How much Vitamin C can you absorb at a time?

pomegranateLeena writes:

“I listened with great interest to your recent episode about the role of vitamin C in reducing toxins in the bloodstream. Before I run out the door to get some vitamin C supplements, I have a question about the best way to take it. You said the recommended dose is 1000 mg daily. But could I increase absorption by splitting that into smaller amounts throughout the day?”

Leena raises an excellent point. There is, in fact, a limit to how much the vitamin C the body can absorb into its tissues at one time.  If you take in 200 mg of vitamin C, virtually all of it will end up in your bloodstream. If you take 1000 mg at one time, a large portion of it will probably end up in your urine.  In terms of keeping your blood levels consistently high, taking 500 mg twice a day, or 250 mg four times a day would probably be more effective than taking 1000 mg once a day.

However, the study that I described in my recent podcast on reducing toxins in the bloodstream used a single 1000 mg dose. It would take another study to establish whether breaking that dose into multiple smaller doses would make any difference in reducing PCB levels in your body. It might work better. It might not work as well! For all we know, it’s the absorption of excess vitamin C by the kidneys that leads to increased excretion of PCBs. (That’s why we test these things!)

Here’s how you might hedge your bets, though. You could take 1000 mg of vitamin C once a day, as they did in the study. In addition, you could choose more Vitamin C rich foods at all your meals throughout the day. That way, you’d have the best of both worlds: a single large dose (just in case that’s the secret sauce) and multiple smaller doses throughout the day. And you’d be eating more fruits and vegetables in the bargain. That sounds like a win-win-win.

25 thoughts on “How much Vitamin C can you absorb at a time?

  1. Is there a difference between people for how much of a vitamin they should receive on a daily basis? For example my grandma is 95 and weighs like 80 lbs and is not even five feet tall. Does she need the same vitamin C daily intake as say Shaq, or a giant power lifter?

  2. That is something to think about – you don’t want to take a vitamin and not have it really benefit you, by most of it being excreted through your urine. Interesting information, thanks for sharing!

  3. If you supplement with Vitamin C, go grab the bottle right now.
    Because 99% of Vitamin C sold today is not the real thing.
    Just make sure it’s not the kind you find on most store shelves, because…
    Most Vitamin C Sold in Stores isn’t “Real” Vitamin C!
    It’s Absorbic Acid
    Look on the nutrition label and you’ll probably see the words, “Vitamin C (as ascorbic acid).”
    Do you know what ascorbic acid is?
    Well, it is NOT vitamin C. In fact, it is just ONE of the many nutrients that make up the complete Vitamin C molecule.
    Think of the complete Vitamin C (well, ANY vitamin really) molecule as an egg. If all of those other nutrients make up the yolk and the egg whites, ascorbic acid would just be the shell surrounding it.
    The complete Vitamin C molecule contains P, K, and J factors, the tyrosinase enzyme, at least 14 known bioflavonoids, various ascorbagens, five copper ions, iron, manganese, zinc, selenium, phosphorus, magnesium and yes, ascorbic acid.
    If you’re just getting ascorbic acid when you buy Vitamin C…
    You’re Being Sold a Fake!

    1. I’m afraid that’s simply not true. Ascorbic acid is real vitamin C. It is also a complete molecule. There are other closely related molecules that can also be described as vitamin C because all of these molecules have vitamin C activity in the body.

      The other compounds you list (bioflavonoids, enzymes, minerals, etc.) are not part of the vitamin C molecule, nor are they Vitamin C (although they may have synergistic actions).

        1. Not sure where you’re getting your information, but it might be time to seek more reliable sources. Scurvy is a condition caused by a deficiency of vitamin C. You don’t “kill” scurvy, you prevent it…with ascorbic acid (which is vitamin C).

        2. Not true! It is ascorbic acid that cures/prevents scurvy not the so called “complex” many refer to. This is old news! Google – pauling protocol or the vitamin c foundation and get the facts. Stop listening to marketers trying to peddal their ovrtpriced wares.

      1. Hi Monica,
        I’m a biochemist and engineer.
        Actually Jim is right — ascorbic acid is a component of Vitamin C.
        FYI: Our company teaches healthcare professionals about this and other aspects of nutritional science and cell biology.

        Sincerely,
        Thomas

        1. Hello All,
          I am a molecular biologist and research scientist. Thomas and Jim are correct. Vitamin C is a complex micronutrient that is comprised of many components, where ascorbic acid is just ONE of those components.
          In the lab, we can create ascorbic acid but we can’t create the other components of Vitamin C. Since ascorbic acid has antioxidant properties it was convenient and financially beneficial to sell ascorbic acid as Vitamin C.
          The fact that so many people believe that ascorbic acid is Vitamin C demonstrates how effective we were with selling a lie. 🙂

          1. From Linus Pauling Institute (Oregon State University): “I have read that vitamin C is not ascorbic acid, and that there are other components that make of vitamin C. Is this true?”

            Absolutely not.

            Ascorbic acid is vitamin C because it can prevent and cure the disease that forms from its deficiency – scurvy. This is part of the definition of a vitamin.

            Some people have postulated that vitamin C does not work alone in the body, i.e., that it needs to be present in a “complex” of other factors to work properly. This is contrary to all the scientific literature. At one point in time, the man who discovered the chemical structure of ascorbic acid, Albert Szent-Györgyi, thought he had found that bioflavonoids were necessary for the action of vitamin C and were found in a complex in plants, but this turned out to be a false lead.

            Ascorbic acid, as recommended by Linus Pauling over 40 years ago, is sufficient to satisfy your body’s requirements for vitamin C.

  4. From Dr. Andrew Weil:

    For the record, I used to recommend taking 2,000 to 6,000 mg of vitamin C daily (divided into three doses). However, in 1999 I lowered my recommendation to 200 to 500 mg (divided into two doses) after reviewing two well-designed studies showing that this amount of vitamin C more than saturates the body’s tissues, and thus is sufficient to protect against cancer, heart disease and other chronic illnesses. One of the studies that influenced my decision analyzed clinical trials published in the April 21, 1999 issue of the Journal of the American Medical Association. It concluded that 200 mg a day is the maximum amount of vitamin C that human cells can absorb, making higher dosing on a daily basis pointless.

    The second study came from the Linus Pauling Institute (Pauling himself took 18,000 mg of C per day) and was published in the June 1999 issue of the American Journal of Clinical Nutrition. It identified a similar dose, 120 to 200 mg, as the optimal amount for reducing the risk of cardiovascular disease, cancer, cataracts and other chronic conditions.

    https://www.drweil.com/vitamins-supplements-herbs/vitamins/overloading-on-vitamin-c/

  5. I eat sauerkraut, etc. with sodium benzoate which shouldn’t be combined with vit C. When I take vit C supplement, how long does it take to be absorbed by the body before I eat fermented foods?

    1. Depending on what it is consumed with, vitamin C would be cleared out of the stomach and into the intestines anywhere from 30 minutes to 3 hours after you take it. Food eaten after that point would be unlikely to have much contact or interaction with it. However, cabbage (which is fermented to produce sauerkraut) contains a substantial amount of vitamin C. Fortunately, I think concerns about vitamin C and sodium benzoate have been blown way out of proportion. I really don’t think you need to worry about it.

  6. I took 2oomg of vitamin c yesterday, and I woke up with mild anxiety, unusual for me. I took a 2nd dose this morning, and within a couple of hours my anxiety was so bad, this must be related to the vitamin c. I only took it because I get constant colds, since October to July. I think I won’t take anymore, as I eat lots of fruit and veg. I should not need a supplement, but I thought it might help with these constant colds, never again. Kate.

  7. after having “Natural C” from Amway for 2 days , I am having a mild headache today. Is there any relation between Vit C and headache. I am also having less urine output today.

  8. At our last immunology appt I was told to increase my son’s vit c to 2000mg twice daily. About a week later I noticed his past chewing issues had increased. When I checked into it my suspicions were confirmed. My so takes magnesium and zinc for medical reasons and the vitamin c dosing has been depleting his zinc and magnesium causing increased sensory behaviors. I plan to reduce back to his previous lower dosing and if the vitamin C needs to be high again down the road I will adjust his mag and zinc before those symptoms return.

  9. Monica,
    Ive recently read that the amount of vitamin C absorbed from a single dose is conditional on the presence of “disease” – the more disease there is, the more C will be absorbed and used instead of remaining in the gut to cause ‘bowel intolerance’. Conversely, if the person is extremely healthy then only a fraction of the vitamin C will be absorbed. What is your opinion on this topic? thanks!

  10. Joseph, I have that same question. I have also read that the more diseased the body, the more Vitamin C it requires.

    1. That’s what it sounds like to me too, Andy. And yet, here’s a peer-reviewed study finding that taking 1,000 mg of vitamin C a day led to a measurable reduction in the amount of POPs in human subjects’ blood after two months. This was a small pilot study but based on the encouraging results, researchers are repeating the study with a larger group of subjects. http://www.ncbi.nlm.nih.gov/pubmed/27090108

  11. I’m not the least interested in how much vitamin C gets absorbed into cells; I care how much gets built into new collagen. That’s the issue – maintenance of strong skin and arteries.
    As for the statement: “If you take in 200 mg of vitamin C, virtually all of it will end up in your bloodstream. If you take 1000 mg at one time, a large portion of it will probably end up in your urine…” well, to get into your urine it has to get into the bloodstream first and circulate throughout the body. That’s how the kidneys (or kidney in my case) get it into the urine – from the bloodstream. It can’t bypass the bloodstream and go directly into the urine.

    1. I’m not a professional like Monica …yet, still studying, but as a former nurse, if my education and memory serve, that component would work something like this. The blood is made up of multiple components. Plasma and blood cells. blood may have and carry these nutrients but the cells can only physically absorb and utilize a certain amount to do the building and repairs at one time. So while the vitamin C is in there and flowing in your blood stream, it’s not being broken down and utilized. Think of it like a potted plant being watered. Too much at one time and it just leaks out the bottom, That doesn’t mean it wont eventually be absorbed if it stays there like if said plant were put on a plate that can catch the excess, but in the case of the blood, it will be filtered out before the cells have the chance.

  12. Hi Monica,
    I am writing a piece on proper serving sizes and how much of certain nutrients can be absorbed at one time. I completely understand what you are saying about splitting that recommended daily does into smaller portions but is there an approximate amount of vitamin c that the body can absorb? Is it 250 mg or is it even smaller than that? Thanks!!

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