Vitamin D continues to capture the attention of scientists, doctors, and the public as a result of a growing body of research revealing D's critical role in a number of critical functions in the body, including innate immunity.
Vitamin D Useful Against Cancer, Bone Issues, Colds and Flu, and More
Despite the name, vitamin D isn't actually a vitamin; it's a secosteroid hormone that targets over 2000 genes in the human body. Vitamin D has been shown, according to the Vitamin D Council, to have a positive effect on bone health, immunity, cancer prevention and inflammation.
Vitamin D3 or cholecaciferol is made in large quantities when sunlight strikes bare skin. Ergocalciferol, also referred to as vitamin D2 or Calciferol, is available in supplement form, although it is not the naturally occurring form of vitamin D in humans.
Dr. John Jacob Cannell, MD, Vitamin D Council’s Executive Director, notes on the Council's website that current research links Vitamin D deficiency to at least 17 variations of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more.
In addition, vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations. This critical substance is needed for bone growth and remodeling, and without a sufficient amount, bones can become thin, brittle, or misshapen. Vitamin D can prevent rickets in children, osteomalacia in adults, and can help protect older adults from osteoporosis.
Upper Respiratory Infections Prevention and Vitamin D
Most vitamin D is created when a person's skin is exposed to UV-B radiation from the sun. As a result, vitamin D deficiency is more common in the winter, when cold and flu levels reach their peak in populations.The rapid spread of the flu usually stops by May when population 25(OH) D levels quickly rise.
A large study appearing in the February 2009 Archives of Internal Medicine found that people with the lowest blood vitamin D levels reported having more recent colds or flu. The risks rose in adults and children who had acute or chronic respiratory disorders. "The findings of our study support an important role for vitamin D in prevention of common respiratory infections, such as colds and the flu," says Adit Ginde, MD, MPH, UC Denver Division of Emergency Medicine and lead author of the study.
There are no significant dietary sources of vitamin D, so unless people receive adequate sun exposure (midday sun during the late spring, summer, and early fall, exposing as much of the skin as possible for 20–30 minutes, being careful not to burn), or take supplements during the winter months, their immune system is likely compromised.
Vitamin D Activates Innate Immune System
The body's immune system naturally produces antimicrobial, (destroying or inhibiting the growth of microorganisms), peptides or (AMPs). These AMPs won't work with every virus it comes in contact with, but for the ones they do, the body's immune system automatically springs into action.
When microbes like the influenza virus reach upper respiratory airways, they stimulate the production of an enzyme that converts 25(OH)D, the circulating inactive form of vitamin D, into the hormonally active 1,25(OH)2D (1,25-dihydroxyvitamin D). 1,25(OH)2D is needed to activate the genes that produce antimicrobial peptides.
Bottom line, without vitamin D there is no innate immunity in the body.
Vitamin D Levels Must Be High Enough To Aid Flu Prevention
Although the risk of vitamin D3 toxicity is very unlikely, people's fear of overdosing remains high.
Dr. Cannell and other vitamin D researchers recommend taking enough Vitamin D3 to get 25(OH)D levels above "substrate starvation levels," 50 ng/mL or 125 nmol/L. Current recommendations are inadequate to maintain optimal health, and certainly to prevent or treat colds and flu.
The Vitamin D Council recommends people supplement with vitamin D before getting a blood test, then adjust their dose so their 25(OH)D level is between 50–80 ng/ml during both the summer and the winter. The council cautions that these are conservative dosage recommendations. People who avoid the sun, and nearly all dark-skinned people need to increase their dose if their blood levels are still low, even after two months of the above dosage, particularly during the winter months.
Exact levels, explains Dr. Cannell, are difficult to determine because requirements vary by age, body weight, percent of body fat, latitude, skin coloration, season of the year, use of sun block, individual variation in sun exposure, and how sick someone is.
“If you use suntan parlors once a week,” says Dr. Cannell, “or if you live in Florida and sunbathe once a week, year-round, do nothing.” However, if you receive very little UVB exposure the Council recommends the following dosing levels of D3:
- Health children under the age of 2 - 1,000 IU per day*
- Healthy children over the age of 2 - 2,000 IU per day*
- Adults and adolescents - 5,000 IU per day.
*The American Academy of Pediatrics recommends 400 mg per day for children.
Consult with a health care provider before taking vitamin D, particularly if you have any of the following conditions: sarcoidosis, primary hyperparathyroidism, granulomatous disease, or other conditions that cause high blood calcium.
Vitamin D has received increased attention due to its critical role in bone health, cancer prevention and immunity. People who test low or who have risk factors need to supplement. Take the optimal form and dose particularly during the winter months to prevent and treat colds and flu.
Further Reading:
Magnesium: The Missing Health Supplement
Tamiflu for Swine Flu Not Always Best Option
Swine Flu Vaccine Additives Complex Issue
Resources:
Dr. J.J. Cannell, Executive Director Vitamin D Council ,“H1N1 and Vitamin D,” http://www.vitamindcouncil.org/newsletter/h1n1-flu-and-vitamin-d.shtml
Adit A. Ginde; Jonathan M. Mansbach; Carlos A. Camargo Jr., “Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey,” Archives of Internal Medicine, 2009.
Cannell, JJ, Vieth R, Umhau, JC, Holick MF, Grant WB, Madronich S, Garland CF, Giovannucci E., “Epidemic influenza and Vitamin D,” Epidemiology and Infection 2006 Dec;134(6):1129-40. Epub 2006 Sep 7.
Vieth R et al, “The urgent need to recommend an intake of vitamin D that is effective,” American Journal of Clinical Nutrition, 2007;85:649-650.
Laura Owens - Laura Owens has a B.S. in Psychology from Rollins College & U of FL. She is a freelance writer with expertise in motivation & wellness.
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