Vitamin D (Vitamin D), also known as vitamin D, is a basic nutrient for maintaining health and a member of the steroid hormone family. It was discovered in the early 20th century to prevent rickets in children. It is called D because it was discovered The fourth in the vitamin sequence
Globally, its deficiency is a major public health problem affecting all ages and ethnic groups, and it has surpassed iron deficiency as the most common nutritional deficiency in the world.
The two main subtypes are vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol), which have similar effects, and the text will not distinguish between these subtypes unless otherwise specified
In empirical medicine, what is the effect of vitamin D supplementation? Are there any side effects or contraindications? See the text analysis for details
What is Vitamin D?
Vitamin D is a micronutrient that can be metabolized into a multifunctional steroid hormone essential to human health. It is not only an important part of maintaining calcium balance and bone health, but also through binding to vitamin D receptors throughout the body ( Such as the brain, blood vessels, prostate, breast and immune cells), directly or indirectly affect more than 2,000 sets of genes, but there are also non-genomic rapid effects, including direct stabilization of the endothelium
The proven physiological activities of vitamin D also include: inhibiting cell proliferation and inducing differentiation, inhibiting angiogenesis, stimulating insulin secretion, inducing cell apoptosis, inhibiting the production of renin, and stimulating the production of macrophages.
Current studies have also found that vitamin D deficiency is closely related to the occurrence and development of many chronic diseases, including metabolic abnormalities, osteomalacia, osteoporosis, muscle weakness, hip fractures, diabetes, cancer, cardiovascular diseases, arthritis, and autoimmune diseases
At present, there is no nutrient, drug, or hormone that can get so many scientific verifications that are beneficial to the human body like vitamin D. Note 1
Which groups are prone to vitamin D deficiency?
Elderly: With age, the skin becomes thinner, which makes it more difficult for the skin to produce vitamin D3 in the sun
However, some elderly people have mobility problems due to joint deterioration and often stay at home. This means less exposure to sunlight, and sunlight is the best way to naturally increase vitamin D levels.
Darker skin tone: This means that there are more melanin in the skin, and the higher the concentration, it will help protect the skin from the sun’s ultraviolet rays.
However, it also reduces the body’s ability to produce vitamin D3 from the skin, which may make you prone to vitamin D3 deficiency
Living far away from the equator: The place near the equator has plenty of sunshine throughout the year. On the contrary, countries farther from the equator have less sunshine throughout the year (especially in winter, less sunshine).
Diseases related to poor fat absorption: Vitamin D is fat-soluble, so the degree of absorption also depends on the ability of the intestine to absorb fat from the diet.
Therefore, people with diseases related to poor fat absorption are prone to vitamin D deficiency, including irritable bowel disease, Crohn’s disease, liver disease, and patients who have undergone bariatric surgery
What are the recommended empirical effects (benefits) of vitamin D?
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Good for non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease (Non-alcoholic fatty liver disease) is a liver manifestation of metabolic syndrome (including type 2 diabetes, hypertension, insulin resistance, obesity, and dyslipidemia) (defined as the presence of ≥5% liver steatosis) , Is a clinicopathological condition including simple fatty liver, steatohepatitis, fibrosis and cirrhosis, and is observed in individuals without evidence of excessive alcohol consumption, affecting approximately 20% to 35% of adults
Among them, non-alcoholic steatohepatitis (NASH) is a potential variant of non-alcoholic steatohepatitis (NAFLD), which occurs in 10% to 20% of patients with non-alcoholic steatohepatitis, making them susceptible to liver cirrhosis and liver cells Cancer (HCC).
A meta-analysis of the literature (including 16 randomized controlled trials) pointed out that compared with the control group, vitamin D supplementation helps to improve the following anthropometric and biochemical indicators, including: weight (Weight), body mass index (Body Mass Index, waist circumference, high-density lipoprotein cholesterol (HDL-C), alanine aminotransferase (ALT), fasting blood sugar, insulin resistance (HOMA-IR). Note 1
＊Conclusion: For patients with non-alcoholic fatty liver disease, vitamin D supplementation may bring positive help, but limited by the small number of samples, more studies are needed to confirm the optimal dosage and time of use
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Beneficial sarcopenia
The loss of muscle quality and strength is inevitable in the process of human aging. This degeneration is summarized as “Sarcopenia”, which is a syndrome included in the 10th edition of the International Classification of Diseases, a musculoskeletal disease
The associated degradation is estimated to start at the age of 40 and is detectable at about the age of 50, occurring at a rate of 1% to 3% each year. Its progress is closely related to fractures, metabolic dysfunction, the development of heart and respiratory diseases, mortality and overall quality of life.
A meta-analysis of the literature (including 9 randomized controlled trials with 1,420 participants with sarcopenia) pointed out that the combination of vitamin D, protein and exercise can significantly increase grip strength and also show a tendency to increase muscle quality. Note 2
＊Conclusion: Adding vitamin D to the standard treatment plan of sarcopenia may help functional recovery
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Good for chronic urticaria
Urticaria (Urticaria) is a rash characterized by dark red, raised, itchy bumps that affects about 15%-20% of the population. It is classified as acute urticaria (less than 6 weeks) or chronic urticaria (At least twice a week, lasting more than 6 weeks), the ratio of women to men is about 2:1
Chronic urticaria can be further divided into two different subtypes, namely chronic idiopathic urticaria (the lesions occur spontaneously) and chronic induced urticaria (requires specific triggers, which can be drugs, physical stimulation, or pressure that cause urticaria. happened).
A systematic literature review and integrated analysis (meta-analysis, including 17 observational studies and 5 interventional studies) pointed out that for the urticaria population, especially adult chronic urticaria patients, it may be compared with the serum 25(OH)D concentration. Low is related, and vitamin D supplementation can reduce the severity and improve the quality of life. Note 1
＊Conclusion: For chronic urticaria in adults, vitamin D supplementation may bring positive help, but due to the small number of samples and heterogeneity, more studies are needed for further verification
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Good for benign paroxysmal postural vertigo
Benign paroxysmal positional vertigo (Benign paroxysmal positional vertigo) is the most common peripheral vestibular organ disease, which is typical of a sudden and short rotation sensation, accompanied by characteristic nystagmus (the lifetime prevalence rate is 2.4 %, the peak incidence is about 50 to 60 years old, and there are more women, the ratio is about 2 to 1 or 3 to 1)
Symptoms are caused by changes in head position, and their severity ranges from mild dizziness to debilitating attacks that may cause nausea or vomiting, and severely hinder daily functions
A systematic literature review and integrated analysis (meta-analysis, including 7 controlled trials, 1133 patients with benign paroxysmal postural vertigo) pointed out that vitamin D supplementation can significantly reduce the recurrence and improvement of benign paroxysmal postural vertigo Vitamin D deficiency. Note 1
＊Conclusion: For benign paroxysmal postural vertigo, vitamin D supplementation may bring positive help, but due to the small sample size and heterogeneity, more research is needed for further verification
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Beneficial sleep disorders
Insomnia (Insomnia) is a disease that is dissatisfied with sleep time and sleep quality, which means it is difficult to start and maintain sleep, and it is easy to be unable to fall asleep after waking up.
Insomnia increases the risk of many health problems, such as cardiovascular disease, arterial hypertension, myocardial infarction and chronic heart failure, type 2 diabetes, cognitive impairment, depression, etc., which has brought a heavy burden to society and individuals.
About 30% of the world’s population suffers from insomnia, and only about 10% of patients receive appropriate treatment.
A meta-analysis of literature (including 25 studies) pointed out that serum vitamin D levels in patients with sleep disorders are often lower than normal, and vitamin D supplementation can improve sleep quality (measured by the Pittsburgh Sleep Quality Index/Pittsburgh Sleep Quality Index) . Note 1
＊Conclusion: For sleep disorders, vitamin D supplementation may bring positive help, but due to the low quality of existing evidence, more studies are still needed to support it
5 alternative therapies to improve insomnia (the fourth one is easy to learn)
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Good for knee osteoarthritis
Osteoarthritis (osteoarthritis) is the most common form of arthritis (common in hand joints, knee joints, hip joints, feet, spine and other weight-bearing joints), characterized by the progressive disintegration of articular cartilage, at the bottom of cartilage lesions and joints The edges (osteophytes) form new bone and cause chronic disability
Most people over 65 have imaging evidence of osteoarthritis, and age, gender, weight, repetitive trauma, occupational activity, genes, gender, lower limb dysplasia and heredity are important risks that affect the performance of osteoarthritis factor.
A systematic literature review and meta-analysis (including 6 randomized controlled trials with a total of 1599 osteoarthritis patients) pointed out that vitamin D supplementation can help improve the scores of the Degenerative Knee Arthritis Scale (WOMAC), including Pain score, function score and stiffness score. Note 1
In the subgroup analysis (subgroup analysis), it was found that the effect of reducing the stiffness score was the most significant when the vitamin D dose was less than 2000 IU
In addition, vitamin D supplementation can reduce the progress of joint synovial fluid, but it is not statistically significant for improving tibial cartilage volume, joint space width, and bone marrow disease.
＊Conclusion: For osteoarthritis, vitamin D supplementation may improve the pain and functional status of patients, but it has no clinical significance in preventing structural progression. More large long-term trials are needed for further verification.
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Beneficial for pneumonia prevention
Pneumonia (Pneumonia) is a lung infection caused by bacteria, viruses or fungi. These syndromes can lead to different manifestations and sequelae, especially in the elderly and immunosuppressed people
Complications of untreated or undertreated pneumonia include respiratory failure, sepsis, metastatic infection, empyema, lung abscess, and multiple organ dysfunction
A systematic literature review and meta-analysis (including 13 randomized controlled trials with 4786 participants) pointed out that vitamin D supplementation significantly increased serum 25(OH)D levels and reduced the chance of repeated pneumonia attacks. Note 1
Subgroup analysis showed that among trial participants whose population was children, the disease course was less than 3 months, and the vitamin D dose was greater than 300,000 IU, vitamin D supplementation had a greater effect on reducing repeated pneumonia attacks
In addition, in the stratified follow-up with a follow-up time of less than 3 months, the decrease in the intensive care unit/hospital rate was statistically significant.
＊Conclusion: High-dose vitamin D intervention may reduce the chance of recurring pneumonia by enhancing the immune effect
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Beneficial for new coronavirus infection
The new coronavirus infection (COVID-19 infection) has become a serious global health problem. Although most patients have mild symptoms and do not even need hospitalization, nearly 30% of adult patients have severe pneumonia and acute respiratory distress syndrome (ARDS). ), even with sepsis (sepsis) or septic shock (septic shock), and multiple organ (kidney, liver, heart) failure.
Patients with acute respiratory distress syndrome and systemic complications require intensive care and are at higher risk of death. Due to the lack of effective anti-SARS-COV-2 drugs, the main treatment method is supportive treatment.
A systematic literature review (Systematic Review, including 9 studies) pointed out that blood vitamin D levels are significantly related to the risk, severity, and mortality of COVID-19 infection. Those who lack it have an increased risk of infection and a worse prognosis. Note 1
Another systematic literature review and meta-analysis (including 10 case-control studies involving 376,596 participants) pointed out that vitamin D deficiency or insufficiency is associated with an increased risk of COVID-19. In addition, the risk of COVID-19 positive individuals Vitamin D levels are lower than negative individuals. Note 2
＊Conclusion: Vitamin D deficiency or insufficiency is related to a higher rate of new coronavirus (COVID-19) infection and a poor prognosis. However, further research is needed to evaluate the impact of vitamin D supplementation on the clinical severity and prognosis of COVID-19.