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Nutrition, Vitamins & Supplements for Seniors
Vitamin D May Prevent Half of Breast Cancers,
Two-Thirds of Colorectal Cancer
Daily intake of 2,000 IU of vitamin D3 best
achieved with diet, supplements and sunlight
 Feb. 6, 2007 A new prescriptions for possibly
preventing up to half of the cases of breast cancer and two-thirds of
the cases of colorectal cancer in the United States vitamin D - has
been found in two studies. The studies using a sophisticated form of
analysis called meta-analysis, in which data from multiple reports is
combined, was conducted by a core team of cancer prevention specialists
at the Moores Cancer Center at University of California, San Diego (UCSD),
and colleagues from both coasts. (Data on vitamin D below news
report.)
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September 13, 2006 - The risk of getting pancreatic
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Drink milk, get modest exposure to the sun and take a vitamin pill
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Vitamin D Intake by Older People Should be Increased
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Nov. 17, 2005 - The American Medical Women's
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on
Nutrition, Vitamins & Supplements |
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The breast cancer study, published online in the
current issue of the Journal of Steroid Biochemistry and Molecular
Biology, pooled dose-response data from two earlier studies - the
Harvard Nurses Health Study and the St. George's Hospital Study - and
found that individuals with the highest blood levels of
25-hydroxyvitamin D, or 25(OH)D, had the lowest risk of breast cancer.
The researchers divided the 1,760 records of
individuals in the two studies into five equal groups, from the lowest
blood levels of 25(OH)D (less than 13 nanograms per milliliter, or 13 ng/ml)
to the highest (approximately 52 ng/ml). The data also included whether
or not the individual had developed cancer.
"The data were very clear, showing that individuals
in the group with the lowest blood levels had the highest rates of
breast cancer, and the breast cancer rates dropped as the blood levels
of 25-hydroxyvitamin D increased," said study co-author Cedric Garland,
Dr.P.H. "The serum level associated with a 50 percent reduction in risk
could be maintained by taking 2,000 international units of vitamin D3
daily plus, when the weather permits, spending 10 to 15 minutes a day in
the sun."
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Older
adults and Vitamin D
Americans age 50 and older are believed to be at increased risk
of developing vitamin D deficiency, according to the Office of
Dietary Supplements of the National Institutes of Health.
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. |
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The colorectal cancer study, published online
February 6 in the American Journal of Preventive Medicine, is a
meta-analysis of five studies that explored the association of blood
levels of 25(OH)D with risk of colon cancer. All of the studies involved
blood collected and tested for 25 (OH)D levels from healthy volunteer
donors who were then followed for up to 25 years for development of
colorectal cancer.
As with the breast cancer study, the dose-response
data on a total of 1,448 individuals were put into order by serum
25(OH)D level and then divided into five equal groups, from the lowest
blood levels to the highest.
"Through this meta-analysis we found that raising
the serum level of 25-hydroxyvitamin D to 34 ng/ml would reduce the
incidence rates of colorectal cancer by half," said co-author Edward D.
Gorham, Ph.D.
"We project a two-thirds reduction in incidence
with serum levels of 46ng/ml, which corresponds to a daily intake of
2,000 IU of vitamin D3. This would be best achieved with a combination
of diet, supplements and 10 to 15 minutes per day in the sun."
Vitamin D3 is available through diet, supplements
and exposure of the skin to sunlight, or ultraviolet B (UVB).
In the paper, the researchers underscored the
importance of limiting sun exposure such that the skin does not change
color (tan) or burn. For a typical fair-skinned Caucasian individual,
adequate vitamin D could be photosynthesized safely by spending 10 to 15
minutes in the noontime sun on a clear day with 50 percent of skin area
exposed to the sun.
Darker skinned individuals may require more time in
the sun, such as 25 minutes. For people with photosensitivity disorders,
or anyone with a personal or family history of nonmelanoma skin cancer,
any amount of extra sun exposure would be inadvisable.
The meta-analysis on colorectal cancer includes
data from the Women's Health Initiative, which had shown in 2006 that a
low dose of vitamin D did not protect against colorectal cancer within
seven years of follow-up. However, the researchers wrote, the
meta-analysis indicates that a higher dose may reduce its incidence.
"Meta-analysis is an important tool for revealing
trends that may not be apparent in a single study," said co-author
Sharif B. Mohr, M.P.H. "Pooling of independent but similar studies
increases precision, and therefore the confidence level of the
findings."
The authors recommend further research to study
individuals for the effect of vitamin D from sunlight, diet and
supplements on the risk of cancer.
Editor's Notes:
Co-authors on both the breast cancer and colorectal
meta-analysis papers are Edward D. Gorham, MPH, Ph.D., Cedric F.
Garland, Dr.P.H.; Frank C. Garland, Ph.D.; Sharif B. Mohr, MPH; William
B. Grant, Ph.D; Martin Lipkin, M.D.; Harold L. Newmark, ScD; Edward
Giovannucci, M.D., ScD; and Michael F. Holick, M.D., Ph.D. Co-author on
the colorectal meta-analysis paper only was Melissa Wei, B.S. Authors'
institutional affiliations are UCSD Department of Family and Preventive
Medicine and Moores UCSD Cancer Center (Gorham, Garland, Garland); Naval
Health Research Center, San Diego (Gorham, F.C. Garland, Mohr);
SUNARC-Sunlight, Nutrition and Health Research Center, San Francisco
(Grant); Strang Cancer Prevention Center of Rockefeller University, New
York, NY (Lipkin); Rutgers--The State University of New Jersey and
Cancer Institute of New Jersey (Newmark); Harvard Schools of Public
Health and Medicine (Giovannucci, Wei); and Boston University School of
Medicine (Holick).
Funding for this research was provided by a
Congressional allocation to the Hollings Cancer Center of the Medical
University of South Carolina through the Department of the Navy.
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About Vitamin D by
Office of Dietary Supplements, National Institutes of Health |
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. Calciferol 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 concert 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 sufficiency 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. |
Table 1:
Selected food sources of vitamin D
| Food |
International Units(IU) per serving |
Percent DV* |
| Cod liver oil, 1 Tablespoon |
1,360 |
340 |
| Salmon, cooked, 3½ ounces |
360 |
90 |
| Mackerel, cooked, 3½ ounces |
345 |
90 |
| Tuna fish, canned in oil, 3 ounces |
200 |
50 |
| Sardines, canned in oil, drained, 1Ύ
ounces |
250 |
70 |
| Milk, nonfat, reduced fat, and whole,
vitamin D fortified, 1 cup |
98 |
25 |
| Margarine, fortified, 1 Tablespoon |
60 |
15 |
| Pudding, prepared from mix and made
with vitamin D fortified milk, ½ cup |
50 |
10 |
| Ready-to-eat cereals fortified with
10% of the DV for vitamin D, Ύ cup to 1 cup servings
(servings vary according to the brand) |
40 |
10 |
| Egg, 1 whole (vitamin D is found in
egg yolk) |
20 |
6 |
| Liver, beef, cooked, 3½ ounces |
15 |
4 |
| Cheese, Swiss, 1 ounce |
12 |
4 |
*DV = Daily Value. DVs are reference numbers developed by the
Food and Drug Administration (FDA) to help consumers determine
if a food contains a lot or a little of a specific nutrient. The
DV for vitamin D is 400 IU (10 μg) for adults. Most food labels
do not list vitamin D content unless a food has been fortified
with this nutrient.
The percent DV (%DV) listed on the table above
tells you the percent of the DV provided in one serving. A food
providing 5% of the DV or less is a low source while a food that
provides 10-19% of the DV is a good source and a food that
provides 20% or more of the DV is high in that nutrient.
It is important to remember that foods that
provide lower percentages of the DV also contribute to a
healthful diet.
For foods not listed in this table, please
refer to the U.S. Department of Agricultures Nutrient Database
Web site:
http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl.
For the
complete Fact Sheet on Vitamin D by the Office of Dietary
Supplements, click here.
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