What is the Optimal Vitamin C Intake?

What is the Optimal Vitamin C Intake?

“What is the Optimal Vitamin C intake?” For many years, the RDA, the
recommended daily allowance for vitamins, was just based
on preventing deficiency, with a margin of safety, but the miniscule amount of vitamin C,
for example, needed to avoid scurvy is not necessarily the ideal
intake for optimal health. So what might be the
optimal intake of vitamin C? Let’s ask the body.
How might we do that? By seeing how much the
body absorbs and excretes. If you swallow 15 mg of vitamin C,
which is what you would get eating about a quarter of an orange,
your body sucks up nearly 90% of it. But if you take a supplement
containing 1,250 mg, your body seems to realize that’s too much,
and so clamps down on absorption at the intestinal lining level, and you
end up absorbing less than half. So by doing experiments where
you slowly ratchet up the intake you can see when the body
starts to say, OK, that’s enough, and that magic level of intake
appears to be about 200 mg a day. When you take up to 200 a day
your body sucks it all up, but above that your body tries
to block further absorption suggesting our intestinal vitamin C
transport mechanisms have evolved to fully absorb up to about
200 mg of vitamin C a day. In addition, vitamin C is reabsorbed in
our kidneys back into our bloodstream to maintain our vitamin C blood levels up
at around 70 or 80 micromoles per liter. That’s the shaded region there, which is what you reach at a vitamin C
intake of about 200 mg a day. So even if you take 10 times as
much vitamin C supplements, you know, 2000 mg a day, your
body will just pee and poop it out to keep your blood levels
in that narrow range. So based on these kind of data, one might propose that 200 mg is
the optimal daily intake of vitamin C. You can confirm using disease data. At what daily intake of vitamin C is
there the lowest stroke risk, for example? Apparently at about 200 mg a day. While dietary vitamin C intake was
associated with lower stroke risk, vitamin C supplements
were not, which is consistent with
the overall body of evidence showing that antioxidant
supplements in general don’t seem to protect against
heart attacks or strokes. But wait… Can you get all up to an intake of 200 mg
a day without taking supplements? No problem. Single servings of fruits and
vegetables may have about 50 mg each, so a measly 5 servings
of fruits and veggies a day could get you to
ideal blood levels.



  • surfing hobo

    the green screen stuff is creepy and a little cheesy

  • WisdomTooth

    Based on the life we live today full of pollution, toxins and geo-stress 2000-3000mg a day should be good and pair it with MSM(organic sulfur) for rapid detox/alkalizing purposes. For regular daily intake 250-500mg a day from whole foods should be enough.

  • TheFancyAgenda

    Those pop ups like at 0:24 are annoying otherwise these are really good videos.

  • Nikolay Nikolov

    If I take less than 600 mg (3 x 200) a day my gums start hurting.

  • experiment54

    when your mouth and belly says enough stop idiot I said stop cut it no more. That 🙂

  • Spartan Elf

    when you're a vegan and your pee could be a great supplement against heart disease

  • Mehmet Remzi

    another fantastic reason to eat fruit and vegetables.

  • Loui K

    Please make a video about iron deficiency in a vegan diet
    Great videos!

  • AnimalIndustry

    Delighted that this topic is so easy to overview and understand, great!

  • Russell Hough

    you didn't mention real vitamin c vs absorbic acid

  • בני ×—

    So what if the body absorb 100percent.. if the body can absorb more than it kind of evidence that it may the optimal..,let's give someone 2000 and see how much the body absorb and maybe this is the optimal dose

  • Lichtblick

    5 servings of fruits and vegetables have only 200mg vitamin c? this can't be right

  • Mac MacPherson

    Is there a similar study for Vit D, that actually looks at min to avoid problems and max to optimise health?

  • L30887

    Stop talking like that it's fucking annoying.
    Can I not receive this good information without having to listen to this weird pausing and rising and falling in tone please.

  • Daniel Rose

    Vit C supplements are acid. What if they were a Magnesium salt of the ascorbic acid? That is what I do. Maybe the fruits and veggie C is a salt, not an acid? I also eat half a grapefruit per day, which can also be alkalized with MgO.. Also, vit C supplements are notoriously unstable. Does MgO make them more stable?

  • Syrales

    so 4 times 15 is 60 for 1 orange, and about 89% of the c vitamins get absorbed until the blood is saturated. i guess 4 oranges a day then, 240 and 90% of that is 216, which is slightly above 200, and remembering 4 oranges is easy.

  • Antoine Leonidas

    what about orange juice? there's mentions about possible harm from the "sugar", but what about 100% orange juice, nothing else added? would that be safe to consume?

  • Dinner Chief

    Hey boss what is good food to eat when sick??? Is spinach good

  • Jane Tatum

    What about the Linus Pauling Institute and their long time research. This is really interesting, but I've heard such compelling research and results of short term high dose vitamin C therapy for certain health issues. Long term, def not good for GI flora if in acid form I'd think.

  • Vio Phile

    So how many citrus fruits should I eat daily?

  • Nour

    What about athletes? Or for regular people exercising?

  • Moderator NutritionFacts.org

    Visit the NutritionFacts.org website! There are short videos to address most any nutrition question imaginable, including those below.

  • etobiCRACKscorpions

    The power of plants!

  • 59seank

    I find the floating head bit distracting and unsettling.

  • overlogg

    So the only way to bypass this, is to inject it intramuscularly or intravenously

  • DronePilot Canadian

    Hey Dr. Gregor I was hoping you could allow me to post something in your comment section it's to find my missing brother , if it's not OK you can remove it immediately and I will understand but please check it out yourself and possibly share for me , this is not spam or a scam of any sort I am actually a regular viewer of yours and I'm reaching for any help possible . https://m.gofund.me/reunite-with-brother-after-12-years

  • Wi Co

    "Table 1. Bioavailability in 7 healthy males at steady state for each dose."
    Too few test subjects, not double blind, only one sex, and narrow ranges to name a few of the many limits of this study to form any conclusion.

    You ignored what else the first study said:
    " These RCTs show that vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers."

    You then used Yizhou Ye, Jing Li, and Zhongxiang Yuan study which counters the study you first mentioned done by the Linus Pauling Institute

    You don't get to pick and choose what parts of a study support your conjectures; that is the confirmation bias fallacy, not science.

  • Arachnid Soul

    Good info here. On a whole food plant based diet, you pretty much just stumble onto this recommended amount of vitamin c each day without really trying. Some food that are high in vitamin c include the following: bell peppers, dark leafy greens, kiwifruit, broccoli, berries, citrus fruits, tomatoes, peas, and papayas….(the list goes on).

  • Ellie Moore

    how much is 5 servings of fruit thou?

  • Wayne Fergerstrom

    Is this why Airborne, etc are useless?

  • Poo Paa

    Yea but Dr how many oranges is that

  • Andrea C.

    Are there any studies on liposomal vitamin C?

  • Masoud Abdun-Noor

    What I want to know is what was going through the minds of the nine people who give this a thumbs down? Who could really honestly have a problem with this?

  • Zem

    What are the foods highest in vit C?

  • SultanNify

    doctor why you never talk about candida?

  • Wak Job

    I always questioned the supplements I buy that have like 6000% of the DV.
    I wondered is it harmful? Is it a waste? Any benefits?
    Thanks Doc, this was enlightening.

  • Nikki H

    What about your body's use of Vit C when your sick?

  • Karl Laur

    What about Vitamin A?

  • Fernando Crociani


  • jpmathematician

    Great video!

  • Bradley Trent

    Hey Dr. Greger! My cousin and I both have the autoimmune disease sjogren's syndrome. After reading your book, How Not to Die, he decided to go vegan and has felt significantly better. I am about to follow his footsteps and see if it helps with my health as well. Could you make a video about sjogren's syndrome, the causes, and the best diet/foods to help it? Thank you so much for your work.

  • Joseph

    Fake news it makes me laugh so loud. That was such a lie the powers that want to be are scared shitless

  • Junior Slice

    Doc, grow back your beard! You look healthier with it

  • Go T

    What about cell concentration level? Animals that dont produce their own get about 30mg (NATURAL) vit C per kg bodyweight per day through their diet. It must come in combination with natural cofactors like polyphenoles etc. to enable proper absorbtion and utilisation.

  • teeminator30

    So taking camu camu or acerola cherry powders are pointless then?

  • Coe Hart

    Question. Does taking it in one dose vs. multiple doses change anything. I just wonder if it would change if you break up the doses like you would meals.

  • cyc00000

    This may have already been stated, in Aus about 95% of the population fail to eat the RDI for fruit and vegetables – it's not good.

  • Ronnie & Minh

    Thank God I am RAW and I don't have to think about any of this. No supplements in my diet, just fresh food. Thanks Doc, love your videos and information.

  • beyonceps

    Please do a video on the Raw diet!!! And also, are plants better medicinally than cough syrup or aspirin? (and other common cold medication)

  • lori amora

    not milligrams…but grams of vit c…my sources say…

  • Jean-Luc Charron

    it would be interesting if Dr Greger would do another video on vitamin C and incorporating research and clinical trials (maybe not the correct terminology) conducted and or cited by the vitamin C foundation. They indicate reversing cancer with intravenous therapy of high dose sodium ascorbate; as well as reversing heart disease and reversing diabetes with vitamin C alone.

  • tamcon72

    Very useful info; please do more of these "What's the Optimal Level of X, Y, or Z According to Research" videos! TFP : )

  • Ben Cantu

    I, heretofore, had a lot of respect for Dr. McGregor. This video however is way off the mark. In just a 3 minute video, Dr. McGregor has completely dismantled the work of Dr. Linus Pauling.

    Since Pauling's death, the medical establishment has reclaimed the scientific position with a series of experiments on vitamin C. In particular, the NIH measured the distribution of vitamin C in the body and claimed that Pauling was wrong about the need for high doses, as the blood could be saturated at low doses [Proc. Natl. Acad. Sci. USA, 93, 3704-9.]. They added that doses higher than one gram were potentially dangerous. From this point on, the high dose vitamin C lobby were on the defensive.

    If the body could be saturated at low doses, the argument went, higher doses were simply a waste or even potentially dangerous. However, clinical reports of the utility of high dose vitamin C had been repeated in the literature for over 50 years. These reports continued, particularly in the fields of heart disease, infections and cancer, contradicting the NIH conclusions. Either the clinical reports of the efficacy of high doses were incorrect, or the NIH experimental work was flawed.

  • Claire Adamson

    Bought your book today! Figured it was the least I could do for all the great, free info you provide in your videos. Thanks so much!

  • Marlon Welter

    I really dont like this "Dr Gregers head walking" in the video. It is about the facts, not the presenter. Also I feel like it gives away so much of the seriousness of the videos. I don't like to share these videos anymore, cuz it just doesn't feel like science anymore (and the first impression is really important to people) but rather some doctor wanting to present himself. It makes me sad to see these newer videos. Unfortunately Dr Greger must have had a lot of bad advisors (or rather fanboys) lately.

  • Jeff Lebowski

    I will reiterate what others are saying about ascorbic acid not being the same as Vitamin C, ascorbic acid is produced by bacteria in a factory while natural Vitamin C is produced by a plant. Ascorbic acid is an organic acid but it doesn't have the same properties as the Vitamin C found in fruits and vegetables. I prefer to eat natural instead of taking a supplement.

    Here are a few ways to get 200 mg of natural Vitamin C:
    15 oz of orange juice
    7 oz of lemon juice
    2 cups of broccoli
    4 oranges
    1 papaya
    2 cups brussel sprouts

    Another point is you should split the 200 mg into two or more servings per day, for example I have a glass of orange juice with breakfast and a cup of broccoli with dinner.

  • Victor Crosswell

    supplements vs real fruit? maybe the body doesnt want the supplement

  • Truthseeker1961

    My searches have indicated a cup of orange juice has just 124mg of Vitamin C…Obviously not enough C for the day even in an entire cup of OJ, a ''cup'' which I'm assuming is 8 ounces…WOW, not nearly enough C for the day there in that OJ…lovely. Anyway the "ascorbic acid" in most supplements is NOT real Vitamin C, I read awhile back it's only ONE EIGHTH the molecule of Vitamin C, it's garbage, so overall with just those two factoids mentioned above, no wonder most have colds and such in the Winter, most of us are simply not getting enough C in the first place.

  • Jimmy

    I highly doubt the linaer increase of the graph regarding the vitamin C intake after 200mg. It also doesn't correlate with his sentence before "You body will just pee or poop it out if you take too much." The y-scale is already quite huge, so you want to tell me that I can induce myself a stroke if I heavily overdose vitamin C? I really like this channel but some graphs seem way to handy. This seems like a simple curve fit done with Igor Pro or a similar program. The 95% confidence interval also suggest that the fit was pretty mediocre.

    It also doesn't correlate with what he wrote on his homepage regarding the success of intravenous vitamin C treatment: "Studies in the 70’s appeared to show an extraordinary survival gain in terminal cancer patients with vitamin C". Did all those patients die of stroke afterwards or what?

    Strange video overall. Funny enough he also did not list that study in his link.

  • Felipe Herrera salinas

    May differ in a point, the intake of vitamin C needed depends of the requirements of the vitamin (remember that's a cofactor of collagen) that varies between individuals. Without any pathology and if you are between the age span of the study is 200 mg a day, with pathologies it rises and a rises a lot. So the basal need may be 200mg but not the therapeutic need. See a great book called Ascorbate, by two biochemists phd Hillary Roberts and Steve hickey.


  • Torulv

    what about a body under stress? will the body increase uptake of vitamin c in this instance?

  • Elise Wouters

    Along depression name hkmlxv nobody ill involve order.

  • Myra San Jose

    But what if you are trying to fight an infection? How much should you take?

  • lori amora

    acerola cherries…

  • D Master

    high dose vitamin C has been shown in many cases over the last 80 years to cure many diseases. A much better way of asking the body how much vitamin C does it need is to take vitamin C up to bowel tolerance. when the body is sick it can not only handle 20 gram per day but that dose can cure viral infections within days. when the body is healthy bowel tolerance is only a few grams per day.

  • Buster Brown

    I'm Caucasian, so I should get around 20 minutes of noonday sunshine under ideal conditions. Take a stick and if the shadow is longer than the stick you won't be getting any vitamin D from the sun. I would say the optimal place to get your vitamin D is in the mountains of Quito, Ecuador.

  • DCD


  • Jeff Lebowski

    200mg per day is a close number for adults but recent studies have shown 3mg per kg of weight is more accurate. So a 30kg(66lb) child should get 90mg while a 80kg(176lb) adult should get 240mg.

  • The One and Only

    I take 11gram (11.000mg) a day

  • T C

    What doesn't make sense is that this video says that if someone takes 1250mg of Vitamin C the body absorbs only 46% of it. Sorry, but I did the math and 46% of 1250mg is a lot more than 200mg.

  • Christopher Burian

    Absorption by the intestine might simply be due to osmotic or similar reason. Just because the body can't absorb more doesn't mean consumption has reached its healthful optimal level. It just means that supplementation becomes less efficient, and like you said, the excess is excreted in the stool. Maybe we need to explore time-released version, or taking smaller doses repeatedly. The body can store at least six months worth (the time it takes for scurvy to appear when properly pre-loaded). So the upper concentration in the blood could just as easily mean the excess is being stored in tissues, rather than merely excreted in urine.

    If we're really only supposed to have an intake of 200 mg per day, then why in the world do goats make 13,000 mg in their bodies every day, and even more when stressed? The huge amount of Vitamin C generated per body weight in most mammals strongly suggests that losing the ability to make Vitamin C is a significant shortcoming only minimally mitigated by being able to consume, store and recycle Vitamin C by various mechanisms.

  • Dustin G

    Seems wrong

  • I Am Not A Robot

    This channel is a hoax

  • Joshua A

    Dont listen to this shit advice. The sicker you are the more C your body needs. Another doc gave advice to administer 50 grams of intravenous C to a relative the hospital in new Zealand was giving up on / in coma about to die. The patient rapidly recovered once megadosing of intravenous C started but not before the hospital tried desperately to drop the C down to One gram in hopes patient would relapse. Took an attorney to force hospital to continue. Patient walked out two weeks later. Doc said he once gave docs against C the benefit of the doubt but no longer does so. Says the docs would rather patients die than go against the established anti C peers

  • Michael Schwartz

    Dr. Fredrick Klenner, Dr. Linus Pauling, and Dr. Suzanne Humphries would all beg to differ.

  • Tacitus

    Excellent video. Thank you so much sir.

  • Christian JimĂ©nez

    What is the optimal Magnesium intake?

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