Six Facts about Vitamin C

By January 2, 2018 Health, Nutrition
Fruit high in Vitamin C

Vitamin C is the aspirin of the dietary supplement industry, but just like the seemingly benign pain-killer, there are some important health considerations if you take this synthetic nutrient.


Vitamin C products are the most successful business venture in the multi-billion-dollar dietary supplement industry.

What most people know as “vitamin C” is actually industrially produced synthetic ascorbic acid —made by drug companies. This chemical form of vitamin C is widely used as both a nutritional supplement and as a preservative in the food, pharmaceutical and animal feed sectors. Much of the synthetic vitamin C in the world is sold to health-conscious consumers.

Synthetic supplements have lower bioavailability than real foods, which means you can’t absorb them nearly as well. Studies have shown that vitamin C from food is absorbed 35 percent better and excreted more slowly than synthetic vitamin C. In addition, the body attempts to eliminate synthetic vitamin C, so in some circumstances taking higher doses may actually cause excess loss.

Conversely, real vitamin C as found in real food is accompanied by a complex of many other naturally occurring phytonutrients. As such, the body’s vitamin C requirements are best met from foods rich in this nutrient.

Natural vitamin C is required for growth and repair of tissues in all parts of your body. It plays an important role in the production of collagen and certain neurotransmitters, and is valuable in healing and protein metabolism. A powerful antioxidant, it impacts immune function, and its presence in food can influence various conditions such as cancer, cardiovascular disease, high blood pressure, asthma, osteoarthritis, macular degeneration and cataracts, and others.

Nature provides plenty of real vitamin C in foods. Broccoli, Brussels sprouts, kale, acerola and other foods are particularly rich sources not only of vitamin C but thousands of other phytonutrients associated with vitamin C. You can also find large amounts of vitamin C in animal sources, especially the adrenal and thymus glands, brain, bone marrow, pancreas, liver and kidney (even the eyes though few people eat these). While most people don’t eat organ meats, many unfortunately also avoid the most vitamin C-rich portions of plant foods: the white pulp of peppers and citrus (including the skins).

Nutritional need for vitamin C varies with age, sex and state of health for all individuals, with higher levels required by smokers and others with special requirements. The new daily value (DV) for vitamin C is 90 mg for adults and children age 4 and older.

Because this nutrient generates so much money throughout the industry, the negative potential effects of improper vitamin C intake are not usually brought to light. Here are six of them:

1. Synthetic vitamin C is ineffective. From the common cold and cancer, to heart disease and overall mortality, scientific studies continue to show synthetic vitamin C supplements have little to no benefits. Furthermore, evidence remains mixed regarding the purported effect of synthetic vitamin C on overall health, sports performance, and recovery from muscle damage.

2. Most vitamin C is fake — and it’s made from sugar. Almost all vitamin C supplements on the marketplace are synthetic. Since glucose and vitamin C have similar chemical structures, it’s easy and cheap to produce fake vitamin C from sugar, typically using corn. A look at the label is all that’s needed to tell whether vitamin C is naturally sourced: Since even the foods richest in vitamin C don’t contain very high concentrations, doses above 300 mg in a supplement almost always indicate a synthetic source.

3. Vitamin C absorption is impaired by carbohydrates. In the intestines, vitamin C absorption competes with glucose for absorption. Ironically, many vitamin C products and food products with added vitamin C also contain added sugar. So consuming junk food could result in lower absorption rates for vitamin C.

4. High doses may produce serious side effects. A variety of side effects are attributed to vitamin C doses of 500-1,000 mg. Popular doses can produce harmful free radicals when they react with iron in the body or other dietary supplements. In addition, higher doses of synthetic vitamin C themselves can become pro-oxidants. Published studies demonstrate that 1000 mg/day of synthetic vitamin C can interfere with cell signaling in working muscles. This blocks the body’s ability to adapt to training, reducing endurance performance gains. Other side effects may include heartburn, diarrhea, nausea, abdominal bloating, risk of forming kidney stones and inhibition of vitamin B12 function. In addition, synthetic vitamin C can adversely react with many over-the-counter and prescription medications.

5. Less is more. Up to 200 mg of natural vitamin C may be contained in a meal of fresh fruits and vegetables. In this natural presentation and dosage, almost all of the vitamin can be absorbed. However, our bodies can utilize at most 500 mg of a vitamin C supplement leading to reductions of over 50 percent in the absorption rate of higher doses. Studies show levels above this amount can have unhealthy effects. Even Linus Pauling, a proponent of very high dose synthetic vitamin C, said in 1974 that “the first 250 mg is more important than any later 250 mg. The first 250 mg leads you up to the level where the blood is saturated.”

6. Real food works best. Studies have long shown that people whose diets were rich in real foods naturally high in vitamin C — typically around 200 mg per day — have a lower risk of heart disease, certain cancers and other diseases. Vitamin C in foods have not been shown to cause any of the problems of synthetic supplement use. In addition, food sources of vitamin C have not been shown to cause adverse reactions to medications.

The portrayal of vitamin C as a safe and effective supplement is a broad generalization promoted by an industry that is making billions off high-dose synthetic products. Although we all need adequate amounts of vitamin C for good health, this nutrient is best obtained as nature intended — from real, natural foods.


  • pat says:

    Wow what bunch of nonsense .

  • Yoni says:

    How about citing your references? What studies are you Refering to? How can anyone check your claims otherwise?

  • Daniel says:

    Vitamin C supplementation is for those depending on carbohydrates as an energy source. Vitamin C & sugar use the same pathways. In the presence of sugar, vitamin C is pushed aside. Cutting the Carbs is the best move one can take. And all that talk about scurvy in sailors, has to do with the fact that their main source of nutrition was biscuits and other dried food and a ration of rum (sugar again). So no wonder that introduction of lemons cured them. Same problem with two separate expedition to the north pole. The group that mainly relied on carbs, got sick and died out there (everyone of them). The group that relied on meats and lots of fat (hunted wild animals) did very well and lived to talk about it.

  • I adcribe to orthomolecular Wisdom: “synthetic” vit C is all L-ascorbic acid, the same molécule that all mammals make in their livers (with the exception of primates, guinipigs and bats). A 70kg Goat would make upwards of 20 grams à day, so I do Min 22 NET grams of C per day of DIY Lipo C….. For55months now and there immune cleansing of 55 years of collected pathogens continues.. But always shows öogical progression. The brain biofilms and cns Viruses are tough to clean but cleansed they can be. This natural vit c Stuff is nice, but goats livers don’t make rosehips.

  • Bill Dahl says:

    Does this apply to pharmaceutical grade Ascorbic Acid powder, as well? Thanks.

  • Jj says:

    What do you say to the people who use vitamin c to fight cancer? They take it intravenously..

  • Catherine Langford says:

    I’d love to know your thoughts on lypospheric vitamin C.

    • Steve Muller says:

      I have started taking Liposomal Vit C as an adjunct to chemo and radiation for my Astrocytoma (brain cancer). It is in liquid form, manufactured from sunflower lecithin, distilled water, and natural flavors- no sweetners. A much cheaper alternative than IV infusion.
      Apparently there are no studies that show that it actually kills cancer, but it would seem it would boost the immune system.
      I really enjoy and benefit the many podcasts that Phil has done and would love to hear your thoughts and info on brain cancer.
      Dr. Maffetone, what would you do if you were diagnosed with brain cancer??

  • andres says:

    Dear Phil,
    I agree with you that vitC is a business and a very juicy one. I read once from the website of an alopatic dr that pretty much all vitC supplements in North America are manufactured by one single company in Connecticut, Cincinnati, or similar sound. Then all supplement companies buy them bulk slap their logo labels and voi la!
    About the rest you wrote,, well, I do not agree with much. I’ll explain why.
    1. Despite they do not advertise it openly to avoid potential ridicule and criticism from peers, there are allophatic doctors that have successfully treated cancer patients with extreme doses of IV-supplied vitC. In effect, you can find in internet similar ‘protocols’ for cancer treatment from patients in remision themselves! I doubt that the vitC is natural given the colossal concentrations of the order of 100K mg. I do not have cancer, but every time I have a cold or a flu I immediately increase my daily consumption to 10K mg every few hours. The results are phenomenal, as I feel the inflamation (congestion and ache) decreases rapidly.
    2. Yes, most vitC is synthetic, but in this case I would be more cautious in labeling fake. I understand why you use that term, but because for me has worked well, then synthetic does not translate in fake. You’re correct though in that synthVitC is usually made of GMO-based corn (so much for those wishful thinking imagining a Florida orange juice).
    3. I always laugh when someone thinks that the food was created for us. No, animals are the ones who have adapted to be able to survive from that natural food. All citrics, berries, tomatoes, broccoli, etc, have high content of natural vitC, yet many of them are carbohydrates themselves, many including simple ones. If it was true the impairing of vitC absroption, humans would have not included them as food of choice.
    4. Go to point 1.
    5. Go to point 1.
    6. Rather trivial. Always prefer natural vitC to sythentic vitC.

    • Marisa De More says:

      Well said, Andres, thanks for your input. If Vitamin C was totally blocked by sugar ingested at the same time, then we’d all have been dead long ago since ALL fruit and veg which contain Vit C also contain carbohydrates in greater or lesser degrees. I’m learning to beware of any article failing to cite scientific research to back up their claims.

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