The relationship between low vitamin D levels and breast cancer has been strongly suggested in a number of studies released over the past few years, but an excellent new study out of Germany strengthens the evidence. This is the first large study where blood levels of vitamin D were measured in a group of women with breast cancer and compared to a similar group of women without breast cancer. Those with breast cancer had significantly lower levels of vitamin D.  Read more here.....

Vitamin D3

 

Vitamin D is a fat soluble vitamin that is found in food and can also be made in your body after exposure to ultraviolet (UV) rays from the sun. Sunshine is a significant source of vitamin D because UV rays from sunlight trigger vitamin D synthesis in the skin.

Vitamin D exists in several forms, each with a different level of activity. Vitamin D3 is the most active form of vitamin D. Other forms are relatively inactive in the body. The liver and kidney help convert vitamin D to its active hormone form.   Once vitamin D is produced in the skin or consumed in food, it requires chemical conversion in the liver and kidney to form 1,25 dihydroxyvitamin D, the physiologically active form of vitamin D. Active vitamin D functions as a hormone because it sends a message to the intestines to increase the absorption of calcium and phosphorus.

The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. By promoting calcium absorption, vitamin D helps to form and maintain strong bones. Vitamin D also works in combination with a number of other vitamins, minerals, and hormones to promote bone mineralization. Without vitamin D, bones can become thin, brittle, or misshapen. Vitamin D prevents rickets in children and osteomalacia in adults, two forms of skeletal diseases that weaken bones.

Research also suggests that vitamin D may help maintain a healthy immune system and help regulate cell growth and differentiation, the process that determines what a cell is to become.

 

It can be difficult to obtain enough vitamin D from natural food sources. For many people, consuming vitamin D fortified foods and adequate sunlight exposure are essential for maintaining a healthy vitamin D status. In some groups, dietary supplements may be needed to meet the daily need for vitamin D.


Americans age 50 and older are believed to be at increased risk of developing vitamin D deficiency.  As people age, skin cannot synthesize vitamin D as efficiently and the kidney is less able to convert vitamin D to its active hormone form. It is estimated that as many as 30% to 40% of older adults with hip fractures are vitamin D insufficient. Therefore, older adults may benefit from supplemental vitamin D.
 
Homebound individuals, people living in northern latitudes such as in New England and Alaska, women who wear robes and head coverings for religious reasons, and individuals working in occupations that prevent sun exposure are unlikely to obtain much vitamin D from sunlight. It is important for people with limited sun exposure to consume recommended amounts of vitamin D in their diets or consider vitamin D supplementation.


References:

Singh YN.  Vitamin D part 1:  Are we getting enough?  US Pharm. 2004;10:66-72.

Singh YN.  Vitamin D part 2:  Low status and chronic diseases.  US Pharm. 2004;12:39-49.

National Institutes of Health:  Office of Dietary Supplements.  Dietary supplement fact sheet:  Vitamin D.  http://www.ods.od.nih.gov/factsheets/vitamind.asp.  Accessed on April 23, 2005.

United States Department of Agriculture:  National Agriculture Library.  Dietary references intakes:  Vitamins.  http://www.nal.usda.gov/fnic/etext/000105.html.  Accessed on April 20, 2005.

The United States Pharmacopeial Convention, Inc.  Drug information for the health care professional.  Greenwood Village:  MICROMEDEX; 2003.

Holick MF. Vitamin D Deficiency. N Engl J Med. 2007; 357:266-81.

Campbell TC, Campbell TM.  The China Study:  Startling implications for diet, weight loss and long-term health.  Dallas, TX:  BenBella Books, 2006.

GrassrootsHealth:  A Public Health Promotion Organization [homepage on the Internet].  c2008 [updated 2009 Jul 7; cited 2009 Aug 2].  Scientists’ Call to D*action :  The Vitamin D Deficiency Epidemic.  Available from:  http://www.grassrootshealth.net/epidemic.

Prepared for:  Glen Ellyn Pharmacy (Robert Listecki, RPh) 486 Roosevelt Road, Glen Ellyn, IL

Prepared by:  Nicole Ashrafi, UIC Pharm Candidate 2005.   April 2005

Updated by:  Deborah Schick, MWU PharmD Candidate 2008.  June 2008

Updated by:  Sujata Raol, MWU PharmD Candidate 2009.  August 2009

Updated by:  Denice Beach, MWU PharmD Candidate 2011. March 2010

Estimated equivalency of vitamin D production from natural sun exposure versus oral vitamin D supplementation across seasons at two US latitudes



Background

The relationship between oral vitamin D supplementation and cutaneous photosynthesis is not well understood.

Objective

We sought to provide estimates of the equivalency of vitamin D production from natural sun exposure versus oral supplementation.

Methods

Using the FastRT simulation tool, we determined sun exposure times needed to achieve serum vitamin D3 concentrations equivalent to 400 or 1000 IU vitamin D for individuals of various Fitzpatrick skin types living in Miami, FL, and Boston, MA, during the months of January, April, July, and October.

Results

Peak ultraviolet B irradiation for vitamin D synthesis occurs around 12 pm Eastern Standard Time (EST). In Boston, MA, from April to October at 12 pm EST an individual with type III skin, with 25.5% of the body surface area exposed, would need to spend 3 to 8 minutes in the sun to synthesize 400 IU of vitamin D. It is difficult to synthesize vitamin D during the winter in Boston, MA. For all study months in Miami, FL, an individual with type III skin would need to spend 3 to 6 minutes at 12 pm EST to synthesize 400 IU. Vitamin D synthesis occurs faster in individuals with lighter Fitzpatrick skin types. The duration to attain 1000 IU of vitamin D is longer in all scenarios.

Limitations

Results of the computer model are only approximations. In addition, calculations were made based on the assumption that ¼ of 1 minimal erythema dose directed at ¼ body surface area is equal to 1000 IU of oral vitamin D.

Conclusions

Although it may be tempting to recommend intentional sun exposure based on our findings, it is difficult, if not impossible to titrate one's exposure. There are well-known detrimental side effects of ultraviolet irradiation. Therefore, oral supplementation remains the safest way for increasing vitamin D status.



Refers to article:

Commentary: Ultraviolet irradiation and oral ingestion as sources of optimal vitamin D , 05 April 2010
William G. Tsiaras, Martin A. Weinstock
Journal of the American Academy of Dermatology
June 2010 (Vol. 62, Issue 6, Pages 935-936)


 

Vitamin D Updates

Higher intake of vitamin D through combined use of foods, supplements, and sunlight exposure was found to reduce risk of developing estrogen receptor-positive
/progesterone receptor-positive (ER+/PR+) breast cancer by nearly half, and both ER-/PR- and mixed (ER=/PR-) by nearly one quarter. (Blackmore, Lesosky et al. 2008) Another study published one year earlier found similarly strong results, although the researchers did not distinguish between types of breast cancer. (Knight, J.A., M Lesosky et al. 2007 “Vitamin D and reduced risk of breast cancer: a population-based case-control study.” Cancer Epidemiol Biomarker Prev 16(3):422-29.)