What is Vitamin D?
Vitamin D is a fat-soluble vitamin that is naturally present in fatty fish, beef liver, cheese and egg yolks. Vitamin D is also found in fortified dairy products, orange juice, soy milk, and cereals. Vitamin D is nicknamed the “sunshine vitamin” because our bodies are capable of producing it when our skin is exposed to UVB rays from the sun.
What does Vitamin D do?
The human body must have vitamin D to absorb calcium and maintain adequate levels of phosphorus in the blood, two factors that are extremely important for maintaining healthy bones. Too little vitamin D results in soft bones in children (rickets) and fragile, misshapen bones in adults (osteomalacia). Vitamin D also plays an essential role in muscle function and the immune system.
Vitamin D deficiency has been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, weight gain and other maladies.
How Much Vitamin D Do You Need?
Vitamin D dosage recommendations are not a one-size-fits-all recommendation because the body requires different amounts of vitamin D at different stages of life.
There are the age-based recommended daily allowance (RDA) amounts for vitamin D given by the National Institute of Medicine:
- Infants– 400 IU, or 10 mcg per day.
- Children and Teenagers – 600 IU, or 15 mcg per day.
- Adults– 600 IU, or 15 mcg per day.
- Elderly (Over Age 70) – 800 IU, or 20 mcg per day.
However, people living in northern climates may require greater vitamin D intakes. Osteoporosis Canada advises healthy adults aged 19-50 to consume a 400-1,000 IU vitamin D supplement daily. Those over 50, or younger adults at high risk, should use a supplement containing 800-2,000 IU daily.
The tolerable upper limit of vitamin D is 4000IU per day, meaning that you can safely supplement with up to 4000IU per day without experiencing any adverse side effects.
Why Are Vitamin D Supplements Important for Canadians?
In Canada, we don’t get enough sunlight to produce adequate vitamin D. Further, the skin’s ability to make vitamin D decreases as we age. There are also very few food sources of vitamin D, making it nearly impossible for adults to get sufficient vitamin D from diet alone. Therefore, Osteoporosis Canada recommends vitamin D supplementation for Canadian adults year-round.
Other factors that can lead to vitamin D deficiency
- Age – The skin’s ability to make vitamin D decreases with age.
- Mobility– People who are homebound or are rarely outside (e.g. in nursing homes) rarely get sun exposure.
- Skin color– Dark-colored skin makes less vitamin D than fair-colored skin.
- Human breast milk– Breast milk only contains a small amount of vitamin D. Infants who are not regularly exposured to sunlight are at risk for not receiving enough vitamin D.
Vitamin D Supplements
The recommended supplemental form of vitamin D is vitamin D3 or cholecalciferol. This is the natural form of vitamin D that your body makes from sunlight.
Vitamin D supplements are available to purchase as capsules, tablets, oral spray or drops. Read supplement labels carefully because there is variation in quality between the different forms. Most people find that an oral spray is the most convenient for the whole family (swallowing capsules can be difficult for many). Also, some doctors recommend the oral spray because it is more easily absorbed and utilized by the body.
Food Sources of Vitamin D
| Food | Serving Size | IU’s per Serving |
| Swordfish, Baked or Broiled | 75 g | 761 |
| Salmon, pink, Canned, Drained with solids and bones | 75 g | 435 |
| Cod Liver Oil | 5 mL/1 tsp | 426 |
| Salmon (Sockeye), Baked or Broiled | 75 g | 394 |
| Snapper, Baked or Broiled | 75 g | 392 |
| Milk (all types) | 1 c/250 mL | 103-105 |
| Soy Beverage, Enriched | 1 c/250 mL | 86 |
| Yogurt, Plain, Vitamin D Added | 175 g | 82-113 |
| Egg Yolk, cooked | 2 Large | 64 |
| Tuna, canned in water, drained unsalted | 75 g | 60 |
| Orange Juice, Fortified | 1/2 c/125 mL | 50 |
| Margarine, fortified | 5 mL/1 tsp | 25-36 |
| Mushrooms, white | 125 mL/ 1/2 c | 4 |
Source: Canadian Nutrient File April 2017