Current Vitamin D Daily Requirement Questioned

Vitamin D is produced naturally in reactions between exposed skin and sunlight, although it can also be found in supplements and other dietary forms, such as fortified milk and fatty fish. Since the best way to maintain adequate levels of vitamin 0 is to be exposed to sunlight on a daily basis,

it should come as a surprise to no one that deficiencies have increased. Today, more people are spending time inside and when they do go outside, they often cover up to protect against the sun’s harmful rays. Moreover, wearing sunscreen with a sun protection factor (SPF) of 8 or more inhibits vitamin D production in the skin by more than 95%.

The last updates made about vitamin D recommendations occurred in 1997 and were made primarily for the prevention of bone disease, such as rickets in children and osteoporosis in the elderly.

The current guidelines recommend 200 to 600 international units (IU) a day; some believe this number should be increased to 2,000 IU, perhaps following the Canadian Cancer Society’s recent increase to 1,000 IU.

Recent studies show that vitamin D is beneficial for much more than bone diseases. Also, there is evidence to suggest that vitamin D deficiency plays a role in many diseases, such as high blood pressure, heart disease, tuberculosis, the flu, multiple sclerosis, rheumatoid arthritis, schizophrenia, depression and many forms of cancer—including colon, breast, ovarian, prostate and, ironically, skin cancer.

While prolonged sun exposure is not recommended because of increased cancer risk, it seems a little sunlight may do more good than harm.

Unfortunately, some in the medical community don’t believe sufficient evidence exists to warrant a change in the federal guidelines.

Low Vitamin D associated with Cognitive Decline

According to a report in the July 12 issue of Archives of Internal Medicine older adults with low levels of vitamin D appear more likely to experience declines in thinking, learning and memory over a six-year period.

Image Courtesy:www.marleysghost.net

An estimated 40 percent to 100 percent of older adults in the United States and Europe are deficient in Vitamin D, This deficiency has been linked to fractures, various chronic diseases and death. Vitamin D may help prevent the degeneration of brain tissue by having a role in formation of nervous tissue, maintaining levels of calcium in the body, or clearing of beta-amyloid, the substance that forms the brain plaques and tangles associated with Alzheimer's disease.

David J. Llewellyn, Ph.D., of University of Exeter, England, and colleagues assessed blood levels of Vitamin D in 858 adults who were age 65 or older when the study began in 1998. Participants completed interviews and medical examinations and provided blood samples. At the beginning of the study and again after three and six years, they repeated three tests of cognitive function -- one assessing overall cognition, one focusing on attention and one that places greater emphasis on executive function, or the ability to plan, organize and prioritize.

Participants who were severely deficient in vitamin D (having blood levels of 25-hydroxyvitamin D of less than 25 nanomoles per liter) were 60 percent more likely to have substantial cognitive decline in general over the six-year period and 31 percent more likely to experience declines on the test measuring executive function than those with sufficient vitamin D levels. "The association remained significant after adjustment for a wide range of potential confounders and when analyses were restricted to elderly subjects who were non-demented at baseline," the authors write. However, no significant association was seen for the test measuring attention.

The authors conclude, "If future prospective studies and randomized controlled trials confirm that vitamin D deficiency is causally related to cognitive decline, then this would open up important new possibilities for treatment and prevention,".

"Vitamin D has been known for many years to play a critical role in skeletal health, such that very low levels of this hormone (less than 20 nanomoles per liter) can cause osteomalacia, a disorder of impaired bone mineralization," write Andrew Grey, M.D., and Mark Bolland, M.B.Ch.B., Ph.D., of University of Auckland, New Zealand, in an accompanying editorial. "More recently, observational studies have reported inverse associations between levels of serum 25-hydroxyvitamin D, the metabolite that best reflects overall vitamin D status, and the risk of a wide range of disease, including cancer, vascular disease, infectious conditions, autoimmune diseases, osteoporosis, type 2 diabetes mellitus and obesity."

The authors says that the results of these observational studies have prompted calls for widespread treatment of individuals with low levels of Vitamin D and the establishment of public health programs aimed at raising the population levels of vitamin D to 'healthy' values.

"It is now time to test the various hypotheses generated by observational studies of vitamin D, including that of Llewellyn et al, in adequately designed and conducted randomized controlled trials," they conclude. "Very importantly, such trials will also provide an opportunity to systematically assess potential harms of vitamin D supplementation, an issue that has been largely overlooked or dismissed. We should invest in trials that provide the best possible evidence on the benefits and risks of vitamin D before we invest in costly, difficult and potentially unrewarding interventional strategies." he says.

Source:
ScienceDaily
July 13, 2010

Vitamin D ...the Ultimate Anti-Aging Vitamin

According to Times of India, Vitamin D may not make you flexible, but is the ultimate anti-aging vitamin as you age. It may give you an edge when it comes to keeping your balance, your grip strength, and your foot speed.

Dangers of Vitamin D Deficiency
They also mention that a lack of vitamin D is actually fairly common in the US; up to 40% of people may not be getting enough. And shortfalls increase with age. This is not good, because a study recently revealed that people around the age of 65 and older who are low on vitamin D do poorly on tests of handgrip strength, walking speed, balance, and the ability to stand up from a seated position. More research is needed, but scientists feel there is already enough evidence of vitamin D’s positive effect on the muscle strength to warrant being on a D-alert.

Where to get yours
They go on to say that you can get your vitamin D from the sun and from food (including fortified foods), but most people need a supplement to get enough, especially as the winter sun rays get a little weaker.

Reference:
Source: www.timesofindia.indiatimes.com, Posted on 29 Oct 2008,

Vitamin D Deficiency Related To Increased Inflammation In Healthy Women

According to a recent study in the Archives of Internal Medicine, 75 percent of Americans do not get enough Vitamin D. Researchers have found that the deficiency may negatively impact immune function and cardiovascular health and increase cancer risk. Now, a University of Missouri nutritional sciences researcher has found that vitamin D deficiency is associated with inflammation, a negative response of the immune system, in healthy women.

Increased concentrations of serum TNF-α, an inflammatory marker, were found in women who had insufficient vitamin D levels. This study is the first to find an inverse relationship between vitamin D levels and concentrations of TNF-α in a healthy, non-diseased population. This may explain the vitamin's role in the prevention and treatment of inflammatory diseases, including heart disease, multiple sclerosis and rheumatoid arthritis.

"The findings reveal that low vitamin D levels negatively impact inflammation and immune response, even in healthy women," said Catherine Peterson, assistant professor in the MU College of Human Environmental Sciences. "Increased inflammation normally is found in people with obesity or chronic diseases; a small decrease in vitamin D levels may aggravate symptoms in people who are sick."

The results support the need to re-examine the biological basis for determining the dietary reference intake (DRI) of vitamin D, Peterson said. The Institute of Medicine's DRI for vitamin D is 200 IU for people age 50 and younger and 400 IU for people 50 to 70 years old. The guidelines, created in 1997, are being revised to reflect new research, and Peterson is confident the DRI will be increased.

"Adequate vitamin D levels identified in this study are consistent with recent research that suggests the DRI should be increased," Peterson said. "To improve vitamin D status and achieve its related health benefits, most people should get at least 1000 IU of vitamin D per day. Sunlight is a readily-available, free source of vitamin D. Exposing 25 percent of the skin's surface area to 10 minutes of sunlight three days per week will maintain adequate levels in the majority of people; however, people with darkly-pigmented skin need more. Only a few foods contain vitamin D naturally, such as fatty fish; other sources are dietary supplements and vitamin-D-fortified foods, including milk and orange juice."

In future studies, Peterson will determine the effectiveness of Vitamin D in reducing disease symptoms and reducing blood glucose levels in diabetics. The study, "Serum tumor necrosis factor-alpha concentrations are negatively correlated with serum 25(OH) D concentrations in healthy women," was published in the July, 2008 issue of the Journal of Inflammation

Source:
Science Daily
Apr. 14, 2009

Vitamin D Good for Seniors

ScienceDaily.com tells us that Dr. Denise Houston from the Sticht Center on Aging at Wake Forest University and her team studied the relationship between
Vitamin D status and physical function in a group of relatively healthy seniors living in Memphis, TN and Pittsburgh, PA. .

This study was part of the Health, Aging, and Body Composition (Health ABC) study initially designed to assess the associations among body composition, long-term health conditions, and mobility in older adults.

For Houston's segment of the investigation, she studied 2788 seniors (mean age: ~75 years) for 4 years. At the beginning of the study, they assessed vitamin D status by analyzing each person's blood for 25-hydroxyvitamin D, a precursor for activated vitamin D. At baseline and then 2 and 4 years later, the research team then determined whether circulating 25-hydroxyvitamin D was related to the participants' physical function. Specifically, they looked at how quickly each participant could walk a short distance (6 meters) and rise from a chair five times as well as maintain his or her balance in progressively more challenging positions. Each participant was also put through a battery of tests assessing endurance and strength.

When the results were tabulated, participants with the highest levels of 25-hydroxyvitamin D had better physical function. And, although physical function declined over the course of the study, it remained significantly higher among those with the highest vitamin D levels at the beginning of the study compared to those with the lowest vitamin D levels. The scientists were not surprised to learn that, in general, vitamin D consumption was very low in this group of otherwise healthy seniors. In fact, more than 90% of them consumed less vitamin D than currently recommended, and many were relying on dietary supplements.

The good news: higher circulating 25-hydroxyvitamin D is related to better physical function in seniors. But it's impossible to tell from this type of research whether increasing vitamin D intake will actually lead to stronger muscles and preserve physical function. This is partly due to the fact that our bodies can make vitamin D if they get enough sunlight. So, it is possible that the participants with better physical function had higher vitamin D status simply because they were able to go outside more often.

Indeed, the ominous "chicken-or-the-egg" question can only be answered by carefully controlled clinical intervention trials. Nonetheless, it is possible that getting more vitamin D from foods (like fortified milk and oily fish) or supplements will help maintain youth and vitality as we enjoy longer life spans..

As Houston points out: "Current dietary recommendations are based primarily on vitamin D's effects on bone health. It is possible that higher amounts of vitamin D are needed for the preservation of muscle strength and physical function as well as other health conditions. However, clinical trials are needed to definitively determine whether increasing 25-hydroxyvitamin D concentrations through diet or supplements has an effect on these non-traditional outcomes."

Will vitamin D research lead us to The Fountain of Youth? Probably not. But paying attention to how much vitamin D we get is likely important at every age and will help enhance the "quality" component of life as we enter our senior years.

Note:
Their results were presented on April 25 as part of the scientific program of the American Society for Nutrition, composed of the world's leading nutrition researchers, at the Experimental Biology 2010 meeting in Anaheim, California.

Source:
ScienceDaily.com

Vitamin D Important for Teenagers

Low levels of vitamin D were associated with an increased risk of high blood pressure, high blood sugar and metabolic syndrome in teenagers, researchers reported at the American Heart Association's 49th Annual Conference on Cardiovascular Disease Epidemiology and Prevention.

In a study, researchers analyzed 3,577 adolescents, 12 to 19 years old (51 percent boys), who participated in the nationally representative National Health and Nutrition Examination Survey (NHANES) conducted from 2001–2004.

After adjusting for age, sex, race/ethnicity, body mass index, socioeconomic status and physical activity, researchers found the adolescents with the lowest levels of vitamin D were:

•2.36 times more likely to have high blood pressure;
•2.54 times more likely to have high blood sugar; and
•3.99 times more likely to have metabolic syndrome.

Metabolic syndrome is a cluster of cardiovascular disease and diabetes risk factors including elevated waist circumference, high blood pressure, elevated triglycerides, low levels of high-density lipoprotein (HDL or “good”) cholesterol and high fasting glucose levels. The presence of three or more of the factors increases a person’s risk of developing diabetes and cardiovascular disease.

“We showed strong associations between low levels of vitamin D and higher risk of high blood pressure, hyperglycemia and metabolic syndrome among adolescents, confirming the results of studies among adults,” said Jared P. Reis, Ph.D., the study’s lead author and post-doctoral research fellow at Johns Hopkins Bloomberg School of Public Health in Baltimore.

Researchers used a biomarker of vitamin D to measure levels in blood. The biomarker measures vitamin D obtained from food, vitamin supplementation and exposure to sunlight.

The ethnic breakdown was similar to the general U.S. population: 64.7 percent non-Hispanic whites; 13.5 percent non-Hispanic blacks; and 11 percent Mexican Americans.

The study highlights the association between high levels of vitamin D and lower risk of heart disease. The highest levels of vitamin D were found in whites, the lowest levels in blacks and intermediate levels in Mexican Americans. Whites had almost twice as high levels as blacks.

In whites, the average level of vitamin D was 28.0 nanograms per milliliter (ng/mL); in blacks, 15.5 ng/mL; and in Mexican Americans, 21.5 ng/mL.

“Although our study is important, we believe clinical trials designed to determine the effects of vitamin D supplementation on the risk of heart disease risk factors in adolescents should be conducted before recommendations can be made for vitamin D in the prevention of cardiovascular disease,” Reis said.

The Institute of Medicine recommends a daily intake of vitamin D of 200 International Units (IU) for those less than 50 years, which includes children and adolescents. More recent recommendations, however, from the American Academy of Pediatrics suggests a daily intake of 400 IU daily. While these intakes have been shown to be important in the prevention of skeletal conditions such as rickets in children and osteoporosis in adults, some specialists have suggested intakes of at least 1,000 IU daily may be needed for overall health.

Low levels of vitamin D are strongly associated with overweight and abdominal obesity. Since vitamin D is a fat-soluble vitamin, it may be sequestered within adipose tissue. This may explain why those who are obese are more likely to be vitamin D deficient, Reis said.

Vitamin D plays a useful role in general human health, particularly in bone health. Other roles are emerging, Reis said. “This is an exciting time; since we are just now beginning to understand the role that vitamin D may play in cardiovascular health.”

“These data on serum vitamin D levels in young people raise some concern about their food choices and even the amount of time they spend in the sunshine,” said Robert H. Eckel, M.D., American Heart Association past president. “The American Heart Association recommends an overall healthy diet and lifestyle, and that people get their nutrients primarily from food sources rather than supplements.”

Co-authors are: Denise von Muhlen, M.D., Ph.D.; Edgar R. Miller III, M.D., Ph.D.; Erin D. Michos, M.D., M.H.S.; and Lawrence J. Appel, M.D., M.P.H.

Source:
Science Daily
March 2009

Vitamin D Reduces Breast Cancer Risk

According to a new Research Study carried out by K M Blackmore & colleagues, Mount Sinai Hospital, Ontario, Canada and published in American Journal of Epidemiology, intake of vitamin D through diet and exposure to the sun was associated with a 24% reduced risk of estrogen-receptor(ER)- and progesterone-receptor(PR)-defined breast cancer.

The researchers compared 758 cases of breast cancer and 1,135 controls without the disease and found those who had high intake of vitamin D were also found to have a 26% reduced risk of ER or PR breast cancer and a 21% decreased risk of ER or PR tumors. The study also suggests that vitamin D is associated with a reduce risk of breast cancer regardless of ER/PR status of the tumor.

Vitamin D is found in a limited number of foods including oily fish, fortified foods such as juices, cereals and milk and most is conveniently synthesized after an individual is exposed to sunshine.

Reference:
Source: American Journal of Epidemiology

Vitamin D Requirements

Today, more people are spending time inside and when they do go outside, they often cover up to protect against the sun’s harmful rays. Moreover, wearing sunscreen with a sun protection factor (SPF) of 8 or more inhibits vitamin D production in the skin by more than 95%.

The last updates made to the vitamin D recommendations occurred in 1997 and were made primarily for the prevention of bone disease, such as rickets in children and osteoporosis in the elderly. The current guidelines recommend 200 to 600 international units (IU) a day; some believe this number should be increased to 2,000 IU, perhaps following the Canadian Cancer Society’s recent increase to 1,000 IU.
Importantly, recent studies indicate vitamin D is beneficial for much more than bone diseases.

In addition, evidence suggests vitamin D deficiency plays a role in many diseases, such as high blood pressure, heart disease, tuberculosis, the flu, multiple sclerosis, rheumatoid arthritis, schizophrenia, depression and many forms of cancer—including colon, breast, ovarian, prostate and, ironically, skin cancer. While prolonged sun exposure is not recommended because of increased cancer risk, it seems a little sunlight may do more good than harm. Unfortunately, some in the medical community don’t believe sufficient evidence exists to warrant a change in the federal guidelines.