Vitamin D Science

Vitamin D Research

Vitamin D is one of the oldest hormones, having been produced by life forms for over 750 million years. Phytoplankton, zooplankton, and most animals that are exposed to sunlight have the capacity to make vitamin D. In humans, vitamin D is critically important for the development, growth, and maintenance of a healthy body, from gestation until death.

We invite you to browse the various studies to be found in the sections below and see for yourself the scientific evidence of just how vital vitamin D is to life. To view listing of studies for an area of interest, click on corresponding heading below. Note: Lists are not all-inclusive.

Announcement: Due to the time-intensive project currently underway of our complete website overhaul, we are unable to keep our Vitamin D Research section updated with the latest research. We apologize for the inconvenience, but would like to assure you that our new website — with full PubMed integration — will have all the latest research on vitamin D, updated in real time.

Research Areas

• Addison's Disease Data suggest that VDR genotype is associated with Addison's disease and that a considerable proportion of patients on long-term glucocorticoid replacement therapy are at increased risk for osteoporosis.
• Allergic Hypersensitivity There is evidence that vitamin D3 could modulate allergic contact dermatitis by its clearly demonstrated suppressive effects on the activation of dendritic cells. In one study, a 2-week course of heliotherapy caused a marked healing of atopic dermatitis.
• Alzheimer's Disease In a cross-sectional study, vitamin-D-sufficient Alzheimer patients had significantly higher Mini-Mental State Examination scores as compared to vitamin-D-insufficient ones, indicating a relationship between vitamin D status and cognition in patients.
• Ankylosing Spondylitis Evidence indicates that high disease activity in Ankylosing Spondylitis is associated with an alteration in vitamin D metabolism and increased bone resorption and that interaction of the vitamin D system, cytokines, and bone could define new diagnostic and therapeutic implications.
• Asthma Evidence suggests maternal vitamin D intake during pregnancy is inversely associated with asthma symptoms in early childhood and lower vitamin D levels in children are associated with increased markers of asthma severity.
• Autism Research has shown that low maternal vitamin D3 has important ramifications for the developing brain. Vitamin D is a steroid hormone with many important functions in the brain, mediated through the nuclear vitamin D receptor (VDR). Disfunctional VDR demonstrate altered emotional behavior and specific motor deficits.
• Autoimmune Illness Researchers are discovering an increasing number of links between the immune, nervous, and endocrine systems. Hormones of the endocrine system, such as vitamin D, help the immune and nervous systems defend the body, with defects in this intricate system leading to autoimmune disorders.
• Benign Prostatic Hyperplasia Research shows that VDR genotype plays an important role in determining the risk of benign prostatic hyperplasia (BPH) and that vitamin D analogs are able to arrest prostate growth in BPH patients.
• Best Science Breakthrough science that has played a significant role in broadening humanity's understanding of vitamin D and its importance in the maintenance of health.
• Bladder Cancer Data suggest that VDR (Fok-I) polymorphism is associated with the risk of bladder cancer and that UVB radiation is inversely related to bladder cancer risk.
• Brain Cancer Research shows 1,25(OH)2D3 induces glioma cell death, making the hormone of potential interest in the management of brain tumors. Evidence also shows that vitamin D analog 1 alpha-hydroxyvitamin D2 inhibits growth of human neuroblastoma and that solar UV irradiance is inversely related to brain cancer risk.
• Breast Cancer Studies show women with low levels of vitamin D have a 222% increased risk for developing breast cancer. Ecologic studies have shown an inverse correlation between breast cancer mortality and sun exposure and dietary vitamin D intake. Blood levels of vitamin D at the time of diagnosis of breast cancer accurately predict a woman's survival. The cancer is much more aggressive in those with low serum vitamin D levels: they are 94% more likely to have the cancer metastasize and 73% more likely to die within 10 years of diagnosis.
• Cancer Vitamin D inhibits inappropriate cell division and metastasis, reduces blood vessel formation around tumors, and regulates proteins that affect tumor growth. It also enhances anti-cancer actions of immune system chemicals and chemotherapy drugs.
• Celiac Disease Due to malabsorption, patients with Celiac Disease have a high prevalence of calcium and vitamin D deficiencies, and are therefore at increased risk of bone disease, such as rickets, osteomalacia, or osteoporosis.
• Cerebral Palsy Adequate vitamin D levels are particularly important for children with cerebral palsy or other neuromuscular disorders who are at an increased risk of osteoporosis.
• Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease includes two main conditions: emphysema and chronic obstructive bronchitis. Research indicates an association between vitamin D binding protein (VDBP) gene, vitamin D deficiency, and COPD susceptibility.
• Chronic Pain Vitamin D deficiency is a major contributor to chronic low back pain as well as persistent, nonspecific musculoskeletal pain.
• Cognitive Function Recent research indicates vitamin D deficiency is associated with low mood and cognitive impairment in the elderly.
• Colon and Rectal Cancer Both circulating 25(OH)D and vitamin D intake are inversely associated with colorectal adenoma incidence and recurrent adenomas. Recent studies suggest that women who are vitamin D deficient have a 253% increased risk for developing colorectal cancer.
• Commentaries and Editorials Commentaries and editorials written by vitamin D scientists and experts as published in the medical journals.
• Cystic Fibrosis The prevalence of vitamin D deficiency and poor skeletal health is high in patients with cystic fibrosis (CF). Studies show cholecalciferol increases serum 25(OH)D concentrations significantly in CF patients, with the maximum response occuring in persons with the lowest baseline concentrations.
• Depression and Seasonal Affective Disorder Depression severity has been shown to be significantly associated with decreased serum 25(OH)D levels. In one study, in those who had both major and minor depression, vitamin D levels were 14% lower than in people who did not suffer from depression.
• Diabetes Vitamin D helps maintain adequate insulin levels. Preliminary evidence suggests supplementation can increase insulin levels in people with type 2 diabetes. Prolonged supplementation may help reduce blood sugar levels.
• Endometrial Cancer In an ecological study of 107 countries, an inverse association was found between ultraviolet B irradiance and endometrial cancer, indicating the role of UVB and vitamin D in risk-reduction of endometrial cancer.
• Epilepsy Research shows that cholecalciferol may play an anticonvulsant role in the brain and can influence the efficacy of antiepileptic drugs.
• Ethnicity Ethnicity is an important factor in the determination of vitamin D status of an individual, due somewhat to dietary factors but mostly to skin coloration. Those with darker pigmentation are at much higher risk of vitamin D deficiency than those who are lighter-skinned.
• Eye Cancer Eye cancer includes intraocular melanoma and retinoblastoma. In athymic mice in both a large-tumor study and a long-term study, vitamin D analog 1alpha-OH-D(2) was effective in inhibiting retinoblastoma tumor growth compared with controls.
• Gastrointestinal Function Absorption of vitamin D from the intestine is negatively impacted by a number of gastrointestinal diseases and in the evaluation of a patient with vitamin D deficiency or insufficiency, a gastrointestinal etiology should be considered.
• Gaucher's and Fabry's Disease Research indicates vitamin D deficiency is frequent among Gaucher's disease patients and that vitamin D supplementation should be recommended to optimize treatment. Multivariate models of haplotypes of the VDR gene polymorphisms are significantly associated with variation in the Fabry phenotype.
• Genetics The hormone 1,25-dihydroxyvitamin D3 influences the growth and differentiation of a number of cell types by regulating the expression of key target genes. These functions are mediated through the vitamin D receptor (VDR); therefore, an understanding of the regulation of VDR expression is important when considering the molecular mechanisms of differentiation induced by vitamin D3 and its analogues.
• Graves' Disease Research shows vitamin D receptor gene polymorphisms are associated with Graves' disease in many ethnic groups and that patients with Graves' disease have a different pattern of seasonality of birth when compared with the general population.
• Hashimoto's Thyroiditis Data suggest that common haplotypic variants within the VDR gene 3' region may be involved in the pathogenesis of Hashimoto's Thyroiditis.
• Heart Disease Studies have indicated reduced ultraviolet B exposure in CHF patients during childhood, adolescence, and early adulthood. Activated vitamin D has been shown to increase survival in patients with cardiovascular disease. In one study, severe heart failure due to hypocalcemia was fully resolved after 15 months of supplementation with calcium and vitamin D.
• HIV and AIDS An inverse association between 1,25(OH)2D concentrations and mortality has been reported from a small cohort study of HIV-infected adults, and some cross-sectional studies have indicated positive correlations between 1,25(OH)2D and CD4+ cell counts. Studies also suggest that VDR haplotypes might influence the risk of HIV-1 acquisition.
• Hypertension Clinical and experimental data support the view that vitamin D metabolism is involved in blood pressure regulation and other metabolic processes.
• Inflammatory Bowel Disease The active form of vitamin D, 1,25(OH)2D3, has been shown to inhibit development of inflammatory bowel disease and play a critical role in the response of the colon to chemical injury.
• Influenza Recent discoveries indicate vitamin D upregulates the endogenous antibiotics of innate immunity. It is hypothesized that vitamin D's seasonal and population effects on innate immunity are a major factor in the epidemiology of influenza. (Note: Page also includes research on the effects of ultraviolet light on the influenza virus.)
• Innate and Adaptive Immunity People with low levels of vitamin D are 40% more likely to report respiratory infections such as colds and flu. Research indicates that infants and children appear more susceptible to viral rather than bacterial infections in the face of vitamin D deficiency. The connection between vitamin D, infections, and immune function in the pediatric population indicates a possible role for vitamin D supplementation in potential interventions and adjuvant therapies.
• Liver Cancer Studies indicate that Seocalcitol, a vitamin D analog, is an effective growth inhibitor of hepatocellular cancer tumors and that calcitriol (activated vitamin D) inhibits the growth of MHCC-97 heptocellular cell lines.
• Liver Function Diseases of the liver can impact the metabolism of vitamin D to its circulating form, 25(OH)D. Research shows that VDR is expressed in human hepatocytes and may play a critical role in the inhibition of bile acid synthesis, thus protecting liver cells during cholestasis.
• Lung Cancer In vitro studies, performed with lung cancer cell lines, have shown an inhibitive effect of vitamin D derivatives on cell-growth and proliferation. In one prospective cohort study, women with the highest vitamin D blood levels were 84% less likely to develop lung cancer. Young participants with the highest levels were 66% less likely to have the disease.
• Lymphoid Cancer Lymphoid cancer includes lymphoma, myeloma, and leukemia. Studies suggest sunlight has a protective effect against non-Hodgkin lymphoma. Epidemiological data indicate season of diagnosis is a strong prognostic factor for Hodgkin's lymphoma, with approximately 20% lower case fatality for patients diagnosed during autumn (as opposed to winter) and an autumnal survival rate higher than 60% for patients younger than 30 years. This may be the result of higher endogenous levels of vitamin D in autumn.
• Melanoma An inability to tan is the number one risk factor for melanoma. Those who tan easily or who have darker skin are far less likely to develop the disease. A new theory is that melanoma is actually caused by sunlight (vitamin D) deficiency and that safe sun exposure actually helps prevent the deadly disease.
• Mental Illness Vitamin D deficiency has been implicated in various psychiatric and neurologic disorders.
• Mineral Metabolism Vitamin D is well known for its involvement in mineral metabolism, especially its necessity in the facilitation of intestinal absorption of calcium. Vitamin D also stimulates absorption of phosphate and magnesium ions.
• Mortality Low vitamin D status is being associated with a multitude of diseases and higher overall mortality. (Note: page includes studies on all-cause mortality as well as mortality related to specific health issues.)
• Multiple Sclerosis Epidemiological evidence combined with clinical and laboratory analyses, and experimental animal models, suggest a possible influence of vitamin D on MS susceptibility as well as clinical disease activity.
• Muscular Weakness and Falls Specific receptors for vitamin D have been identified in human muscle tissue. Cross-sectional studies show that elderly persons with higher vitamin D serum levels have increased muscle strength and a lower number of falls.
• Obesity Serum vitamin D is significantly lower in obese individuals, putting them at increased risk for the many health disorders related to vitamin D deficiency.
• Osteoarthritis Low intake and low serum levels of vitamin D appear to be associated with an increased risk for progression of osteoarthritis.
• Osteomalacia Osteomalacia is most often caused by a prolonged lack of vitamin D. Treating osteomalacia with vitamin D and calcium has been shown to be highly effective.
• Osteopenia Vitamin D intake level in adolescence, and the course of vitamin D intake from adolescence into adulthood, are positively related with bone mineral density in adulthood.
• Osteoporosis Research indicates a diet rich in calcium, other minerals, and vitamin D in association with physical activity represents the most effective way to lower osteoporosis risk.
• Otosclerosis Research indicates vitamin D deficiency is possibly a factor in the etiology of otosclerosis. Calcium and vitamin D replacement therapy has resulted in significant hearing improvement in some otosclerotic patients.
• Ovarian Cancer Epidemiological data indicate a positive association between higher latitude and ovarian cancer incidence and mortality rates, suggesting that vitamin D insufficiency may contribute to ovarian cancer development.
• Pancreatic Cancer Ecological studies associate sun exposure with lower death rates for pancreatic cancer. In two United States cohort studies, higher intakes of vitamin D were associated with lower risks for pancreatic cancer, indicating a potential role for vitamin D in the pathogenesis and prevention of pancreatic cancer.
• Parathyroid Function Low plasma vitamin D3 is quite common in patients with parathyroid disease.
• Parkinson's Disease Chronically inadequate vitamin D intake is hypothesized, due to several lines of documented evidence, to be a significant factor in the pathogenesis of Parkinson's Disease.
• Pediatrics Research indicates vitamin D deficiency is common in children and adolescents worldwide, even if they are healthy. In a US study, the prevalence was highest in African American teenagers and during winter, although the problem seemed to be common across sex, season, and ethnicity.
• Pharmacology Though several vitamin D analogues have been shown to be effective in various studies, the effectiveness of plain vitamin D3 cholecalciferol continues to remain superior.
• Physiology Since its discovery, the nuclear vitamin D receptor (VDR) has been found to be present in over 30 tissues and organs of man, indicating a broad sphere of influence over health and vitality.
• Postmenopause Serum 25-hydroxyvitamin D levels have an independent inverse association with total body and regional fat mass in nonosteoporotic, overweight, postmenopausal women. Adequate vitamin D intake should be encouraged for all postmenopausal women to reduce bone loss.
• Pregnancy and Lactation Due to widespread vitamin D deficiency, most human breast milk is deficient in vitamin D. Studies show high-dose vitamin D (4000 IU/day) is effective and safe in increasing 25(OH)D levels in breastfeeding mothers to optimal levels, without evidence of toxicity or any vitamin D-related adverse events to mother or infant.
• Premenstrual Syndrome Studies show a significant association between low 25(OH)D levels and higher incidence of premenstrual syndrome (PMS). Treatment with calcium plus vitamin D decreases symptom severity in women with PMS.
• Prostate Cancer Research shows that men with higher vitamin D levels are 50% less-likely to develop aggressive forms of prostate cancer than those with lower levels. Calcitriol, the active form of vitamin D, significantly limits the ability of prostate cancer cells to invade healthy cells. In one study, patients with the highest vitamin D levels (>32 ng/mL) were 7 times less-likely to die from their prostate cancer over the 3.5 years of the study.
• Renal Function A high proportion of renal patients are vitamin D deficient/insufficient. Research indicates cholecalciferol supplementation is an effective treatment to correct vitamin D status in patients with chronic kidney disease.
• Requirements Research indicates that well adults and adolescents should receive at least 5,000 IU vitamin D3 per day (either from sunlight or supplementation) to achieve blood levels in the desired range of 50–80 ng/mL. For adults, the 5 microgram (200 IU) vitamin D recommended dietary allowance may prevent osteomalacia in the absence of sunlight, but much more is needed to help prevent osteoporosis, secondary hyperparathyroidism, and all other vitamin D deficiency-related diseases.
• Reviews Peer-reviewed papers on vitamin D.
• Rheumatoid Arthritis Evidence of the role of vitamin D in the regulation of T cells and B cells, macrophages, dendritic cells, and keratinocytes continues to accumulate and provides a link between vitamin D and many autoimmune diseases, including rheumatoid arthritis.
• Rickets Vitamin D deficiency rickets is considered to be the most common non-communicable disease of children worldwide. Research shows daily vitamin D supplementation of 400 IU/L or more prevents rickets in infants and young children.
• Sarcoidosis Many studies suggest an association between Gc-globulin phenotypes and resistance, or susceptibility, to sarcoidosis. Although sarcoidosis frequently causes a dysregulation of vitamin D production, sarcoidotic patients should generally be advised to avoid sun exposure due to a high prevalence of complications with co-existent hypercalcemia.
• Sickle Cell Disease Vitamin D deficiency is common in children with homozygous SS sickle cell disease (SCD-SS) due to their increased skin melanin concentrations, reduced levels of physical activity, and poor vitamin D intake. Treatment of adult sickle cell disease with vitamin D and calcium has been shown to restore 25(OH)D levels to normal and improve bone mineral density.
• Skin Cancer Studies reveal a critical role for VDR in the repair and removal of severely damaged keratinocytes and adaptation of the skin to chronic UV exposure.
• Stroke Low levels of 25(OH)D and 1,25(OH)2D are independently predictive for fatal strokes, suggesting that vitamin D supplementation is a promising approach in the prevention of strokes. Data also indicate that vitamin D3 reduces ischemia-induced brain damage.
• Toxicity One of the least toxic substances to humans, overdose of vitamin D3 doesn't occur until more than 100 times (approximately one bottle of vitamin D3 tablets) the daily RDA has been taken daily for several months. Acute, one-time overdoses require over 50 mg (10,000 times the RDA).
• Toxin and Radiation Exposure Research indicates vitamin D is a significant factor in detoxification and protection against environmental toxins and that vitamin D3 may protect hair follicles from radiation toxicity.
• Treatment Vitamin D has proven to be a safe and effective treatment for a wide range of health disorders.
• Tuberculosis Vitamin D receptor (VDR) genotypes have been shown to be associated with differential susceptibility or resistance to tuberculosis.
• Turner's Syndrome Women and girls with Turner syndrome (TS) generally have a lower bone mineral density (BMD) and have been shown to have a 25% higher risk of fracture. Studies show that 1,25(OH)2D3 administration raises serum osteocalcin levels in those with TS.
• UV Exposure Sunlight has an enormous impact on health via the skin's neuroendocrine system. Exposure to UVB enables the body to build a strong skeletal structure, heart, and muscles as well as optimize the immune system and utilization of sugar. Compared with nontanners, tanners have been found to have robust levels of 25-hydroxyvitamin D at winter's end and, as a result, higher bone density.
• Veterinary and Animal Studies Animal and veterinary research wherein vitamin D is listed as a factor.
• Vitamin D Deficiency Vitamin D Deficiency is a world-wide epidemic, with over one billion people at risk for its associated diseases.
• Worst Science The Vitamin D Council reviews three studies which, due to their faulty science, have done a grave disservice to humanity by preventing adequate vitamin D nutrition.