No time to read!? Not thaaat interested in getting to know vitamin D “in depth”?! Then simply know and remember this one basic thing ::
Health Canada’s DRIs – Dietary Reference Intakes suggest daily intakes of 600IU of vitamin D for individuals aged 1 to 70. From that point, total goes up to 800IU for older adults. Any dose higher than these reference values should be evaluated by a health care professional.
There! These are the numbers that should cover the needs of the majority of healthy individuals who don’t have the opportunity to expose their skin to the sun sufficiently.
These suggested values represent a sufficient amount for most but not necessarily an optimal one for all. Individualising these suggestions should be considered, but in order to do that, I’m afraid you’ll have to keep reading and/or meet up with a health specialist who can give you the blabla and save you the reading. 😉
Vitamin D :: the what and the how?
There are 2 basic rules that define a “vitamin” ::
- It is essential to reactions in the body
- The body cannot produce it itself
Following this logic, one could argue vitamin D is either an exception or a labelling glitch; it’s actually most accurately described as a steroïd/ cholesterol based hormone.
Its production within the human organism, just like cholesterol’s, is absolutely possible; vitamin D is synthesized in the skin when it is exposed to UVB rays.
The sunshine vitamin comes in 2 forms ::
- D2 :: ergocalciferol
- D3 :: cholécalciferol
*If you are curious about all the pathways and structures involved in endogenous vitamin D production, read this piece :: ” Human body; a vitamin D production plant“.
Vitamin D’s main job is to regulate calcium and phosphate levels circulating in the body. Simply put, it has the power to boost these minerals’ absorption in the intestinal tract AND can release them from their storage organs, mainly, the skeleton.
It is estimated that vitamin D regulates more than 2 000 genes. Its receptors can be found in ALL tissues of the body, including the brain; thus, suggesting that its action goes far beyond mineral regulation. Adequate intakes of this vitamin seem to be linked to greater longevity1.
Main source
- RESPONSIBLE exposition to the sun’s rays
While the sun’s rays have been demonized for a while now, I reckon it’s time to give them back the level of recognition they deserve.
Having full trust in the omniscience of Nature, I find it impossible to believe it would have elaborated such a complex and masterful mechanism of “in-house” production of vitamin D via the sun’s energy only to have us avoid sunbeams at all costs.
The sun is a FREE source of vitamin D and contrary to external supplementation, it plays harmoniously with our own self-regulating mechanisms.
*Bonus, sunlight has the power to replenish our CoQ10 stores; an antioxidant our cells use for growth and repair. It also acts favorably on blood pressure and arterial function by liberating a substance, nitric oxide, which is present in the blood stream after ingestion of nitrite/nitrate containing foods. Dark leafy greens and beetroot are great precursors of this phenomenon.
Emphasis should be placed on the fact the SUN’s rays are able to do all this, NOT isolated vitamin D supplementation2,3. Supplementation is not a bad idea, it simply should be done with a certain level of restraint and not be your only option and source of any nutrient.
Safely taking advantage of the sun’s rays
- Therapeutic UV exposition should not be done between the hours of 10am and 4pm.
During these “high sun” hours, all public health recommendations should be followed :: hat, sunglasses, sun protection in the form of SPF30 minimum sunscreen and/or protective clothing4.
Photoaging, increased incidence of cataracts, damages to our DNA and skin cancers linked to IRRESPONSABLE sun exposure are not questioned here.
It is critical that we approach the sun’s beneficial and vitalizing rays in a judicious and parsimonious way.
A great (and dead simple!) indicator of UV rays’ strength is the following :: if your shadow is taller than your actual height, then sun protection might not be necessary. Once this ratio is equal or reversed and your shadow becomes shorter than you :: protection becomes mandatory5.
- In Canada, on average, 10 to 25 minutes/ day of sun exposure without protection during the months representing spring and summer are sufficient to obtain adequat amounts of vitamin D.
Aspects influencing time of exposure ::
- Skin colour :: darker skin typically requires more time
- Age :: the older we get, the more time we need
- Exposed surface area :: the more covered we are, logically the more time we need to allow sufficient production
In winter, considering roughly 10% of our bodies are exposed (face and possibly hands), required time in the sun goes up ::
- At 10 :00 –> 9.7hrs would be necessary
- At 16 :00 –> 5.7hrs would be necessary
The sun’s angle simply isn’t conducive to the production of significant amounts of the sunshine vitamin. These values being impossible to achieve, supplementation in localities north of latitude 37′, during the months representing winter, is very much suggested6,7,8.
Therapeutic exposition to the sun’s energy should not serve as a tanning tool. For those of us who enjoy a little tan ::
It is worth noting that regular consumption of carotenoids (dark leafy greens and orange hued fruits and veg) allows the body to create a similar pigmentation from within. Turns out it even is, apparently!?, even more attractive than its “sunbaking” counterpart.
Going full on “rotisserie chicken” mode in the sun for hours on end is guaranteed to bring about trouble in the long run. Smoothie drinking and enhanced physical fitness both actually offer increased vitality and a healthier glow which is just as attractive, if not more!, as skin damaging, overdone sun worshipping9,9A,9B.
Sources, D3 ::
- Fish
- Haddock :: chunks, 1 cup/ 136g – 32IU
- Cod :: chunks, 1 cup/ 136g – 63IU
- Eel :: chunks, 1 cup/ 136g – 572IU
- Salmon :: chunks, 1 cup/ 136g – 473IU
- Tuna (Albacore) :: chunks, 1 cup/ 136g – 109IU
- Calve’s liver :: cooked, 136g – 234IU
- Egg yolk :: 2 large, cooked – 72IU
- D3 fortified products :: produced from lanolin (Extracted from sheep’s wool)
- Microalgae that has been exposed to UV :: found in some vegan supplements
- Lichen :: found in some vegan supplements
Sources, D2 ::
- Certain mushrooms
Vitamin D concentration is conditional to UV exposure10 :: UV fungi are generally clearly identified on their label. Certain companies also offer UV treated, D2 rich, mushroom powder for culinary purposes. Mushrooms that are grown with standard “in-the-dark” processes are NOT a significant source of D2.
- Portobello UV, raw :: 1 cup, diced/ 86g – 976IU
- Cremini UV, raw :: 1 cup, diced/ 72g – 919IU
- White button mushrooms, raw :: 1 cup, sliced/ 70g – 732IU
- Fortified products or supplements enriched with a type of yeast (Saccharomyces cerevisiae) that has been exposed to UV light.
**While the D2 type, from food or supplements, has been shown to contribute to the elevation and maintenance of vitamin D levels in the body; the D3 form is thought to offer a slightly better efficacy when supplement forms are compared. Luckily, D3 supplements on the market today come from various sources. Omnis and vegans can find a suitable D3 product to suit their needs and ethics11.
Precautions
Certain foods that are rich in D are also highly concentrated in vitamin A. This vitamin, when ingested in excess, is associated with an increased risk of prostate cancer, cardiovascular disease and has shown deleterious effects in neurodegenerative conditions such as Alzheimer‘s and Parkinson‘s disease12.
A great example is cod liver oil :: each tablespoon will exceed both vitamin D and A recommended intakes. 1 tbsp represents 1 360IU of vitamin D (which is high but still below the maximal tolerated daily intake of 4 000IU) and 13 600IU of preformed vitamin A (Tolerable upper intake level :: 10 000IU!!). A daily consumption of such a food will quickly “pile on the excess” to your detriment.
An excessive intake of vitamin A is thought to disturb mitochondrial function and structure; mitochondria are the body’s tiny energy plants. Hair loss and/ or diarrhea are common signs of excessive intake of vitamin A.
People suffering from Williams Beuren syndrome or infantile idiopathic hypercalcemia both present anomalies in their regulation of calcium and vitamin D. They should definitely consult their doctors before supplementing either of these nutrients13.
Risks of exagerrated intakes
Vitamin D is a fat soluble substance; just like vitamins E and A, it is best absorbed and assimilated in the presence of fats and oils.
Unlike water soluble nutrients which can be excreted in urine when the body has more than it knows what to do with; excess vitamin D intakes end up being stored in the fatty tissue of our bodies where it accumulates.
Exaggerated intake of vitamin D supplements, and the saturation of our fat cells, can result in a blood level exceeding the upper limit of 150nmol/L. This (avoidable) imbalance can lead to an overabundance of calcium in the body, calcification of tissues and calcium deposits in tissues where it does not belong and dehydration.
Dietary intake and responsible sun exposure are the best ways to fulfill the body’s needs while avoiding deleterious effects.
Superfluous vitamin D in the body can translate into the following signs :: confusion, apathy/ lethargy, vomiting, abdominal pain, frequent urination and thirst that is intense and difficult to quench (polyuria/ polydipsia). Note :: redundant over supplementation of vitamin D during long periods of time could increase certain cancer risks (pancreas, breast, prostate) and all-cause mortality 14,15.
Sub-optimal intakes and associated risks
- Demineralisation of bones and increased risk of fracture
- While establishing a distinction between sun exposure and adequate vitamin D levels might not always be obvious or even feasible, links between inadequate vitamin D levels and certain conditions and discomforts have been suggested and are presently being studied16 ::
- In growing children and adolescents, rickets is to be kept in mind :: the condition is linked to poor bone quality characterised by osteomalacia (soft bones) and osteoporosis (fragile bones). It is tightly linked to a mineralisation deficit of the skeleton.
Specific needs
- Menopausal women
- Young children :: breastfeeding women should shave their vitamin D tested, support its adequate concentration and should consider a source of supplementation for their infant/ child.
- Obese individuals :: vitamin D having such a strong affinity for adipose tissue, it could end up being sequestered in fat cells before it can meet the receptors that are responsible for its activation.
- Inversely, an obese individual on a weight loss journey could see their vitamin D level naturally rise as fat (and the stored vitamin D within it!) is released from storage. Supplementation in this case would be futile.
- Elderly population :: diminished renal function, decreased presence of precursors within the skin, limited sun exposure and reduced appetite can all impact vitamin D intake and assimilation.
- Dark skinned individuals :: the important presence of pigments in the skin makes photoproduction of vitamin D a touch more difficult.
- Individuals with conditions that make the digestion of fat difficult such as those diagnosed with Crohn‘s or celiac disease. Vitamin D’s absorption being linked to presence of fat in the diet, optimal absorption might be compromised.
- Persons taking glucocorticoid type medication (prednisolone/ prednisone, hydrocortisone…) should consult their doctors and evaluate their needs to avoid glucocorticoid induced osteoporosis.
- People suffering from known malabsorption issues should also consult with their medical doctors to evaluate their needs.
While evaluating vitamin D needs, the following elements should be kept in mind ::
- Country of residence’s latitude. Montréal is located at latitude 45’, and therefore follows general sun exposure guidelines referring to latitudes comprised between 40’ and 50’.
- Time of year :: from April to October, the sun’s angle is favorable to adequate cutaneous production of vitamin D. From November to March however, people residing north of the 37e parallel should consider supplementing their diet19.
- Lifestyle and time spent outdoors during months when endogenous production is possible.
- Skin color :: the lighter the skin, the easier the internal production, the smaller the needs.
- Age :: as skin atrophies with time’s passing, vitamin D production becomes less and less efficient. Absorption through diet also decreases with age20.
- Actual consumption of “natural” and fortified vitamin D sources.
- Vitality of organs involved in vitamin D activation :: liver and kidneys. A diagnosed pathology of either of these structures requires medical advice. Naturopathy can most definitely tag along as a vitality support and prevention of function decline modality.
- Integrity of parathyroid glands regulating PTH hormone. A diagnosed pathology of these structures requires medical advice. Naturopathy can most definitely tag along as a vitality support and prevention of function decline modality.
- Bone density and all lifestyle and dietary factors that could influence it.
- Obesity21
- Other supplements being taken regularly. Ex. :: isolated calcium supplementation could lead to kidney stones.
One has to remain smart, educated and somewhat timid when considering supplementation :: it is NOT a panacea. Numerous studies have attempted to link “vitamin D supplementation and healing properties” and could not put forth a strong correlation.
Vitamin D is first and foremost and prevention tool and “more” most definitely is not automatically linked with “better”.
Blood tests
*Blood tests are prescribed and interpreted by medical doctors. Total vitamin D can be included in blood tests, all you have to do is ask.
Reference values ::
- 75 to 150nmol/L is considered ideal.
- 50 to 74nmol/L reads as “insufficient”
- 50nmol/L or less, reads as a “deficiency”
As with most things related to health, this one blood value is not enough to evaluate needs and actual state of vitality; other aspects must be investigated to round out the results.
*I think it is also worth mentionning that African tribes living an “ancestral lifestyle” have been studied in the context of vitamin D levels :: Massaii and Hadzabe tribes live a life that is very active, quasi nude and abundantly exposed to the sun year round at a latitude that is conducive to uninterrupted vitamin D production in the skin. This demographic presents average vitamin D levels around 115nmol/L. One could hypothesize this value to be what nature had in mind when it created human beings as self-regulating vitamin D production entities; we should therefore keep the door open to further studies that could define optimal levels closer to this figure in the futur22.
A few precisions on dosage, timing of ingestion and supplement choice
According to a study from the Journal of Bone and Mineral Research, most studied individuals achieve adequate vitamin D levels with a daily intake of 400 to 600IU for children and around 800IU for adults.
Data suggests that doses as high as 1000IU for children and 2000IU for adults (obviously depends on individual profiles) are well tolerated and safe for long term use in most cases23.
Taking a vitamin D supplement WITH the largest meal of the day seems to boost absorption24.
Dietary supplements are most definitely not all created equal. One should look for a lab that opts for third party testing to confirm the accurate concentration and quality of its product.
There we have it :: vitamin D in a nutshell!
A few studies have been linked throughout this article, get acquainted with the data if you wish to know more about this topic; this post is merely a quick and simplified intro into the subject.
Research papers are always a great way to approach a discussion with your health care provider, feel free to share them with yours if you think it would be useful in the evaluation of your specific needs and the enhancement of your vitality.
Stay curious and humble,
Be well,
Vicky x
Vicky Bachand ND.A is a naturopath :: a naturopath does NOT replace a medical doctor.
Ideas provided in this article are presented as information only and do not aim to provide in depth details about the chosen topic nor replace the advice of a qualified health care provider.
Information shared here does not constitute a consultation, a diagnosis nor a medical opinion and therefore should not be interpreted as such.
Always consult with your chosen health care provider if you have questions about your personal health.
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