Vitamin D relieves respiratory infections

Doctors hammer it: the majority of French people lack vitamin D. It must therefore be taken as a supplement – in drops or in ampoules sold in pharmacies – because it has multiple health benefits. It boosts the immune and cardiovascular system, promotes the intestinal absorption of calcium and its fixation in the bones, acts on the brain, etc. A study, published on January 11 in the journal The Lancet has just added an asset to this list: vitamin D could also reduce the duration and intensity of the symptoms of certain diseases. Nevertheless, according to scientists from the QIMR Berghofer Medical Research Institute, a medical research institute based in Australia, this precious vitamin does not prevent patients from falling ill, but may reduce the severity of their pathology. These are mainly winter-related ailments: colds, flu and other respiratory infections. To carry out their work, the researchers analyzed the data of 16,000 Australians, aged 60 to 84. Some took vitamin D monthly for 5 years, while others had a placebo at the same frequencies and over the same period. All had to complete an annual report on their health and keep a winter diary, in which they recorded the number of illnesses they had contracted.

“Vitamin D may boost the immune system”

“Our clinical trial showed that people who took vitamin D were infected with colds and flu at the same rate as those who received placebos. Those who took vitamin D, however, reported a slight reduction in the number of days they experienced symptoms (on average about half a day), said Rachel Neale, principal investigator and group leader, in a statement. QIMR Berghofer Cancer Etiology and Prevention. The results suggest that vitamin D may boost the immune system.” But the study has a limit, which the researchers themselves have pointed out. They believe that their results may be skewed because the study was carried out in Australia, where the population is not deficient in vitamin D. A phenomenon that is not observable in most other countries, where the inhabitants are generally in vitamin D deficiency. “It is possible that a greater protective effect is observed in countries where a high proportion of the population is deficient in vitamin D”, added Rachel Neale. In other words, if the study had been conducted elsewhere, perhaps the people who took vitamin D would have had fewer diseases than those who took placebos.

Avoid deficiency but also overdose

According to Health Study on Environment, Biomonitoring, Physical Activity and Nutrition (Esteban 2014-2016), published by Public Health France in 2019, only 1 in 4 French adults and 3 in 10 children reach an adequate threshold of vitamin D. This is synthesized by the skin under the action of ultraviolet rays. It is found in small quantities in food, such as in egg yolk, butter, fatty fish or cheese. But, especially in winter, it is preferable to take vitamin D as a supplement, via drops to be taken every day or in ampoules, the intakes of which are more spaced out. Beyond the benefits it brings, vitamin D deficiency in adults can also lead to problems, such as bone demineralization. A low rate could also increase the risk of being infected with Covid-19. This is what suggests a spanish study published last October. The researchers analyzed the vitamin D level of several Covid-19 patients. Their results indicate that more than 80% of them were deficient, compared to 47% of the general population. Note that the deficiency is set at less than 20 nanograms (billionth of a gram) per milliliter of blood. But be careful not to take too much either, as overdose can lead to other problems. It is therefore best to set the doses with your doctor.