The 7 possible causes of vitamin D deficiency


A vitamin D deficiency is not always related to insufficient sun exposure. Other causes should be investigated, especially in women.

A lack of sun exposure

Vitamin D is produced in 70% through the skin under the influence of ultraviolet radiation from the sun. The remaining 30% is provided by food, explains Florence Foucaut, dietician-nutritionist and member of the French Association of Dietitian-Nutritionists. Most often, the lack of vitamin D is caused by insufficient exposure to sunlight. “In winter we lack sunshine. The light is weaker and short-lived compared to the spring/summer season. Moreover, we are more covered in winter; therefore we are less exposed and the synthesis of vitamin D is less good. Conversely, exposing your forearms for a few minutes a day in the summer is sufficient to build them up. In addition, vitamin D can be stored. So it is possible to exhibit in the summer (except from 12 noon to 4 p.m.) to increase our supply, which will slowly be depleted during the winter“.

Low consumption of oily fish

About a third of vitamin D is obtained through food. Consuming certain rich foods, combined with adequate exposure to daylight, can meet daily needs. Worldwide, a deficiency can occur in the absence of consumption of foods that are a source of vitamin D as oily fish (sardines, salmon, mackerel, etc.)dairy products (especially those fortified with calcium and vitamin D), cod liver oil, certain mushrooms, egg yolk, offal (especially meat liver).

Having dark skin promotes shortcomings

They contain a large amount of melanin that can block UV rays.

People with olive and dark skin are at greater risk of vitamin D deficiency. says our nutritionist. They indeed have a large amount of melanin, skin pigment that can block UV and in fact the synthesis of vitamin D. On medical advice, they may be advised to supplement this during the winter period..” Furthermore, among people who excessive use of the entire screensynthesis is less efficient.

A hormonal change

THE hormonal changes have an impact on the biosynthesis of vitamin D. Pregnant women and women after menopause are therefore populations at risk of deficiency“explains our interlocutor. Hormonal fluctuations can cause bone demineralization, which increases the risk of fractures.

Overweight and obesity

Vitamin D is fat soluble, so it is stored in adipose tissue. Being overweight or obese may occur cause a lack of bioavailability of vitamin D” she explains. Certain pathologies are also at risk, especially those that cause intestinal malabsorption, such as celiac disease (gluten intolerance) or after bariatric surgery.

A vegan diet

Diets eliminating meat, fish, eggs or dairy products promote the risks of vitamin D deficiency. advises Florence Foucaute consult for prevention a nutrition professional, a dietitian nutritionist or even their pharmacist, especially for adult populations at risk of deficiency.

Age, a proven risk factor

Babies and the elderly are particularly at risk of a vitamin D deficiency.”As we age, our skin synthesizes less vitamin D. The skin of older people is very thin. So less vitamin D is made“explains Florence Foucaut. A deficiency of this vitamin in the elderly promotes the occurrence of osteoporosis and the risk of femoral neck fracture. To ensure the proper growth of their skeleton and prevent rickets, newborns are systematically supplemented in France on medical prescription. “Babies born from September onwards are more concerned, which is related to insufficient exposure to natural light, essential for the synthesis of vitamin D. In autumn and winter, babies are covered, well wrapped and virtually no skin surface is exposed“, describes our expert. Babies born in summer can, in turn, leave their arms uncovered during a walk, without of course exposing them to the sun (it is rather advisable to wake your baby between 12 noon and 4 p.m. not to be left running: 00 hours when it is warm outside).

With thanks to Florence Foucaut, dietician-nutritionist and member of the AFDN (French Association of Dietitian-Nutritionists).

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