Posted by Dr. Anthony G. Payne
Recently I was asked (on Facebook) how much vitamin C I take, which begs the question: What is the optimal intake of vitamin C for most people?
This is from my Facebook reply:
In order to answer this, I need to jump in the Way Back machine:
Back when I was studying for my doctorate in nutritional medicine (mid 1980s) there was a spirited debate going on among researchers, doctors, nutritionists and others concerning how much vitamin C a human being needed and could handle. Because I came into the realm of human nutrition with a background in biological anthropology (BS, MA) – training I actually undertook purposely not only because I dearly love bio anthro but also because I consider the insights and tools it provides foundational to understanding evolutionary players in human health & disease (and by virtue of this helpful in setting the stage for medical or paramedical studies) – I looked at the quantities of vitamin C produced in mammals that have retained the capacity to do so (Humans and many other primates such as gorillas lost this ability long ago). What emerged is that most nonhuman primates synthesis 25 mg of vitamin C per kilogram of body weight. If one applies this figure to an average (70 kg) human, this comes out to 1750 mg total daily.
There are, of course, mitigating factors. We know 70-90% of the vitamin C people get from food and supplemental forms are absorbed. However, too much taken all at one time reduces absorption! (If you take 1 gram of vitamin C only 50% will be absorbed). However, people with certain chronic diseases appear to absorb and use more even at high intakes.
With all this said, conventional thinking indicates that any amount of vitamin C over 180 mg daily will exceed what the tissues throughout the body can handle (i.e., saturation is reached) and the excess will be processed by the kidneys and dumped in the urine.
After years of dealing with people with chronic diseases, I have come to believe they should be taking 1750 mg to as much as 4 grams of vitamin C in divided doses daily (as their bodies can handle so much more C and apparently need this to support innate disease fighting processes). For healthy young to middle-aged folks, 180 mgs in divided doses or in slow or time release form should be adequate to meet the body’s demands for vitamin C.
Now to your specific question: How much C do I take daily? 500 mg Metabolic C in divided doses (100 mg every 3 hours from morning until evening). I take more than the 180 mg I mentioned above because I am getting older (62) and believe additional C is a good preventative measure as chronic disease processes are often subtlety at work (in even the healthiest of us) with increasing age.
Some folks argue for mega dosing – to “bowel tolerance” – whether healthy or not – which I think is a bit reckless (Most do it to “prevent various diseases especially cancer”). Vitamin C works as an antioxidant at low doses but can promote the production of ROS (reactive oxygen species) molecules when serum levels are very high. These ROS molecules can damage cell membranes and cause other biophysiological problems. As I recall, Nobel prize winning chemist Dr. Linus Pauling ingested mega doses of C daily for years on end. He lived to be 93 but died of prostate cancer. Some have argued his disease was triggered by his mega dosing on C. Dr. Pauling contended his high dose C kept his cancer at bay for years. One thing is certain: Years before Pauling’s’ demise, controlled studies were carried out to see if high dose C impacted various forms of cancer in animals and humans. The bottom line: It was ineffective. Advocates of high dose use of C rejected these studies for various reasons, while most of the scientific community accepted them as valid. The debate goes on to this day in various quarters
A parting word of advice: Do not “super mega dose” to prevent or treat disease. Those individuals reading this who have cancer and are considering using vitamin C to fight it should peruse https://www.cancer.gov/about-cancer/treatment/cam/patient/vitamin-c-pdq
And so it goes……as do I…….