Studies about vitamin D and immunity:
Conclusion: The vitamin D levels of 70 children being treated for urinary tract infections were measured and compared to a group of 61 healthy children with no infection. The UTI group had a slightly lower average vitamin D level compared to the control group.
Conclusion: 60 adult tuberculosis patients were enrolled in a randomized, case-controlled clinical trial testing the effectiveness of vitamin D for TB treatment. All were taking anti-tuberculosis drugs, but half were given a one-time vitamin D dose of 200,000 IU. The vitamin D group experienced a “rapid decline” in their tuberculosis severity compared to the control group. The study also found that 90% of all the enrolled TB patients had low vitamin D levels. “Vitamin D accelerates the improvement observed in vitamin D supplemented TB therapy. Vitamin D is safe when added to anti-tuberculous drugs. Vitamin D deficiency/insufficiency is common among TB patients.”
Conclusion: In the somewhat recent past (and perhaps the future?), an effective treatment for curing severe infections (e.g. life-threatening staph and sepsis infections) was to withdraw 5-7% of a patient’s blood, irradiate it with ultraviolet light using a special machine, and then intravenously reintroduce the UV-treated blood back into the patient. This is known as the “Knott Technique,” named after the technique’s inventor Emmett Knott, or Ultraviolet Blood Irradiation (UBI). The treatment method was largely abandoned after the advent of antibiotics, but the rise of antibiotic-resistant pathogens is causing a renewed interest in blood irradiation.
Conclusion: 112 clostridium difficile infection patients who had their vitamin D levels measured within 3 months of their CDI diagnosis were evaluated – 56 patients with vitamin D deficiency and 56 patients with sufficient vitamin D levels. Researchers found that the deficient group suffered more severe cases featuring more days with diarrhea and a higher sepsis rate.
Conclusion: The vitamin D levels of 66 children with Hepatitis C were measured and compared to the vitamin D levels of 28 healthy, matched controls. The Hepatitis C group had a lower average vitamin D level compared to the control group.
Vitamin D Deficiency is Associated with Community-Acquired Clostridium Difficile Infections: A Case Control Study (2014)
Conclusion: Study compared the vitamin D levels of 58 people suffering from clostridium difficile infection and 58 matched healthy controls. The infection group had lower vitamin D levels than the controls. “Low serum 25(OH)D < 15 ng/mL was associated with increased risk of CA-CDI. This suggests vitamin D may have a role in determining susceptibility to CA-CDI.”
The Association Between Serum Vitamin D Levels of Vitamin D and Recurrent Urinary Tract Infections in Premenopausal Women (2013)
Conclusion: The vitamin D levels of 93 women with a history of recurrent urinary tract infections were measured and compared to 93 similar-aged women with no history of recurrent of urinary tract infections. The average vitamin D level of the women with UTI problems was less than half of the average vitamin D level of the healthy control group. The lowest vitamin D level found was a severe 4 ng/ml and this woman had suffered 6 UTIs in one single year. The highest level found was in the control group.
Influence of Vitamin D Status on Respiratory Infection Incidence and Immune Function During 4 Months of Winter Training in Endurance Sport Athletes (2013)
Conclusion: In a 4-month winter study of 225 endurance athletes it was found that those with the lowest vitamin D levels suffered more upper respiratory tract infections compared to those with optimal vitamin D levels. Athletes with good vitamin D levels who did get sick also tended to recover faster than the deficient athletes.
Note: Good article providing a basic overview of vitamin D’s role in immunity.
Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials (2013)
Conclusion: This is a meta-analysis of 11 placebo-controlled studies investigating the effect of vitamin D against respiratory tract infections. In total, the 11 studies included 5,660 patients as test subjects. This meta-analysis concluded that vitamin D does significantly improve immunity and provides a protective effect against respiratory tract infections. Also, interestingly, the meta-analysis found that daily dosing of vitamin D is more effective than occasionally mega-dosing.
Randomized Trial of Vitamin D Supplementation and Risk of Acute Respiratory Infection in Mongolia (2012)
Conclusion: In a randomized control trial involving 247 Mongolian schoolchildren during winter, those given a measly 300 IU of vitamin D daily through vitamin D-fortified milk experienced fewer acute respiratory infections compared to school children given non-fortified milk.
Vitamin D for Prevention of Respiratory Tract Infections: A Systematic Review and Meta-Analysis (2012)
Conclusion: This meta-analysis of five different clinical trials investigating the effect of vitamin D supplementation on reducing respiratory tract infections found that people who supplement with vitamin D are less likely to develop RTIs. “On the basis of this study, we can conclude that vitamin D is useful in prevention of respiratory tract infections.”
Effect of Vitamin D3 Supplementation on Upper Respiratory Tract Infections in Healthy Adults – The VIDARIS Randomized Controlled Trial (2012)
Conclusion: This 18-month-long randomized, double-blind, placebo-controlled trial of 322 healthy New Zealand adults tested the effect of high-dose oral vitamin D supplementation on upper respiratory tract infection rates. Subjects receiving the vitamin D were given 200,000 IU of vitamin D monthly the first two months and then 100,000 IU monthly for the rest of the 18 months. The vitamin D group had only a slightly lower rate of URTIs compared to the placebo group. 100,000 IU per month averages out to about 3,500 IU per day of vitamin D, which is probably not enough for the average adult. The researchers also speculate the possibility that daily dosing of vitamin D may be more effective than monthly mega-dosing. This study did find, however, that, contrary to what the medical establishment states, 3,500 IU of vitamin D daily is a perfectly safe long-term dose, did not cause a single case of hypercalcemia, and resulted in a consistent, year-round, optimal mean vitamin D level.
Vitamin D Insufficiency and Sepsis Severity in Emergency Department Patients with Suspected Infection (2011)
Conclusion: 81 emergency room patients being treated for suspected sepsis infection were evaluated for vitamin D deficiency. 79% had insufficient vitamin D levels. 67% of those with lower vitamin D levels (<30 ng/ml) developed severe sepsis, whereas only 29% of those with higher vitamin D levels (>30 ng/ml) developed severe sepsis. Those with lower vitamin D levels also suffered more organ failure and all of the fatalities were people with lower vitamin D levels.
Oral Supplementation With 25(OH)D3 Versus Vitamin D3: Effects on 25(OH)D Levels, Lower Extremity Function, Blood Pressure, and Markers of Innate Immunity (2011)
Conclusion: This 4-month study tested two different forms of vitamin D on 20 postmenopausal women with low vitamin D levels to compare the effectiveness of the forms on a variety of health markers. The two different forms of vitamin D were also given in two different ways each – either a daily maintenance dose of 800 IU or a weekly bolus dose of 5,600 IU. Despite being given two different forms of vitamin D at very low doses, all women experienced a significant increase in their vitamin D levels, a decrease in their parathyroid hormone levels, and increases in immunity. The study also found that there wasn’t much outcome difference for supplementing with a weekly mega-dose versus a daily maintenance dose.
Conclusion: In a year-long study of 41 NCAA division 1 athletes, it was found that those with lower vitamin D levels suffered more illnesses compared to athletes with higher vitamin D levels.
Note: Technical article explaining vitamin D’s role in immunity against infection.
Serum 25-Hydroxyvitamin D and the Incidence of Acute Viral Respiratory Tract Infections in Healthy Adults (2010)
Conclusion: People who maintain adequate vitamin D levels have a significantly lower risk of developing viral respiratory tract infections.
Randomized Trial of Vitamin D Supplementation to Prevent Seasonal Influenza A in Schoolchildren (2010)
Conclusion: In this randomized, double-blind, placebo-controlled trial involving 334 school children over a 4-month period, the vitamin D group experienced nearly 50% fewer colds and even fewer asthma attacks compared to the placebo group.
Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey (2009)
Conclusion: People with higher vitamin D levels experience fewer upper respiratory tract infections.
Low Serum 25-Hydroxyvitamin D Level and Risk of Upper Respiratory Tract Infection in Children and Adolescents (2008)
Conclusion: 743 children were observed during flu season from December to January, during which time their vitamin D levels were measured. The median vitamin D level of the group was an inadequate 25 ng/ml and 229 of the kids (30%) developed an upper respiratory tract infection during this study. Those with lower vitamin D levels were found to have a much higher rate of infection compared to those with higher vitamin D levels. Kids with levels below 30 ng/ml had a 50% higher rate and those with levels below 20 ng/ml had a 70% higher rate.
Note: Extremely comprehensive overview of the evidence linking vitamin D deficiency, sun exposure deficiency, and seasonal changes in solar radiation on influenza rates.
Note: Technical article explaining vitamin D’s role in immunity as it relates to infection, autoimmune disease, and transplant tolerance.
Conclusion: “Low vitamin D levels were associated with a 5-fold increased risk for progression to tuberculosis” in a study of Pakistan tuberculosis cases.
Conclusion: Tuberculosis rates were higher among people with lower vitamin D levels in this study.
Conclusion: Regular sun exposure increases immunity in children.
Cod Liver Oil: A Five-Year Study of its Value for Reducing Industrial Absenteeism Caused by Colds and Respiratory Disease (1936)
Conclusion: In a five-year study, daily ingestion of vitamin D-rich cod liver oil was found to be effective for reducing the number of colds worker’s experienced.
Conclusion: This study exposed five different groups of people to varying amounts of UV light to see what effect this would have on the number of colds they suffer. The groups which received more UV irradiation suffered “27.9” fewer colds than those who received less or no supplementary UV exposure over the course of the study.