Real food supplements to support healthy functioning and to upgrade your health

*This page may contain affiliate links. We only recommend products and services that we have tried, trust and love. For more information, you can read our terms and conditions.

Which vitamin D supplement to use this winter

Most people know by now that taking a vitamin D supplement is a necessity for most people not living near the equator. However, there is much confusion of dosage and optimal form to use. I will dive into the best way for a safe and effective vitamin D supplementation for you in this short summary post.

Why do we even need to supplement? Our ancestors didn’t!

A question I get asked a lot is why we need to supplement, when our ancestors were just fine without it. Great question!

Our ancestors naturally adjusted their diets to include more foods with high vitamin D content during the winter months when sunshine is insufficient to generate enough vitamin D in the body. Some might remember their grandma handing them a spoon of the dreaded cod liver oil in winter, or having to eat liver paté. A lot of us don’t necessarily include these foods into our winter diet anymore, and hence most are lacking vitamin D. Even during summer most patients I see have vitamin D levels well below optimal, due to their indoors lifestyle combined with use of sunscreen and fear of sun damage.

  • Lack of sun exposure such as during winter or working indoors, especially people living in latitudes >34° north or south (S).
  • Fear of sun rays and excessive use of sunscreen.
  • Low intake of foods high in vitamin D such as liver, fatty fish (salmon), cheese, egg yolks.
  • Malabsorption conditions such as inflammatory bowel disease, celiac disease, and chronic diarrhea (S).

But what’s the big deal with vitamin D anyhow?

Vitamin D is sometimes called the ‘sunshine vitamin’ because it’s produced in your skin in response to sunlight.

Your body produces vitamin D naturally when it’s directly exposed to sunlight. You can also get it through certain foods. Vitamin D is fat soluble.

Vitamin D has several important functions. The one that gets the most press in conventional medicine is its vital role in regulating the absorption of calcium and phosphorus. Getting a sufficient amount of vitamin D is important for normal growth and development of bones and teeth.

If your body doesn’t get enough vitamin D, you’re at risk of developing bone abnormalities such as soft bones (osteomalacia) or fragile bones (osteoporosis).

However, there is so much more to it:

  1. Immune system: It is essential for a balanced immune system in the way that it calms the immune system if overactive (such as in autoimmune disease) and boosts its function if too low (such as in cancers and infections such as the flu). Vitamin D is a neurohormone that tells dividing cells to stop dividing (which contributes to its anti-cancer effect). Studies have shown that patients with Multiple Sclerosis (an autoimmune condition affecting the nervous system) has been associated with vitamin D deficiency (S) and has a higher prevalence in countries with less sunshine (S).
  2. Mood disorders: There has been research examining the relationship of vitamin D to seasonal affective disorder (SAD), schizophrenia, and depression (S).
  3. Hormone health, sex life & libido: Vitamin D levels have been linked to sex hormone levels such as testosterone, estrogen, their precursor DHEA and sex hormone binding globulin which influences how much estrogen and testosterone is available (S). Low sex hormone levels are associated with lower libido and sex life. Increasing vitamin D to optimal levels has been shown to increase hormones and may be just what you need to start spending more time back in the sheets with your partner.

The best assessment of vitamin D is by a serum 25-hyroxyvitamin D (25-OH D) level (S). Vitamin D deficiency is defined as a level less than 20 ng/mL and vitamin D insufficiency is a level less than 30 ng/ml. However, for optimal health, levels of 50-80 ng/ml or 125-200 nmol/l may be more adequate. The normal upper limit has been considered to be 55 to 60 ng/ml, but is being re-evaluated as levels up to 125 ng/dl have been reported without adverse effects (S). This means, that even if your test results come back as ‘normal’ from your doctor’s, you may in fact still have below optimal levels which can contribute subtly to the above problems. Even more so if you have a SNP (genetic ‘polymorphism’ or better known as a ‘mutation’) in your vitamin D receptor genes. If you have one of these fairly common genetic variants, the vitamin D you have circulating in your body may have trouble getting into your cells to do its job, and you may in fact really need to make sure that your vitamin D levels are at the high end of the optimal range to prevent detrimental health effects.

So what is the best way to supplement this important vitamin?

The majority of vitamin D formulations available on the market in the form of tablets, capsules or sachets are conventional fat-soluble preparations. However, vitamin D being a non-polar lipid that has low solubility in the fluids of the gastrointestinal tract it demonstrates poor bioavailability. To improve bioavailability, nanoemulsions such as liposomal vitamin D preparations have recently been developed and have started entering the market. These nanoemulsions are considered superior to conventional vitamin D preparations for the following reasons: 

  1. They have better absorption rates, which may be particularly important for people with malabsorption syndromes such as inflammatory bowel disease, celiac disease, short bowel syndrome, hepatobiliary disorders, pancreatic insufficiency and bariatric surgery
  2. Better compliance as the are liquid and can be taken directly (poured onto a teaspoon) or with water/juice etc. No need to swallow a pill.
  3. Vitamin D nanoemulsions may also have also greater hepato-protective effect against high fat diet induced liver injury as observed in rats compared to conventional oral vitamin D preparations.

What is a good dosage of vitamin D supplementation?

Older studies have suggested a range of 400–1,000 IU/day for adults, yet newer research suggests that to achieve an optimal level it may even have to be as high as 4,000 or 5,000 IU/day for some (S).

Risk factors associated with high dose vitamin D supplementation

However, it is important to add in vitamin K2 if supplementing vitamin D at the higher doses to prevent potential less wished for side effects. Vitamin D enhances absorption of calcium, which usually is a good thing. However, if this is coupled with low vitamin K2 levels, the body might not know where to put this calcium, with associated problems like irregular heart rhythms (S), joint and kidney problems. We need vitamin K2 to tell that calcium where to go.

Supplementation should be coupled with appropriate supervision and monitoring. Ideally you test your vitamin D but also calcium, and potentially your parathyroid hormone from time to time and discuss your results with an experienced Functional Medicine practitioner.

I personally like the Vitamin D with K2 from Lipolife. I generally recommend taking up to 4 droppers per day (4000 IU) for adults during winter, in addition to the small amounts (400-1000 IU) that are generally found in good quality multivitamins. Another option is a similar one by Superself which only requires one dropper to get the full dosage, or the easy spray version by BetterYou.

Let me know your experience with vitamin D in the comments below!

Picture of Mirthe


It is my goal to empower you to become the CEO of your health trajectory, preventing and optimising with precision and science backed strategies to live your best life & thrive.

Leave a Reply

Your email address will not be published. Required fields are marked *



It is my goal to empower you to become the CEO of your health trajectory, preventing and optimising with precision and science backed strategies to live your best life & thrive.

Let's Connect!
Blog Categories
Get your FREE
Ebook on How to get rid of your muffin top - for good
To Download your free ebook

12 tricks to beat the bloat and get rid of that muffin top for good - and why it matters in the long run