Friday, May 8, 2015
Vitamin D Fights Asthma
According to an article published September, 2010 in Annals of Allergy, Asthma & Immunology, the scientific journal of the American College of Allergy, Asthma and Immunology (ACAAI): “There is a possible cause-and-effect relationship between vitamin D deficiency and uncontrolled asthma. Evidence suggests that vitamin D has a number of biologic factors that are important in regulating key mechanisms in asthma.”
Authors conducted a review of almost 60 years of literature on vitamin D and asthma. According to the article, vitamin D deficiency is associated with increased airway hyperresponsiveness, lower lung functions, and inferior asthma control. Vitamin D deficiency is more common with obesity, in African American ethnicity and westernization of countries reflecting a higher-risk population for asthma.
Low vitamin D levels associated with more asthma symptoms and medication use
Low levels of vitamin D are associated with lower lung function and greater medication use in children with asthma, according to researchers at National Jewish Health. In a paper published online in the Journal of Allergy & Clinical Immunology, Daniel Searing, MD, and his colleagues also reported that vitamin D enhances the activity of corticosteroids, the most effective controller medication for asthma.
"Asthmatic children in our study who had low levels of vitamin D were more allergic, had poorer lung function and used more medications," said Dr. Searing. "Conversely, our findings suggest that vitamin D supplementation may help reverse steroid resistance in asthmatic children and reduce the effective dose of steroids needed for our patients."
The researchers examined electronic medical records of 100 pediatric asthma patients referred to National Jewish Health. Overall, 47 percent of them had vitamin D levels considered insufficient, below 30 nanograms per milliliter of blood (ng/mL). Seventeen percent of the patients had levels below 20 ng/mL, which is considered deficient. These levels were similar to vitamin D levels found in the general population.
Patients low in vitamin D generally had higher levels of IgE, a marker of allergy, and responded positively to more allergens in a skin prick test. Allergies to the specific indoor allergens, dog and house dust mite, were higher in patients with low vitamin D levels. Low vitamin D also correlated with low FEV1, the amount of air a person can exhale in one second, and lower FEV1/FVC, another measure of lung function. Use of inhaled steroids, oral steroids and long-acting beta agonists were all higher in patients low in vitamin D.
"Our findings suggest two possible explanations," said senior author Donald Leung, MD, PhD. "It could be that lower vitamin D levels contribute to increasing asthma severity, which requires more corticosteroid therapy. Or, it may be that vitamin D directly affects steroid activity, and that low levels of vitamin D make the steroids less effective, thus requiring more medication for the same effect."
The researchers performed a series of laboratory experiments that indicated vitamin D enhances the action of corticosteroids. They cultured some immune cells with the corticosteroid dexamethasone alone and others with vitamin D first, then dexamethasone. The vitamin D significantly increased the effectiveness of dexamethasone. In one experiment vitamin D and dexamethasone together were more effective than 10 times as much dexamethasone alone.
Study links rheumatoid arthritis to vitamin D deficiency
Women living in the northeastern United States are more likely to develop rheumatoid arthritis (RA), suggesting a link between the autoimmune disease and vitamin D deficiency, says a new study led by a Boston University School of Public Health researcher.
In the paper, which appears online in the journal Environmental Health Perspectives, a spatial analysis led by Dr. Verónica Vieira, MS, DSc, associate professor of environmental health, found that women in states like Vermont, New Hampshire and southern Maine were more likely to report being diagnosed with RA.
"There's higher risk in the northern latitudes," Dr. Vieira said. "This might be related to the fact that there's less sunlight in these areas, which results in a vitamin D deficiency."
The study looked at data from the Nurses' Health Study, a long-term cohort study of U.S. female nurses. Looking at the residential addresses, health outcomes and behavioral risk factors for participants between 1988 and 2002, researchers based their findings on 461 women who had RA, compared to a large control group of 9,220.
RA is a chronic inflammatory disease that affects the lining of the joints, mostly in the hands and knees. This chronic arthritis is characterized by swelling and redness and can wear down the cartilage between bones. RA is two to three times more common in women than in men.
Although the cause of RA is unknown, the researchers wrote, earlier studies have shown that vitamin D deficiency, which can be caused by a lack of sunlight, has already been associated with a variety of other autoimmune diseases.
"A geographic association with northern latitudes has also been observed for multiple sclerosis and Crohn's disease, other autoimmune diseases that may be mediated by reduced vitamin D from decreased solar exposure and the immune effects of vitamin D deficiency," the authors wrote.
The authors said further research is needed to look into the relationship between vitamin D exposure and RA.
Dr. Vieira said she and her co-authors were somewhat surprised by the findings. A previous geographic study of RA had suggested an ecologic association with air pollution, she said.
"The results were unexpected," Dr. Vieira said. "Prior to the analysis, we were more interested in the relationship with air pollution. I hadn't given latitudes much thought."
In addition to the geographic variation, the study suggested that the timing of residency may influence RA risk. "Slightly higher odds ratios were observed for the 1988 analysis suggesting that long term exposure may be more important than recent exposure," the study said.
Sunlight may help ward off rheumatoid arthritis in women
Regular exposure to sunlight—specifically ultraviolet B (UVB)—may reduce the risk of developing rheumatoid arthritis, indicates a large long term study published online in the Annals of the Rheumatic Diseases.
But the effect of UVB exposure was only evident among older women, possibly because younger women are more aware of the hazards of sunlight and so cover up with sun block, suggest the authors.
They base their findings on participants in two phases of the US Nurses' Health Study (NHS), the first of which has tracked the health of more than 120,000 nurses since 1976, when they were aged between 30 and 55, until 2008.
The second (NHSII) has tracked the health of a further 115,500 nurses since 1989, when they were aged between 25 and 42, until 2009.
Rather than simply relying on geography to quantify likely levels of UVB exposure, the researchers used a more sensitive assessment, known as UV-B flux, which is a composite measure of UVB radiation, based on latitude, altitude, and cloud cover.
It is measured in R-B units: a count of 440 R-B units over 30 minutes, for example, is sufficient to produce slight redness in untanned white skin.
Exposure was then estimated according to the US state of residence, and ranged from an annual average of 93 in Alaska and Oregon to 196 in Hawaii and Arizona. Likely estimates of UV exposure at birth and by the age of 15 were also included.
Over the study period, 1314 women developed rheumatoid arthritis. Among nurses in the first NHS cohort, higher cumulative exposure to UVB was associated with a reduced risk of developing the disease.
Those with the highest levels of exposure were 21% less likely to develop rheumatoid arthritis than those with the least, the analysis showed.
This backs up the findings of other studies, showing a link between geography and the risk of rheumatoid arthritis as well as other autoimmune conditions, including type 1 diabetes, inflammatory bowel disease, and multiple sclerosis, say the authors.
But no such association for UV-B exposure was found among women in NHSII. These women were younger than those in the first NHS, and so might have been more savvy about the potential hazards of acquiring a tan, suggest the authors.
"Differences in sun protective behaviours (eg greater use of sun block in younger generations) may explain the disparate results," they explain.
They add that it is unclear at what stage of life the protective effect of UV-B occurs. Many of the study participants didn't move house between birth and their teens, and there was no difference in the results for these time points.
But they conclude: "Our study adds to the growing evidence that exposure to UV-B light is associated with decreased risk of rheumatoid arthritis. The mechanisms are not yet understood, but could be mediated by the cutaneous production of vitamin D and attenuated by use of sunscreen or sun avoidant behaviour."
Vitamin D fights chronic digestive conditions
New research points to a potential role for UV light exposure and vitamin D levels in chronic digestive conditions; Crohn's disease, a serious inflammatory condition in the small intestine; and ulcerative colitis (UC), which similarly affects the colon.
In two separate studies presented at the American College of Gastroenterology's 76th Annual Scientific Meeting, (2011) a group of investigators from Massachusetts General Hospital probed the connection between geography, UV exposure and incidence of inflammatory bowel disease while another group from Weill Cornell Medical Center looked at different levels of supplementation with Vitamin D to determine impact on severity of Crohn's disease.
"Geographic Variations and Risk of Crohn's Disease and Ulcerative Colitis"
Results from two large prospective studies among large cohorts of nurses enrolled in the U.S. Nurses Health Study I and II revealed a significant north-south gradient in the association between latitude and incidence of Crohn's disease and ulcerative colitis in the United States. Such geographic variation has been reported in Europe, however comparable data in the United States are lacking, so this study advances understanding of the epidemiology of chronic inflammatory bowel disease, which affects as many as 1.4 million patients in the United States.
"This differential risk may be explained by differences in UV light exposure, vitamin D status, or pollution," explained Dr. Hamed Khalili, who, along Dr. Andrew Chan and colleagues at Massachusetts General Hospital, analyzed data that included a 4,209,454 person-year follow up in which they confirmed 284 cases of Crohn's disease and 332 cases of ulcerative colitis.
While the mean age of diagnosis among the women was 51 for Crohn's and 48 for UC, the investigators found that the women's geographic location at age 30 was strongly associated with incidence of disease. Based on geographic location at age 30, compared to women in northern latitudes, women in southern latitudes had an adjusted hazard ratio of 0.51 for Crohn's and 0.65 for UC suggesting that the risk of disease is 50% and 35% lower in the southern latitudes compared to northern latitudes for CD and UC, respectively. Further studies are warranted on underlying lifestyle and environmental factors that mediate this association, as well as their interaction with known genetic risk factors for CD and UC.
"High-dose Vitamin D3 Improves Clinical Activity in Crohn's Disease"
Results of an interim analysis of the first 15 patients in a study conducted at Weill-Cornell Medical and presented at the ACG Annual Scientific Meeting by Dustin Boothe, MD, sought to determine if high doses of Vitamin D3 supplementation in Vitamin D deficient patients with Crohn's disease leads to improved clinical outcomes.
Two groups of patients with Crohn's disease, who had baseline levels of Vitamin D that were low, were randomized to either low-dose (1,000 IU/day) or high-dose (10,000 IU/day) Vitamin D treatment and assessed at day 1, and after 8 weeks and 26 weeks of treatment. The investigators measured the patients's symptom severity using the Harvey-Bradshaw Index (HBI) an index of disease activity in Crohn's.
Results from the first 15 patients suggest that after 26 weeks of therapy, there were persistently significant differences in Vitamin D levels between the high-dose and low-dose groups, but importantly the low-dose group had no significant change in disease activity as measured by HBI at 26 weeks compared to baseline, whereas the high dose group did.
"Our interim analysis suggests that supplementation with 10,000 IU of Vitamin D3 may be an effective adjunctive therapy for ameliorating symptoms in Crohn's disease patients," commented Dr. Boothe on the presentation of these preliminary data.
Vitamin D Supplements Could Fight Crohn's Disease
A new study has found that Vitamin D, readily available in supplements or cod liver oil, can counter the effects of Crohn's disease. John White, an endocrinologist at the Research Institute of the McGill University Health Centre, led a team of scientists from McGill University and the Universite de Montreal who present their findings about the inflammatory bowel disease in the Journal of Biological Chemistry test.
"Our data suggests, for the first time, that Vitamin D deficiency can contribute to Crohn's disease," says Dr. White, a professor in McGill's Department of Physiology, noting that people from northern countries, which receive less sunlight that is necessary for the fabrication of Vitamin D by the human body, are particularly vulnerable to Crohn's disease.
Vitamin D, in its active form (1,25-dihydroxyvitamin D), is a hormone that binds to receptors in the body's cells. Dr. White's interest in Vitamin D was originally in its effects in mitigating cancer. Because his results kept pointing to Vitamin D's effects on the immune system, specifically the innate immune system that acts as the body's first defense against microbial invaders, he investigated Crohn's disease. "It's a defect in innate immune handling of intestinal bacteria that leads to an inflammatory response that may lead to an autoimmune condition," stresses Dr. White.
Dr. White and his team found that Vitamin D acts directly on the beta defensin 2 gene, which encodes an antimicrobial peptide, and the NOD2 gene that alerts cells to the presence of invading microbes. Both Beta-defensin and NOD2 have been linked to Crohn's disease. If NOD2 is deficient or defective, it cannot combat invaders in the intestinal tract.
What's most promising about this genetic discovery, says Dr. White, is how it can be quickly put to the test. "Siblings of patients with Crohn's disease that haven't yet developed the disease might be well advised to make sure they're vitamin D sufficient. It's something that's easy to do, because they can simply go to a pharmacy and buy Vitamin D supplements. The vast majority of people would be candidates for Vitamin D treatment."
"This discovery is exciting, since it shows how an over-the-counter supplement such as Vitamin D could help people defend themselves against Crohn's disease," says Marc J. Servant, a professor at the Universite de Montreal's Faculty of Pharmacy and study collaborator. "We have identified a new treatment avenue for people with Crohn's disease or other inflammatory bowel diseases."
Vitamin D protects against diarrhea and colitis
A new study shows that patients with low vitamin D levels who develop Clostridia difficile (C. diff) have a higher recurrence rate and possibly higher hospital mortality. C. diff is a bacterium that causes diarrhea and more serious intestinal conditions such as colitis, and often occurs after taking antibiotics.
Previous studies have shown that normal levels of vitamin D are associated with improved outcomes in hospitalized patients, and conversely, low levels of vitamin D have been associated with higher mortality rate in hospitalized patients. Investigators at New York Hospital Queens –Weill Cornell Medical College, led by Moshe Rubin, MD, director of gastroenterology, sought to determine whether vitamin D levels are associated with a persons' ability to resolve their infection.
Researchers tracked 83 patients who had been admitted to the hospital who were then diagnosed with C. diff. They measured vitamin D levels in all of the patients, then followed their hospital course. Researchers noted how many patients were still alive after 30 days, and compared the outcome of patients with normal vitamin D levels to those with low levels. They found that up to 40 percent of people, especially in an older age group with multiple illnesses, died from some cause if they developed C. diff during that hospitalization.
Furthermore, while they may not die from C. diff, Dr. Rubin said it definitely adds a major complication that contributes to high mortality.
Researchers found that those with normal levels of vitamin D had a higher resolution rate, and a lower recurrence rate than those with low vitamin D levels. These findings are consistent with what is currently understood about vitamin D — it plays a role in immune function, may be an important factor in fighting infection, low levels seem to be a marker for not resolving diseases in general and it is associated with higher mortality rates.
Sixty-two patients were tracked for 30 days; 45 percent had normal vitamin D levels while 55 percent had low vitamin D levels. In the normal vitamin D group, they found 53 percent remained disease-free for 30 days, but in the group with low vitamin D levels, only 26 percent resolved their C. diff infections. Dr. Rubin noted that since this study was observational, it does not prove a cause and effect relationship between vitamin D levels and recurrence of C. diff, but it does identify an association.
Dr. Rubin said that since the study sample was relatively small, it should be repeated with a larger patient population to corroborate the data.
"We're starting to understand the importance of vitamin D in relation to overall health and to particular infections, like C. diff," said Dr. Rubin. "It's important to pay attention to nutritional issues and possibly even supplement vitamin D in patients with low levels to help fight serious infections."