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Medicine Science

Reducing One Amino Acid Could Increase Lifespan 286

John Bryson writes "Eating less of one amino acid might lengthen your life. There have been lots of previous studies showing that many species live long on highly restricted calories, but a lot of this benefit may be possible by only restricting one amino acid. Amino acids that have shown this have been tryptophan and methionine. A recent study, published online December 2 in Nature, a highly respected journal, may help explain some of the health benefits of restricted-calorie diets."
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Reducing One Amino Acid Could Increase Lifespan

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  • by Anonymous Coward on Sunday December 06, 2009 @04:02AM (#30341802)

    Tryptophan also naturally occurs in bananas. It metabolizes through a few stages into serotonin.

  • by Paltin ( 983254 ) on Sunday December 06, 2009 @04:09AM (#30341832)
    Tryptophan inducing the Thanksgiving sleep is a nice myth--- but it's a common amino acid, and is actually in a higher concentration in chicken than turkey.

    The sleep inducing factor in your favorite November holiday is actually the fact that you stuff yourself. Eat four pounds of chicken and gravy, and then we'll see if you stay awake. :)
  • by millennial ( 830897 ) on Sunday December 06, 2009 @04:10AM (#30341834) Journal
    Not quite. [wikipedia.org] But yeah, I had the same thought :)

    One belief is that heavy consumption of turkey meat (as for example in a Thanksgiving or Christmas feast) results in drowsiness, which has been attributed to high levels of tryptophan contained in turkey. While turkey does contain high levels of tryptophan, the amount is comparable to that contained in most other meats. Furthermore, postprandial Thanksgiving sedation may have more to do with what else is consumed along with the turkey, in particular carbohydrates and alcohol.

  • by Psychotic_Wrath ( 693928 ) on Sunday December 06, 2009 @04:21AM (#30341862)
    There is more tryptophan in a glass of milk than a serving of turkey
  • Re:Yes, but... (Score:5, Informative)

    by John Whitley ( 6067 ) on Sunday December 06, 2009 @04:24AM (#30341872) Homepage

    TFA directly addresses that point:

    Piper and his colleagues don’t know what the correct amino acid balance might be for humans, and he says it would be a nearly impossible feat to adjust people’s diets to get just the right mix. Instead, the team is investigating how tweaking amino acid content in the diet affects cells. If the researchers can identify pathways affected by amino acid imbalances, they might be able to design drugs or other therapies that could give the benefits of caloric restriction without cutting calories.

  • by Psychotic_Wrath ( 693928 ) on Sunday December 06, 2009 @04:36AM (#30341914)
    1 serving of 2% milk and 1 serving of turkey. Milk has significantly more. I don't really want to look up the serving sizes but if you google em you'll find em :). I do understand your argument tho.
  • Link to actual study (Score:5, Informative)

    by Anonymous Coward on Sunday December 06, 2009 @05:04AM (#30341976)

    http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08619.html for the actual study

  • No tryptophan in TFA (Score:5, Informative)

    by mangu ( 126918 ) on Sunday December 06, 2009 @05:23AM (#30342022)

    I am the one slashdotter that reads TFA (the full article) before posting. I even did a search for tryptophan. Nope, it's not there. Maybe the submitter forgot a link, but tryptophan is never mentioned in the sciencenews.org article.

  • Tryptophan? (Score:2, Informative)

    by Nithendil ( 1637041 ) on Sunday December 06, 2009 @05:30AM (#30342042)

    The summary mentions tryptophan but it isn't anywhere in the article. And I wonder if the decreased longevity is due to the excessive methionine itself or a result of its byproducts such as SAM and homocysteine.

  • by jonnat ( 1168035 ) on Sunday December 06, 2009 @06:17AM (#30342194)

    If you are interested, here is a list of food products containing high levels of methionine:

    http://www.nutritiondata.com/foods-000084000000000000000-w.html [nutritiondata.com]

    And tryptophan:

    http://www.nutritiondata.com/foods-000079000000000000000-w.html [nutritiondata.com]

  • by Bent Mind ( 853241 ) on Sunday December 06, 2009 @07:40AM (#30342448)

    anecdotes =/= science

    Not sure what your point was. Were you saying that there isn't any science in your post?

    I found the answer in a wikipedia link [wikipedia.org] provided in another message. The link suggests that the sleepiness is not caused by tryptophan alone. Rather, carbohydrates trigger the release of insulin. Insulin causes muscle to take in LNAA, but not tryptophan. This leaves a larger ratio of tryptophan in the blood to be taken across the blood-brain barrier into the central nervous system. There it is converted into serotonin. The serotonin is metabolized into melatonin. Melatonin makes you sleepy.

    So, tryptophan by itself does not make you sleepy. However, tryptophan combined with carbohydrates leads to the right conditions needed to make you sleepy. It has nothing to do with stuffing yourself. Nor is tryptophan's involvement a myth. It just needs the right conditions. Skip the mashed potatoes and you shouldn't get sleepy from turkey.

  • Re:Yes, but... (Score:5, Informative)

    by RAMMS+EIN ( 578166 ) on Sunday December 06, 2009 @07:42AM (#30342458) Homepage Journal

    ``Ideally, if giving up Trytophan is beneficial with no negative side effects, they'd create a pill that prevents your body from digesting it.''

    Interestingly, there are actually pills that contain tryptophan. Tryptophan is an essential amino acid and is one of the precursors to serotonine. Serotonine is a neurotransmitter, and low serotonine levels are associated with such conditions as depression and anxiety disorders. So people take extra tryptophan (or, more commonly, 5-HTP, the direct precursor to serotonine) to boost serotonine levels.

  • Re:Yes, but... (Score:3, Informative)

    by CRCulver ( 715279 ) <crculver@christopherculver.com> on Sunday December 06, 2009 @09:49AM (#30342860) Homepage

    I want you to think about how expensive a drug to extend life would end up being. You think world and economic leaders want to see the lifespan of all humans suddenly extended?

    Recently I went back and reread Kim Stanley Robinson's trilogy beginning with Red Mars [amazon.com] . One of the plot points is how a gene therapy is developed that essentially prolongs lifespan indefinitely. Robinson spends much time exploring the demographic and political ramifications of this. A decade ago, this was all very relevant reading.

    However, in the years since this kind of science fiction enjoyed its heyday, there's been so much talk about the possible coming Singularity by futurists like Kurzweil. If the integration of the biological and the machine is right around the corner, then that would seem to overturn the Mathusian vision of the future evoked by the presence so many normal humans.

    The integration of technology with biology is usually discussed as being so gradual that your suspicion that this immortality wouldn't be available to all people is not necessarily the case. Look around the developing world, and you'll see more and more people having access to all kinds of gadgetry.

  • Re:Yes, but... (Score:3, Informative)

    by Opportunist ( 166417 ) on Sunday December 06, 2009 @11:42AM (#30343412)

    That depends on whether we just get older or whether we also get healthier.

    So far we've been busy finding ways to keep people from dying. This is, of course, quite costy. My great grandma was bedridden for the last 15 years of her life. Just extending that span will certainly put a very heavy strain on any social budget and the institutions supposed to care for those people. If that additional lifetime can be spent active because people also stay healthy and agile longer, the only ones who have to worry are retirement fonds.

  • by SydShamino ( 547793 ) on Sunday December 06, 2009 @01:06PM (#30343960)

    Because it has 33% less fat than regular milk, but still tastes about the same?

  • Re:Amino Acids (Score:2, Informative)

    by structural_biologist ( 1122693 ) on Sunday December 06, 2009 @01:49PM (#30344266)
    You are correct that it is well known that limited diets (i.e. caloric restriction) increase lifespan and also decrease fertility. Many believe the mechanism involves just what you said: in conditions of limited resources, the body shifts resources away from reproduction.

    The authors of the study set out to test the hypothesis that the decreased fertility from caloric restriction results from a lack of calories. The authors predicted that if this hypothesis is true, it should not be possible to find nutrient conditions that increase lifespan without decreasing fertility. However, the authors found that they could restore normal fertility levels while maintaining the increased lifespan in calorie restricted flies by adding methionine to the flies' diet. Thus, as the authors state in the paper's abstract: "reallocation of nutrients therefore does not explain the responses to dietary restriction."

    Furthermore, they found that it is primarily the lifespan increases in caloric restriction come primarily from restricting amino acids. Adding carbohydrates or fats to the diets of calorie restricted flies did not reduce the increases in lifespan due to calorie restriction. So yes, the summary is completely wrong. Restricting the intake all amino acids except for methionine could increase lifespan (in flies) without harming fertility, not the other way around as the summary implies.

    Of course, it's an open question whether any of this applies to humans or whether this fountain of youth works only for fruit flies.
  • Re:Yes, but... (Score:3, Informative)

    by General Wesc ( 59919 ) <slashdot@wescnet.cjb.net> on Sunday December 06, 2009 @03:17PM (#30345032) Homepage Journal

    That was through reductions in child mortality, not extending the life of people who manage to live to adulthood. See this chart [elderweb.com] for specifics. Newborns have an extra ~30 years, but 65-year-olds only have an extra ~5, on average.

  • by Paul Fernhout ( 109597 ) on Sunday December 06, 2009 @08:56PM (#30347816) Homepage

    Except today's hunter/gatherers are the ones who have been pushed onto the most marginal lands with the least natural productivity. The agricultural empires in general took over the best land (including using bronze weapons). If you look at Marshall Sahlins wrote, in many productive areas, hunter/gatherers spend maybe two hours a day on food related work most of the time -- and it is mostly fun and interesting and engaging work. It is things like fishing to catch just one big fish. Or collecting ripe fruit off a tree in season.

"The pathology is to want control, not that you ever get it, because of course you never do." -- Gregory Bateson