To fill up with vitamin D, nothing beats the sun, since this vitamin is synthesized by the skin under the effect of UV rays. Only from November to March the UVB intensity is insufficient. Hence the fatigue often felt in the heart of winter.
For healthy people, we talk about vitamin D insufficiency when the blood level drops below 20 nanograms (20 billionths of a gram) per ml of blood. “All the experts consider that this is the correct minimum,” confirms Professor Jean-Claude Souberbielle, researcher at the Necker Hospital in Paris.
We talk about vitamin D deficiency when this concentration drops below 10-12 nanograms per ml of blood. But it is much rarer and mostly affects very old people with diseases such as kidney failure.
Vitamin D helps build strong bones. It allows both a better absorption of calcium and phosphate in the intestine, but also the reabsorption of calcium in the kidney. Should we still fear a deficiency when the bone capital is built up?
“This does not happen in a winter, concedes Jean-Claude Souberbielle, but the lack of vitamin D contributes to the loss of bone density past the fifties. Before that age, we don’t have the studies to tell. And it is very difficult to assess the rate at which bones lose their density because it varies so much from person to person. ”
Vitamin D deficiency also causes muscle weakness, which is the cause of falls in older people. Supplementing yourself therefore allows you to optimize your muscle mass and reduce the risk of fractures. Other pathologies are associated with it:
In winter, the deficit could be one of the causes of the rise in infectious respiratory diseases. Many studies indeed suggest that vitamin D regulates immunity. By activating the anti-microbial response, it would prevent infectious diseases such as the common cold or the flu.
“Other studies have shown a higher risk of developing dementia syndrome, and in particular Alzheimer’s disease, in the event of deficiency,” notes Dr. Cédric Annweiler, geriatrician. Indeed, vitamin D has anti-inflammatory and antioxidant properties: it protects neurons and vessels, thus influencing cognitive performance.
Vitamin D deficiency has also been linked to the onset of cancers (colorectal, breast, pancreas, prostate) and autoimmune diseases (thyroiditis, type 1 diabetes, rheumatoid arthritis, etc.)
This deficit is also associated with an increased risk of hypertension and cardiovascular disease.
But “association” does not mean “causality”. It remains to be confirmed that the lack of vitamin D has a role in the occurrence of all these diseases. It could also be a consequence. And, to date, studies do not know whether supplementation protects against these diseases.
Vitamins and minerals: what we need to know about our needs
Vitamin D: what is the risk in the event of a deficiency?
To fill up with vitamin D, nothing beats the sun, since this vitamin is synthesized by the skin under the effect of UV rays. Only from November to March the UVB intensity is insufficient. Hence the fatigue often felt in the heart of winter.
Vitamin D, essential for healthy bones
Alzheimer’s, cancers, flu … related to vitamin D deficiency?
Who Should Take Vitamin D Supplements?
A dosage not always useful for the Haute Autorité de santé
How to increase your vitamin D level in winter?
For healthy people, we talk about vitamin D insufficiency when the blood level drops below 20 nanograms (20 billionths of a gram) per ml of blood. “All the experts consider that this is the correct minimum,” confirms Professor Jean-Claude Souberbielle, researcher at the Necker Hospital in Paris.
We talk about vitamin D deficiency when this concentration drops below 10-12 nanograms per ml of blood. But it is much rarer and mostly affects very old people with diseases such as kidney failure.
Who Should Take Vitamin D Supplements?
After 65 years, supplementation has an interest in preventing falls and non-vertebral fractures, such as the femoral neck.
“It is also useful in postmenopausal women suffering from osteoporosis, because the treatments work much less well in the event of insufficiency”, underlines Jean-Claude Souberbielle.
People who are overweight, dark-skinned, spend little time outdoors in the summer, wear covering clothing or are on a diet are also advised to take supplements, as they often have a deficiency or even loss. deficiency, especially in winter.
Vitamin D supplementation is recommended all year round for pregnant and breastfeeding women, young children 2 to 5 years old and the elderly living in institutions.