Few are the supplements that medical professionals recommend out of hand! Vitamin D is an exception. Considering the few food sources and the long winter months, taking a vitamin D supplement is often encouraged! Update on this sunshine vitamin!
Vitamin D is essential for bone health, as it facilitates the absorption of calcium and helps it be deposited in the bones. It is also useful for the proper functioning of the immune system, muscles and nerves.
In summer, the body produces this vitamin under the action of UVB rays from the sun. However, between the months of October and March, the radiation is insufficient to meet the body’s needs. It is therefore necessary to resort to diet and supplementation.
What are the vitamin D requirements?
Vitamin D requirements vary according to the age of individuals.
For children and adults 9 to 70 years old, the recommended amount is 600 international units (IU) or 15 micrograms (μg) per day.
For adults over 70, the recommended amount increases to 800 IU or 20 μg per day. These amounts include vitamin D from foods and supplements.
Vitamin D and diet
In terms of food, few foods naturally contain vitamin D. It is mainly found in fatty fish, such as salmon and sardines, egg yolks and certain mushrooms. On the other hand, there are products enriched with vitamin D, such as cow’s milk, vegetable drinks (eg: soy) and certain yogurts. The table below lists the best sources of vitamin D.
Why take a vitamin D supplement?
As few foods contain vitamin D and winter radiation is not sufficient to meet the body’s needs, it is very likely that a supplement will be necessary. In fact, Health Canada recommends that adults over the age of 50 take a supplement of 400 IU (10 μg) of vitamin D every day. As we age, the body also synthesizes less vitamin D. When exposed to the same light radiation, a 70-year-old person will produce 75% less vitamin D than a 20-year-old person. Dark-skinned people also naturally produce less vitamin D when exposed to the sun.
Osteoporosis Canada recommends that people over 50 and high-risk young adults (with osteoporosis, multiple fractures, or living with a condition that inhibits vitamin D absorption) consume between 800 and 2,000 IU per day. As for the Canadian Cancer Society, based on the protective role of vitamin D in relation to certain cancers (colon and breast in particular), it recommends taking 1000 IU per day. Not everyone metabolizes vitamin D in the same way, it is advisable to do a blood test to assess your circulating vitamin D and ensure that the level exceeds 50 nmol/L. This desired plasma level is mainly based on bone health, several experts recommend concentrations equal to or greater than 75 nmol/L considering the role of vitamin D in the prevention of several diseases. To achieve the desired target, it is preferable to give daily doses of vitamin D rather than intermittent high doses (once a week for example).
Which supplement to choose?
Vitamin D supplements come in two different forms: vitamin D2, or ergocalciferol, and vitamin D3, or cholecalciferol. Both of these vitamins are well absorbed from the gut, but most scientific evidence indicates that vitamin D3 further increases serum levels (i.e. blood concentration) of this vitamin and maintains higher levels longer than vitamin D2.
Note that several multivitamin and mineral supplements already contain vitamin D (between 400 and 800 IU depending on the brand).
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