Vitamin C in human health and disease is still a mystery

Abstract

Ascorbic acid is one of the important water soluble vitamins. It is essential for collagen, carnitine and neurotransmitters biosynthesis. Most plants and animals synthesize ascorbic acid for their own requirement. However, apes and humans can not synthesize ascorbic acid due to lack of an enzyme gulonolactone oxidase. Hence, ascorbic acid has to be supplemented mainly through fruits, vegetables and tablets. The current US recommended daily allowance (RDA) for ascorbic acid ranges between 100–120 mg/per day for adults. Many health benefits have been attributed to ascorbic acid such as antioxidant, anti-atherogenic, anti-carcinogenic, immunomodulator and prevents cold etc. However, lately the health benefits of ascorbic acid has been the subject of debate and controversies viz., Danger of mega doses of ascorbic acid? Does ascorbic acid act as a antioxidant or pro-oxidant ? Does ascorbic acid cause cancer or may interfere with cancer therapy? However, the Panel on dietary antioxidants and related compounds stated that the in vivo data do not clearly show a relationship between excess ascorbic acid intake and kidney stone formation, pro-oxidant effects, excess iron absorption. A number of clinical and epidemiological studies on anti-carcinogenic effects of ascorbic acid in humans did not show any conclusive beneficial effects on various types of cancer except gastric cancer. Recently, a few derivatives of ascorbic acid were tested on cancer cells, among them ascorbic acid esters showed promising anticancer activity compared to ascorbic acid. Ascorbyl stearate was found to inhibit proliferation of human cancer cells by interfering with cell cycle progression, induced apoptosis by modulation of signal transduction pathways. However, more mechanistic and human in vivo studies are needed to understand and elucidate the molecular mechanism underlying the anti-carcinogenic property of ascorbic acid. Thus, though ascorbic acid was discovered in 17^th century, the exact role of this vitamin/nutraceutical in human biology and health is still a mystery in view of many beneficial claims and controversies.

Historical perspective

The sea voyager/sailors developed a peculiar disease called scurvy when they were on sea. This was found to be due to eating non-perishable items and lack of fresh fruits and vegetables in their diet. A British naval Physician, Lind documented that there was some substance in citrus fruits that can cure scurvy. He developed a method to concentrate and preserve citrus juice for use by sailors. British Navy was given a daily ration of lime or lemon juice to overcome ascorbic acid deficiency. Ascorbic acid was first isolated from natural sources and structurally characterized by Szent-Gyorgyi, Waugh and King. This vitamin was first synthesized by Haworth and Hirst . Currently ascorbic acid is the most widely used vitamin supplement through out the world.
Continuing.....

Bing Advertising Network

Bing Ads (formerly Microsoft adCenter and MSN adCenter) is a service that provides pay per click advertising on both the Bing and Yahoo! search engines. As of the fourth quarter 2013, Bing Ads has 15.6% market share in the United States.


Microsoft was the last of the "big three" search engines (which also includes Google and Yahoo!) to develop its own system for delivering pay per click (PPC) ads. Until the beginning of 2006, all of the ads displayed on the MSN Search engine were supplied by Overture (and later Yahoo!). MSN collected a portion of the ad revenue in return for displaying Yahoo!'s ads on its search engine



As search marketing grew, Microsoft began developing its own system, MSN adCenter, for selling PPC advertisements directly to advertisers. As the system was phased in, MSN Search (now Bing) showed Yahoo! and adCenter advertising in its search results. Microsoft effort to create AdCenter was led by Tarek Najm, then general manager of the MSN division of Microsoft. In June 2006, the contract between Yahoo! and Microsoft had expired and Microsoft was displaying only ads from adCenter until 2010.

In November 2006 Microsoft acquired DeepMetrix, a company situated in Gatineau, Canada, that created web-analytics software. Microsoft has built new product AdCenter Analytics based on the acquired technology. In October, 2007 the Beta version of Microsoft Project Gatineau was released to a limited number of participants^.

In May 2007, Microsoft agreed to purchase the digital marketing solutions parent company, aQuantive, for roughly $6 billion Microsoft later resold Atlas, a key piece of the aQuantive acquisition, to Facebook in 2013^.
Microsoft acquired ScreenTonic on May 3, 2007, AdECN on July 26, 2007 and YaData on February 27, 2008 and merged their technologies into adCenter.
On February 23, 2009, Publisher Leadership Council was created under the umbrella of Microsoft Advertising. The council was responsible to deliver the next-generation advertising platform for the publishers of digital media resulting in the formation of Microsoft pubCenter.



In January 2010, Microsoft announced a deal in which it would take over the functional operation of Yahoo! Search, and set up a joint venture to sell advertising on both Yahoo! Search and Bing known as the Microsoft Search Alliance. A complete transition of all Yahoo! sponsored ad clients to Microsoft adCenter occurred in October 2010.
On September 10, 2012, adCenter was renamed to Bing Ads, and the Search Alliance was renamed the Yahoo! Bing Network.