Vitamin D and MS

What is vitamin D and how is it related to MS?

Vitamin D is a fat-soluble essential nutrient that is produced when your skin is exposed to the sun. It can also be taken as a supplement or absorbed from foods such as oily fish, egg yolks, and vitamin D-fortified dairy products.  

It plays many important functions in the body to maintain health and prevent disease.  Vitamin D deficiency is a known risk factor for multiple sclerosis.

What does vitamin D do for the body?

  • Vitamin D builds and maintains strong bones 
  • It has a role in the body’s immune (defense) system, and heart and brain health 
  • Vitamin D may be involved in the function of the placenta during pregnancy 
  • It may also play a role in how sugars are broken down by the body

Vitamin D Recommendations

How much vitamin D do you need every day?

The table below lists the 2024 Health Canada recommendations for daily intake of vitamin D. The recommended amount is given in International Units (IU), which is a standardized measure used for some vitamins.

Age group

Recommended daily intake

Maximum daily intake

Infants 0 – 6 months old

400 IU

1000 IU

Infants 7 – 12 months old

400 IU

1500 IU

Children 1 – 3 years old

600 IU

2500 IU

Children 4 – 8 years old

600 IU

3000 IU

Children and adults 9 – 70 years old

600 IU

4000 IU

Adults >70 years old

800 IU

4000 IU

Pregnant and breastfeeding women

600 IU

4000 IU

If you have MS or have a relative with MS, how much vitamin D do you need?

Canadians at risk of developing MS and those living with MS are encouraged to follow Health Canada recommendations for daily vitamin D. Your doctor may recommend taking higher levels of vitamin D if you have MS, to get your levels to the optimal range.

If you have a sibling, parent, or child with the disease, you are considered at higher risk of developing MS. Other factors contributing to an increased risk of developing MS include smoking and obesity. 

Can you take too much vitamin D?

  • Up to 4000 IU per day of vitamin D supplements can be taken without the guidance of a doctor unless you have certain medical conditions.  
  • Taking too much vitamin D from supplements can lead to a build-up of calcium in your blood (called hypercalcemia). This condition can cause nausea and vomiting, weakness, and frequent urination, and might progress to bone pain and kidney problems. 
  • Supplements taken as directed and up to 4000 IU per day for adults would not lead to toxicity. This is not intended as medical guidance, so it is recommended that you speak with your healthcare provider about the appropriate levels of vitamin D to take.
  • Your doctor may give you more than 4000 IU per day of vitamin D if you have MS and very low vitamin D levels in your blood, to get your levels to the optimal range.
  • If you are taking more than 4000 IU per day your vitamin D levels may be monitored by your doctor. 

Is vitamin D a treatment for MS?

  • Vitamin D deficiency is a known risk factor in the development of MS and other chronic diseases. MS is believed to be caused by a combination of genetic and environmental factors.
    • Therefore, everyone can decrease their chances of developing MS by making sure they are getting enough vitamin D every day by following Health Canada recommendations.
  • Vitamin D is not an effective treatment for MS. 
    • Vitamin D supplements should not be taken instead of a disease-modifying therapy. It can be taken safely in combination with a disease-modifying therapy. Consult your healthcare provider before starting any new medication or supplement. 
  • MS may increase the risk of falls, bone fractures, and developing osteoporosis. 
    • Taking vitamin D supplements to meet the recommended daily intake can keep bones healthy and maintain overall health. 

How do you get vitamin D?

Exposure to the sun:  

  • The skin makes vitamin D when it is exposed to ultraviolet rays from the sun.
  • It’s still important to practice safe sun exposure and use sunscreen to protect against the risk of skin cancer.  The time required to make sufficient vitamin D is less than the amount of time needed for skin to redden and burn. 
  • Vitamin D produced in the skin from sun exposure does not lead to harmful levels of vitamin D. 


  • Fatty fish such as salmon, trout, sardines, and mackerel 
  • Egg yolks
  • Vitamin D-fortified foods including cow’s milk, margarine, and some types of plant-based beverages like orange juice and almond milk


Vitamin D supplements come in 2 forms:

  • Vitamin D3 (cholecalciferol) – a type of vitamin D made by the skin following sun exposure, and supplements. 
  • Vitamin D2 (ergocalciferol) – a plant-based type of vitamin D that is often used in dairy-free milk, and supplements.

Cod liver oil supplements containing vitamin D is another option. Because it may also contain vitamin A at levels higher than the Health Canada recommended daily intake, consult a doctor about its benefits and safety.

How should you take vitamin D supplements?

  • Supplements and fortified foods should ideally be taken with a meal that is high in healthy fats.
  • Vitamin D can dissolve in fats and oils, so this can help the body absorb more of the vitamin (try avocadoes, nuts, fatty fish, and extra virgin olive oil).
  • Vitamin D can be taken at any time. The amount of vitamin D absorbed by the body does not change depending on the time of day it is taken.

How do you know if you have the right levels of vitamin D in the body? 

You can estimate the total amount of vitamin D a person gets based on the food they eat and the supplements they take. However, a true picture of vitamin D levels is determined by a blood test.  Vitamin D testing is advisable, but not essential.

  • Blood levels of vitamin D are measured as the number of nanomoles (nmol) of 25-hydroxyvitamin D per liter of blood (nmol/L). 
  • The optimal level of 25-hydroxyvitamin D in the blood ranges from 50-125 nmol/L.  
  • Provinces and territories do not generally cover the cost of vitamin D tests for the general public or those living with multiple sclerosis, but please consult with your healthcare provider. 

What if I have other health conditions in addition to MS?

Be sure to speak with your healthcare team. People with certain medical conditions, such as kidney disease, parathyroid disease, and endocrine malignancies should consult their doctor before taking vitamin D supplements.  

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