Featured Research

from universities, journals, and other organizations

Don't Forget The Vitamin A When Working With Its Carrier Protein

Date:
October 2, 2008
Source:
Society for Experimental Biology and Medicine
Summary:
In a recent study, researchers discovered that not only was the carrier protein for vitamin A, retinol-binding protein (RBP), elevated in obese individuals compared to leaner controls, but some of it was not attached to vitamin A. This is called apo-RBP by vitamin A scientists. Further research is needed to determine whether this RBP is bound to some other compound in the circulation.

Vitamin A is an essential nutrient involved in vision, growth, cellular differentiation, and immune function. Because vitamin A is fat-soluble, it is chaperoned through the body on carrier proteins.

Related Articles


Researchers at the University of Wisconsin-Madison in a study funded by USDA and NIH, discovered that not only was one of the carrier proteins for vitamin A, retinol-binding protein (RBP), elevated in obese individuals compared to leaner controls, but some of it was not attached to retinol, the main circulating form of the vitamin. RBP that is not bound to vitamin A is called apo-RBP by vitamin A scientists. Their study will appear in the October 08 issue of Experimental Biology and Medicine.

The research team led by Sherry Tanumihardjo, an associate professor of Nutritional Sciences, originally was interested in determining the degree of hypervitaminosis A in the cohort for preliminary data on excessive liver storage of the vitamin. Her graduate student, Jordan Mills, was interested in determining the retinol-binding protein concentrations.

While the degree of hypervitaminosis A was remarkable at 4% prevalence for the obese cohort, the relationship of retinol to RBP was a more interesting discovery. The retinol to RBP ratio (retinol:RBP) was significantly lower in the obese subjects than nonobese subjects. This was attributable to more RBP circulating in the serum not bound to vitamin A. RBP was strongly associated with vitamin A in both groups, but more so in the nonobese individuals.

"A series of studies in mice and humans revealed a strong relationship between serum RBP and obesity-induced insulin resistance. While some studies validated these original observations of elevated RBP in obesity and insulin resistance in humans, others have not. Often lacking in these publications are data for serum retinol, arguably RBP's most important physiological companion, representing a possible explanation for conflicting results," said Mills.

Tanumihardjo added, "Our results further the understanding of the relationship of retinol, RBP, and BMI and suggest that apo-RBP should be evaluated. Retinol:RBP may add new insights and be a better clinical diagnostic for potential insulin resistance than RBP alone."

The authors say, "This elevated serum apo-RBP may be adipose-derived and it is unknown whether it is a direct contributor to insulin resistance in obese individuals. Alternatively, apo-RBP from adipose may transport an unidentified ligand that is responsible for mediating insulin signaling."

Further research is needed to determine whether apo-RBP is bound to some other compound in circulation. Dr. Steven R. Goodman, Editor-in-Chief of Experimental Biology and Medicine, said "this interesting study, led by Dr. Tanumihardjo, opens the door to the determination of the role of apo-RBP in insulin resistance in obese individuals. This will be an important issue for those working on type 2 diabetes."


Story Source:

The above story is based on materials provided by Society for Experimental Biology and Medicine. Note: Materials may be edited for content and length.


Cite This Page:

Society for Experimental Biology and Medicine. "Don't Forget The Vitamin A When Working With Its Carrier Protein." ScienceDaily. ScienceDaily, 2 October 2008. <www.sciencedaily.com/releases/2008/09/080926194607.htm>.
Society for Experimental Biology and Medicine. (2008, October 2). Don't Forget The Vitamin A When Working With Its Carrier Protein. ScienceDaily. Retrieved October 31, 2014 from www.sciencedaily.com/releases/2008/09/080926194607.htm
Society for Experimental Biology and Medicine. "Don't Forget The Vitamin A When Working With Its Carrier Protein." ScienceDaily. www.sciencedaily.com/releases/2008/09/080926194607.htm (accessed October 31, 2014).

Share This



More Health & Medicine News

Friday, October 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Fauci Says Ebola Risk in US "essentially Zero"

Fauci Says Ebola Risk in US "essentially Zero"

AP (Oct. 30, 2014) NIAID Director Anthony Fauci said the risk of Ebola becoming an epidemic in the U.S. is essentially zero Thursday at the Washington Ideas Forum. He also said an Ebola vaccine will be tested in West Africa in the next few months. (Oct. 30) Video provided by AP
Powered by NewsLook.com
Nurse Defies Ebola Quarantine With Bike Ride

Nurse Defies Ebola Quarantine With Bike Ride

AP (Oct. 30, 2014) A nurse who vowed to defy Maine's voluntary quarantine for health care workers who treated Ebola patients followed through on her promise Thursday, leaving her home for an hour-long bike ride. (Oct. 30) Video provided by AP
Powered by NewsLook.com
Pot-Infused Edibles Raise Concerns in Colorado

Pot-Infused Edibles Raise Concerns in Colorado

AFP (Oct. 30, 2014) Colorado may have legalized marijuana for recreational use, but the debate around the decision still continues, with a recent - failed - attempt to ban cannabis-infused edibles. Duration: 01:53 Video provided by AFP
Powered by NewsLook.com
British Navy Ship Arrives in Sierra Leone With Ebola Aid

British Navy Ship Arrives in Sierra Leone With Ebola Aid

AFP (Oct. 30, 2014) The British ship RFA ARGUS arrived in Sierra Leone to deliver supplies and equipment to help the fight against Ebola. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins