Citrus Peels & Cancer: Zest for Life?

Citrus Peels & Cancer: Zest for Life?
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The reason eating citrus fruits appears to protect against cancer may be because of DNA repair enzyme-boosting powers of a compound concentrated in the peel.

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New data demonstrating a DNA protective agent was present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection and repair of DNA strand breaks.

The carotenoid beta cryptoxanthin, found primarily in citrus, seems to be at least one candidate. If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA, but in less than an hour, our DNA repair enzymes can weld most of our DNA back together. But if you add some of that citrus phytonutrient, you can effectively double the speed at which the DNA is repaired. But this is all just cells in a petri dish, what about in a person?

If you have people drink a glass of orange juice and draw their blood two hours later, the DNA damage you can induce with an oxidizing chemical drops, whereas if they just had like orange Kool-Aid, it didn’t help.

So, do people who eat more fruit walk around with less DNA damage? Yes, particularly in women. Does this actually translate into lower cancer rates? Yes, citrus alone is associated with a 10% reduction in odds of breast cancer.

Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given; so, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat our food.

Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that the whole food may be important in modulating DNA repair processes.

Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. However, the most striking feature was the protection purported by citrus peel consumption. Who eats orange peels? Lots of people evidently. Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60% increase in risk; so again, better to stick with the whole fruit. And you can eat citrus extra-whole by zesting some of the peel into your dishes.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Images thanks to PublicDomainPictures via Pixabay.

New data demonstrating a DNA protective agent was present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection and repair of DNA strand breaks.

The carotenoid beta cryptoxanthin, found primarily in citrus, seems to be at least one candidate. If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA, but in less than an hour, our DNA repair enzymes can weld most of our DNA back together. But if you add some of that citrus phytonutrient, you can effectively double the speed at which the DNA is repaired. But this is all just cells in a petri dish, what about in a person?

If you have people drink a glass of orange juice and draw their blood two hours later, the DNA damage you can induce with an oxidizing chemical drops, whereas if they just had like orange Kool-Aid, it didn’t help.

So, do people who eat more fruit walk around with less DNA damage? Yes, particularly in women. Does this actually translate into lower cancer rates? Yes, citrus alone is associated with a 10% reduction in odds of breast cancer.

Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given; so, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat our food.

Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that the whole food may be important in modulating DNA repair processes.

Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. However, the most striking feature was the protection purported by citrus peel consumption. Who eats orange peels? Lots of people evidently. Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60% increase in risk; so again, better to stick with the whole fruit. And you can eat citrus extra-whole by zesting some of the peel into your dishes.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Images thanks to PublicDomainPictures via Pixabay.

Doctor's Note

That’s why my favorite citrus fruit is kumquat—because you can eat the peel and all!

For other foods that may keep our DNA intact, see my Which Fruits and Vegetables Boost DNA Repair? video. Kiwifruit (Kiwifruit and DNA Repair), broccoli (DNA Protection from Broccoli), and spices (Spicing Up DNA Protection) may also fit the bill.

More on citrus in Keeping Your Hands Warm With Citrus and Reducing Muscle Fatigue With Citrus,  and Can Vitamin C Help with Lead Poisoning?.

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

 

153 responses to “Citrus Peels & Cancer: Zest for Life?

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    1. From Dr. Greger’s transcript today: “Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that the whole food may be important in modulating DNA repair processes.”
      It is the whole food, not the essential oil, that seems to do the trick.

          1. Lisa – Would you take a look at my post toward the top of the page re: the actual research transcripts describing that it was the “retinols plus supplements” that offered protection. I took that quote from the abstract. My question is: What exactly is the protective part? Dr. G indicates its the zest, but that’s not what I thought the research was reflecting. Let us know what you find out when you get a chance. Thx.!!

            1. GEBrand: The reason I asked Lisa about limonene is because I’ve seen reports on the positive effects of limonene, and other terpenes, on cancer (One paper available free online has the title “Prevention and Therapy of Cancer by Dietary Monoterpenes”)
              And limonene, as I understand” is present only in the peel. Probably limonene contributes to the anticancer benefits of citrus zest, but I don’t know what Dr. Greger’s sources say about limonene.

        1. No, he was not. He was talking about the difference between supplements and food. Carotenoid supplements or carrots (to get the natural source of carotenoids). It is almost universally true that studies that compare the bioactive ingredient separated from the food itself do not seem to work in the body. There are studies that show activation in test tubes, or peetree dishes, but not in humans.

          1. Does it make a difference whether you eat the whole carrot or run it through a blender to drink it as a juice along with other delicious greens? In my case I would be doing this in a VitaMix or a Ninja blender rather than a juicer which extracts the pulp.

            1. Damien, in at least one of Dr. Greger’s videos, it talks about how blending foods can drastically increase bioavailability of nutrients. So blending is definitely a good thing and doesn’t damage anything.

    2. I just shared this on FB prefaced with…”For those of you who think supplements, vitamins and juicing are a short cut to eating WHOLE food as a complete package…” Maybe simplistic, but nature has been perfecting it’s creations for a lot longer than we’ve been trying to duplicate them, wouldn’t it be a whole lot easier and more beneficial to just take advantage of that amazing gift? We have a tendency to want to take things apart and find the “best” (and easiest) component, but it’s always a package deal!

      1. And the ultimate whole food is a living food. A living plant is more than the sum of its chemical constituents. There’s a pinch of mystery here, just to keep us scientists humble.

  1. This citrus peel nutrition effect is such a fascinating discovery (at least for me). After reading a comment here on NutritionFacts about a year ago, I started putting a whole organic lemon in my blended smoothies. I did take the seeds out first, since I don’t know whether they are healthy or harmful when blended. This video is great confirmation that using the whole fruit is best!

          1. I was thinking about the freezing the lemon then grating it method, but that would also grate the seeds. Maybe dehydrate the peels then, then powderize in coffee grinder.

            1. Today i just cut the lemon in wedges, this makes it easy to remove the seeds, then tossed them into the smoothie to get the advantages of the peel. But i only make smoothies two times a week so i need more strategies.

              1. I also take seeds out of lemons, place all of them in my blender with green tea and blend. Pour on a tray and freez. Ones frozen i break into chunks and store in a bag in the freezer. When i do a drink in my blender i use piece of the lemon but you could also use this in your cooking, soups, stir fry…..

    1. I do the same, mostly limes cuz they are cheap here, but it’s actually the white pith below the rind that is bitter and that people sometime object to, so proceed accordingly, but I’ve grown fond of the bite, (and I’m lazy!). So many cuisines enjoy the bitter quality of foods in a balance with the other flavors, here we seem to shun it, besides maybe in coffee. Apparently it’s a taste well worth cultivating!

        1. Good point about the bitterness. So my idea was to balance the bitterness in orange peels with sour by fermenting them. They are too dry for me to eat by themselves otherwise and strong-flavored. The fermentation keeps all of the enzymes alive. I add it to my multi-species sauerkraut and top my salad with it. I like it. Make sure you’re using organic oranges or you’ll be eating a lot of pesticide with your fruit.
          John S

    2. Good idea – I’ve been doing the same with oranges in my smoothies (I use organic Valencia oranges which I can usually find at a reasonable price – not sure but I’m assuming the if you’re going to use the peels, that organic is probably a lot better), i.e. I cut the orange in half and throw a half, peel and all, into the smoothie. The peel actually adds nice flavor.

  2. New regimen starting today: eating some citrus (lemon, orange) peel after dipping it in my new fave sweetener, healthful dark maple syrup, to make it more palatable.
    It’s all good!

    1. Calling dark maple syrup “healthful” doesn’t actually make it healthful. What evidence is there that it is? It is mainly just sugar after all.

      1. Popular:
        New research suggests that maple syrup, despite being a concentrated source of “sugar,” possesses significant anti-cancer properties.
        “A provocative study published recently in the journal Oncology Reports reveals that a commonly used sweetener, maple syrup, inhibits the growth and invasion of human colorectal cancer cells.”
        http://www.greenmedinfo.com/blog/maple-syrup-cancer-killer-study-suggests

        Technical:
        http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358083/

        1. Does such protection offer enough counter-weight against the harm that sugars do by spiking blood insulin levels and destroying leptin receptors? I doubt it, because spiked insulin and the brain not being able to read the presence of leptin are strongly implicated in the biggest killers, like stroke and heart disease.
          Joseph in Missoula

          1. I know I can’t do maple syrup without gaining unwanted weight. In my younger years I could seem to handle it, but not now in my late 40’s.

            1. One would think. What you say is the common-sense view of it, but science says otherwise. Science has shown that sweeteners of any kind, even artificial sweeteners, are highly addictive. It’s the “you can’t eat just one” syndrome for almost everyone. Check out Dr. Robert Lustig’s book “Fat Chance”, and Dr. Susan P. Thompson at brightlineeating.com on this question. If you want to be become slim and stay that way for the rest of your life, check out Dr. Thompson, a neuroscientist and psycholgist — her Ph.D. is in Brain & Cognitive Sciences.
              Joseph in Missoula

              1. You know, I’m as interested in staying healthy as the next NF.org follower.
                I also indulge a treat now and then without worrying about it — I just enjoy it.

                It is sometimes good to remember that neither common sense nor science (with its ever-changing findings and conclusions) are carved into stone tablets by the finger of God.

                According to our commonly accepted nutrition science this woman should have croaked from arteriosclerosis decades ago.
                Behold! the oldest woman alive (and buckle your seat belt for her diet :-) ):
                http://time.com/4337417/new-oldest-person/

                1. Not everyone is the same about all kinds of things, including the susceptibility of addiction to sweeteners. Some can do it from time to time and it doesn’t become habitual. Others can’t get close to it and then walk away without having that sweet treat. The latter is almost always heavy or obese. For them, it’s just as important to make it an iron-clad rule to never have any in order to pull themselves out of their disorder. For them it’s just like so many cigarette smokers, but not all, who can’t have just one puff. One puff and within days they’re back to 2 packs a day.
                  Joseph in Missoula

        2. Dr. Greger has turned us on to research that tests the therapeutic value of food by having subjects eat the food, and then drip the blood on the test tissues, rather than dripping the pureed food on the test tissue. Unfortunately, the maple syrup research design was the latter.

        3. Thanks for the links. My reading is that this study, partially funded by an association of maple farmers, suggests that maple syrup is superior to plain sugar for inhibiting cancer cell growth in a test tube. However, my understanding is that most foods are superior to sugar in this particular area.
          This is a common technique used by the food industry – compare your product to something you know is worse.
          Sure, dark maple syrup is less bad than pure sugar – but that does not make it healthful.
          Dr G has a number of videos on cancer fighting foods, all of which I suspect will much better for you than maple syrup.

      2. Just to add, “dark” maple syrup is dark as a result of processing the maple tree sap into syrup. All maple syrup has the same sugar content. The lower the sugar content of the sap, the longer the sap needs to cook to get to the right sugar concentration. And the longer the cooking takes, the darker the sugar gets (caramelization which changes the color and flavor). Any nutrition in maple syrup from the tree sap is trivial. But … it sure is delicious!

        For nutritious sweetening, soak some pitted dates in water and then puree them for a sweet dip.

        1. Just to add, “dark” maple syrup is NOT dark from processing. Otherwise how do you explain light and dark syrups? The color is affected by growing conditions and when the sap is collected. There is Maillard browning during processing, but this is not what makes some syrup dark and some light.

          1. Lee, Thanks for stimulating me to do more research and to talk with a maple farmer in Vermont. There are multiple reasons for variation in maple syrup color. One is the when the syrup is collected. Early season sap has a higher concentration of sugar than later in the season so requires less time in the evaporator with less time for caramelization and Maillard browning. But how much bacteria infiltrate the sap after harvesting, the amount of time the sap sits between harvesting and evaporation and other growing and weather conditions also affect the color. Like in life, things are more complicated than first thought.

    2. Now that sounds wonderful! Try another trick: after dipping in dark maple syrup, you can dredge it in unsweetened cocoa powder – which has the second highest polyphenol content of any food. It becomes an antioxidant treat!!!!!!!!!!

      1. Lisa, I’ve stopped consuming cocoa powder and switched to cocoa bars because of the cadmium issue with the powder as recently reported by Consumer Lab.
        Their testing reveals the highest polyphenols / lowest cadmium content in various brands.

          1. From what I’ve read (at the moment don’t recall where) it’s the grinding process that accounts for the higher cadmium levels in powders. Seems that the cacao readily picks up cadmium from the metal grinding blades.

        1. Dommy: As I understand it, if you adjust for fat intake/amount used in a serving, the chocolate bars and chocolate powders really ended up being about the same. (Neither of which is good/ideal…)

          From Berkeley (and thank you Tom Goff for finding this article!): “On the other hand, when comparing chocolate bars and cocoa powders by serving sizes (about 40 grams and 5 grams, respectively), the bars had nearly as much cadmium, on average, as the powders.”

          From: http://www.berkeleywellness.com/healthy-eating/food-safety/article/there-cadmium-your-cocoa

          Considering that, and that the saturated fat from full chocolate is not so healthy either, I just decided not to worry about the form of chocolate I am eating. If I’m eating it, I know that I’m accepting some risk along with benefit and leave it at that. (That’s my personal philosophy on chocolate/cocoa at the moment.)

          1. I’ve been having chocolate cake everyday, the Lindsay Nixon recipe just replace the sugar with erythritol, i don’t gain any bodyfat from it. But now the cadmium issue. I wonder if our WFPB diet protects us from the cadmium.

            1. Ben: ooooh, chocolate cake! Sounds *great* to me.
              .
              I don’t know what to say about the cadmium issue. If you read the article I linked to above, you can see that the body doesn’t absorb dietary cadmium all that well. But at the same time, they do recommend people limit dietary cadmium, because it is a known problem (as I understand it). So, how to judge the risk level of eating chocolate cake every day, especially in light of an otherwise whole plant food diet? I think no one knows the answer to that. Based on my (admittedly limited) knowledge, this is one of those areas where people just have to do what feels right.
              .
              I will say this, though: If after thinking about the issues, you decide to keep eating that chocolate cake, either every day or less frequently, then really enjoy it and don’t worry about the cadmium in that case. That’s my best advice. :-)

        2. Yes, I bought the nibs with the lowest cadmium but really like the powder, so I used our coffee grinder to make powder from the nibs. Worker great.

    3. I’ve just eaten the peel of two satsumas along with the fruit. Nothing more was needed and it imparted a lovely tingly feeling to the tongue. Why spoil this by adding a processed sugar? Apparently, the only processed sugar with any nutrient value is date sugar…. I don’t even buy sugar to consume myself – except I do have to keep some for visitors, and always have to hunt through my cupboard when it’s needed. I’m aiming to live to 120, and relying on Dr Greger to help me get there – hahahaha! (At just 60, a new aquaintance thought I was the same age as her – 43 – which is 6 months younger than my eldest daughter! So maybe I’m doing something right…:)

  3. I took a course in graduate school called Bioactive compounds. What I learned is the protective parts of plants, the peels, pits, and things that are inedible to humans (but keep insects from eating plants) contain the highest amounts of bioactivity. So, I peeled a mango (studying the effects of Mangosteen, the bioactive compound in mangoes), roasted it seasoned with cumin and coriander, and we ate it. It was terrible! It is helpful to remember that things like lemon and orange zest (used for hundreds, perhaps thousands of years) use the parts of plants in creative ways to capture the bioactive compounds!!

    1. Right now I have a jar full of mango peels, pineapple scraps, apple cores, melon rinds, and strawberry tops steeping with a vinegar mother from another batch…free fruit vinegar from nutritious scraps and bruised fruit that can still go into the compost pile later! Now thinking I should add some citrus peels! Being poor can help you flex your mental muscles and be healthier too! :) Sometimes our blessings aren’t necessarily the ones we would choose, but simplifying life and getting back to basics has been very liberating. Just to keep with the theme…when life gives you lemons…utilize the whole thing! lol

    2. The pith (the white part, somewhat bitter but not as much as the rind) has lots of nutrients in it too. When I peel an orange, I try to leave a moderate amount of pith, but not so much to ruin the sweet taste of a fresh orange.

    3. I would tend to agree with your general characterization that certain peels and pits are inedible. Though I would say in small quantities, and in certain forms, these may be palatable. For example I cut up organic pomegranate peel, freeze it and then add small pieces of the peel to my daily smoothie, about 1/2″ square for 4 cups. To your point, I were to double the quantity the smoothie is too bitter.

    4. Careful who you give those mango peels to. People like me who have a heightened sensitivity to poison ivy are extremely allergic to mango peel. (Same family of poison.) The last time I ate mangoes, I peeled them and ate the fruit, throwing the peel away. Two days later I was on steroids due to a systemic reaction to the peel I hadn’t even eaten.

  4. I love kumquats too, but I’ve added another routine since reading about the health benefits of citrus pith & rinds. I wash my citrus fruits (oranges, tangerines, clementines, &c) thoroughly (even organic) before peeling, then dehydrate the peels and powder them in my coffee grinder. I add the powder to my hibiscus & green tea for added flavor & nutrition. Any little pieces that resist powdering give mini citrus hits reminiscent of Constant Comment tea.

    Interesting that heat seems to vitiate the protective effect of lemon peels, since heating helps modify citrus pectin to make it water-soluble. The resulting material is a hot item in some circles because of its reputed anti-cancer and heavy metal chelating properties. See:
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2782490/
    http://www.ncbi.nlm.nih.gov/pubmed/26686103
    http://www.ncbi.nlm.nih.gov/pubmed/12488479

    People with access to the Asian citrus called hallabong (aka dekopon) may want to consider chowing on their peels as well: http://www.ncbi.nlm.nih.gov/pubmed/26778161

    1. I, too, noticed that data on beta-cryptoxanthin in pumpkin, squash, and red bell peppers. I’m now wondering if these foods will give the same effect as citrus peel or is the effect the result of a synergism among only citrus fruit compounds. I guess more studies are needed. Either way, they’re all super healthy foods compared to the SAD diet :-)

      1. The pumpkin and butternut squash would lack limonene, but I get my limonene from orange peel flavored chocolate (yeah, I know, not supposed to eat chocolate, sat fat and sugar…) I could probably make a date-cashew-chocolate-orange peel truffle type thing. One of these days.

  5. Another indictment on fruit juice I hear at the end. That would be a good lead in for explaining to folks how supplements _cannot_ work. In my world tea and coffee are more nutritious than juice. Funny world.

    also: I zested lime onto my breakfast and into my tea this morning.

    1. I read this and immediately ran to the fridge for a lime which I zested over my lunch of udon, black beans, tomatoes, cilantro and scallions. Delish! Thanks!

  6. Please let me rephrase a question I asked the other day in a different video: does anyone have experience with using lemon juice and/or lemon oil topically, for skincare purposes? A controversial topic which appears to divide people online into two polarized camps.

    Input appreciated.

  7. Grapefruit, especially the rind is high in nootkatone, an AMPK activator, like vinegar, which lowers blood glucose, MTOR activity, cholestrol and triglycerides and increases insulin sensitivity, fat oxidation, autophagy, mitochondral biogenesis, apoptosis, ketone bodies, NO and ceremide synthesis. So, I put a piece of grapefruit rind in my smoothie regularly. Nice to know that it may also prevent cancer.

      1. My first reaction to your comment Ron, was that as Buck seems to know a bit about that of which he’s writing, he probably doesn’t need to be taking statins, because of the quality of the diet he consumes (presuming that he makes his smoothies green and without any milk, or milk derived products). Grapefruit is generally contraindicated when taking ANY allopathic preparations, not just statins…. Personally, I’d much rather stay well through consuming as much plant-based nutrition as possible. At age 60, on no meds with no health issues and, as I said earlier in this thread, being told by a 43 year-old woman that she thought I was the same age as her, There must be something in this ‘whole food, plant-based’ lifestyle that I’ve been on board with for the last two years plus! Success leaves clues!!!

  8. This is going to sound like a stupid question, but what if the peels were boiled in sugar first (the confection known as “candied peel”)?

  9. By “peel,” do you mean the whole peel, like the orange outside part of the skin on an orange or will the white inner part do as well?

      1. Right, but my point was are the benefits obtained from the peel limited to the zest (“flavedo”) or are they obtained just as well from the white pith (“albedo”)?

        1. I don’t know what else is in the white pith, but I recall that they are full of bioflavonoids. I used to chop them up into 1/4″ pieces and swallow a small handful, especially during hay fever season, because bioflavonoids help with allergies.

  10. What about just adding to my tea orange/lemon peel but without zesting? Only a slice of the peel.
    I know eating the peel would be better but I’ve been doing this since my childhood and was curious to know if it is helpful or helpless.

    1. Curious too as I do the same, but I think it’s because I heard that the white part is actually full of some nutritional benefit too, I just can’t remember what off hand! lol

      1. I, too, eat both the pith and the peel (from organic citrus) in my smoothie. Here’s some info I found at the following website: http://www.ehealthzine.com/the-health-benefits-of-orange-pith-uncovered.html

        “Although the citrus fruit itself has flavonoids content, but the
        highest concentration of flavonoids was found in the pith of the orange
        (the white part between the fruit and the peel) – which means you should
        eat the fruit with the white pith to get the maximum flavonoid effects.

        One of the most powerful substances in the flavonoids are naringenin, which is found in all citrus fruits and tomatoes. Research has shown that the naringenin in citrus fruits can inhibit tumor growth by repairing damaged DNA.”

  11. This is off topic, but I recently noticed a change in myself and I didn’t see any topics about it on this site.
    I’ve had dandruff since a very very early age, probably around 12, I’ve tried to stop using dandruff shampoos, went the medicated route for a while, then just settled into Head and Shoulders daily, the last time I was in the store, I stopped and told myself.. what if it was diet related? So I bought a normal non-dandruff shampoo, and the condition has cleared up on eating a WFPB diet. Has any study about this ever been done? I remember being told it was a fungus and some people were genetically prone to it, etc, but clearly that was a lie.

      1. I know this sound totally off-beat, but have him try not using any shampoo or soap, just hot water (or baby shampoo if he objects), and rinse with dilute vinegar for a few shampoos. Some people have sensitivities to the slew of cosmetic ingredients in personal care products, and that’s a good way of finding out. I like to steep mint, rosemary or citrus in the vinegar for a week or two for a better scent, and use about a TBS per quart.

      2. I thought that I had chronic dandruff for the first 50 years of my life. No shampoo ever made a difference. It turned out that I actually have scalp psoriasis. A WFPB diet manages it but has not eliminated the problem. Perhaps your boyfriend’s dandruff is actually another condition altogether.

        1. I think identification of the problem is important, I did a lot of experimenting in my younger years to find out my dandruff issues. I also get rashes and bumps on my skin if using cheaper shampoos or skin products, deodorants would burn unbearably mid-day all of a sudden. My skin has cleared up, I haven’t seen any rashes or bumps, so I don’t know if it is cured as well but definitely much less sensitive. I still get dry skin on my arms, but its only 10% as bad as before, baby steps I guess.

    1. Clearly standard medicine knows NOTHING about nutrition Nick because changing to a WFPB diet as an experiment to control diabetes not only reversed it in short order, but also a slew of other major and minor health issues I had been plagued with for many years that were “NOT related to diet”, ahem. It still amazes me all these years later, and since nobody wants to hear about changing their diet to improve their health, I now challenge them to “try it for a few weeks and prove me wrong” as a more effective motivation to see for themselves!

    2. To add to Vege-tater’s response below. Try dilute baking soda, 1tbsp per quart, for shampooing. Rinse and then follow with vinegar solution at same dilution. I just use organic apple cider vinegar, but Vege-tater’s is an interesting recipe.

      1. Well, I don’t have any issues anymore, I stopped using the old shampoo a month ago, and before if I went out somewhere for work for more than a couple days it would start back up.

  12. I slice small sweet satsumas or tangerines with thin skins and dehydrate them. These crispy slices of bright orange are delicious. I add them, chopped, to my home made muesli and energy bars. I had a feeling the peel was good too.

    1. Great idea! I live in FL, the land of sun and citrus, and have been thinking about cobbling together a solar dehydrator to take advantage of both!

      1. You know when they put bananas on sale…banana chips without sulfur. NOW I know what I’m going to do with that sliding door I’ve been saving.

  13. Ok, . . so I went ahead and took a look at the abstract that Dr. G. was quoting. Here’s a quote from the paper: “Only retinol intake from foods plus supplements appeared protective within a subgroup of women . . .” (supplements? what supplements?)
    I was curious because Dr. G was stating that zesting is the way to go to get the protective benefit. My question is – Was the zest itself tested? or the pith? or the zest and pith together? Nowhere in that research did it state that the zest was the place where the the retinol “lived”. So I’m wondering if anyone knows just where the retinol is located in citrus?
    Having said all of that. . . One of Ann Esselstyn’s favorite sandwiches is an open faced (cooked) kale sandwich to which she adds very thin slices of lemon, rind and all. I’ve had it. It’s excellent and you don’t taste the bitter rind.
    One more thing and then I’ll be quiet :-) I recently got some information that the food industry (don’t we just love ’em?) sprays citrus – oranges for certain – with a coloring that is cancer-causing but makes the citrus look ripe. The oranges may actually be ripe but look a little less colorful, so they color-spray them. Does anyone know if that stuff can be washed off? (I’m not talking about the ethelyne gas de-greening process explained here: http://www.riversweet.com/degreening2.htm ). Thanks!

    1. I kind of doubt it, but was so shocked after we moved here (FL) and actually got to see what citrus that is tree ripened looks like! Not much like the uniformity you see in stores! They turn orange and fall off when they are mostly past their prime, so how does this silly perfectionism and visual appeal even get started, and out-class flavor and nutrition? I hate shopping at the big box stores and hit the ethnic stores and farmers markets for what I don’t grow myself. Better variety AND quality, just not as “pretty”!

      1. Yes, V-tater – I was surprised to find that a perfectly ripe orange can look green. That was new to me. I won’t feel hesitant now when I see a greenish orange in the store. Might even prefer it!
        Would rather not eat chemicals.

      2. That’s really interesting. When my mom lived in California she had a couple of orange trees and the fruit turned orange and looked quite enticing long before they were sweetly delicious. They stayed that way for a month or more before they were really ripe. They were probably a different orange – navels instead of perhaps Valencias – than what you grow in Florida.

        1. You’re probably right about the varieties, because even our navel oranges here are different from the CA ones. Ours have more fibrous sections, thicker skin and just look different. We are also losing our citrus because of a disease called citrus greening and there is no cure yet, kinda sad.

  14. I came across a short YouTube video a couple of years ago, in which the presenter was advocating freezing whole lemons, and grating them into a container to be stored in the freezer for use as needed. This guy was so passionate about it that I was moved to try it for myself. I found that it was indeed really tasty, so a most palatable way of consuming the peels, but that grating the frozen lemons is exceedingly hard work (perhaps my grater isn’t sharp enough) and, also, I found myself left with sizeable chunks of lemon which I could no longer grip for grating, so had to discard. Following today’s video, I am tempted to try the technique again, but using oranges. I just checked, and the youtube video is stil there, along with quite a few others about freezing lemons: https://youtu.be/ygxFYIuGWPs

    1. Joss – One thought that comes to my mind would be to cut the lemons into quarters or eighths (or whatever) and then freeze them. Then I would think they could be put in a food processor and chopped to small bits that way. Might save the old tips of fingers. Ouch! Another thought might be to slice while unfrozen with a mandolin then freeze on a cookie sheet. Thanks for the video, very interesting and thoughtful.

    2. Joss – If it were me, I’d use the grating feature/blade of my food processor. I’m all about power tools in the kitchen. :-)

      1. Good idea, but the seeds are also getting grated up. I wonder if there could be issues with consuming lemon seeds regularly.

        1. Ben: Someone else asked a similar question and I tried to find an answer at that time. Result: I couldn’t find a source of information that seemed reliable enough to point people to. My sense is that the general consensus is that consuming some lemon seeds is either neutral or mildly healthful. But there are some people who think it might be mildly harmful. And I couldn’t confirm either way.
          .
          Baring any real info I can rely on, and knowing that people commonly put lemon slices with seeds and peel and all into their smoothies without obvious downside, I personally would not balk at eating some lemon seeds now and then that are ground up in whatever else I am eating. My guess is that my consumption amount would be too low to matter even if there are some potential downsides. But that begs the question – what would be an ideal limit/cut-off for those people who want to go wild with their grated frozen lemons? I don’t know…

  15. I got interested in this limonene thing about a year ago and did some research on it and saw at least one study in which topical application DID result in accumulation of the desired substance in fatty tissues, including breast tissues. They had women apply an essential oil with a certain concentration for a certain amount of time before breast lump removals, and there was a drop in some cancer marker that occurred between biopsy and lump removal only in the women using that oil. I also read that although the peel has the most health benefits, the pith also has a high level. I use an organic red grapefruit in my regular smoothie and sometimes I force myself to eat a little piece of the peel while I’m peeling the grapefruit, but it doesn’t taste good and it will ruin the smoothie if I actually put it in there. So I just try to leave a lot of the pith on instead. How much of the peel do you have to eat to see the cancer-fighting benefits?

  16. I like this since if you only use the juice of the lemon ,your throwing half of the produce away. Saves me money! I just bought a watermelon and I weighed it , cut it up and found the rind was 50% of the weight. So I juiced the rind, threw in a whole lemon in the blender with rind juice…..pretty good
    cheers

    1. esben andersen: My dog LOVES watermelon rinds. So, I eat the red part and he gets cut up pieces of the rest. Just sharing.

      I remember I researched watermelon rind preserves some years ago. It was an interesting idea, but of course, it was heavily boiled and smothered with sugar. So, not exactly the health food we are going for here. Still, the topic/idea is interesting as I had never heard of that dish/condiment before.

        1. Awww. What a cute dog!

          re: pickled pumpkins. That’s another new one on me. I like trying new foods, so it interests me. Maybe someday…

      1. Hi Thea, When we have juiced watermelons with a Champion juicer, we would juice the rind as well as the red flesh. It reduces the sweetness and was much preferred for its balance. Our cats will eat all kinds of fruit and vegetables, but I doubt they will go for the watermelon rinds.

        1. robert: re: juicing. That’s another interesting idea. I remember trying a watermelon drink in Mexico once that was so refreshing and just tasted like watermelon juice. But it was also probably pretty sweet. I like your idea on how to get some balance.

          re: cat liking fruits and veggies. I love your cat! You go kitty!!

  17. I can’t believe people are asking such stupid questions about individual components of the fruit…(“essential oil in the peel”,Is it just the carotenoids?…)…The whole fruit, vegetable or almost anything else is a “complex” meant to be consumed all together….It won’t work unless consumed as a “complex”….I have ALWAYS consumed the entire lemon and orange….Whole lemons are great to cook with….

    1. Calling other people’s questions “stupid” is offensive, downgrades the quality of our site, and discourages the free and open Q & A. How about saying something like, “I find the questions about the individual components of fruit to miss the point. I believe…?”

      1. You seem to be rabidly salivating to correct something that someone wrote….
        What area of expertise is your PhD in? English?
        It’s very offensive that a supposed woman is correcting a man here instead of being in a kitchen preparing a healthy meal for Mr. Gayle Delaney…. Fulfilling your divine duties….
        (Gayle probably even wears pants…)….

  18. Since I drink Hibiscus tea and It taste better with a bit of citrus in it, How about zesting in some lemon/orange peal into the mix?? Then squeeze the rest in it too… I’m gonna give it a try…

    mitch

  19. Off topic question. I have tried to use turmeric as a supplement. I’ve added it to food but for me it ruins the taste so I want to just take it as supplement by itself. I’ve read that heating it up increases it’s bioavailability. I thought that making Golden Paste may be a good idea and then I could just eat that straight, but that recipe includes oil. So to my question… if I am not going to add turmeric to food what is the best way to take it. Is Golden Paste a good idea? Should I just mix the raw powder with pepper with some water and drink that? Please let me know. Thanks!

    1. Dr G says we only need 1/4 teaspoon of turmeric a day, and that tiny amount is easily hidden in my quart of morning tea concoction, which contains both green and Earl Grey, chopped ginger, a bit of black pepper to make the turmeric much more absorbable.

    2. Thanks for your question!

      Before using turmeric, I recommend you watch this video to ensure that turmeric is appropriate for you or not. To answer your question, I will use the practical recommendations provided by the University of Maryland:

      – Cut root: 1.5 to 3 g per day
      – Dried, powdered root: 1 to 3 g per day
      – Standardized powder (curcumin): 400 to 600 mg, 3 times per day
      – Fluid extract (1:1) 30 to 90 drops a day
      – Tincture (1:2): 15 to 30 drops, 4 times per day

      Hope this answer helps!

  20. I used to love the dark chocolate-covered candied orange peels made by Fannie May. It was a sugar overload, but it was a great treat. Would orange marmalade be an acceptable way to eat the orange peel or too much sugar?

    1. From Monday’s video, Dr. Greger sites that; “However, if you boiled the lemon first for 30 minutes, the effect was lost.” So heat, or at least boiling destroys the effect.

      Marmalade is boiled. The recipe that I looked at called for boiling the marmalade ingredients for 10 minutes. Presumably, some if not all of the cancer fighting effect found in the orange peel will have been lost in the process. Best to do what Annalisa Mather, “Joy of Yum” does and put slices in a food dehydrator which will concentrate the sweetness of the fruit and hopefully preserve some if not all of the citrus peel goodness…

      1. Our store sometimes carries fresh kumquats, so I guess I’ll stick to them. (And maybe dip them in a bit of melted dark chocolate.)

  21. As pesticides collect mostly in the peel of fruit, it seems a bit risky to eat any part of it. Won’t the toxins undo the DNA-repair of the zest? Unless it is the peel of organic fruit.

    1. Would there be pesticides in the peel of organic fruit? I’m guessing not or at least far less. All peel needs a good wash and scrub imo though.

      1. Organic citrus is still often sold with a wax coating. This is very thin and easily scrubbed off with hot water. The pesticides on conventional citrus are quite nasty. Buy organic if you plan to eat the peel.

        1. I didn’t realise that organic citrus fruits still (or may still) be waxed. I just assumed they didn’t have it, esp on their appearance and feel/texture. I shall keep a look out at the various brands I buy to see if they give me details.

  22. In India it’s common to pickle lemon, sometimes with sugar and/or salt, and sometimes with oil, always with a lot of spices. some make it sweet and some spicy. Usually you grab about 1/4 of a lemon pickle and eat it with your rice and yogurt, or with chapatis, veggies and daal. This is a daily thing, and it adds some salty and spicy flavor to your meal. Here is a sugar and oil-free recipe if anyone is interested. This is worth the work. Luckily our relatives in India send it every now and then for us. http://www.indiankhana.net/2013/09/lemon-pickle-nimboo-ka-achar-no-oil.html

    And for those who are even more extremely patient, there is a black lemon pickle which takes a year or longer to really ferment, but the taste is quite amazing, and goes especially well with kichadi. You can search for a few recipes on the ‘net. Now you can buy so-called Indian “picle” from the Indian store however they often contain preservatives including sulfites. Sunlight is an essential ingredient for these pickle recipes. In this way, the citrus peel is preserved and eaten once a day with this popular pickle.

    Careful attention is required to keep the pickle from spoiling, but if done right it can keep for a long time.

  23. I wonder what the bottom line would be on eating candied orange peel, something I have always loved but gave up due to the sugar content. Just read maple syrup might be protective, so maybe orange peel candied in maple syrup? I’m one of the weirdos that actually loves Christmas fruit cakes too. Same wonder re ginger.

  24. I’m still in complete shock that there is so easy and simple solution ,for almost all of the misery and suffering in ours life ( plant based diet) and yet,all those years of million of deaths,the health service didn’t bother to inform us. this is unethical.

    i suffered many years from bleeding out of my rectum ,i had hemorrhoids,i was almost needed to have a surgery,i took it as a fact of life,until i started a vegan diet from moral reasons,and i was shock that my hemorrhoids and my bleeding completely gone,and i didn’t felt any pain anymore while dumping . so then i decided to research this diet benefits further.

  25. Hello Dr. Greger, will you please post a topic about vaccines? I know you mentioned in other videos that the benefits farly outweigh the risks but can you please make one about the “studies” those antivaxxers use for reference?

  26. As someone that consumes the juice of half a lemon first thing in the morning everyday, and then discarding the lemon, I shall now be buying organic lemons and limes and grate the peel into a container and store in the freezer for use in my daily veggie smoothie. I’ll make sure to wash the produce first of course. I did know about this beneficial properties of citrus fruits but had forgotten lol. So cheers for the reminder Dr G

  27. WHOA – citrus fruits like oranges are pesticide heavy. Yes, go organic, but do you need the actual peel with fiber, or simply the ‘zest’ meaning the spray from slicing off a curlicue? Let’s review what a “zest” is – this is a word that is an odd one!

  28. I am not a Doctor and could not find the info on google. How about eating rotten fruits (apples, cantaloupes, oranges, tomatoes, potatoes). Are they really dangerous or are the fungus on them healthy and boost the body’s immune system ? Of all, rotten apples are my favorite and quite sweet and delicious.

  29. After learning about how nutritious citrus peels are I googled and found that their peels are also great as a vitamin C mask. So whenvever I eat citrus, I eat everything except 1/4 of the peel. I remove the pith and add it to my collection of other peels , which I leave out in the sun for a few days. Once a week, I grind a few of these dried peels, mix with honey and put on my face till it dries. Then I scrub it away and viola, I get smooth, glowing skin for a few days. Careful if you have sensitive skin though, it can burn !!

  30. How about making an orange julius type smoothie with vanilla almond milk, vegan protein, orange sections, and orange peel zest ? Use a zester for this.

  31. What is the best value in citrus? Oranges and lemons both contain limonene, but oranges cost half as much per pound, and grapefruit is even cheaper. I know its all good, but hey, I’m always looking to keep that grocery bill under control. Good food ain’t cheap. :)

  32. Right just through in the whole orange or lemon into you smoothie, all the runner groups in my area eat oranges like they eat apples … which I am sure is what most of our ancestors did …
    70 Going On 100

  33. i don’t have any recipes that use orange peel….. what would it be good in? do you have any recipes or general recommendations?

    also, have there been any studies done with kumquats? i actually used to eat them as a kid, because one of my friends had them in her backyard… but i only see them occasionally in the store.

  34. check this out: Oral intake of purple passion fruit peel extract reduces pain and stiffness and improves physical function in adult patients with knee osteoarthritis. Double blind placebo controlled 33 patients https://www.ncbi.nlm.nih.gov/pubmed/20934601
    There must be something common in various fruit peels that help with arthritis. Keeps coming up in studies. Is it the enzymes or something else? It would be great if Dr. Greger and team could gather all of the studies on the peel of fruit to see what the benefits are and possible pinpoint what it is about fruit peel that has benefits for various conditions. Thanks!

  35. what about the effect of oranges – tangeretin – on tamoxifen? this study shows tangeretin negated the cancer preventative effects of the drug.
    https://academic.oup.com/jnci/article/91/4/354/2543934

    “In our study, the tumor growth-inhibiting effect of oral tamoxifen was reversed upon addition of tangeretin to the diet. Our data argue against excessive consumption of tangeretin-added products and supplements by patients with mammary cancer during tamoxifen treatment.”

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