According to the French National Academy of Medicine, 80% of the Western population is thought to be deficient in vitamin D, including 20% with a deficiency. In short, the vast majority of us lack vitamin D. Why is vitamin D essential to our health? How can we obtain it naturally? How can we supplement properly? Discover everything you need to know about vitamin D in this article.
Vitamin D is essential for bones, but not only!
Vitamin D, or calciferol, is known primarily for its important role in bone metabolism. It acts in the intestines and kidneys to absorb calcium and phosphorus and thereby promote bone mineralization (cartilage, bone, teeth). Vitamin D thus ensures the strength and good health of our bones and teeth.
Since the groundbreaking study conducted by researchers Alison Avenell, William J. Gillespie, Lesley D. Gillespie, and Dianne O’connell on vitamin D, we have known that this small molecule helps prevent osteoporosis (which affects nearly 30% of women over 50). After age 65, take it whenever possible: a dose of more than 800 IU/day reduces the risk of fracture by 50%. And for everyone else... remember that 80% of the French population lacks vitamin D.
But vitamin D has many other benefits! It also plays a role in:
- Muscle contraction; recent research has shown that it is essential for proper muscle function and promotes the renewal of muscle fibers.
- Nerve transmission; vitamin D appears to protect neurons, helping prevent the decline of intellectual abilities with advancing age.
- Immune activity; vitamin D modulates the functioning of the immune system, and its role in protecting against certain cancers and autoimmune diseases (diseases in which the body produces antibodies against its own tissues), such as type 1 diabetes or rheumatoid arthritis, is being considered but has not been demonstrated. According to the National Academy of Medicine, “a significant correlation between low serum levels of vitamin D and mortality from Covid-19 has been shown. Vitamin D cannot be considered a preventive or curative treatment for infection due to SARS-CoV-2; however, by alleviating the inflammatory storm and its consequences, it could be considered an adjunct to any form of therapy”.
- Hormonal regulation, particularly insulin and pituitary hormones; vitamin D does indeed improve insulin sensitivity and, by reducing inflammation and the risk of high blood pressure, could help prevent cardiovascular diseases.
- Blood clotting.
- The renewal of our cells.
Why are we deficient in vitamin D?
A long, long time ago, long before lockdowns and online shopping... We were naked. Yes! All day long, out in the open air, with the sun caressing our skin, we roamed around “almost naked.” Nature being well designed, our bodies quietly produced vitamin D thanks to this magnificent exposure to the sun. Today, between pollution, down jackets, COVID-19 masks, and the climate disaster, things have become a little more complicated. We do not get enough sun exposure (which is nevertheless beneficial in preventing skin cancer!). Furthermore, for those who wear contact lenses or glasses, anti-reflective coatings interfere with the synthesis of vitamin D.
Fortunately, vitamin D has a dual origin:
- One-third of vitamin D comes from the diet, mainly through oily fish, raw egg yolk, and mushrooms.
- Two-thirds of vitamin D is synthesized by the body in the skin under the action of solar rays (UVB) and a cholesterol derivative present in the skin layers, mainly around the forearms and retina.
So what should we do? How can we naturally increase our vitamin D intake?
As a first step, it is recommended that everyone, in all geographic regions and during all seasons, spend at least 20 minutes in the sun at least 3 times a week. 20 minutes of summer sunshine provides us with up to 20,000 IU of vitamin D.
Go outside, walk in nature, exercise outdoors rather than at the gym, spend 20 minutes outside during your lunch break or simply sit on a bench in the sun before going home in the evening... all good excuses to boost your intake of vitamin D. Admittedly, in winter, adopting the “tank top-sunglasses combo” may be complicated, but for the remaining ¾ of the year, don't hesitate. What's more, the vitamin D produced by the skin is stored in the liver, muscles and fatty tissues for approximately 1 month so that it can be used by the body during the winter months. You don't need to take supplements as soon as winter arrives if you have been regularly exposed during the autumn.
When it comes to food, vitamin D is found mainly in the liver oils of oily fish. Include the following in your menu twice a week: salmon, Greenland halibut, carp, salted mackerel, fish roe, marinated or smoked herring, sardines in oil, as well as raw egg yolk, dark chocolate, veal liver and mushrooms, which are rich in vitamin D. For example, 50 g of canned tuna (half a can) + 1 egg + 30 g of Emmental (one serving) + 10 cl of milk enriched with vitamin D (a small glass) = 100% of the recommended vitamin D intake for a child or adult.
For the hardiest among you, opt for the old-fashioned solution: if you have a blocked nose, take one or two spoonfuls of cod liver oil every day (yes, we know!).
The EFSA (European Food Safety Authority) recommends a daily intake of 15 ug of vitamin D, or 600 IU, for everyone and 10 ug for infants. One tablespoon of cod liver oil per day is enough to meet this daily intake.
Please note that vitamin D supplementation is not automatic!
Never take supplements without a genuine need. Always have a blood test beforehand to check your vitamin D level.
What are the signs of vitamin D deficiency? The clinical signs of vitamin D deficiency are mainly bone diseases such as rickets, osteomalacia and osteoporosis. Reduced muscle tone, tetany attacks and seizures (related to hypocalcemia) are sometimes signs of anemia. We have also found a link between gluten intolerance and vitamin D deficiency.
What are the dangers of excessive vitamin D intake? In cases of excess, because vitamin D is fat-soluble, it can accumulate in the body and cause various problems such as headaches, nausea, vomiting, weight loss, and intense fatigue. Although vitamin poisoning has become rare, it is important to respect the safe upper limit of vitamin D at 100 µg per day in addition to dietary intake.
How can a vitamin D deficiency be remedied with dietary supplements?
If you do not like oily fish, fish liver oil makes you terribly nauseous, and you cannot tolerate sleep, dietary supplements are still an option.
For supplementation, you can buy vitamin D at an organic store.
There are two forms of vitamin D: vitamin D2, ergocalciferol, produced by plants, and vitamin D3, cholecalciferol, produced by animals. The latter is synthesized endogenously in our skin.
How much vitamin D should you take per day? Therefore, opt for vitamin D3 at a dosage of 1,000 to 2,000 IU per day. Vitamin D2 is in fact five times less active than D3 because it needs to be converted before being used.
Vitamin D3 supplements come from two sources:
- The vegetarian version based on sheep's lanolin, meaning the fat covering sheep's wool
- The vegan version based on boreal lichen
How can vitamin D be better absorbed? Ideally, consume vitamin D with fat for better absorption. Vitamin D is indeed a fat-soluble vitamin, meaning it dissolves in fats. A useful tip is to add it to your bottle of olive oil so you can consume it easily every day.
Vitamin D: dosages according to the condition
As previously mentioned, vitamin D3 is essential for calcium fixation in the body, participating in anti-inflammatory, immune, and “remineralization” processes; it is THE vitamin for all bone disorders. Thus, vitamin D is recommended as a supplement for many conditions:
- In case of osteoarthritis or arthritis, take vitamin D in capsule form at 10 mcg = 400 IU: 1 with breakfast, every day, for life.
- In case of immune weakness, take:
- Or liquid vitamin D derived from lanolin (sheep's wool), dosed at 5 mcg: 1 pump of 0.5 ml with breakfast for 3 months
- Or capsules of vitamin D derived from cod liver oil, dosed at 10 mcg: 1 capsule with breakfast for 3 months.
- Or tablets of plant-based vitamin D derived from lichen, dosed at 20 mcg: 1 tablet with breakfast for 3 months.
- In case of itching and pruritus, take 1 cod liver oil capsule containing 10 mcg of vitamin D and 180 mcg of vitamin A: 1 with breakfast for 4 months.
- In case of depression, vitamin D is of interest for its action against seasonal depression related to a lack of sunlight; take it according to the following dosages:
- Liquid vitamin D derived from lanolin (sheep's wool), dosed at 5 mcg: 1 pump of 0.5 ml with breakfast
- Vitamin D derived from fish liver oils, dosed at 10 mcg: 1 capsule with breakfast for 4 months
- Plant-based vitamin D derived from lichen, dosed at 20 mcg: 1 tablet with breakfast for 3 months, ideally for 6 months from October to March.
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In case of osteoporosis,
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In case of colds and sinusitis, vitamin D is of interest for its overall immune-stimulating and anti-inflammatory action; take it according to the following dosage:
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Where can you find vitamin D? You can find it very easily in any pharmacy or health food store. The benefits of vitamin D are no longer in doubt in France, so you should have no difficulty finding it.
Remember that every individual is unique. This advice is general, and it is strongly recommended that you seek advice from a doctor, nutrition therapist, or naturopath before taking any supplements.
The best supplementation is still the most natural: getting adequate sun exposure and eating a diet rich in fish.
