Vitamin D is a pro hormone, meaning that it has no hormone activity itself, but is converted to the active hormone 1,25-D through a tightly regulated synthesis mechanism. Production of vitamin D in nature always appears to require the presence of some UV light; even vitamin D in foodstuffs is ultimately derived from organisms, from mushrooms to animals, which are not able to synthesize it except through the action of sunlight at some point in the synthetic chain. For example, fish because they ultimately exist on calories from ocean algae which synthesize vitamin D in shallow waters from the action of solar UV.
Synthesis in the skin involves UVB radiation which effectively penetrates only the epidermal layers of skin. While 7-Dehydrocholesterol absorbs UV light at wavelengths between 270–300 nm, optimal synthesis occurs in a narrow band of UVB spectra between 295-300 nm. Peak isomerization is found at 297 nm. This narrow segment is sometimes referred to as D-UV. The two most important factors that govern the generation of pre-vitamin D3 are the quantity (intensity) and quality (appropriate wavelength) of the UVB irradiation reaching the 7-dehydrocholesterol deep in the stratum basale and stratum spinosum.
Vitamin D is important in maintaining the healthy calcium and phosphorus levels that are needed to build healthy bones and teeth. Known as “the sunshine vitamin” because it is produced in the body when exposed to sun, new evidence shows that it has an analgesic effect on chronic musculoskeletal pain, functioning as a hormone in various tissues.</p>
Adequate Intake (AI) for Vitamin D Recommended by the Institute of Medicine
|Infants||0-6 months||5 mcg (200 IU)||5 mcg (200 IU)|
|Infants||7-12 months||5 mcg (200 IU)||5 mcg (200 IU)|
|Children||1-3 years||5 mcg (200 IU)||5 mcg (200 IU)|
|Children||4-8 years||5 mcg (200 IU)||5 mcg (200 IU)|
|Children||9-13 years||5 mcg (200 IU)||5 mcg (200 IU)|
|Adolescents||14-18 years||5 mcg (200 IU)||5 mcg (200 IU)|
|Adults||19-50 years||5 mcg (200 IU)||5 mcg (200 IU)|
|Adults||51-70 years||10 mcg (400 IU)||10 mcg (400 IU)|
|Adults||71 years and older||15 mcg (600 IU)||15 mcg (600 IU)|
|Pregnancy||all ages||–||5 mcg (200 IU)|
|Breast-feeding||all ages||–||5 mcg (200 IU)|
Vitamin D Deficency
There seems to be a lot of problems caused by vitamin D difficency from simple bone problems, to diabetes, obesity, cancer and much more.
In 22 studies of vitamin D, conducted with 3,670 participants, 48% to 100% of those with musculoskeletal pain displayed vitamin D deficiencies. With supplementation, almost all reported a lessening or complete elimination of bone and muscle pain. Another study of 360 participants with back pain showed that all had insufficient levels of vitamin D, and 95% showed relief after three months of supplementation, assuming there was no injury, such as a slipped disc. A study at the University of Minnesota noted that the majority of those with severe deficiency were under the age of 30. Studies of over 40,000 participants taking vitamin D showed a reduction in hip fractures by 18%.
Multiple Sclerosis in Children
Multiple sclerosis is a degenerative disease of the nervous system in which the myelin sheath that insulates nerve cells breaks down, leading to problems in the transmission of nervous signals. Symptoms can range from tingling and numbness to tremors, paralysis or blindness. An estimated 2.5 million people around the world suffer from the disease, which is rarely diagnosed before the age of 15.
In one study, researchers from the University of Toronto tested the vitamin D blood levels of 125 children who had exhibited symptoms indicating some form of damage to the myelin sheath.
“Three-quarters of our subjects were below the optimal levels for vitamin D,” lead researcher Heather Hanwell said.
Canada has one of the highest multiple sclerosis rates in the world. One of the few countries with a higher rate is Scotland, which has regions reached by only a quarter of all available sunlight. Recent research has confirmed a strong connection in Scotland between vitamin D deficiency and poor health status.
Alzheimer’s and Vascular Dementia
In 2008, numerous studies concluded that people with higher serum levels of vitamin D had a greatly reduced risk of cardiovascular disease as well as a lowered chance of death due to cardiac causes. Curiously, all of these seemingly separate conditions are either known risk factors for dementia or tend to strike before dementia is diagnosed. Now scientist William B. Grant, PhD, of the Sunlight, Nutrition, and Health Research Center (SUNARC) has put these facts together and has come up with a startling new hypothesis about the cause of mind-robbing Alzheimer’s disease and other vascular dementias: vitamin D deficiency.
Dr. Grant cites several studies that have correlated tooth loss with the development of cognitive impairment and Alzheimer’s or vascular dementia. Why do people lose teeth? Primarily, he points out in his article, tooth loss is the result of dental caries and/or periodontal disease — and both those conditions are linked to low levels of vitamin D.
In addition, Dr. Grant’s article explains that ample biological evidence has accumulated showing how critical vitamin D is to healthy brain development and function. In fact,vitamin D in sufficient amounts seems to protect brain cells and reduce inflammation. It has been associated with increased inflammation and a pro-inflammatory state has been linked, in turn, with dementia.
Dr. Grant is calling for studies of levels of vitamin D in people before dementia is diagnosed and research to determine if supplementation is warranted to potentially prevent dementia. In addition, because elderly people are frequently deficient in vitamin D, he suggests that those over 60 years old should consider having their serum vitaminD level tested and, if their it is low, he recommends taking 1000 to 2000 IU a day of vitamin D3 supplements and/or increasing the time they spend in the sun year round.
For this study, the research team examined the levels of plasma 25-hydroxyvitamin D (25[OH]D) in a clinical research database at Emory University School of Medicine. The participants had been recruited into the study from May 1992 to March 2007. In all, three groups of people were compared – 99 healthy adults to act as the control group, 97 Alzheimer’s Disease (AD) patients, and 100 PD patients. The study subjects were matched for age, gender, race and geographic location.
You may be wondering why the group of AD patients was included. That was because the study team wanted to find out if there was a link between vitamin D insufficiency and other diseases which also cause a loss of nerve cells.
The findings of the study revealed that 55% of the PD patients had insufficient levels of vitamin D. The corresponding figures for AD and healthy people were 41% and 36% respectively. When it came to severe vitamin D insufficiency, the correlations were similar – 23% of PD patients were deficient in the vitamin, compared with 16% of AD patients and 10% of healthy people.
One interesting finding was that PD patients had less vitamin D than AD patients. According to the study team, this suggests that lack of vitamin D may be linked specifically to Parkinson’s, rather than to neurodegenerative diseases in general.