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Long Covid linked to vitamin D deficiency

A new study led by Vita-Salute San Raffaele University and the IRCCS San Raffaele Hospital in Milan has found that low levels of vitamin D could increase the risk of long Covid – a condition in which individuals previously infected with SARS-CoV-2 experience various symptoms for over three months after contracting the initial infection. These findings suggest that people should have their vitamin D levels checked after Covid infections.

Recent studies have argued that long Covid – a still poorly understood condition characterized by a persistent range of post-Covid symptoms, including fatigue, shortness of breath, chest pain, joint pain, cognitive difficulties, sleep disturbances, depression, anxiety, and fever – affects 50 to 70 percent of patients previously hospitalized for Covid-19. 

Although a risk factor for worse outcomes for hospitalized Covid patients – such as intubation, mechanical ventilation, or even death – is known to be low vitamin D levels, its role in long Covid has not yet been thoroughly assessed.

The experts examined 100 patients aged 51-71, with or without long Covid. None of these patients had any previous bone-related conditions, and did not end up in intensive care units (ICUs). By measuring their vitamin D levels when first admitted to the hospital and six months after their discharge, they found lower levels of vitamin D in those with long Covid. 

Moreover, the vitamin D levels were lower in patients who experienced so-called “brain fog” symptoms, such as confusion, forgetfulness, or poor concentration.

“Previous studies on the role of vitamin D in long Covid were not conclusive mainly due to many confounding factors,” said senior author Andrea Giustina, an expert in Endocrine and Metabolic Sciences at the Vita-Salute San Raffaele University. 

“The highly-controlled nature of our study helps us better understand the role of vitamin D deficiency in long Covid, and establish that there is likely a link between vitamin D deficiency and long Covid.”

In future research, the scientists aim to investigate whether vitamin D supplements could reduce the risk of long Covid. 

“Our study shows that Covid-19 patients with low vitamin D levels are more likely to develop long Covid but it is not yet known whether vitamin D supplements could improve the symptoms or reduce this risk altogether,” Giustina concluded.

The study is published in the Journal of Clinical Endocrinology & Metabolism and will be presented at the 25th European Congress of Endocrinology in Istanbul (13-16 May, 2023).

More about long Covid

Long Covid, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), refers to a condition where individuals experience persistent symptoms or new symptoms that last beyond the acute phase of a COVID-19 infection. 

While many people recover from COVID-19 within a few weeks, some individuals continue to experience a range of physical, mental, and neurological symptoms for several weeks or months. The specific symptoms and their severity can vary widely among individuals.

Common symptoms of long Covid include:


Persistent and extreme tiredness or exhaustion, even after minimal physical or mental exertion.


Difficulty breathing or shortness of breath, even during simple activities.

Cognitive difficulties

Often referred to as “brain fog,” individuals may experience problems with memory, concentration, or thinking clearly.

Muscle and joint pain

Persistent or intermittent pain in muscles, joints, or other parts of the body.

Chest pain

Some individuals may experience chest discomfort or pain, which can be sharp or dull.


Frequent or chronic headaches that can be severe and persistent.

Sleep disturbances

Insomnia, difficulty falling asleep, staying asleep, or experiencing non-restorative sleep.

Anxiety and depression

Feelings of anxiety, depression, or changes in mood.

Loss of taste and smell

A lingering or recurring loss or alteration of the sense of taste or smell.

Other symptoms

People with long Covid may also experience heart palpitations, dizziness, gastrointestinal issues, skin problems, or other persistent symptoms.

The exact cause of long Covid is not yet fully understood, and it can affect people regardless of the severity of their initial COVID-19 infection. Some theories suggest that it could be due to persistent inflammation, immune system dysregulation, or the presence of viral remnants in the body.

Long Covid can significantly impact a person’s quality of life, making it challenging to carry out daily activities, return to work or school, and participate in physical or social activities. The condition can affect people of all ages, including those who initially had mild or asymptomatic cases of COVID-19.

Managing long Covid requires a comprehensive and multidisciplinary approach. Treatment options may include a combination of medication, physical therapy, occupational therapy, cognitive rehabilitation, psychological support, and lifestyle modifications.

Why is vitamin D important?

Vitamin D is an essential nutrient that plays a crucial role in maintaining overall health and well-being. 

Here are some key reasons why vitamin D is important:

Bone Health

One of the primary functions of vitamin D is to facilitate the absorption and utilization of calcium and phosphorus in the body. These minerals are vital for the development and maintenance of strong and healthy bones. 

Adequate vitamin D levels help prevent conditions like rickets in children and osteomalacia or osteoporosis in adults, which are characterized by weakened bones.

Calcium Regulation

Vitamin D helps regulate calcium levels in the blood by enhancing its absorption in the intestines and reducing its excretion through the kidneys. This balance is essential for proper muscle function, nerve signaling, and maintaining optimal bone density.

Immune Function

Vitamin D has immunomodulatory properties, meaning it helps regulate the immune system’s response to pathogens and inflammation. It plays a role in both innate and adaptive immunity, influencing the production and activity of various immune cells. 

Sufficient levels are associated with reduced risks of respiratory infections, autoimmune diseases, and certain types of cancer.

Mood and Mental Health

Vitamin D receptors are found in areas of the brain involved in mood regulation. Research suggests that maintaining adequate vitamin D levels may be important for mental health and the prevention of conditions such as depression, seasonal affective disorder (SAD), and cognitive decline.

Cardiovascular Health

Some studies have shown that vitamin D deficiency is associated with an increased risk of cardiovascular diseases, including hypertension, heart disease, and stroke. 

Adequate vitamin D levels may help maintain healthy blood pressure, reduce inflammation, and support overall cardiovascular function.

Muscle Function

Vitamin D plays a role in muscle function and strength. Sufficient levels of vitamin D are important for optimal muscle performance, coordination, and balance, which can help reduce the risk of falls and fractures, especially in older adults.

Gene Expression

Vitamin D influences the expression of numerous genes involved in various physiological processes, including cell growth, differentiation, and apoptosis (cell death). It is believed to have potential effects on preventing or controlling certain types of cancers, although further research is needed in this area.

The primary source of vitamin D is sunlight exposure, as the skin synthesizes it when exposed to ultraviolet B (UVB) rays. It can also be obtained from dietary sources such as fatty fish (e.g., salmon, mackerel), fortified dairy products, eggs, and some mushrooms. 

In cases of deficiency, vitamin D supplements may be recommended by healthcare professionals to ensure adequate levels are maintained. However, it is important to consult a healthcare provider for guidance on supplementation, as excessive vitamin D intake can be harmful.

It’s worth noting that individual vitamin D requirements may vary based on factors such as age, skin pigmentation, geographic location, season, and overall health. Regular monitoring of vitamin D levels and discussions with healthcare professionals can help ensure optimal vitamin D status.


By Andrei Ionescu, Staff Writer

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