Many people are aware that Vitamin D is important for many body functions such as bone health, immune system strengthening, and regulation of calcium and phosphorus levels in the body. However, did you know that scientists are researching how it may be helpful in preventing certain types of cancer, particularly colorectal and breast cancers?

The Canadian Cancer Society states that “there is evidence that vitamin D may reduce the risk of some types of cancer, particularly colorectal and breast cancers.” This news is especially important for Canadians with our long winters which cause many people to hibernate in their cozy living rooms, away from the cold – and direct sunlight.

40% of Canadians Lack Vitamin D in Winter

Many Canadians are aware that vitamin D is a critical nutrient, but few people know that vitamin D deficiency is a significant concern, especially in the winter months. In the winter, the angle of the sun is low, resulting in fewer UVB rays that can penetrate the atmosphere and reach the earth.

Furthermore, in Canada, the sun’s rays are too weak to generate vitamin D synthesis in the skin between October and April. As a result, about 40% of Canadians have been found to be below the cut-off in winter, compared with 25% in the summer.

Does Vitamin D Help With Cancer Prevention?

Studies have shown that vitamin D may play an essential role in reducing the risk of certain types of cancer, particularly colorectal and breast cancers. In fact, some studies have found that people with higher levels of vitamin D in their blood had a lower risk of developing these cancers than those with lower levels however the research has yet to conclude that Vitamin D directly contributes to cancer prevention.

Early researchers were intrigued that incidence and death rates for certain cancers were lower among individuals living in southern latitudes, where levels of sunlight exposure are relatively high, than among those living at northern latitudes.

Because exposure to ultraviolet light from sunlight leads to the production of vitamin D, researchers investigated whether variations in vitamin D levels might account for this association. Later studies suggest that Vitamin D does not directly contribute to the prevention of cancer and that studies previously conducted can only highlight associations, not prove cause and effect.

Researchers, continue to study how Vitamin D may slow down or prevent the growth of cancer cells, looking at how the vitamin may help the body remove old, damaged cells, thereby reducing the risk of cancer growth. Additionally, vitamin D may also promote the differentiation of cancer cells into healthy cells, reducing the risk of cancer development.

How to Get Vitamin D

There are several ways to get vitamin D, including through nutrition, sun exposure, and supplements.


Foods high in vitamin D include fatty fish like salmon and tuna, egg yolks, and fortified dairy products. However, it is challenging to get enough vitamin D through food alone, especially during the winter months.

Preparing food in a certain way may affect vitamin D levels. For example, when cooking salmon, grilling, and broiling result in higher vitamin D levels than baking or frying. Steaming or boiling mushrooms for a short period may also increase vitamin D levels.

The Sun

The body naturally produces vitamin D when the skin is exposed to sunlight. However, the amount of vitamin D produced depends on several factors, such as skin tone, time of day, season, and geographic location. To ensure adequate vitamin D levels, individuals should aim to get about 10-15 minutes of sun exposure on their face, arms, and legs several times per week during the summer months. However, it’s essential to protect your skin from the sun’s harmful UV rays by wearing sunscreen and protective clothing.


If you cannot get enough vitamin D through nutrition or sun exposure, taking a supplement is an option. There are two types of vitamin D supplements: D2 (ergocalciferol) and D3 (cholecalciferol). Research suggests that D3 is more effective in raising vitamin D levels in the body. It is essential to talk to your doctor before taking any supplements to determine the appropriate dosage for your individual needs.

Vitamin D Dosage

The recommended daily intake of vitamin D varies by age, sex, and other factors.

Vitamin D is essential for overall health, but how much should Canadians be taking daily? According to Health Canada, the recommended daily intake of vitamin D for adults is 600 to 4000 IU per day, depending on age and gender. For children, the recommendation is 600 to 2000 IU per day, and pregnant or breastfeeding women require 600 to 4000 IU per day.

During the winter months when sunlight exposure is limited, Canadians may need to increase their vitamin D intake through supplements or fortified foods. However, it’s important to speak to a healthcare professional before taking any supplements, as too much vitamin D can be harmful.

For children, vitamin D is especially important for bone health and development. Infants who are breastfed exclusively may require a vitamin D supplement, as breast milk may not provide enough vitamin D. Children over the age of one can get their vitamin D through food sources such as fortified milk or fatty fish.

Women also have specific vitamin D requirements. Pregnant and breastfeeding women need adequate amounts of vitamin D to support their own health and the development of their babies. Perimenopausal and menopausal women may also benefit from vitamin D supplementation, as it can help maintain bone health during this time of hormonal change.

To ensure that you are getting enough vitamin D, it’s important to talk to your family doctor and get yourself tested to find out your current vitamin D levels. This will help determine if you need to increase your intake through supplements or fortified foods. Remember, too much or too little vitamin D can have negative effects on your health, so it’s important to find the right balance.

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