Vitamin D recommendations outlined in the Institute of Medicine’s Dietary Reference Intakes (DRI) report aim to help people maintain good bone health.1 This is based on the evidence that vitamin D is required along with calcium for skeletal health throughout life. Too little vitamin D can cause blood levels of calcium and phosphorus to decrease which leads to calcium being pulled out of the bones to maintain blood levels within the normal range.2 Sufficient vitamin D is required to prevent rickets in children, and osteoporosis and fractures in older adults.2,3
In practice
Cow’s milk is fortified with vitamin D and is a reliable food source of this vitamin in Canada. Food sources like cow’s milk and fatty fish can help Canadians meet their daily vitamin D needs for bone health.
- Cow’s milk is an excellent source of vitamin D and is the main source of vitamin D in the Canadian diet.2
- Fatty fish and egg yolks are the only natural sources of vitamin D in the Canadian diet.2
- Drinking 2 cups (500 mL) of cow’s milk a day and eating fatty fish such as salmon, mackerel, tuna or sardines makes a good contribution to vitamin D intakes.
- Everyone over the age of 50 should also take a daily vitamin D supplement of 400 IU.
Recommended daily vitamin D intakes
The DRI report outlines recommended daily vitamin D intakes for different age groups as Recommended Dietary Allowances (RDAs) as shown in the table below.1 The Institute of Medicine set the RDA for people between 1 and 70 years of age at 600 IU (15 mcg) of vitamin D per day. This includes pregnant and lactating women. Adults over 70 years of age need 800 IU (20 mcg) of vitamin D daily.
| Age Group | Recommended Dietary Allowances (RDAs) |
| Children 1 to 8 years | 600 IU (15 mcg)/day |
| Children 9 to 13 years | 600 IU (15 mcg)/day |
| Teens 14 to 18 years | 600 IU (15 mcg)/day |
| Adults 19 to 70 years | 600 IU (15 mcg)/day |
| Adults > 70 years | 800 IU (20 mcg)/day |
| Pregnant women | 600 IU (15 mcg)/day |
| Lactating women | 600 IU (15 mcg)/day |
The RDAs for vitamin D were established based on the assumption of minimal sun exposure. Although our bodies can make vitamin D when exposed to the sun’s ultraviolet (UV) rays, this doesn’t occur for about half the year in Canada, due to our Northern latitudes. Many factors affect the amount of UV radiation received and vitamin D synthesis in addition to the season, darker skin pigmentation, sunscreen use, cloud cover, smog and time of day.
Milk is a major dietary source of vitamin D
Cow’s milk is a major dietary source of vitamin D in Canada.2 Fatty fish and egg yolks are the only natural sources of vitamin D in the Canadian food supply.2 That’s why in Canada, cow’s milk must be fortified with vitamin D according to national regulations to help Canadians meet their vitamin D needs.2
Vitamin D is a nutrient of concern in Canada
According to Health Canada, many Canadians do not meet their requirements for vitamin D from food sources.4 Almost all adults have inadequate intakes of vitamin D from foods, below their Estimate Average requirements, including 98% of women and 94% of men.5 In addition, a national analysis of blood levels of vitamin D showed that about one third of Canadians (32%) had levels below 50 nmol/L, the cut-off considered sufficient for healthy bones.6
Drinking 2 cups (500 mL) of milk a day and eating fatty fish can go a long way towards helping Canadians meet their vitamin D needs. In addition, because there are so few food sources of vitamin D and exposure to the sun’s UV rays is limited, Health Canada recommends that adults 50 years of age and older also take a daily vitamin D supplement of 400 IU (10 mcg).2
Beyond bone health
Although the Institute of Medicine's recommendations for vitamin D is based on levels needed to build and maintain bone health, vitamin D plays many other functions.1,2,6,7 Vitamin D also plays an important role in supporting immune health.7,8 Some research also suggests that adequate vitamin D levels may lower the risk of certain cancers, cardiovascular disease and multiple sclerosis; however, more research is needed to better understand these areas.1,2,7,9
Discover the differences between vitamin D3 and D2 here.
References
1. Institute of Medicine. Dietary Reference Intakes for calcium and vitamin D. Washington, DC: National Academy Press, 2011.
2. Health Canada. 2020. Vitamin D and calcium: Updated Dietary Reference Intakes. www.canada.ca. Accessed June 25, 2021.
3. Weaver CM et al. The National Osteoporosis Foundation’s position statement on peak bone mass development and lifestyle factors: A systematic review and implementation recommendations. Osteoporos Int 2016;27:1281-1386.
4. Health Canada. Evidence review for dietary guidance: Summary of results and implications for Canada’s Food Guide. Ottawa, Ontario: Health Canada. 2016.
5. Ahmed M et al. Nutrient intakes of Canadian adults: results from the Canadian Community Health Survey (CCHS)-2015 Public Use Microdata File. Am J Clin Nutr 2021;nqab143. Online ahead of print.
6. Janz T and Pearson C. Health at a glance: vitamin D blood levels of Canadians. Statistics Canada, 2013; catalogue no. 82-624-X.
7. National Institutes of Health. 2021. Vitamin D. Fact sheet for health professionals. www.ods.od.nih.gov. Accessed June 28, 2021.
8. Calder PC et al. Optimal nutritional status for a well-functioning immune system is an important factor to protect against viral infections. Nutrients 2020;12:1181.
9. Sintzel MB et al. Vitamin D and multiple Sclerosis: A comprehensive review. Neurol Ther 2018;7:59-85.
