Turkey and Tryptophan: Thanksgiving Myth Debunked

Turkey and Tryptophan: Thanksgiving Myth Debunked

ƵƵƶƶ Why do we feel sleepy after a big meal? You’ve probably blamed the Thanksgiving turkey for having too much tryptophan, an amino acid that the body converts to serotonin and melatonin, two sleep-inducing compounds. But it turns out that tryptophan has to be consumed on an empty stomach and not with gourmandish excess of cranberry sauce and pumpkin pie, to be effectively blamed for your soporific state.  Did you know that even oat bran and soybeans contain more tryptophan than turkey? Check out this infographic ▶ http://goo.gl/pQtLTp .

ƵƵƶƶ Another popular theory is that after a big meal, our body diverts blood supply to the gut, and away from the brain, to help digestion. While this seems logical, it turns out that cerebral blood flow and oxygenation are kept stable through autoregulation mechanisms even when blood flow to the gut or muscles increase after a meal or during exercise.  Blood vessels in the brain expand or contract in response to changes in blood pressure to keep flow constant. Another myth debunked! 

ƵƵƶƶ The most likely culprits are gut-brain hormones that regulate both feeding and sleep. Orexin is one such example: it promotes hunger and alertness, but is inhibited by gastric distention and satiety. The ability of hunger to promote alertness is thought to be an evolutionary adaptation that keeps us motivated to search for food. Interestingly, mutations in orexin were recently linked to narcolepsy, a pathological form of sleepiness. Finally, it has been argued that sleep allows for “cognitive reinforcement” of the circumstances that led to your energy acquisition, an important survival skill! So when postprandial somnolence hits you after your big Thanksgiving meal, you’re actually learning an age-old survival mechanism 🙂 

Ref: http://www.ncbi.nlm.nih.gov/pubmed/15488646

Gif: Via http://www.reactiongifs.com/tag/sleepy/

#ScienceEveryday   #HappyThanksgiving  

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120 Responses to Turkey and Tryptophan: Thanksgiving Myth Debunked

  1. Glad to read this article today!  Thank you so much for sharing it.  “Cognitive reinforcement” of the circumstances that led to your energy acquisition, an important survival skill!  I love that phrasing!

  2. Rajini Rao says:

    Hehe, now you have an erudite excuse 😀

  3. Kawthar A says:

    Awwww loving the gif 😀 a very informative and interesting read as always, Rajini! 🙂

    Happy Thanksgiving! ❤

  4. hamid asadi says:


    i enjoyed that

  5. Rajini Rao says:

    Kawthar A they are so cute..what about the little fellow stuffing his face in the back?! 🙂 

  6. Kawthar A says:

    He didn’t waste his time 😀 such kissable cheeks :*

  7. used to think it was the blood supply!

  8. Rajini Rao says:

    A tasty kiss too, I can almost fill my tummy by kissing him 😛 

  9. Kawthar A says:

    hehehe..well played Rajini..well played :p 

  10. Rajini Rao says:

    Thanks, you too Nutin Honie 🙂

    Vasudevan Tirumurti I thought so too..in fact, in my last post we had a discussion about why we feel sleepy after a meal (with David Archer and Chad Haney ), and the blood supply theory seemed reasonable until I looked it up. 

  11. Glad to see a new generation that are totally in touch with the FSM.


  12. One kid is more efficient than the other, I see… ^__^

  13. Rajini Rao says:

    arromazam pepe , lol. My friend Buddhini Samarasinghe will appreciate the comment. 

  14. Rajini Rao says:

    Daniela Huguet Taylor your kids must have done this, no? 😀

    As for me, I just fell asleep on the couch after dinner last night, watching my favorite Masterpiece Mystery. When I woke up, the mystery had been solved and I was none the wiser. 

  15. Marian Wirth says:

    Happy Thanksgiving, Rajini Rao!

  16. Rajini Rao says:

    Marian Wirth thank you 🙂 Did you notice that I’m being more of a twit? 


  17. Marta Rauch says:

    Rajini Rao thank you for the interesting post 🙂

  18. Rajini Rao I know the feeling, happens to me a lot more now I’m older, and yes, kids too, hehe, but never as funny as these (my loss!). My brother on the other hand was fully capable of sleeping and eating (from a spoon) at the same time!

  19. Jim Gorycki says:

    I think the main reason is that we have too many carbs — stuffing and mashed potatoes. I read that the stomach is like a second brain which may also cause the sleepy effects. The second brain is probably where they get the quote “gut feeling” from.

  20. Who knew??! Mozzarella, cheddar and parmesan cheese made the list!! These are in my dishes almost everyday. Thanks for the interesting read Rajini Rao. Happy Thanksgiving!

  21. Marian Wirth says:

    Rajini Rao No, I didn’t. For me, you’re still the G+ star with a fan crowd the size of a German mid-size city 😀

  22. Rajini Rao says:

    Jim Gorycki , yes indeed! The enteric nervous system or “gut brain” has as many neurons as the spinal cord. The gut brain can influence our mood too and apparently most of our serotonin comes from here. 

  23. Rajini Rao says:

    Susana M. I was really surprised by that infographic too. Happy thanksgiving to you too! 

  24. Ramen! Thanks for the tag Rajini! Will read the post when I get home – out celebrating at the moment! 🙂

  25. Increased tryptophan/serotonin produces fatigue which is nothing but the catabolism of muscle proteins. Serotonin also increases ACTH and cortisol secretion and which continues, influences the rate of aging too! Tryptophan is the only aminoacidthat is also carciniogenic! 🙂

  26. Gary Ray R says:

    Thank you Rajini Rao 

    A perfect post for the Science bunch, so I had to share it.

    May everyone have plenty of gastric distention and satiety on this day.

     Thank You.

  27. How interesting and I just love the blissful experience of the little child on the right Rajini Rao  🙂

  28. Rajini Rao says:

    Glad you enjoyed it, and happy thanksgiving to you too Gary Ray R 🙂

    Rebecca Rippin the one on the right is a mother’s delight 🙂

  29. But I think even the brain blood vessels forget to function when someone is falling in love 🙂

  30. Thanks for making me smarter, Rajini Rao !

  31. Rajini Rao says:

    I guess science and sense goes out the window when one falls in love, R Prakash Prakash !

    Jeff Jockisch happy thanksgiving (dinner and snooze, if you indulge).

  32. Nick James says:

    Great post, following the previous discussion.  Immaculate timing:-)

  33. Rajini Rao says:

    Nick James I’m glad you remembered that conversation from the BAT post 🙂

  34. Great post, Rajini Rao. As a brief note on the blood flow concept: there may still be something to it, just not with regards to low flow to the brain (which, of course, is tightly regulated). The increased flow to gastrointestinal structures is associated with an increase in parasympathetic nervous system up-regulation (and concomitant reduction of sympathetic firing to the GI arteries, which opens them up). Parasympathetic up-regulation tends to also fire up other “resting” physiology, which may include hormone responses. So, in a sense, options 2 and 3 may be coupled, just not via O2 movement to the brain.

  35. Rajini Rao says:

    Michael Habib , good points and thanks for the extra details on how blood flow to the GI is increased after a meal. Also in the case of exercise, there is increased blood flow to the muscles but again, cerebral blood flow stays the same. 

  36. Nick James says:

    Rajini Rao BAT…mostly famous for guano:-)

  37. Excellent point, Rajini Rao. Key differences in how the CNS and PNS are treated with regards to blood flow. I did a post on viscerosensory and autonomic nerves a little while back if any of your readers are curious. 🙂  Cheers!

  38. Rajini Rao says:

    Here’s the link to Michael Habib ‘s post explaining how the “gut brain” and the nervous system develops, paired with a beautiful image: http://goo.gl/pH2Gua

  39. Rajini Rao says:

    Gracias, maribel amador 🙂

  40. Very interesting post Rajini Rao and I’m sure many people will be practicing their survival skills today 😀

  41. Rajini Rao says:

    Buddhini Samarasinghe I’m going to be gif-worthy soon (still cooking)…I already have a strong tendency to fall asleep after eating 😉 

  42. Rajini Rao Haha! Pics or it didn’t happen 😛 I miss being in the US during Thanksgiving time, even though I didn’t have family there I always got invited to lab stuff and got lots of yummy food as a result!

  43. Liz Krane says:

    I always thought the tryptophan explanation sounded a little silly. I’ll be sharing those links with my folks next time they blame tryptophan. 🙂 Happy Thanksgiving Rajini Rao!!

  44. Thanks! Great read as always.

  45. Dian pink says:

    Hahahsha hahahahaha….my little brother at suppertime …his head would be bobbing an jerking around and then ..pop…his head went down into his plate of food… face covered..as children , we laughed hysterically. …we still tease “tiffy” him about those times.Hahahahahaha. .:-D:-D:-D:-D:-D

  46. I don’t have thanks giving its a light salad only as just me and the dog ,I don’t like turkey , HAve a good one. All

  47. Yohan Wadia says:

    try explaining tryptophan to my mom!! She’ll still think I’m giving off excuses!!

  48. Rajini Kumar says:

    Good one. Thanks for sharing Rajini Rao. 🙂 

  49. Sam Sharma says:

    Rajini Rao thanks for the post, love the kid on the right, he has just positioned himself for sleep eating, he has even cut the nodding stage out…. Now that’s adaptation lol

  50. Bimal Sharma says:

    i allways read ur knowldgable post good luck nd keep this pace allways

  51. NV NEO says:

    I hope I can explain to my friends the same way it was posted, hopefully…

    “You get sleepy…because… you.. eat something, that’s contained in turket..yeh 😕

  52. Dave Harris says:

    Great post Rajini Rao 

  53. Kawthar A says:

    awww.this cutie again :* :* 

  54. Rajini Rao says:

    Haha, hello there Kawthar A 🙂

  55. Kawthar A says:

    Morning, Rajini! 🙂 

  56. Rajini Rao says:

    Good afternoon, Kawthar A ! Nothing like a cup of coffee to recover from the excesses of Thanksgiving dinner. No turkey for me though, just stuffed, spiced whole cauliflower 🙂

  57. Kawthar A says:

    Yummy! no leftovers!? leftovers are my best part of the holidays dinner 😀

    I’m just done with lunch, I had few homemade potatoes pastry, they were Devine :p 

  58. Thanks for clearing that up, Rajini Rao. Hope you had a nice holiday. 

  59. Rajini Rao says:

    Excellent, thank you Gideon Rosenblatt. A no-stress day with the family.

  60. 🙂  Another fine, interesting post Rajini Rao I hope you had a nice day.

  61. Azlin Bloor says:

    They are far too cute!

  62. Rajini Rao says:

    Azlin Bloor you found me out! The science was just an excuse to post this cute gif 🙂

  63. Rajini Rao says:

    Cheryl Ann MacDonald , thanks- I had a nice relaxing day which is stretching out into the weekend. Hope you had a good thanksgiving day too. 

  64. Same here Rajini Rao and I am staying away from the shopping crowds today 🙂    Call me antisocial.  Take care.

  65. Panah Rad says:

    Well, I had it on an empty stomach. I don’t care about sauce, fillings, and silly things like that. I shoot straight for meat. 🙂 But great information!

  66. Rajini Rao says:

    Panah Rad so you’re not the one on the right? He is going for the carbs. 😀

  67. Panah Rad says:

    Rajini Rao haha. funny 🙂

  68. LOL! I need to learn more about orexin!

  69. Rajini Rao says:

    Haha, may be better than coffee in keeping us alert.

  70. So having a nice sized supper close to bedtime could pass as a sleeping aid? The French eat very late (compared to Americans), sometimes at 8PM, and they are known to have long lasting meals. Also, this post made me think of the ancients with their reclining on couches while eating.

    I have heard often that eating close to bedtime causes an easier gain in weight.  I somehow doubt that hypothesis. 

  71. Rama Drama says:

    My word of the day is Postprandial Somnolence Rajini Rao 🙂 Hope you had a lovely time with family and friends!

  72. Rajini Rao says:

    Indeed, I did – and succumb to some somnolence myself, Rama Drama . Hope you had some days off too! 

  73. Rama Drama says:

    I sure did. Tofurkey was butchered successfully in the home Rajini Rao 🙂

  74. Rajini Rao says:

    Haha, I let the turkey trot too Rama Drama !

  75. This year I will see family but not for XMAS a funeral my uncle died yesterday so I don’t think anyone will be celebrating much except the kids ,it’s to commercial and I still get my folks a small gift each but the funeral I think is a bad time I think to give it to them ,unless my step daughter goes there to where they live and drops it off or I give to me sister at the funeral ,to give mum on XMAS week , what do you,s think ? DRS so I’d best move and eat or miss me bus . I’d rather a subway or a roast myself for XMAS .

  76. Rajini Rao says:

    Sorry to hear about your loss, Susan Gormley . A quiet dinner sounds good. 

  77. Anil Kumar says:

    I didn’t have that

  78. Akenese Liu says:

    Wow! I never see that before.

  79. Dilip Babu says:

    I experience d same thing.

    I use do it whn im child, To skip my dinner. lolzz..! 😀

  80. Thanks but I have had XMAS now with the dog for two years now just the first without my stepdaughter will be harder this year ,I,ll be fine it’s me ex and other step daughter I’m worried about !!!

  81. I wonder if blood sugar levels could also be a factor?

  82. Rajini Rao says:

    Most definitely, Donna Pezeshki . I should have made that clear, thanks for bring it up. Blood sugar elevation depresses the release of orexin. Also, insulin levels rise after a meal and that has several effects leading to sleepiness. 

  83. Rajini Rao In China, there is the ancient tradition of drinking during meals lukewarm tea, unsweetened of course, in order to make easier and faster  the digestion. 

    Two herbal products, most effective in improving digestion, are papaya and pineapple, exceptional especially for proteins.

  84. Rajini Rao says:

    annarita ruberto , or just eat less 😉

    Papaya and pineapple have proteases, papain and bromelain, that digest proteins. 

  85. Rajini Rao …eat less is always a good solution;)

  86. Me I don’t feel hungry and that’s half the problem ,and when I do it’s a kids size plate but I was told by a dietitian 5 small meals a day I struggle with two a day and now have a no salt or sodium level in me body the water you drink to rid the. Sugar washes away the salt can’t win situation oh well find out out MONDAY another blood test and hope the pill one of three for b,p has given me back some salt as I don’t normally eat salt now I do hope for good news ,

  87. Rajini Rao my people call it “the itis.” Lol.

    Thanks for this very concise explanation. To be honest, I’d never really thought of this. Just always assumed that a full tummy(or just a glass of red wine ;)) was the recipe to falling asleep.

  88. Rajini Rao says:

    Tiffany Henry now you can send your family to sleep with the scientific explanation 😉

  89. Lol Rajini Rao! Actually, they would all be interested to know this. Especially my Gram who does most of the cooking ^_^

  90. Rajini Rao you are kidding me: THIS is a myth?  >>> “after a big meal, our body diverts blood supply to the gut, and away from the brain, to help digestion. ”  you are changing my life?  so why tell the kids not to swim after lunch?

  91. Probably for the adults to be able to rest and not have to watch out, and to convince the kiddos to have a nap.

  92. Daniela Huguet Taylor i always thought: the blood goes to the gut, the brain gets less, you swim, blood goes to muscles, even less for the brain, you faint, you drown.  now Rajini Rao says it’s all wrong

  93. Waooo, give me the secret. Lol

  94. Omgsh that is soo cute

  95. Quiero ver películas Quiero ver película de de narcos

  96. Veeeeeeeeery nice phottos,my.D.Rajini Rao***

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