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How Citrus Might Help Keep Your Hands Warm

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 quercitin, 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, hesperidin 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 cut our risk of stroke the most.

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

For example, if you measure the changes in genetic expression, orange juice consumption induces changes in the expression of 3000 of our genes, whereas hesperidin alone only modulated the expression of about 2000. Still, nearly 2000 stretches of our DNA expressed differently because we consumed just one of the thousands of phytonutrients in plants is pretty mind-blowing.

These changes in blood flow are not just in “theory.” Researchers took volunteers with cold sensitivity (cold hands and 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. The fingers of those consuming low or high doses of citrus didn’t get nearly as cold because their blood flow remained steady. If you click on the above video, you can see the laser test of their blood flow. When you’re exposed to cold temperatures your body starts to clamp off peripheral blood flow to keep your 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 their finger temperature rebounded faster towards normal in the citrus group, demonstrating that citrus phytonutrients not only keep your extremities warmer but also warm you back up faster.

Just don’t brush your teeth immediately after consuming citrus. Make sure to rinse your mouth with water and wait 30 minutes before brushing to protect your tooth enamel (see Plant-Based Diets: Dental Health).

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 orange juice. I’ll discuss the difference more in Friday’s blog about my video Reducing Muscle Fatigue with Citrus.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Related:
Which Common Fruit Fights Cancer Better?
Prunes, Metamucil, or a Plant-Based Diet?
The Best Way to Prevent the Common Cold?

Read more: Health, Diet & Nutrition, Eating for Health, General Health, Natural Remedies, Videos, , ,

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Dr. Michael Greger

A founding member of the American College of Lifestyle Medicine, Michael Greger, M.D., is a physician, author, and internationally recognized speaker on nutrition, food safety, and public health issues. Currently Dr. Greger serves as the Director of Public Health and Animal Agriculture at The Humane Society of the United States. Hundreds of his nutrition videos are freely available at NutritionFacts.org.

87 comments

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1:54PM PST on Dec 20, 2013

thanks

3:22AM PST on Dec 19, 2013

Thanks

3:19AM PST on Dec 19, 2013

My fave fruit right now are tangerines. Lots in the shops. Interesting article, thank you. Jane R. have you tried those hand warmers you can buy in pound stores. you just activate them and put them inside your gloves for toastie hands.

1:57PM PST on Nov 30, 2013

With permanently frosty fingers and toes in winter, I am definitely increasing my citrus fruit intake. :)

8:32AM PST on Nov 28, 2013

interesting, thanks

8:51PM PST on Nov 25, 2013

Jane R: This will probably have zero effect on your Reynaud's. Sorry. However, drinking OJ could help you prevent a stroke.

I have drunk OJ every day I have been on this planet - at least I have one good habit!

8:05AM PST on Nov 25, 2013

Interesting... if a little too jargony to suit me.

9:12AM PST on Nov 23, 2013

Thank you!

5:19PM PST on Nov 22, 2013

I am going to test this out. I have Raynaud's Syndrome. When I get cold the blood flow to my fingers is cut off and they turn white. I could cut my finger and not even bleed. I have to put my hands in very warm water for a few minutes to get the blood flowing again. Wearing gloves outside does not prevent this from happening.

5:04PM PST on Nov 22, 2013

very interesting thank you - have gone immediately and eaten an orange.

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Disclaimer: The views expressed above are solely those of the author and may not reflect those of
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