamin D if they don’t get enough sun exposure or supplement)
those who have severe kidney disease (the kidneys have to convert vitamin D to the active form)
those who have to avoid the sunlight for other medical reasons
those who do shift work
It’s estimated that in the U.S. up to 80% of adults are deficient in this key hormone, so in Canada you can amplify this.14
Are there any safety concerns?
Fat soluble supplements are stored in the tissues so they build up over time. As such, toxicity can develop if you are continually taking too much. That is less likely if you take D with vitamin A, as found in Cod Liver Oil. The vitamin A helps protect against toxicity. It’s best to have your physician test your levels annually as part of your check up. Testing once and not retesting is not enough!
If you supplement with vitamin D and feel unwell, or if your bone density is declining despite good 25(OH)D levels and calcium levels in the blood, it may be wise to check some other levels, as well. Testing parathyroid hormone, calcium, inactive (25-hydroxyvitamin D) and active vitamin D levels (1,25-dihydroxyvitamin D) together can help clinicians understand if there is a problem with the body robbing calcium from the bones to sequester enough for the blood. In this case your 25(OH)D levels seem great but bone density is not good and you are at higher risk of disease. In such a case, additional vitamin D supplementation is not a good thing. This is where you need a professional to guide you.
I also note that some clients can’t absorb fat soluble vitamins readily due to digestive/ hepatic issues and there are others with conversion issues due to renal disease (vitamin D is converted into the active form via the liver and kidneys). In these clients supplementing can be more complicated and I recommend seeing a professional like myself who understands how to repair or bypass this to keep your levels optimal.
What’s the best source?
When possible, it’s always best to get vitamin D from sunlight. Second to that oily fish and organ meat are best, but they don’t give us enough if we don’t get regular, direct sunlight. In the winter, unless we’re tanning, we need to supplement.
My preference when I do advise clients to supplement is to use quality, sustainable cod liver oil (CLO), as this is a whole food supplement with vitamins A and D (they work synergistically), as well as EPA and DHA omega 3s for maximal benefit. To this I often add 4,000 to 5,000 IU of vitamin D per day, depending on a client’s blood levels and symptomatology. If someone is particularly low I’ll go as high as 8,000 for a short time, then drop it when their blood level is optimal. It’s theorized that a good A:D ratio helps protect against vitamin D toxicity and I would agree with that. If things are packaged together in nature it’s usually for good reason. Add a daily dose of vitamin K2 in the form of Emu oil or natto and some magnesium and you have done more to protect your bones and teeth than almost anything else you can do!
My personal preference is vitamin D via tanning as opposed to D supplements, but I always take the CLO, K2, and Omegas. If I don’t tan (even when supplementing with D3) I notice the drop in energy and immunity over time, especially in winter months. I think studies in vitamin D should evolve to study the effects of natural broad spectrum sunlight on disease, but because it can’t be patented and sold (yet) I don’t think that’s likely anytime soon. I theorize there is a lot we don’t understand about the benefits of UV light. I think this is a huge part of why people are so happy and rejuvenated by trips to sunny destinations: the medicine in the sun’s rays!
Remember to take all your fat soluble vitamins (like these ones) with meals that contain some fat! This helps the fat emulsify and be absorbed by the body.
Thank you, Midhun, for the great question! As always, if readers have a health or nutrition related question, I welcome you to submit it in the forum. And if you’re looking for more specific health information check out my website at hopenotdope.ca, where you can contact me directly. I provide 1:1 mental health coaching and a variety of webinars online to help people better manage their mental health holistically. Stay safe and enjoy this wonderful snow!
Namaste!
Nonie Nutritionista
CNP, ROHP
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