Vitamin D #FoodFacts

As we transition from the sunny summer days to the cozy fall evenings, this #vitamin is always a hot topic- ESPECIALLY these days with so much immunity talk going around! With the changing seasons, this time of year can be really hard for some people – especially those that experience seasonal depression, struggle with low immunity or suffer from skin irritations such as eczema, acne and psoriasis. So how can Vitamin D help with this?


#FunFact, Vitamin D is actually more like a hormone than a vitamin! Yup, a hormone! This may be one of the reasons why we feel extra sensitive or moody when the sun slowly starts to fade away and our Vitamin D levels start to slowly drop. The production of Vitamin D is actually quite fascinating and important to know when understanding why we need it, why getting a variety of different forms is important and why it requires more whole-body participation than any other vitamin!

The process starts with the skin. When UV (ultraviolet) light from the sun contacts the skin cells, 7-dehydrocholesterol (a form of CHOLESTEROL) interacts with the sunlight to create cholecalciferol (a from of Vitamin D). This is then transferred to the liver or kidneys to be converted into a storage form of Vitamin D called calcidiol. When the body needs Vit D, the calcidiol stored in the liver must be sent to the kidneys using a special protein called DBP (Alpha-2 globulin vitamin D binding protein- see below why this is essential for absorption) to deliver. Once there, the kidneys then convert it into the most fully active form of Vitamin D, called calcitriol or more commonly known as Vitamin D3.

Because plants do not have cholesterol (which is the initial building block for Vitamin D3), they produce a different but similar steroid molecule called ergostrerol, also known as Vitamin D2. The plants absorb and utilize D2 similarly to how we do however, because they lack the cholesterol base, it does not have all of the same functions as D3. For this reason, Vitamin D2 sources (generally plants, some supplements and the synthetic/fortified version added back to certain milks, cereals, etc.) are not considered the most desirable form of supplementation as they cannot be converted in the body to the fully active form of D3 (found naturally in animal-derived forms, some supplements or direct contact with the sun).


Vitamin D is a fat-soluble vitamin meaning when it is ingested, it is absorbed with other fats and can be stored in the body’s fatty tissue. For optimal absorption, consider consuming your fat-soluble vitamins with other healthy fats- either through diet or supplementation.


Vitamin D naturally boosts the immune system to reduce levels of inflammation throughout the body as well as strengthening skin barriers. This vitamin can have such a strong effect on the skin- especially skin irritations (sometimes good, sometimes bad- see toxicity below) as they are generally a reflection of inflammation somewhere in the body. Whether its digestive, stress, trauma, environmental, etc. if there are imbalances with the body, the inflammation caused by that stress can sometimes appear in symptoms such as eczema, acne, psoriasis, etc.

Vitamin D also contains antimicrobial properties. For this reason, if you experience irritations that may be caused by bacterial overgrowth on the skin (such as not cleansing yourself/clothing properly, swimming in unsafe water, experiencing an acute skin reaction, etc.) using topical vitamin D could also help.

Some other important functions and uses are:

    • Vitamin D is essential in maintaining and regulating bone formation (specifically by helping absorb the main bone minerals; calcium and phosphorus). If D levels are low, blood levels of calcium and phosphorous decrease meaning the body will pull these minerals from the bones if necessary. This creates demineralized, weak bones as well as severely affecting the heart and nervous systems which may result in diseases such as rickets, osteomalacia and perhaps even heart issues and anxiety/depression.
    • Influences the bodies use of minerals such as: increasing the absorption of calcium- not only in the bones but also in the gut (which is interesting when you look at the gut-brain connection and the link between serotonin.. see below!), helps put minerals into the teeth/bones and helping maintain normal blood levels of calcium/phosphorus.
      • Cardiovascular health- especially heart function and blood clotting
      • Immunity and optimal immune health- taking Vitamin D with A has been shown in some studies to reduce the incidence of colds
      • Reduce inflammation and help control infections
      • Bone, teeth and skin health
      • Assisting in hormone regulation & endocrine health
      • Helpful in maintaining the nervous system
      • Works closely with the parathyroid gland/hormone
      • Reduce cancer cell growth
      • May help with: diabetes, allergies, cataracts, visual problems, sciatica pain, skin issues, muscle spasms, anxiety/depression, arthritis, menopause/hot flashes, joint health, hypocalcemia, rickets, crohns, chronic pain and more


As we know, there are a variety of factors that can affect our production and absorption of valuable nutrients. A few of these we can control and some, we can only work with. Here are a few topics to be mindful of:

    • Weather: Wintertime, clouds, fog, etc. can effect the strength and levels of UV absorbed from the sun- both by us and plants! However, you can STILL absorb the D even on those cloudy days- just not as much 🙂
    • Environment: proximity to the equator, smog, smoke, working at night, living in care home facilities, etc. can effect the strength and levels of UV absorbed from the sun. Those that are closer to the equator will have access to the hot sun longer throughout the year than those that are farther away however those that are in the city with more toxins, smog or environmental disruptions may not absorb as much as those that are closer to nature with minimal toxins/smog! Likewise, those that do shift work or work more in the evening/inside as opposed to in the day/outside will naturally absorb less.
    • Pigment: darkly pigmented skin is also known to reduce the body’s production of Vitamin D. This is because Vitamin D synthesis is highly dependent on the concentration of melanin in the skin.  Melanin absorbs and scatters UVR-B, resulting in a less efficient conversion to D3. Therefore, dark-skinned individuals will experience slower vitamin D synthesis than light-skinned ones.
    • DBP (Alpha-2 globulin vitamin D binding protein): referring back to the production of this vitamin, DBP is made by the liver specifically to carry vitamin D around the bloodstream. Therefore, if there is a lack of DBP or malformation then vitamin D deficiency may be a result. This is also a main reason to get your levels properly tested to ensure your body is absorbing and using the Vitamin D you’re intaking efficiently!
    • Sources: depending on the source (from the sun, through diet or supplementation) your body may not be utilizing or absorbing Vitamin D properly. One way to know is to get your levels tested, watch for signs of deficiency (or even toxicity) and ensuring you are getting adequate amounts of all types. For women experiencing menopausal symptoms or absorption issues it is sometimes recommended to take a supplemental version of Vitamin D along with vitamin A, calcium, magnesium and perhaps phosphorus if necessary to help with hot flashes, endocrine and bone health.

“D, David Hanley, MD at the University of Calgary in Alberta, Canada, has concluded that virtually 100% of all Canadians are Vitamin D deficient during some part of the year when sunlight exposure is scarce.” – Elson M. Haas, MD

WHAT TO LOOK FOR in supplements

Although there are plenty of forms of Vitamin D there are two that we mainly pay attention to: Vitamin D3 and D2. As we know, our skin can absorb D and eventually convert it into D3 so that our bodies can properly utilize it. Because of this, D3 is usually the form most people take as it is considered the most available, active form.

As we know, vitamin D is essential for bone health which is why it is sometimes suggested to take a supplement version of D3 with K2. This is because K2 helps ensure the calcium transported by the D is absorbed directly to your bones where it’s needed, rather than accumulating as deposits in your arteries (which is a real thing that no one wants!). Using a liquid supplement is often my go-to suggestion for D because:

      • it’s a fat-soluble vitamin so consuming it with an oil/fat is generally best
      • liquid supplements generally absorb faster and are easier to manage for dosing- especially with kids/children (easy to hide in smoothies, etc!)
      • they stay fresh and shelf-stable for a long period and are usually processed minimally with quality in mind

Depending on where your levels are at will determine how much you will need and what type would be best suitable for you. It’s best to discuss with your doctor and get your levels checked first before choosing a supplement. Supplementation amounts vary greatly depending on each person and each season. For that reason, each person’s RDA (recommended daily amount) will change daily however, this is the AI (adequate intake) recommended by the government of Canada:

The DRIs for vitamin D
Age group Recommended Dietary Allowance (RDA) per day Tolerable Upper Intake Level (UL) per day
Infants 0-6 months 400 IU  (10 mcg) 1000 IU (25 mcg)
Infants 7-12 months 400 IU  (10 mcg) 1500 IU (38 mcg)
Children 1-3 years 600 IU (15 mcg) 2500 IU (63 mcg)
Children 4-8 years 600 IU (15 mcg) 3000 IU (75 mcg)
Children and Adults
9-70 years
600 IU (15 mcg) 4000 IU (100 mcg)
Adults > 70 years 800 IU (20 mcg) 4000 IU (100 mcg)
Pregnancy & Lactation 600 IU (15 mcg) 4000 IU (100 mcg)
Adequate Intake rather than Recommended Dietary Allowance.

Again, it’s important to note that most people will require MORE than what is suggested as most of us ARE deficient! Work with your Doctor to find what is best for you but some examples are:

      • Myself: I will take 1000IU – 3000IU every other day during the summer months here in Canada and about 3000IU – 5000IU every other day during the winter/other months (I don’t generally take it EVERY day because I am out in nature A LOT and have a nutrient dense diet).
      • Case Study: was able to take a minimum of 5000IU – 8000IU per day depending on the season as recommended by her naturopath and doctor to help with a variety of severe diseases. This would NOT be long term but extremely effective for short term.

“Vitamin D lowers one kind of inflammation, which has been linked to suicide. Many parts of the brain, including those involved with depression, contain receptors for Vitamin D. It may increase the available serotonin, the way the SSRIs do.” – Psychology Today


As we know, our beautiful SUN is one of the best ways to absorb Vitamin D (however, stay SUN SAFE with these tips!) but as we also know, it is not the only way! Some other high sources of Vitamin D are:

      • Sun Lamps or Infrared – if you are unable to get access to fresh natural sunlight and supplementing is hard right now, try using a sun lamp or infrared lamp/sauna to help mimic the sun! Although this does not work for everyone and it isn’t proven to help increase D levels, it can help to improve mood, mitochondria function and overall health which my help give you the motivation to supplement or try food sources such as:
      • Runny YOLKS from free-range eggs – PLEASE eat the whole egg and keep the yolks runny! The egg yolks contain the highest nutrient level of the entire egg and are extremely sensitive to heat – cooking the yolk completely can damage and reduce the level of nutrients in the egg.
      • Wild Fish & Seafood – especially salmon and the small fishies like sardines, mackerel and herring.
      • BUTTER – keep it local, free-range and/or grass-fed for best quality. Fat is usually where toxins are stored in us and animals so happy safe dairy products are ideal when buying butter!
      • WILD MUSHROOMS – these awesome guys can absorb AND store Vitamin D and are the only plants that we know of that have some forms of D3! Opt for wild or medicinal types such as shiitakes, oyster, chanterelles, portobellos, turkey tails, chaga, lions mane, reishi….
      • Fish liver oil – specifically cod liver. I know, it’s gross. But extremely effective! Not only is it high in Vitamin D3 it’s also super high in Vitamin A (see my first #FoodFacts post on this), essential fatty acids and sooo much more! You can also buy them in capsule form 🙂
Deficiency & TOXICITY

Symptoms of vitamin D deficiency are hard to pin-point as they can be associated with a lot of other issues. However, some deficiency signs may be:

      • muscle weakness/aches/cramps
      • joint and bone pain
      • mood changes, fatigue, anxiety and depression
      • brittle bones and teeth
      • skin issues or irritations

Although toxicity is generally not a concern for most people when discussing Vitamin D (aside from prolonged exposure which can result in heat-stroke!!), it is something worth noting, specifically when referring to supplementation. The reason being that products fortified with D2 (especially milk) are a synthetic, irradiated version of D and may have negative side effects. Although it was originally added to help with things such as rickets, they may be contributing to the calcification of the arteries from infancy through old age. An example of why would be: the added 400IU per quart of milk is about 15 x the amount normally found in milk which may increase calcium circulation. Some signs of toxicity may be:

      • excessive thirst
      • diarrhea
      • nausea
      • weakness
      • headaches

As always, work with your health care providers (naturopath, doctor, holistic nutritionist, etc.) to ensure you are using the right supplements for your body.

If you have any questions or comments, leave them below or send me a message!



With love,
Heidi MacAulay, R.H.N.
“Eat more plants. Do more yoga. Read more books.”
Learn more about me, my credentials or how to work with me here!

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