Keeping your Hands Warm with Citrus

Keeping your Hands Warm with Citrus
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Phytonutrients in citrus, such as hesperidin, may increase blood flow sufficient to warm the hands and feet of those with cold sensitivity.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

In 1936, Albert Szent-Györgyi, who won the Nobel Prize for discovering vitamin C, described a “vitamin P,” which we now know encompasses a class of thousands of phytonutrients called flavonoids. Some, like quercetin, are “widespread in plant-based foods.” You can tell something is widespread in the plant kingdom when you can even find it in iceberg lettuce.

Others, however, are only found in specific plant families. For example, hesperitin is “found primarily in citrus fruits.” This may be one of the reasons that, out of all the different types of fruit that have been looked at, citrus may help cut our risk of stroke the most.

The citrus phytonutrient hesperitin increases blood flow. Using a machine called a Doppler fluximeter, you can measure blood flow through the skin using a laser beam. A laser Doppler fluximeter; sounds like something from Back to the Future. And, if you give people the amount of hesperitin found in two cups of orange juice, blood flow goes up, though if you instead just give them the orange juice itself, that works even better. So, there’s other beneficial stuff besides just the hesperitin in citrus.

For example, if you measure the changes in genetic expression, orange juice consumption induces changes in the expression in 3,000 of our genes—whereas hesperitin alone only modulated the expression of about 2,000. Still, nearly 2,000 stretches of our DNA expressed differently because we consumed just one of the thousands of phytonutrients in plants—pretty mind-blowing.

And these changes in blood flow are not just kind of “in theory.” Researchers have taken volunteers with cold sensitivity—cold hands, cold feet—put them in an air-conditioned room, and measured the temperature of their fingertips after drinking a placebo drink—like orange Kool-Aid—versus drinks with two doses of actual citrus phytonutrients. In the Kool-Aid group, their fingers got colder and colder, dropping nearly 9 degrees Fahrenheit. But, the fingers of those consuming low or high doses of citrus didn’t as much. That’s because their blood flow remained steady. Here’s that laser test again.

When we’re exposed to cold temperatures, our body starts to clamp off peripheral blood flow to keep our core warm. But, if you eat a bunch of oranges before you go skiing, your risk of frostbite may go down, since you’re keeping up your blood flow to your fingers and toes.

They even took these poor women, and plunged their hands into some chilly water. And, as you can see, their finger temperature rebounded faster towards normal in the citrus group. Of course, having warm hands is nice, but maintaining blood flow to your fingers is not as important as maintaining blood flow to your brain.

Please consider volunteering to help out on the site.

Images thanks to PetitPlat – Stephanie Kilgast via flickr. Thanks to Ellen Reid and Shane Barrett for their Keynote help.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

In 1936, Albert Szent-Györgyi, who won the Nobel Prize for discovering vitamin C, described a “vitamin P,” which we now know encompasses a class of thousands of phytonutrients called flavonoids. Some, like quercetin, are “widespread in plant-based foods.” You can tell something is widespread in the plant kingdom when you can even find it in iceberg lettuce.

Others, however, are only found in specific plant families. For example, hesperitin is “found primarily in citrus fruits.” This may be one of the reasons that, out of all the different types of fruit that have been looked at, citrus may help cut our risk of stroke the most.

The citrus phytonutrient hesperitin increases blood flow. Using a machine called a Doppler fluximeter, you can measure blood flow through the skin using a laser beam. A laser Doppler fluximeter; sounds like something from Back to the Future. And, if you give people the amount of hesperitin found in two cups of orange juice, blood flow goes up, though if you instead just give them the orange juice itself, that works even better. So, there’s other beneficial stuff besides just the hesperitin in citrus.

For example, if you measure the changes in genetic expression, orange juice consumption induces changes in the expression in 3,000 of our genes—whereas hesperitin alone only modulated the expression of about 2,000. Still, nearly 2,000 stretches of our DNA expressed differently because we consumed just one of the thousands of phytonutrients in plants—pretty mind-blowing.

And these changes in blood flow are not just kind of “in theory.” Researchers have taken volunteers with cold sensitivity—cold hands, cold feet—put them in an air-conditioned room, and measured the temperature of their fingertips after drinking a placebo drink—like orange Kool-Aid—versus drinks with two doses of actual citrus phytonutrients. In the Kool-Aid group, their fingers got colder and colder, dropping nearly 9 degrees Fahrenheit. But, the fingers of those consuming low or high doses of citrus didn’t as much. That’s because their blood flow remained steady. Here’s that laser test again.

When we’re exposed to cold temperatures, our body starts to clamp off peripheral blood flow to keep our core warm. But, if you eat a bunch of oranges before you go skiing, your risk of frostbite may go down, since you’re keeping up your blood flow to your fingers and toes.

They even took these poor women, and plunged their hands into some chilly water. And, as you can see, their finger temperature rebounded faster towards normal in the citrus group. Of course, having warm hands is nice, but maintaining blood flow to your fingers is not as important as maintaining blood flow to your brain.

Please consider volunteering to help out on the site.

Images thanks to PetitPlat – Stephanie Kilgast via flickr. Thanks to Ellen Reid and Shane Barrett for their Keynote help.

Doctor's Note

Because different families of fruits and vegetables can have entirely different phytonutrient profiles, variety is important. See, for example:

Eating oranges is always better than drinking juice. I discuss the difference further in Reducing Muscle Fatigue with Citrus.

Please make sure to rinse your mouth with water after consuming sour fruits to protect your tooth enamel (see Plant-Based Diets: Dental Health).

For additional context, check out my associated blog posts: How Citrus Might Help Keep your Hands Warm and Citrus to Reduce Muscle Fatigue.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

48 responses to “Keeping your Hands Warm with Citrus

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      1. Bummer!

        I’m excited about this finding. I also get cold hands and feet quiet often (I believe it is related to my Hashi’s). I am hoping that this citrus finding might help me get the blood flowing. However, I did a similar search as yours Dr. G on PubMed and found nada. :(

        Still, I’m going to try chomping on more oranges to see if I can sense a difference.

      2. I know I am a sample size 1. But I have Raynaud’s and i started running. I noticed significant improvement when i was training to run a 5k. I stopped and my symptoms started getting worse again. I’m going to see how faithful citrus intake impacts my Raynauds. Is it ok for us to post our individual experiences on here?

    1. Great question JB. I’ve always had the ridges in my nails, but it wasn’t until I was an adult that the cold started cutting off the circulation in my fingers. The condition has gotten worse as I have gotten older and it adds an element of fear when I consider participating in outdoors events during the winter. (My doctor’s only help (which to be fair may be all that she had to offer) was to wear gloves – which does absolutely nothing for me.)

      I guess I’ll just have to eat a bunch of oranges this winter and see if it helps.

      1. Agreed that gloves are little help, sometimes even seem to make Raynaud’s cold fingers worse. Ample mittens, big enough to ball your hands up inside, work much better. My partner’s Raynaud’s used to be big trouble; but he’s had no finger shutdowns in the last few years, since taking to a plant based whole foods no added oil diet.

        1. JPotter: Thanks for sharing! I’ve been pretty close to whole plant based diet – though I do sometimes have oils in my diet. (Most of the time I modify a recipe to take the oils out.)

          I’ve also found that the best approach is to keep all the fingers together and curled up into a fist if possible. My approach has been to pull my hands inside my sleeves when I can. I often can’t make-due with mittens. I’m usually out with my dog and end up needing to have actual use of my hands/fingers fairly frequently. I can pull my hands in and out of my sleeves pretty easily, but it’s really not a great solution. Too often I still get the “progressive vessel collapse” (as I think of it).

          I’ve tried those hand-warmers with some, minimal, success.

          Thanks again for sharing.

          1. I use the curled up fist technique, as well.

            Feet are another animal altogether, though. At night, I try to warm my feet on my partner. He does not appreciate that much. So, sometimes I sleep with socks on.

            If time and circumstance allow, I take a hot bath; that seems to warm me up pretty good. If time and circumstance do not allow, I sometimes warm my hands under warm running water.

            1. re: unappreciated warming of one’s feet on one’s partner.
              Oh pish-tosh. What are partner’s for?

              re: running water: Yes, a huge help for me. What causes me concern is when I’m at a place like the beach (which gets very cold and windy here) and I can’t guarantee that I will have access to warm water. I worry about that sort of thing a lot. It’s been fine so far. I just worry. Of course, now I could down a few oranges/orange juice – but then I expect to have some bathroom problems. There’s never any pleasing me.

      2. Raynauds is a problem for me to, so hope the oj works too. As far as the ridges in the fingernails, mine have really improved since being on McDougalls. Keepin it preety tight. Whole only. Going for the healthiest possible outcomes.

    2. JB I will let you know if it works because my son (13 yo) has this problem of Reynauds phenomenon. It’s always worse when he eats dairy, or gets dehydrated which happens when he is playing basketball. So even though it will be anecdotal we are going to try and control the variables [eliminate all dairy (which he almost always does) and stays hydrated] and see if it (the orange) works for him.

        1. It’s rather a funny story. He doesn’t eat dairy a lot but we went camping last week and instead of camp grub we decided to go to a local Mexican food restaurant and get some food. So (in his infinite wisdom–at 13 yo) he decided to order a Cheese Quesadilla which he never eats and happened to be packed with cheese. He even stated to me, “Hey Dad look at this (pointing to the huge amount of stringy mucus–cheese) on his quesadilla and proceeded to eat all that cheese.
          Then after we went back to the camp he went with his friend down to the store which sold Soft-serve ice-cream about 20cm tall!!!
          He told me the next morning it was the worst night of his life! He woke up about 1am and had to run to the bathroom and had explosive diarrhea (visual in effect) that lasted about 20 minutes and for three more times that night.
          The next day his stomach was so upset that Pepto Bismol helped but he said I am never going to eat that crap again.
          Letting kids do what they want is the best lesson of all, rather than “brain-washing” them to believe what “we” already know!
          No, he’s not smoking–yet! ;-(
          At least that I know of.

  1. Interesting. I use orange essential oil in hand lotion on my feet on cold nights. I swear it keeps my feet warmer. Is that possible?

      1. Hi Darryl,
        I really appreciate your thoughtful and scholarly posts. Including orange peel in the diet is intriguing.

        I guess when comparing OJ with whole oranges on the basis of nutrient content, another potentially important variable is the fullness factor. Say OJ gives you half as much of an important nutrient than the equivalent amount of whole fruit but you can consume four times more OJ without feeling as full, then aren’t you still better off going with the OJ?

        1. We use orange and lemon “essence”…peel in foods all the time and the pith is where the bioflavanoids are. I have eaten it since I was a kid. Always liked it. Funny what some of us throw out as garbage.

    1. I have also done reesarch on the vasodilatory effets of flavonoids, and it indeed is the nitric oxide that opens up one’s blood vessels causing the increased blood flow. The nitric oxide is only able to be produced because of hesperidin, so one can say that the hesperidin acts as a vasodilatory compound, opening and expanding one’s blood vessels.

  2. I can vouch for this. I had a long history of cold hands and feet, even in the summer. When I went “raw”, I no longer suffered from bad circulation. When winter came and I ate some cooked lentil soup, my hands and feet got cold again. I thought to myself, “Deer live outdoors all winter…” so I went back to eating raw – especially dark green leafy vegetables – and my hands and feet grew warm again. Green leaves contain chlorophyll, which is only one ion different from hemoglobin. The structure of a leaf reflects the veins and vessels, capillaries in our bloodstream.

    1. Naringin is the flavonoid found in grapefruit, not hesperidin. While there are amounts of hesperidin in grapefruit, the amount is not as well absorbed by the small intestine. Naringin is the best absorbed flavonoid in the grapefruit. The fact that hesperidin is not absorbed through grapefruit does not make grapefruit not as healthy- it only means it has a different flavonoid make up.

  3. Because (1)orange juice contains just as much of the flavanone polyphenol, hesperidin, and the carotenoid, beta-cryptoxanthin, as whole oranges and (2)drinking orange juice has been shown in studies to be substantially less beneficial to our overall health in many ways compared to eating whole oranges, we can conclude that the flavanone polyphenols and the carotenoids in citrus fruits aren’t anywhere near as wonderful as the phytochemicals found in allium vegetables, cruciferous vegetables, legumes, mushrooms, white tea, triphala, Korean red ginseng, psyllium, and wheat bran:
    http://www.inspirationgreen.com/assets/images/Food%20blog%202010/harvard%20weight%20gain%20study.jpg

  4. Does the study mention whether the core gets colder as a result of the increased blood flow to the extremities? Since as you said, our bodies decrease the blood flow to our extremities to conserve heat, I worry that this might have an unwanted effect in that respect.

    1. I’m no expert, just a Raynaud’s sufferer. I have read that the extremities won’t warm up till the core is warmed up sufficiently. That answered my question about why, when I get this blanching or darkening, I have to turn all the heaters on and am completely frozen till I get warmed up “inside” and then and only then, will my fingers return to normal and then I can see why everybody else is saying “It’s hot in here.” Sowwy!

  5. Dr Greger..Thank yolu so much…So interesting. You didn’t mention whole oranges but, I can only imagine that it would be good. Less juice to the serving, of course. I have raynauds and this sounds like something I could use. For some reason I have stopped drinking oj and less whole oranges too. I think it is the fruit sugar/triglyceride/belly fat issue. Also I have a realated question that I’ve been wondering for a long time. Many people have told me not to eat the skins of oranges. Considering they are clean, I don’t understand that. I thought the best source of bioflavanoids is the pith of the orange. I have always liked it. Aaaand don’t we zest the skin of the orange for lots of uses? Can you direct me to some info? I’m trying my best to use whole foods and not rely in supplements which I don’t really think are good for us. Any info would be appreciated. Thank you, Dr. Greger for these great video’s and blogs. Much appreciated. Lynn

  6. I have been diagnosed with Raynaud’s some years ago and have been eating entirely plant-based for six months now. I feel much better in general, but while the Raynaud’s situation has not gotten any worse, it didn’t improve either.

    I tried taking a lot of citrus for a certain period, but it doesn’t seem to help much. I couldn’t find any more information specific to Raynaud’s on the website. I did some research for myself, and found that buckwheat is also a good source of quercetin, which supposedly helps, but alas, I have been eating it for a while but notice no improvements. I also found that caffeine has been believed to have a strong vasoconstrictive effect on the extremities. I also found that theanine, present in tea, ‘counteracts’ the caffeine. Yet I could not find any good information related to Raynaud’s or vasoconstricting/vasodilating effects of tea.

    Could you maybe point me in the right direction? The questions I have are:
    1. Does caffeine / coffee indeed restricts blood flow to the hands?
    2. Is this the same for (green) tea, or does the theanine counteract the caffeine (maybe there is even a small vasodilative effect due to the warmth that needs to be dissipated?)?
    3. Did you maybe come across some more research that might help with Raynaud’s ?

    Thanks in advance!

  7. Any alternative treatments for Raynaud’s phenomenon (primary) worth trying?
    I’ve been following a healthy whole-foods plant based diets for around 5 years, but still experiencing cold hands and feet – even in the summer time.

    What do think about Magnesium supplements for this cause? Is it worth trying out? Are there any side-effects? Or perhaps there are some other supplements that might help out?

  8. Hi, I’ve read that Hesperidin is mainly concentrated in Citrus peel and albedo, hence I wonder if orange juice has, instead, a low concentration of such Flavonoid…

  9. Since this is the only video mentioning nutrigenomics, I’ll try to ask my question here-
    I’m going to apply for college this year, and I’ve been wondering what profession/courses I should take in order to be able to:
    a. do what Dr. Michael Greger does- examining and researching the way food cures illnesses.
    b. Make my own Researches in the area of nutrigenomics and nutrigenetics.
    Thank you :)

  10. Hi Cindy. This is Dr. Daniela Sozanski PhD in Natural Medicine and Moderator on Nutrition facts. I am not privy of that information, but I think it matters less than knowing that vegans can get cardiovascular disease. This could be very important, even live saving information for a vegan. I invite you to watch one of Dr. Gregers videos on youtube, that was nothing short of a revelation to me, personally, years ago: https://www.youtube.com/watch?v=aFFWstlfDRk; it is called A 40 years old vegan dies of heart attack. I hope this helps, Daniela

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