It’s only been a few weeks since I reported on, and started taking, Vitamin D. But there have been several new research studies since then. The title of the first one below tells the story:
Vitamin D is the 'it' nutrient of the moment
Loyola researchers report on benefit of vitamin D in diabetes and other chronic diseases
Vitamin D is quickly becoming the "it" nutrient with health benefits for diseases, including cancer, osteoporosis, heart disease and now diabetes.
A recent review article published by researchers from Loyola University Chicago Marcella Niehoff School of Nursing concluded that adequate intake of vitamin D may prevent or delay the onset of diabetes and reduce complications for those who have already been diagnosed. These findings appeared in the latest issue of Diabetes Educator.
"Vitamin D has widespread benefits for our health and certain chronic diseases in particular," said Sue Penckofer, Ph.D., R.N., study co-author and professor, Loyola University Chicago Marcella Niehoff School of Nursing. "This article further substantiates the role of this nutrient in the prevention and management of glucose intolerance and diabetes."
Many of the 23 million Americans with diabetes have low vitamin D levels. Evidence suggests that vitamin D plays an integral role in insulin sensitivity and secretion. Vitamin D deficiency results in part from poor nutrition, which is one of the most challenging issues for people with diabetes. Another culprit is reduced exposure to sunlight, which is common during cold weather months when days are shorter and more time is spent indoors.
One study examined for this review article evaluated 3,000 people with type 1 diabetes and found a decreased risk in disease for people who took vitamin D supplements. Observational studies of people with type 2 diabetes also revealed that supplementation may be important in the prevention of this disease.
"Management of vitamin D deficiency may be a simple and cost-effective method to improve blood sugar control and prevent the serious complications associated with diabetes," said Joanne Kouba, Ph.D., R.D., L.D.N., study co-author and clinical assistant professor of dietetics, Loyola University Chicago Marcella Niehoff School of Nursing.
Diet alone may not be sufficient to manage vitamin D levels. A combination of adequate dietary intake of vitamin D, exposure to sunlight, and treatment with vitamin D2 or D3 supplements can decrease the risk of diabetes and related health concerns. The preferred range in the body is 30 - 60 ng/mL of 25(OH) vitamin D.
"People at risk for diabetes should be screened for low vitamin D levels," said Mary Ann Emanuele, M.D., F.A.C.P., study co-author and professor of medicine, division of endocrinology and metabolism, Loyola University Health System. "This will allow health care professionals to identify a nutrient deficiency early on and intervene to improve the long term health of these individuals."
Vitamin D deficiency also may be associated with hyperglycemia, insulin resistance, hypertension and heart disease. In fact, Penckofer recently published another study in Circulation that reported on the role of chronic vitamin D deficiency in heart disease.
Lack of vitamin D could spell heart trouble
Researchers issue recommendations to screen for and treat vitamin D deficiency
Vitamin D deficiency—which is traditionally associated with bone and muscle weakness—may also increase the risk of cardiovascular disease (CVD). A growing body of evidence links low 25-hydroxyvitamin D levels to common CVD risk factors such as hypertension, obesity and diabetes, as well as major cardiovascular events including stroke and congestive heart failure.
In their review article, published in the December, 9, 2008, issue of the Journal of the American College of Cardiology (JACC), the authors issue practical recommendations to screen for and treat low vitamin D levels, especially in patients with risk factors for heart disease or diabetes.
"Vitamin D deficiency is an unrecognized, emerging cardiovascular risk factor, which should be screened for and treated," said James H. O'Keefe, M.D., cardiologist and director of Preventive Cardiology at the Mid America Heart Institute, Kansas City, MO. "Vitamin D is easy to assess, and supplementation is simple, safe and inexpensive."
It is estimated that up to half of U.S. adults and 30 percent of children and teenagers have vitamin D deficiency, which is defined as a 25(OH)D level of <20ng/ml. Low vitamin D levels activate the renin-angiostensin-aldosterone system and, in doing so, predispose patients to hypertension and a stiffening and thickening of the heart and blood vessels. Vitamin D deficiency also alters hormone levels and immune function, which can increase the risk of diabetes, a major contributor to CVD.
Recent data from the Framingham Heart Study suggest patients with vitamin D levels below 15 ng/ml were twice as likely to experience a heart attack, stroke or other CV event within the next five years compared to those with higher levels. This risk remained even when researchers adjusted for traditional CV risk factors.
"Restoring vitamin D levels to normal is important in maintaining good musculoskeletal health, and it may also improve heart health and prognosis," said Dr. O'Keefe. "We need large randomized controlled trials to determine whether or not vitamin D supplementation can actually reduce future heart disease and deaths."
Vitamin D Basics
Vitamin D deficiency is more prevalent than once thought, and greater attention to its treatment is warranted, according to Dr. O'Keefe. Although most of the body's vitamin D requirements can come from sun exposure, indoor lifestyles and use of sunscreen, which eliminates 99 percent of vitamin D synthesis by the skin, means many people aren't producing enough.
"We are outside less than we used to be, and older adults and people who are overweight or obese are less efficient at making vitamin D in response to sunlight," said Dr. O'Keefe. "A little bit of sunshine is a good thing, but the use of sunscreen to guard against skin cancer is important if you plan to be outside for more than 15 to 30 of intense sunlight exposure."
Vitamin D can also be consumed through supplements and food intake. Natural food sources of vitamin D include salmon, sardines, cod liver oil, and vitamin D-fortified foods including milk and some cereals.
Major risk factors for vitamin D deficiency include: older age, darkly pigmented skin, increased distance from the equator, winter season, smoking, obesity, renal or liver disease and certain medications.
Treating Vitamin D Deficiency
In the absence of clinical guidelines, the authors outline specific recommendations for restoring and maintaining optimal vitamin D levels in CV patients. These patients should initially be treated with 50,000 IU of vitamin D2 or D3 once weekly for 8 to 12 weeks. Maintenance therapy should be continued using one of the following strategies:
• 50,000 IU vitamin D2 or D3every 2 weeks;
• 1,000 to 2,000 IU vitamin D3 daily;
• Sunlight exposure for 10 minutes for Caucasian patients (longer for people with increased skin pigmentation) between the hours of 10 a.m. to 3 p.m.
Vitamin D supplements appear to be safe. In rare cases, vitamin D toxicity (causing high calcium levels and kidney stones) is possible, but only when taking in excess of 20,000 units a day.
Lack of vitamin D causes weight gain and stunts growth in girls
Canada-US study published in Journal of Clinical Endocrinology & Metabolism recommends young people be screened for low vitamin D levels
Insufficient vitamin D can stunt growth and foster weight gain during puberty, according to a new study published in the Journal of Clinical Endocrinology & Metabolism. Even in sun-drenched California, where scientists from the McGill University Health Centre (MUHC) and the University of Southern California conducted their study, vitamin D deficiency was found to cause higher body mass and shorter stature in girls at the peak of their growing spurt.
While lack of vitamin D is common in adults and has been linked to diseases such as osteoporosis, cancer and obesity, until this study, little was known about the consequences of insufficient vitamin D in young people. The research team measured vitamin D in girls aged 16 to 22 using a simple blood test (25-hydroxy vitamin D). They also assessed body fat and height to determine how vitamin D deficiency could affect young women's health.
"The high prevalence of vitamin D insufficiency in young people living in a sun-rich area was surprising," says study lead author, Richard Kremer, co-director of the Musculoskeletal Axis of the MUHC. "We found young women with vitamin D insufficiency were significantly heavier, with a higher body mass index and increased abdominal fat, than young women with normal levels."
Vitamin D fosters growth, healthier weight
The researchers examined 90 Caucasian and Hispanic girls and discovered that young women with normal vitamin D levels were on average taller than peers deficient in vitamin D. Yet in contrast to what's been previously reported in older women, their investigation found no association between lack of vitamin D and bone strength.
"Although vitamin D is now frequently measured in older adults, due to a higher level of awareness in this population, it is rarely measured in young people – especially healthy adolescents," says Dr. Kremer.
"Clinicians need to identify vitamin D levels in younger adults who are at risk by using a simple and useful blood test," says the co-author, Dr. Vicente Gilsanz, head of musculoskeletal imaging at the Children's Hospital Los Angeles of the University of Southern California.
"Because lack of vitamin D can cause fat accumulation and increased risk for chronic disorders later in life, further investigation is needed to determine whether vitamin D supplements could have potential benefits in the healthy development of young people," added Dr. Gilsanz.
American Academy of Dermatology Issues Position Statement on Vitamin D
The American Academy of Dermatology (Academy) recently issued a position statement on vitamin D, drawing on the scientific literature to support its recommendation for safely obtaining an adequate amount of this vitamin. The Academy recommends that the public obtain vitamin D from nutritional sources and dietary supplements, and not from unprotected exposure to ultraviolet (UV) radiation from the sun or indoor tanning devices, as UV radiation is a known risk factor for the development of skin cancer.
“Vitamin D is essential for optimal health, and the medical literature supports safe ways to get it – a healthy diet which incorporates foods naturally rich in vitamin D, vitamin D-fortified foods and beverages, and vitamin D supplements,” stated dermatologist C. William Hanke, MD, MPH, FAAD, president of the American Academy of Dermatology. “And, according to the medical literature, unprotected exposure to UV radiation from sunlight (natural) or indoor tanning devices (artificial) is not safe. Individuals who intentionally expose themselves to UV radiation for vitamin D are putting their health at risk for developing skin cancer.”
The Academy further recommends that individuals who are concerned about their vitamin D levels seek a physician’s guidance about safe options to obtain vitamin D. The Academy recommends physicians use the National Academy of Sciences Institute of Medicine guidelines for vitamin D as a standard reference for advising patients on proper minimum intake levels. In addition, the Academy advises that a higher dose of supplementation for individuals with known risk factors for vitamin D deficiency should be considered.
The Academy recommends that when you are enjoying yourself outdoors, be smart by taking steps to protect yourself from UV exposure-- seek shade whenever possible, wear sunscreen and cover up with a wide-brimmed hat, long sleeves, pants and sunglasses. Also, avoid tanning beds.
Vitamin D found to fight placental infection
In a paper available at the online site of the journal Biology of Reproduction, a team of UCLA researchers reports for the first time that vitamin D induces immune responses in placental tissues by stimulating production of the antimicrobial protein cathelicidin.
The study involved exposing cultured human trophoblast cells to the active form of vitamin D, leading to production of cathelicidin and an increased antibacterial response in the trophoblast cells.
The team, headed by Dr. Martin Hewison, suspects that the ability of the placenta to synthesize cathelicidin varies widely among women. Their discovery suggests that placental innate immunity can be enhanced if pregnant women supplement their diets with vitamin D.
Induction of cathelicidin production by vitamin D may help the placenta stave off infection by a variety of pathogenic organisms, including staphylococcus, streptococcus, and E. coli bacteria. Vitamin D may also enhance and sustain this bacterial killing by protecting placental trophoblast cells from infection-associated cell death.
The significance of vitamin D in human reproduction has been recognized for the past 20 years, although its exact role has not been completely understood. This study presents a new mechanism for activation of innate immune responses in the placenta to protect it from infectious bacteria and sheds new light on the possible role of vitamin D in pregnancy and pregnancy-associated infection.
Vitamin D deficiency in infants and nursing mothers carries long-term disease risks
Once believed to be important only for bone health, vitamin D is now seen as having a critical function in maintaining the immune system throughout life. The newly recognized disease risks associated with vitamin D deficiency are clearly documented in a report in the December issue (Volume 3, Number 4) of Breastfeeding Medicine, a peer-reviewed journal published by Mary Ann Liebert, Inc. (www.liebertpub.com), and the official journal of the Academy of Breastfeeding Medicine (www.bfmed.org). The paper is available free online at www.liebertpub.com/bfm
Vitamin D deficiency is common across populations and particularly among people with darker skin. Nutritional rickets among nursing infants whose mothers have insufficient levels of vitamin D is an increasingly common, yet preventable disorder.
Carol Wagner, MD, Sarah Taylor, MD, and Bruce Hollis, PhD, from the Department of Pediatrics, Medical University of South Carolina (Charleston), emphasize the need for clinical studies to determine the dose of vitamin D needed to achieve adequate vitamin D levels in breastfeeding mothers and their infants without toxicity.
In a paper entitled, "Does Vitamin D Make the World Go 'Round'?" the authors point out that vitamin D is now viewed not simply as a vitamin with a role in promoting bone health, but as a complex hormone that helps to regulate immune system function. Long-term vitamin D deficiency has been linked to immune disorders such as multiple sclerosis, rheumatoid arthritis, type I diabetes, and cancer.
"Vitamin D is a hormone not a vitamin and it is not just for kids anymore," writes Ruth A. Lawrence, MD, Editor-in-Chief of Breastfeeding Medicine, from the Department of Pediatrics, University of Rochester School of Medicine and Dentistry, in an accompanying editorial. "Perhaps the most startling information is that adults are commonly deficit in modern society. Vitamin D is now recognized as a pivotal hormone in the human immune system, a role far beyond the prevention of rickets, as pointed out in the article by Wagner et al in this month's issue of Breastfeeding Medicine."
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