How much vitamin D should you take all year round?

Vitamin D is called the ‘sunshine vitamin’ because our skin creates vitamin D when it is exposed to sunlight. Unfortunately for people living in Canada, the northern United States or anywhere in the world above the 37th parallel, the right kind of sunlight needed is only available 4-6 months a year (roughly May/June through September/October).

Vitamin D is vital because it helps you maintain normal levels of calcium by increasing absorption in your intestines. Since calcium is so important in maintaining health bones, without enough vitamin D, you are much more likely to develop osteoporosis.

Low vitamin D levels have also been associated with multiple sclerosis, rheumatoid arthritis, diabetes high blood pressure, cardiovascular disease, some cancers an even infections such as COVID-19. More research is needed to prove these links but they are certainly intriguing.

Vitamin D is found in very small quantities in foods such as egg yolks, cheese, cod liver oil, beef liver and fatty fish like tuna, salmon, sardines, herring and mackerel. In North America, foods such as milk, cereal, yogurt and orange juice are fortified with vitamin D. However, even with fortified foods, it is difficult to obtain enough vitamin D through diet alone.

Health conditions that affect the stomach or intestines can decrease the absorption of vitamin D. While your skin does produce vitamin D with sun exposure, if you regularly wear sunscreen or have darker skin, you also may not produce enough vitamin D.

While the daily recommended amount of vitamin D varies from 400-600 IUs a day, this is likely not enough for most people living above the 37th parallel. Perhaps this is why the Endocrine Society recommends up to 1,000 IUs per day for children and up to 1,500 to 2,000 IU of vitamin D daily for most adults adults.

If you have darker skin, a BMI of more than 27 or are over the age of 70, I recommend taking 2,000-3,000 IUs a day of either vitamin D3 or vitamin D2 (if you are vegetarian). Because you can overdose on vitamin D, the maximum recommended amount per day is 4,000 IUs a day for most people.

While some government and insurance plans may not cover a test for vitamin D level (for example OHIP in Ontario does not), I do think that it is worth having this level checked once a year to make sure you are keeping your level in the right range.

If you have ongoing health concerns or a chronic health condition, talk to your doctor before you begin taking any dietary supplement as he or she understands your specific conditions and can give you more customized advice.