SAT加分項(xiàng) 課外閱讀：科學(xué) | Beyond Resveratrol: The Anti-Aging NAD Fad

新SAT考試中，閱讀依然占得比重較多；如何分析閱讀一篇文章并迅速找到需要的信息點(diǎn)呢？今天呢，留學(xué)監(jiān)理網(wǎng)的老師就給大家找了一篇例文，供大家學(xué)習(xí)借鑒。預(yù)祝大家考試順利！

Whenever I see my 10-year-old daughter brimming over with so much energy that she jumps up in the middle of supper to run around the table, I think to myself, "those young mitochondria."

Mitochondria are our cells' energy dynamos. Descended from bacteria that colonized other cells about 2 billion years, they get flaky as we age. A prominent theory of aging holds that （有觀點(diǎn)出現(xiàn)了）decaying of mitochondria is a key driver of aging. While it's not clear why our mitochondria fade as we age, evidence suggests that it leads to everything from heart failure to neurodegeneration, as well as the complete absence of zipping around the supper table.

Recent research suggests it may be possible to reverse mitochondrial decay with dietary supplements that increase cellular levels of a molecule called NAD (nicotinamide adenine dinucleotide). But caution is due（作者觀點(diǎn)出現(xiàn)）: While there's promising test-tube data and animal research regarding NAD boosters, no human clinical results on them have been published.

NAD is a linchpin of energy metabolism, among other roles, and its diminishing level with age has been implicated in mitochondrial deterioration. Supplements containing nicotinamide riboside, or NR, a precursor to NAD that's found in trace amounts in milk, might be able to boost NAD levels. In support of that idea, half a dozen Nobel laureates and other prominent scientists are working with two small companies offering NR supplements.

The NAD story took off toward the end of 2013 with a high-profile paper by Harvard's David Sinclair and colleagues. Sinclair, recall, achieved fame in the mid-2000s for research on yeast and mice that suggested the red wine ingredient resveratrol mimics anti-aging effects of calorie restriction. This time his lab made headlines by reporting that the mitochondria in muscles of elderly mice were restored to a youthful state after just a week of injections with NMN (nicotinamide mononucleotide), a molecule that naturally occurs in cells and, like NR, boosts levels of NAD.

It should be noted, however,（作者觀點(diǎn)） that muscle strength was not improved in the NMN-treated mice—the researchers speculated that one week of treatment wasn't enough to do that despite signs that their age-related mitochondrial deterioration was reversed.

NMN isn't available as a consumer product. But Sinclair's report sparked excitement about NR, which was already on the market as a supplement called Niagen. Niagen's maker, ChromaDex, a publicly traded Irvine, Calif., company, sells it to various retailers, which market it under their own brand names. In the wake of Sinclair's paper, Niagen was hailed in the media as a potential blockbuster.

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