Vitamin D3 is produced in our skin with the help of sunlight. In our latitudes, the sun is low for much of the year and our skin does not get enough sun.
We can also get D3 from food, especially oily fish. Dairy products are often fortified with D3. Vegetarian diets contain virtually no D3.
Therefore, D3 supplementation is usually needed, at least from September through April.
D3 has many important functions in the body, perhaps the best known being to increase the absorption of Ca (calcium) and thus contribute to strong bones and teeth.
D3 is also essential for a strong immune system and cell function, and for the body’s energy metabolism by helping to produce the hormone thyroxine (thyroid).
In addition to weak bones and teeth, deficiencies can lead to a weakened immune system, fatigue, depression, numbness in arms and legs, muscle aches and cramps, and general bone and joint pain.
D3 is a fat-soluble vitamin that is stored in the body and if we sunbathe a lot during the summer, we can survive well into the fall.
The amount most of us take in through food is negligible.
According to several researchers, including physician Mats Humble, supplements of at least 2,500 IU or more per day should be taken.
Our supplement is 5000 IU, which is high. If you want to reduce the dose, you take every other day or a shock dose of 3-4 capsules once a week, which works well as it is stored.