ScienceDaily (Dec. 29, 2008) — 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 new report.
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.
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.”
High Levels of Vitamin D in Older People Can Reduce Heart Disease and Diabetes
ScienceDaily (Feb. 22, 2010) — Middle aged and elderly people with high levels of vitamin D could reduce their chances of developing heart disease or diabetes by 43%, according to researchers at the University of Warwick.
A team of researchers at Warwick Medical School carried out a systematic literature review of studies examining vitamin D and cardiometabolic disorders. Cardiometabolic disorders include cardiovascular disease, type 2 diabetes mellitus and metabolic syndrome.
Vitamin D is a fat-soluble vitamin that is naturally present in some foods and is also produced when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Fish such as salmon, tuna and mackerel are good sources of vitamin D, and it is also available as a dietary supplement.
Researchers looked at 28 studies including 99,745 participants across a variety of ethnic groups including men and women. The studies revealed a significant association between high levels of vitamin D and a decreased risk of developing cardiovascular disease (33% compared to low levels of vitamin D), type 2 diabetes (55% reduction) and metabolic syndrome (51% reduction).
The literature review, published in the journal Maturitas, was led by Johanna Parker and Dr Oscar Franco, Assistant Professor in Public Health at Warwick Medical School.
Dr Franco said: “We found that high levels of vitamin D among middle age and elderly populations are associated with a substantial decrease in cardiovascular disease, type 2 diabetes and metabolic syndrome.
“Targeting vitamin D deficiency in adult populations could potentially slow the current epidemics of cardiometabolic disorders.”
All studies included were published between 1990 and 2009 with the majority published between 2004 and 2009. Half of the studies were conducted in the United States, eight were European, two studies were from Iran, three from Australasia and one from India.
Best form of vitamin D is through exposure to sunlight.
“It is especially important for individuals with limited sun exposure to include good sources of vitamin D in their diets. Homebound individuals, people living in northern latitudes, individuals who wear clothing that completely covers the body, and individuals who always use sunscreen or work in occupations that prevent exposure to sunlight are at significant risk for vitamin D deficiency.
In northern latitudes (above 51° latitude), in spring, summer and fall, we can make vitamin D from exposure to sunlight (15 minutes, 2-3 times per week is all that is needed), but in the winter we cannot make any. Below 35° latitude, vitamin D can be made year round. But at higher and higher latitudes, our ability to make vitamin D gets more and more seasonally limited. At about 51° latitude, we may go 3 months without being able to make vitamin D. At about 71° latitude we may go more than 5 months.
African Americans need significantly more UV exposure to produce adequate vitamin D. This is because darker skin contains more melanin, the pigment that gives skin its color, and the higher melanin content in darker skin reduces the skin’s ability to produce vitamin D from sunlight. Throughout the U.S., as many as 30-50% of African Americans may be vitamin D deficient.”