Saturday, August 23, 2008

Vitamin A (Retinol)


Updated and revised by Jackie Mosure, Dietetic Intern, College of Human Ecology.

This fact sheet is one in a series containing information to help you select foods that provide adequate daily amounts
of vitamins, minerals, and dietary fiber. The Dietary Guidelines Advisory Committee just released the Dietary Guidelines
for Americans 2005 that convey the following nine major messages concerning these topics:
Adequate nutrients within calorie needs
Weight management
Physical activity
Food groups to encourage: fruits and vegetables, whole grains, and nonfat or low-fat milk and milk products
Fat
Carbohydrates
Sodium and potassium
Alcoholic beverages
Food safety

What is the importance of vitamin A?
Vitamin A, a fat-soluble vitamin, plays essential roles in vision, growth, and development; the development and
maintenance of healthy skin, hair, and mucous membranes; immune functions; and reproduction.

How much do you need?
Vitamin A is also called retinol. Measurement of the amount of vitamin A is taken in retinol activity equivalents (RAE).
Carotene, an orange pigment found in food, is split by the body to become two active units of vitamin A. This is also important when calculating the amount of vitamin A in the body. The U.S. Recommended Daily Allowance (RDA) for
vitamin A is 700 RAE per day for women and 900 RAE per day for men. The U.S. RDA given is for adults and changes
for women who are pregnant or lactating; therefore, please consult your healthcare provider for differences.
A good source of vitamin A contains substantial amounts of vitamin A and/or carotene in relation to its calorie content
and contributes at least 10% of the U.S. RDA for vitamin A in a serving.

Do Americans get enough vitamin A?
According to recent surveys by the U.S. Department of Agriculture (USDA), the average intake of vitamin A (and
carotene) by an American adult is adequate.

How to get enough vitamin A.
Eating a variety of foods that contain vitamin A (and carotene) is the best way to get an adequate amount. Healthy
individuals who eat a balanced diet rarely need supplements.In fact, too much vitamin A can be toxic. Select foods that
contain excellent to good sources of vitamin A each day.

How to prepare foods to retain vitamin A.
Vitamin A can be lost from foods during preparation, cooking, or storage. To prevent loss of vitamin A:
Use raw fruits and vegetables whenever possible.
Keep vegetables (except sweet potatoes and winter squash) and fruits covered and refrigerated during storage.

Where to find vitamin A in the Food Guide Pyramid.





Steam vegetables and braise, bake, or broil meats instead
of frying. Some of the vitamin A is lost in the fat during frying.

What about fortified foods?
Low-fat and skim milk are often fortified with vitamin A because it is lost during processing. Margarine is fortified to
make its vitamin A content the same as butter. Most ready-to-eat and instant prepared cereals are fortified
with vitamin A. Fortified ready-to-eat cereals usually contain at least 25% of the U.S. RDA for vitamin A. Cereals vary,
so check the label on the package for the vitamin A content for that cereal.

What is a serving?
The amount of vitamin A in a serving depends on the weight of the serving. For example, ½ cup of a cooked vegetable
contains more vitamin A than ½ cup of the same vegetable raw, because the cooked vegetable weighs more. Therefore,
the cooked vegetable provides vitamin A, just not enough in a ½-cup serving to be considered a good source.
Food companies label their products according to regulations set by the Food and Drug Administration (FDA). Terms
to define a serving of food that has 20% or more of the RDA include: “high,” “rich in,” or “excellent source of” vitamin
A. Terms to define a serving of food that contains 10% or more of the RDA include: “good,” “contains or provides”
vitamin A. Terms to define a serving of food that contains less then 10% of the RDA include: “enriched,” “fortified,”
or “added” vitamin A.

References
Browne, M. B. 1993. Label Facts for Healthful Eating. Mazer Corporation, Dayton, OH.
Federation of American Societies for Experimental Biology,Life Sciences Research Office. Prepared for the
  Interagency Board for Nutrition Monitoring and Related Research, 1995. Third Report on Nutrition Monitoring
  in the United States: Volumes 1 and 2. U.S. Government Printing Office, Washington, DC.
Subcommittee on the 10th Edition of the RDAs, Food and Nutrition Board, Commission on Life Sciences, National
  Research Council. 1987. Recommended Dietary Allowances, 10th ed. Academy Press, Washington, DC.
U.S. Department of Agriculture, U.S. Department of Health and Human Services. Your Health: Dietary Guidelines for
  Americans, 4th ed. Home and Garden Bulletin No. 232.U.S. Government Printing Office, Washington, DC.






Friday, August 22, 2008

VITAMIN D LINKED TO REDUCED MORTALITY RATE IN CHRONIC KIDNEY DISEASE

Washington, DC (Tuesday, May 6, 2008) — For patients with moderate to severe chronic kidney disease
(CKD), treatment with activated vitamin D may reduce the risk of death by approximately one-fourth,
suggests a study in the August Journal of the American Society of Nephrology.
Many patients with advanced CKD take the drug calcitriol, an oral form of activated vitamin D, to
treat elevated levels of parathyroid hormone. "Although activated vitamin D is known to influence many
biological processes, previous clinical knowledge is limited to its effect on parathyroid hormone levels,"
explains Dr. Bryan Kestenbaum of the University of Washington in Seattle, one of the study authors.
The study included 1,418 patients who had stage 3 to 4 CKD, which means moderately to severely
reduced kidney function. All patients also had high parathyroid hormone levels (hyperparathyroidism),
which can contribute to weakening of the bones in CKD. The researchers identified one group of patients
who were being treated with calcitriol to lower their parathyroid hormone levels and another group who
were not receiving calcitriol.

During a two-year follow-up period, mortality rates were compared for patients who were and were
not taking calcitriol. "We then adjusted for differences in age, kidney function, parathyroid hormone levels,
other illnesses, and other medications," says Dr. Kestenbaum.
In the adjusted analysis, the overall risk of death was about 26 percent lower for patients taking
calcitriol. Patients on calcitriol were also less likely to develop end-stage renal disease, requiring dialysis to
replace lost kidney function.

Overall, treatment with calcitriol was associated with a 20 percent reduction in the risk of either
death or dialysis. The reduction in mortality with calcitriol was unrelated to its effect on parathyroid
hormone levels.

"Recently, there has been an increased focus on the effects of vitamin D beyond those on bone
health," Dr. Kestenbaum comments. "Vitamin D deficiency has been associated with risk factors for
cardiovascular disease, such as high blood pressure, diabetes, and inflammation." Previous studies have
suggested that treatment with intravenous vitamin D can improve survival in patients on hemodialysis.
The new results suggest that treatment with oral activated vitamin D may also improve survival in
patients with CKD who do not yet require dialysis. "Randomized clinical trials are needed to test the
hypothesis that vitamin D therapy can improve cardiovascular health and survival in CKD,"
Dr. Kestenbaum adds. "Future studies should also examine the role of non-activated vitamin D, which is
less expensive and less toxic."

The study has some important limitations, including a lack of data on other factors that may have
affected survival in patients taking calcitriol. Also, since the study included mainly older, white men, the
results may not apply to younger, more ethnically diverse populations with CKD.
This study was supported by a Career Development Award (K23 DK63274-01) from the National
Institutes of Health.

Dr. Kestenbaum receives consulting fees from Abbott and Shire as well as grant support from
Amgen.

The study entitled, "Association of Oral Calcitriol with Improved Survival in Nondialyzed CKD,"
will be available online at http://jasn.asnjournals.org/ beginning on Wednesday, May 7, 2008, and in print
in the August issue of the Journal of the American Society of Nephrology (JASN).
The American Society of Nephrology (ASN) is a not-for-profit organization of 11,000 physicians
and scientists dedicated to the study of nephrology and committed to providing a forum for the
promulgation of information regarding the latest research and clinical findings on kidney diseases. ASN
publishes JASN, the Clinical Journal of the American Society of Nephrology (CJASN), and the Nephrology
Self-Assessment Program (NephSAP). In January 2009, ASN will launch a newsmagazine.

Thursday, July 31, 2008

IRON

What it dose

Aids in the production of haemoglobin (the protein in red blood cells that transports oxygen from the lungs to the body's tissue) and myoglobin (a protein that provides extra fuel to muscles during exertion); helps maintain healthy immune system; is important for growth.


Minimum Recommended Daily Allowance

14 mg.


Food Sources

Beef, blackstrap molasses, brewer's yeast, dark green vegetables, dried fruit, legumes, nuts, organ meats,sea vegetables, seeds, soybeans, whole grains.


Toxic Dosage

Iron should not be taken in excess of 35 mg daily without a doctor's recommendation. In high doses, iron can cause diarrhoea, dizziness, fatigue, headaches, stomach-aches, weakened pulse. Excess iron inhibits the absorption of phosphorus and vitamin E, interferes with immune function, and has been associated with cancer, cirrhosis, heart disease.


Enemies

Antacids, caffeine, tetracycline, iron absorption, excessive menstrual bleeding, long-term illness, and ulcer.


Deficiency Symptoms

Anaemia, brittle hair, difficulty swallowing, dizziness, fatigue, hair loss, irritability, nervousness, pallor, ridges in the nails, sensitivity to cold, slowed mental reactions.