What Is the Optimal Vitamin C Intake?

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Experiments showing how much vitamin C our body absorbs and excretes can give us a sense of how many vitamin C rich fruits and vegetables we should be eating each day.

Doctors can circumvent our body’s natural barriers to vitamin C overload by dripping high levels directly in the blood stream of cancer patients. Is this a good idea? See:

What about other common supplements? See, for example:

Thanks for watching. I hope you’ll join in the evidence-based nutrition revolution!
-Michael Greger, MD FACLM

Image Credit: Frank Lindecke via flickr. Image has been modified.

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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!

claireadamson

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

TheVioMelody

another fantastic reason to eat fruit and vegetables.

mehmetremzi

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.

cjburian

I want to read the studies, because other studies, as far back as the 1970s, have suggested much higher intakes to be optimal, some as high as 10 grams a day.

Mainly, I wonder if this 200 mg dose is over the course of the full day or single doses. And of course, how long after ingestion until excretion?

100% of the water you take in is excreted or sweated out, but not too many would say that means you don't need water.

If I take in 200 mg of c at 10 am, does it linger until 10 pm or get eliminated by 11 am? If it takes 12-24 hours to be eliminated, it must be doing something.

If it takes 2 hours for a dose of vitamin c to be eliminated from the body, it seems more reasonable to take another dose every 2 hours.

AND, what about studies on vitamin c and the common cold? Those studies used 2000 mg.

And another one, using 1000 mg a day, found that it removed lead from the body. That sounds like a significant benefit.

StuJones-gnte

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

uberleet

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

BuntxD

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

MacMacPherson

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).

ArachnidSoul

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.

wakjob

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.

heartdragon

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.

janetatum

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.

NebulaShadow_

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

DogLover

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.

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