The days are full of sunshine and they are definitely longer than ever. That said, the sun’s rays are good for more than just your mood. They also have an affect on your body by helping synthesize vitamin D, known as the sunshine vitamin. | By Hubert Cormier, Nutritionist
It got this name because the sun’s ultraviolet (UV) rays allow our bodies to make vitamin D reserves. It’s also present in our daily diet, but is there enough vitamin D in our food to cover our needs, or is a little sunbathing required?
A “real” vitamin?
Vitamin D is incorrectly called a “vitamin.” Its role is more that of a hormone. In fact, in its active form, it’s called “calcitriol,” and it’s in this form that most of the effects attributed to it occur. This vitamin has long been associated with bone health because it enables the absorption of calcium in your body. It is involved in bone metabolism and is believed to prevent osteomalacia, a condition that precedes the development of osteoporosis.
However, this association with skeletal diseases and the risk of falls (and thus the risk of fractures) has been a source of heated debate within the scientific community for a few years. Vitamin D supplements might not have the desired effect on bone health. Luckily, new research has attributed several important roles to it, most notably in the prevention of cardiovascular disease and certain cancers, including colorectal cancer.
The 42nd parallel
In Canada, we are disadvantaged by our geographic location since most of our cities are north of the 42nd parallel. This leads to a lack of sunlight from October to April. For that reason, you are much more likely to experience a vitamin D deficiency in the winter, but other factors also play a role. These include skin pigmentation, the time of day, the use of sunscreen and the percentage of your body that is exposed to the sun.
Vitamin D on the menu
There are very few dietary sources of vitamin D. That’s why you should not rely exclusively on diet to meet your vitamin D needs, especially when you consider that UV rays are responsible for 80 to 90% of vitamin D in the body.
Vitamin D is found in oily fish like salmon, cod and mackerel. You can always buy fish liver oil, which is one of the best dietary sources. Also, in Canada, enriched organic and regular milk, margarine and soy milk provide considerable quantities of vitamin D. It is also found in certain green vegetables, mushrooms and egg yolks, while cheese and yogurt made from enriched milk may contain small quantities.
In short, you have to really like winter to live in Canada! Given that it’s a Nordic country where the latitude means that we might suffer from vitamin D deficiency from October to March, a supplement is basically a must during this period. Plus, vitamin D is a super antioxidant! It is rarely advisable to meet daily vitamin recommendations through supplements, but since vitamin D recommendations are very high, and some experts believe they should be even higher, diet is not sufficient. A supplement of at least 10 micrograms (400 UI) could be useful year-round and especially during the winter, combined with a healthy, varied diet that includes dietary sources of vitamin D.
How much vitamin D do I need?
Recommendations have recently changed and practically tripled. Therefore, adults should take 15 micrograms (600 UI) of vitamin D every day. For reference, a 250 ml glass of milk contains only 3 micrograms (120 UI) of this vitamin. For people over 50, doctors recommend taking a supplement of 10 micrograms (400 UI) year-round to meet recommendations. Finally, for people over 70, the recommendations are a little higher at 20 micrograms (800 UI). Since vitamin D synthesis becomes less effective as we age, the recommended dose is higher for this demographic.