Vitamin D is essential and indispensable for the proper functioning of the body. This vitamin granted largely by the sun, intervenes in the absorption of calcium and phosphorus from the intestines and by the kidneys. Despite the winter, we can compensate for the lack of sun by favoring certain foods.
We find the vitamin D necessary for our body when we offer our body a few rays of sunshine. But in winter, if you live in an area where greyness reigns, opt for a diet rich in vitamin D!
Where can I find vitamin D?
If you're in the sun this winter, stay there! Two exposures of fifteen to thirty minutes per week provide almost all of our body's daily vitamin D needs. More concretely, vitamin D allows calcitriol to form: this hormone is essential to fix calcium in the bones and thus make the skeleton robust. Its effects are numerous: bone mineralization, phosphocalcium metabolism, etc.
On the other hand, if you live in a country or region where sun appearances are more than rare from October to April, monitor your diet and that of family members to make sure that vitamin D needs are covered. Pregnant women and children must meet the needs of their bodies. Otherwise, beware of deficiencies that can promote the appearance of rickets.
Fish, a great ally
Among the foods richest in vitamin D is fish, but not just any. First on the podium, salmon. That's good, it is one of the favorite fish of the French, ahead of trout and cod. Be careful, however, the intake of vitamin D is more important when salmon is steamed than when it is grilled for example.
This is followed by canned mackerel, trout, sardines in oil, fresh or canned tuna (prefer light tuna with a lower mercury content than albacore tuna), herring, cooked eel, fish eggs in general (such as caviar if your wallet allows it), anchovies and oysters.
Liver and dairy products on the menu
The queen of foods (or food supplements) noticed by its rich content of vitamin D remains cod liver oil. A bad childhood memory for some, an invaluable discovery for others, cod liver oil contains 250 micrograms of vitamin D in a 100-gram serving.
You can also consume veal liver (even if children do not like it in general), foie gras, raw or cooked mushrooms. Also note that raw egg yolk is an important source of vitamin D. So prefer fried egg, not overcooked, rather than a hard-boiled egg. The cheeses -Brie, mozzarella, and gruyère in the first place - also allow non-negligible contributions. Cow's milk and soy-fortified beverages give you a few precious daily micrograms.
How much vitamin D should we take?
Like vitamins C and E, which have been the subject of recommended intake since 1980, it is now the turn of vitamin D to be scrutinized. Significant interest in a particular vitamin often arises when it is discovered that, in addition to its primary role, it is involved in cancer prevention. It has long been thought that the only role of vitamin D is to focus on calcium absorption. This shows that low blood levels of vitamin D are associated with a higher risk of colon, prostate, and breast cancer (three of the four most common cancers in Canada). You will easily understand that this association has quickly aroused the interest of researchers in this field of health.
When it comes to vitamin D requirements, recommendations come from all sides: no need to take vitamin D in the summer, take 1,000 IU per day, take 2,000 IU per day, take 400 IU per day after 50 years, a normal diet is enough, have your blood level dosed vitamin D, etc. Results from recent studies show that amounts of 3,800 IU, or even 5,000 IU, per day, would be required in some cases. But what is it really? Do we need a vitamin D supplement so much? And if so, how much to take?
Health Canada's recommendation
Health Canada recommends daily intakes of 200 to 600 IU of vitamin D, depending on age. This organization suggests a daily vitamin D supplement of 400 IU for both men and women over 50.
However, the Institute of Medicine - a not-for-profit and independent scientific organization -, at the request of Health Canada and several US federal agencies, is in the process of revising the Dietary Reference Intakes (DRIs) for vitamin D. The final report should be made public in the spring of 2010.
The recommendation of the American Academy of Pediatrics
In 2008, the American Academy of Pediatrics increased its daily standard from 200 IU to 400 IU for children and adolescents.
The recommendation of the Canadian Cancer Society
In 2007, the Canadian Cancer Society advised taking a vitamin D supplement of 1000 IU daily for adults during the fall and winter months.
The contribution from the sun
It would seem that exposure of the hands, forearms, and face of 10 to 15 minutes between 11 a.m. And 2 p.m., without sun protection, 2 or 3 times a week (for people with pale skin) would be enough to fill our vitamin D intake from April to October. However, important studies indisputably demonstrate the pernicious effects of UV rays. They can cause skin cancer, melanoma, and cataracts. It is therefore not recommended to force sun exposure without protection to get our vitamin D intake.
Food intake
Sources of vitamin D are few. Milk and soy drink contain 100 IU per cup, 2 eggs give 120 IU and 100 g of beef liver provide 40 IU. The best sources come from fish. For example, 100 g of salmon provides from 600 IU to 1,000 IU, depending on the cooking method. Another food rich in vitamin D has been discovered in recent years. This is the shiitake mushroom, the consumption of which 10 of them provides 600 IU. Unless you eat fish or mushrooms every day, it is rather difficult to reach a minimum of 400 IU, especially for adults 50 years and older.
Vitamin D toxicity
According to Health Canada, the tolerable maximum intake of vitamin D per day is 2,000 IU. It should not be forgotten that vitamin D is a fat-soluble vitamin and can accumulate in fats and in the liver. However, the results of recent studies seem to call into question this daily ceiling of 2,000 IU.
What is the best way to take vitamin D?
Under the name of cholecalciferol or vitamin D3, this vitamin is available in tablet or liquid form.
Accurate determination of vitamin D
In recent years, doctors have been able to prescribe vitamin D blood testing for their patients. This practice, which is becoming more and more common, makes it possible to check whether our regular intakes (added to production by means of UV rays) are sufficient.
What I think
According to my clients' dietary records in private consultation, the majority do not even reach the 200 IU recommended by Health Canada before age 50, except for people who systematically drink two cups of milk a day. Most of us are probably deficient in vitamin D. Knowingly since cancer is the most formidable disease today, I would be inclined to follow the advice of the Canadian Cancer Society, which recommends 1,000 IU per day in supplement, which is well above Health Canada's standard of between 200 IU and 600 IU per day. However, I would go further and make it a year-round prescription and not just in the fall and winter, since it is difficult to predict how much time you will spend outdoors, without sun protection, in the spring and summer. But the best would be to have your blood levels dosed with vitamin D, before deciding to take supplements.
And you, do you believe that it is necessary to take vitamin D supplements?
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