Vitamin D: benefits, dosage, contraindications
Other name(s)
calciferols, Alfacalcidol, Calcifediol, Calcipotriene, Calcitriol, Dihydrotachysterol
Scientific name(s)
Ergocalciferol (D2), Cholecalciferol (D3)
Family or group:
Vitamins
Active ingredients:
Vitamin D3
Indications
Rating methodology
EFSA approval.
Vitamin D Deficiency ✪✪✪✪✪
Vitamin D deficiency is common and underdiagnosed. The causes of hypovitaminosis D are multiple: reduced cholecalciferol synthesis, low sun exposure, use of sunscreens, dark skin phototype, liver failure, treatment with isoniazid, genetic anomaly, kidney failure... The clinical manifestations of vitamin D deficiency are primarily musculoskeletal. Osteoporosis, osteomalacia in adults, and rickets in children are well-known bone manifestations. Unlike osteoporosis, osteomalacia is associated with generalized or localized bone pain (pain upon pressure of the sternum or tibial crest). A deficiency can also lead to proximal muscle weakness and result in a gait with lateral rocking movements (referred to as "penguin gait"). In case of insufficient intake, vitamin D is taken in weekly doses of 400 to 2000 IU (10 to 50 µg) for eight weeks. In case of confirmed deficiency-induced rickets in children, in the absence of hypocalcemia, 25-OH vitamin D may be given at a dose of 1500 to 3000 IU per day for six to eight weeks, then 300 to 400 IU per day. In case of hypocalcemia, the hypocalcemia is initially treated for a few days before introducing vitamin D.
Posologie
Orally
400 - 2000 IU
8 - weeks
Adults
Bone Health ✪✪✪✪✪
Vitamin D plays a main role in the regulation of calcemia, phosphatemia, and bone homeostasis. European health authorities (EFSA, European Food Safety Authority, and the European Commission) have estimated that dietary supplements containing vitamin D (calciferols) may claim to contribute to intestinal absorption and utilization of calcium and phosphorus, the maintenance of normal blood calcium levels, normal bone growth in children, and the maintenance of normal bone condition.
Posologie
Orally
600 - 4000 IU
Adults
cholecalciferol
Hypoparathyroidism ✪✪✪✪✪
Oral intake of calcitriol is effective in increasing serum calcium concentrations in individuals with hypoparathyroidism or pseudohypoparathyroidism. Indeed, the relationship between vitamin D levels and parathyroid hormone (PTH) levels seems to be conditioned individually by calcium intake. Dietary calcium influences PTH levels, and in turn, changes in PTH can alter the turnover level of vitamin D metabolites. PTH acts indirectly by stimulating the 1-alpha-hydroxylation of vitamin D, which, activated into 1,25-dihydroxy-vitamin D (1,25(OH)2D3), promotes intestinal calcium absorption. Calcium deficiency could thus exacerbate vitamin D deficiency, whereas high intake could exert a sparing effect on vitamin D. In cases of hypoparathyroidism, vitamin D2 or D3 supplementation should be added in case of associated deficiency or systematically at 400 to 800 IU/day.
Posologie
Orally
400 - 800 IU
Fractures ✪✪✪✪✪
The rate of bone fractures in the elderly seems to be significantly reduced with vitamin D supplementation of 700 IU or more. Most research ranges from 700 to 1000 IU, while lower doses appear ineffective. Moreover, simultaneous supplementation with calcium (and possibly vitamin K) seems to have a protective effect on bones.
Posologie
Orally
700 - 1000 IU
Seniors
Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions
Need for additional calcium to reduce the risk of hip fracture with vitamin D supplementation: evidence from a comparative metaanalysis of randomized controlled trials.
Patient level pooled analysis of 68,500 patients from seven major vitamin D fracture trials in US and Europe.
Osteoporosis ✪✪✪✪✪
In cross-sectional studies, low 25(OH)D values are associated with decreased bone mineral density (BMD), after adjusting for age, body mass index, and calcium intake. The National Osteoporosis Foundation (NOF) recommended in 2014 a daily intake of vitamin D between 800 to 1,000 IU as well as calcium to prevent osteoporosis in adults over 50. In patients with osteoporosis, the NOF recommends the use of vitamin D supplementation to maintain adequate vitamin D levels. These recommendations are supported by clinical research showing that oral intake of vitamin D3 (cholecalciferol) with calcium supplements can reduce postmenopausal bone loss, help prevent osteoporosis, and decrease the risk of fractures.
Posologie
Orally
800 - 1000 IU
Seniors
Vitamin D with or without calcium supplementation for prevention of cancer and fractures: an updated meta-analysis for the U.S. Preventive Services Task Force.
Meta-analyses of therapies for postmenopausal osteoporosis. VIII: Meta-analysis of the efficacy of vitamin D treatment in preventing osteoporosis in postmenopausal women.
Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials.
Vitamin D analogs versus native vitamin D in preventing bone loss and osteoporosis-related fractures: a comparative meta-analysis.
Current Events on Vitamin D
Evidence-based guidelines for the treatment of postmenopausal osteoporosis: a consensus document of the Belgian Bone Club.
Psoriasis ✪✪✪✪✪
The application of vitamin D in the form of calcitriol or other vitamin D analogs appears effective in treating plaque psoriasis in some patients, including chronic form. Topical vitamin D or its analogs combined with topical corticosteroids seems more effective than corticosteroid treatment alone.
Posologie
Topically
calcitriol
Topical vitamin D analogues alone or in association with topical steroids for psoriasis: a systematic review.
A two-compound product containing calcipotriol and betamethasone dipropionate provides rapid, effective treatment of psoriasis vulgaris regardless of baseline disease severity.
Combination treatments for psoriasis: a systematic review and meta-analysis.
Topical treatments for chronic plaque psoriasis.
Mixed treatment comparison of a two-compound formulation (TCF) product containing calcipotriol and betamethasone dipropionate with other topical treatments in psoriasis vulgaris.
Pregnancy ✪✪✪✪✪
Vitamin D, often associated with bone health, also plays a crucial role in managing autoimmune diseases and allergies, as well as maternal and fetal health during pregnancy. Preliminary research has shown that vitamin D supplementation could alleviate the severity of allergy symptoms such as allergic rhinitis, particularly when vitamin D levels are restored to an adequate threshold. Studies also suggest that insufficient levels of vitamin D are linked to an increased risk of exacerbations and a greater need for medication in asthmatic patients. Although clinical research results are mixed, some meta-analyses have indicated that vitamin D supplementation could reduce the rate of asthma exacerbations in adults and children. Furthermore, vitamin D has been evaluated for its impact on other health outcomes during pregnancy, including preeclampsia, gestational diabetes, and markers of insulin resistance, potentially offering benefits in prevention and improvement of glycemic and lipid indices. In terms of infant development, while some research suggests that increased levels of vitamin D during pregnancy are associated with better anthropometric and neurodevelopmental outcomes, other studies have not shown a significant effect of vitamin D supplementation on children's neurological development. In summary, vitamin D supplementation during pregnancy offers significant benefits for maternal and fetal health, as confirmed by a meta-analysis including 30 trials and 7033 women. Although the quality of evidence varies, vitamin D supplementation alone seems to reduce the risks of preeclampsia, gestational diabetes, low birth weight, and could decrease the risk of severe postpartum hemorrhage.
Posologie
Oral route
600 IU
Synergies
Vitamin D supplementation for women during pregnancy
Maternal vitamin D status and risk of gestational diabetes mellitus: A systematic review and meta-analysis of prospective cohort studies
The effect of combined supplementation with vitamin D and omega-3 fatty acids on blood glucose and blood lipid levels in patients with gestational diabetes
Effects of vitamin D supplementation during pregnancy on offspring health at birth: A meta-analysis of randomized controlled trails
Vitamin D Supplementation and Allergic Diseases during Childhood: A Systematic Review and Meta-Analysis
Relationship between vitamin D and asthma from gestational to adulthood period: a meta-analysis of randomized clinical trials
Therapeutic effect of vitamin D supplementation on allergic rhinitis
Vitamin D supplementation during pregnancy and the risk of wheezing in offspring: a systematic review and dose-response meta-analysis
Asthma ✪✪✪✪✪
The analysis of clinical trials shows that taking vitamin D for 3 months to 1 year reduces the number of asthma exacerbations by 31% to 36% in both adults and children with asthma. Vitamin D3 (cholecalciferol) has been used in variable doses, either 100,000 IU followed by 4000 IU per day for 7 months, or 120,000 IU every two months for 1 year.
Posologie
Oral route
4000 - 100000 IU
7 - months
Vitamin D supplementation to prevent asthma exacerbations: a systematic review and meta-analysis of individual participant data.
Vitamin D supplementation in children may prevent asthma exacerbation triggered by acute respiratory infection.
Serum vitamin D levels and severe asthma exacerbations in the Childhood Asthma Management Program study.
Serum vitamin D levels and markers of severity of childhood asthma in Costa Rica.
Premenstrual Syndrome ✪✪✪✪✪
Increasing vitamin D intake appears to decrease the risk of developing premenstrual syndrome (PMS) and the severity of symptoms. Indeed, a clinical study shows that taking 400 IU/day of vitamin D in combination with 1000 mg/day of calcium for 10 days can reduce the severity of PMS symptoms.
Posologie
Oral route
400 IU
10 - days
Women
Synergies
Type 2 Diabetes ✪✪✪✪✪
Observational research has shown that low levels of vitamin D are associated with a higher risk of prediabetes and that a diet rich in vitamin D is linked to a lower risk of developing diabetes. Additionally, in patients with vitamin D deficiency and prediabetes, vitamin D could improve beta cell function, suggesting a decrease in the progression of the disease. Clinical research in adults with vitamin D deficiency shows that taking 50,000 IU of vitamin D per week for 3 months, followed by monthly for another 3 months, slightly improves insulin resistance and beta cell function, but does not affect fasting and postprandial blood glucose compared to placebo. Oral vitamin D could improve glycemic indices in some patients with type 2 diabetes, but clinical study results remain contradictory.
Posologie
Oral route
5000 IU
Vitamin D and type 2 diabetes: a systematic review
Vitamin D supplementation and glycemic control in type 2 diabetes patients: A systematic review and meta-analysis
Does high-dose vitamin D supplementation impact insulin resistance and risk of development of diabetes in patients with pre-diabetes? A double-blind randomized clinical trial
Respiratory Infections ✪✪✪✪✪
Increased vitamin D levels during pregnancy have been associated with a lower incidence of respiratory infections in children. However, two meta-analyses of small clinical studies show a limited effect of prenatal vitamin D supplementation on the incidence of respiratory infections in infants or children (19% reduction in wheezing risk compared to the control group). In children, most research shows that vitamin D supplementation reduces the risk of respiratory infections. A meta-analysis of clinical trials conducted in children aged 1 to 16 years shows that taking vitamin D reduces the risk of suffering from respiratory tract infections compared to the control group. Daily or weekly doses of vitamin D appear to be more beneficial than single doses. Observational studies conducted in adults have shown that low vitamin D levels are associated with worsening complications related to respiratory infections, or even increased mortality due to respiratory infections in adults aged 50 to 75. However, meta-analyses of prospective clinical trials conducted in adults show that taking vitamin D supplements from 300 to 4000 IU per day for 7 weeks to 5 years does not reduce the likelihood of developing a respiratory infection or severe respiratory complications, such as emergency service visits, hospitalization, and death, compared to placebo. Conversely, the largest single clinical trial conducted in adults aged at least 60 shows that taking 60,000 IU of vitamin D3 (cholecalciferol) once a month for up to 5 years reduces the duration of total and severe respiratory symptoms, but does not reduce the incidence of respiratory diseases, compared to placebo.
Posologie
Oral route
4000 IU
Infant Respiratory Tract Infections or Wheeze and Maternal Vitamin D in Pregnancy: A Systematic Review
Vitamin D supplementation during pregnancy: state of the evidence from a systematic review of randomised trials
Vitamin D Insufficiency and Deficiency and Mortality from Respiratory Diseases in a Cohort of Older Adults: Potential for Limiting the Death Toll during and beyond the COVID-19 Pandemic?
Prenatal vitamin D status and respiratory and allergic outcomes in childhood: A meta-analysis of observational studies
The effect of vitamin D supplementation on acute respiratory tract infection in older Australian adults: an analysis of data from the D-Health Trial
Vitamin D for prevention of respiratory tract infections: A systematic review and meta-analysis
Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
Autoimmune Diseases ✪✪✪✪✪
Vitamin D plays a crucial role in managing autoimmune diseases by influencing the immune state through environmental, genetic, and epidemiological factors. Its deficiency has been associated with an increased prevalence of autoimmune disorders, including type 1 diabetes, multiple sclerosis, systemic lupus, and Crohn's disease. Studies on animal models and epidemiological observations suggest that vitamin D could reduce inflammation and improve T cell function, offering protection against autoimmune diseases by regulating immune responses and decreasing inflammatory cytokines.
Posologie
Oral route
400 - 2000 IU
Parkinson's Disease ✪✪✪✪✪
Low serum vitamin D levels are correlated with an increased risk of Parkinson's disease and are further associated with the severity of the pathological state. Indeed, vitamin D may protect neurons from stress factors, although a deficiency does not inherently appear to increase the risk of neuronal damage in cells associated with the disease. Preliminary research shows that taking 1200 IU/day of cholecalciferol (vitamin D3) for a year significantly slows the progression of the disease in affected subjects.
Posologie
Oral route
1200 IU
1 - years
Seniors
Cancer ✪✪✪✪✪
Epidemiological research has revealed that higher serum vitamin D levels are associated with a reduced risk of mortality in patients with colorectal cancer. Indeed, in an analysis of studies evaluating the association between serum vitamin D levels and the risk of colorectal cancer, individuals with serum vitamin D levels of 33 ng/ml or more have a 50% lower risk of developing colorectal cancer compared to those with levels of 12 ng/mL or less. However, it is unclear whether vitamin D supplementation improves survival in patients with colorectal cancer. Some research shows that high calcium intake is associated with a reduced risk of adenoma recurrence and colorectal cancer in people whose vitamin D level is above average. In cases of colorectal cancer, vitamin D has been used in doses of 8000 IU per day during the first cycle of chemotherapy, followed by 4000 IU per day for subsequent cycles. On the other hand, some research has shown that higher vitamin D intake is associated with a 17% reduction in breast cancer risk in pre- and perimenopausal women, but not in postmenopausal women.
Posologie
Oral
4000 - 8000 IU
Depression ✪✪✪✪✪
The role of vitamin D in the treatment of depression is unclear. Meta-analyses show that vitamin D supplementation does not generally improve depressive symptoms. However, some studies suggest that vitamin D might be beneficial for improving symptoms in individuals with clinically significant symptoms and pre-existing vitamin D deficiency prior to supplementation. Vitamin D3 (cholecalciferol) has been administered as a single dose of 150,000 to 300,000 IU, or in daily and weekly doses ranging from 400 to 5,000 IU per day or 20,000 to 40,000 IU per week for 6 weeks to 2 years.
Posologie
Oral
400 - 5000 IU
2 - years
Multiple Sclerosis ✪✪✪✪✪
Demographic studies have shown that long-term vitamin D supplementation in women reduces the risk of multiple sclerosis (MS) by up to 40%. The effect seems dose-dependent. Consuming at least 400 IU per day, mainly in the form of a multivitamin supplement, appears to have the greatest protective effect. Further research has revealed that higher levels of calcifediol (25-hydroxyvitamin D) are associated with a significantly lower risk of developing MS. Vitamin D supplementation does not seem to affect MS relapses. Indeed, meta-analyses show that vitamin D supplementation, at low or high doses, does not affect the MS relapse rate or the number of nerve lesions.
Posologie
Oral
400 IU
Systemic Lupus Erythematosus ✪✪✪✪✪
Clinical studies have shown that taking vitamin D3 (cholecalciferol) at 2000 IU per day or 50,000 IU per week appears to reduce anti-double-stranded DNA antibodies, a marker of disease activity, compared to placebo in patients with systemic lupus erythematosus.
Posologie
Oral
2000 IU
COVID-19 ✪✪✪✪✪
Evidence for the role of vitamin D in COVID-19 prevention is contradictory. Despite some observational research suggesting a low vitamin D level is associated with an increased COVID-19 risk, a large meta-analysis of observational studies revealed vitamin D deficiency in adults was not associated with an increased risk of COVID-19 infection. However, 65% more people with severe disease had vitamin D deficiency. Additionally, vitamin D insufficiency, defined by blood levels below 30 ng/mL, was associated with an over 80% increased risk of hospitalization or mortality due to COVID-19. However, many of these studies did not account for patient age or other comorbidities. Some research has also explored an association between the use of vitamin D supplements and rates of COVID-19 infection or disease severity. In the UK population, observation-based research revealed that habitual use of vitamin D supplements between 2006 and 2010 is associated with a 34% lower risk of COVID-19 infection. This result remained positive after adjusting for baseline health status and use of other micronutrients. However, a high-quality prospective clinical study, conducted on patients hospitalized for moderate to severe COVID-19, shows that taking a single oral dose of 200,000 IU of vitamin D3 does not reduce hospital stay duration compared to placebo. In addition, it does not affect in-hospital mortality, intensive care admission, or the need for ventilation. The majority of patients in this study were sufficient in vitamin D.
Posologie
Oral
400 - 1000 IU
Vitamin D Status Is Associated With In-Hospital Mortality and Mechanical Ventilation: A Cohort of COVID-19 Hospitalized Patients
Vitamin D supplementation, COVID-19 and disease severity: a meta-analysis
Vitamin D deficiency aggravates COVID-19: systematic review and meta-analysis
Vitamin D Insufficiency and Deficiency and Mortality from Respiratory Diseases in a Cohort of Older Adults: Potential for Limiting the Death Toll during and beyond the COVID-19 Pandemic?
Vitamin D concentrations and COVID-19 infection in UK Biobank
Habitual use of vitamin D supplements and risk of coronavirus disease 2019 (COVID-19) infection: a prospective study in UK Biobank
Association of Vitamin D Levels, Race/Ethnicity, and Clinical Characteristics With COVID-19 Test Results
Properties
Essential
Vitamin D plays a primary role in the regulation of calcium levels, phosphatemia, and bone homeostasis. The active metabolite of vitamin D, 1,25(OH)2D, exhibits both genomic and non-genomic effects. Genomic effects are well-known and involve a specific receptor, the vitamin D receptor (VDR) which is expressed in most cell types and thus is expressed in all tissues, meaning that nearly all cells are potential targets of calcitriol. This results in the effects of vitamin D on the regulation of genes involved in metabolic pathways as varied as calcium metabolism, proliferation, cell differentiation, inflammation, apoptosis, angiogenesis... Vitamin D and its metabolites are also responsible for non-genomic effects. These effects of calcitriol depend on a membrane receptor, the protein disulfide isomerase family A member 3 (Pdia3). The role of this receptor has been well described in enterocytes (a type of cell in the intestinal epithelium), where it participates in the rapid uptake of calcium. European health authorities have concluded that products containing vitamin D can claim to contribute to intestinal absorption and usage of calcium and phosphorus, to the maintenance of normal blood calcium levels, to normal bone growth in children, to the maintenance of normal bones, muscles, teeth, and the immune system, to cell division, and to the normal function of the immune system in children aged 3 to 18.
Usages associés
Bone density
Any calcitherapy or consumption of calcium-containing products must be associated with vitamin D, which in its di-hydroxylated form, is involved in the active mineral transport mechanism across the enterocyte wall. Recent studies indicate that 25(OH)D could directly modulate bone cells that possess not only specific receptors (VDR) but also the 1b1-hydroxylase necessary to convert the molecule into its active metabolite. Concerning the demonstration of bone effects of vitamin D, it is evident that secondary hyperparathyroidism that develops during a vitamin D deficiency is extremely deleterious because it causes an acceleration of resorption. For this reason, in cases of deficiency, supplementation can improve remodeling, mass, and bone consolidation.
Usages associés
Anticancer
In addition to bone mineralization and maintenance of calcium balance, 1,25-dihydroxyvitamin D has physiological functions, including the regulation of growth and differentiation of a large number of normal and malignant cells. It is known that cancer cells possess vitamin D receptors, which in turn, act on over 200 genes, some of which are involved in cancer development. Vitamin D acts on cancer cells by reducing their multiplication, by reducing proliferation risk (by decreasing their vascularization), inhibiting the transformation of precancerous cells into cancerous cells, and finally, by inducing apoptosis in some affected cells.
Usages associés
Cardiovascular
Cardiomyocytes, smooth muscle cells, and vascular endothelium express vitamin D receptors and 1-alpha hydroxylase (an enzyme involved in vitamin D metabolism). Genes overexpressed in myocardial hypertrophy, such as atrial natriuretic peptide, possess vitamin D response elements and are repressed by its active form (1,25(OH)2D) in animal models and cell cultures. This active form thus inhibits cardiomyocyte proliferation. However, it stimulates the proliferation of smooth muscle cells in vessels and the expression of VEGF (Vascular endothelial growth factor). Additionally, 1,25(OH)2D and its analog, paricalcitol, modulate the contractile performance of isolated rat and mouse cardiomyocytes.
Immuno-modulator
In the past decade, numerous data have shown that vitamin D has a protective effect against infections and autoimmune diseases. Indeed, vitamin D deficiency is a risk factor for the occurrence of type 1 diabetes (an autoimmune disease), inflammatory or autoimmune diseases (multiple sclerosis, psoriasis, rheumatoid arthritis, systemic lupus erythematosus), and infection (tuberculosis, winter respiratory episodes). However, clinical studies are mainly epidemiological, and randomized clinical trials have not yet reached definitive conclusions. At the cellular level, vitamin D could inhibit the TH1 lymphocyte pathway by stimulating the TH2 pathway, while at the cytokine level, activation of the VDR (specific vitamin D receptor) induces both a decrease in pro-inflammatory cytokines (tumor necrosis factor alpha, interleukin 1, interferon gamma) and an increase in anti-inflammatory cytokines (notably interleukin 10).
Usages associés
Musculoskeletal effects
Vitamin D affects both skeletal and smooth muscle. It appears to enhance the synthesis of muscle proteins. Vitamin D may prevent falls by increasing muscle strength and neuromuscular function in addition to strengthening bones. A deficiency in vitamin D causes muscle pain and proximal muscle weakness accompanied by symptoms such as heavy legs and rapid fatigue.
Hypoglycemic
Vitamin D is essential for normal insulin secretion. In fact, vitamin D impacts beta-cell function by ensuring the control of intracellular calcium flow, which facilitates the conversion of proinsulin to insulin, insulin exocytosis, and glycolysis. Demographic research has revealed that low levels of vitamin D are associated with a higher risk of developing type 2 diabetes compared to higher levels of vitamin D. Some preliminary clinical research suggests that vitamin D deficiency may contribute to impaired insulin secretion.
Usages associés
Neurological
Many researchers consider vitamin D as a neurosteroid. Indeed, there are vitamin D receptors in the central nervous system, including the brain, in areas such as the prefrontal cortex, hippocampus, thalamus, hypothalamus, and substantia nigra. In these regions, there are also enzymes that can convert storage vitamin D, 25(OH)D, into active vitamin D or 1,25(OH)2D. However, it is not very clear how vitamin D could influence the neurotransmitters involved in depression. It seems that active vitamin D increases the expression of genes that enable the synthesis of norepinephrine. It may also protect neurons that synthesize dopamine and serotonin. For example, a vitamin D deficiency could favor the development of Parkinson’s disease, characterized by the destruction of dopaminergic neurons in the brain's substantia nigra.
Usages associés
Safety dosage
Infant 7 to 11 months: 400 IU - 1400 IU (cholecalciferol)
The values relate to vitamin D in the form of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Child 1 to 10 years: 600 IU - 2000 IU (cholecalciferol)
The values relate to vitamin D in the form of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Adult from 18 years: 600 IU - 4000 IU (cholecalciferol)
The values relate to vitamin D in the form of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Lactating woman from 18 years: 600 IU - 4000 IU (cholecalciferol)
The values relate to vitamin D in the form of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Pregnant woman from 18 years: 600 IU - 4000 IU (cholecalciferol)
The values relate to vitamin D in the form of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Child 11 to 17 years: 600 IU - 4000 IU (cholecalciferol)
The values relate to vitamin D in the form of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Interactions
Médicaments
Atorvastatin: moderate interaction
Atorvastatin is metabolized in the gut by cytochrome P450 3A4 (CYP 3A4) enzymes. Vitamin D is thought to induce this enzyme, leading to decreased bioavailability of atorvastatin and other CYP3A4 substrates.
Calcium channel blocker: moderate interaction
High doses of vitamin D can cause hypercalcemia, which may reduce the efficacy of calcium channel blockers (verapamil, diltiazem).
Anticonvulsants: moderate interaction
Enzyme-inducing anticonvulsants like carbamazepine, phenytoin, and phenobarbital increase the hepatic metabolism of vitamin D into inactive compounds, thereby reducing calcium absorption.
Orlistat: strong interaction
Orlistat reduces the absorption of fat-soluble vitamins, including vitamin D, thereby decreasing its plasma levels in some patients.
