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Vitamins & Minerals

Top Ten Nutrition Myths (Part 1)

Truth and Lies About Vitamin C, Kava Kava, St. John’s Wort, Beta Carotene, and more...

by Dr. Zoltan P. Rona, MD, M.Sc. RSS

It has often been falsely reported that Vitamin C causes kidney stones

It has often been falsely reported that Vitamin C causes kidney stones

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(Editor’s note: This month we bring you the first segment of Dr. Rona’s feature on Nutrition Myths, which covers the first two items on his Top Ten list. To see the complete Top Ten, click on the link at end of article.)

This list of nutritional medicine myths hasn’t changed much in nearly 40 years. I hear about one or more of them every day in my private practice. The people making the erroneous assertions tend to be very dogmatic in their views. The source of these misleading facts is most often practising medical doctors untrained in nutritional medicine, or those who are just plain out of date. These are the most widely known fake news items in natural medicine that diehard. Although there are others not listed here, what follows is my current top ten.

NUTRITION MYTH #1: Vitamin C Causes Kidney Stones

This is a classic because, if you ask anyone out there, they have definitely heard about it.  The truth is that vitamin C is generally well tolerated by most healthy individuals.  There is, however, a wide range of tolerance when megadoses are supplemented.  Large doses (500 mg. or more) can cause diarrhea but this appears to be the only significant side effect and only occurs if taken orally (as opposed to intravenously). Interestingly enough, the sicker a person is (i.e. respiratory tract infections, the ‘flu, etc), the more vitamin C they can tolerate without getting loose stools. Alternative health care practitioners often recommend taking high doses of vitamin C (to bowel tolerance level) when a patient is ill. So, some people can take 20,000 mg or more before diarrhea occurs. As one recovers from illness, the dose that causes diarrhea becomes lower.

It has often been falsely reported that vitamin C supplementation causes kidney stones in dosages above 6,000 mg daily.  There is no clear proof of this claim since numerous studies conclude the exact opposite – that vitamin C supplementation prevents kidney stones. There have been studies done on patients who receive as much as 100,000 mg of vitamin C intravenously, several times a week as a cancer suppressive therapy, with no report or evidence of a greater incidence of kidney stones.

It has long been taken as the gospel truth that women who take high doses of vitamin C during their pregnancy risk rebound scurvy in their infants if they suddenly discontinue vitamin C.  Although this is theoretically possible, no one has ever been able to prove it as a fact in any scientific study.

The kidney stone and scurvy myths are not the only common myths about vitamin C supplements. The source of much of this false news was one Dr. Victor Herbert, but he is no longer alive so someone else can come forward to debate me. Here’s a list of other lies, half-truths, and myths about vitamin C:

– causes DNA damage (leading to cancer)

– protects cancer cells from being destroyed by chemotherapy

– causes or exacerbates gastric ulcers and diabetes

– causes thrombosis (abnormal internal blood clotting)

– causes rashes, nausea or other gastric upset, abdominal cramps, headaches, and fatigue

– interferes with the metabolism of other nutrients (e.g. sodium and iron) causing either overload or depletion

– is only a vitamin (micronutrient); typical daily diets supply “enough” ascorbate

NUTRITION MYTH #2: Herbs, Vitamins, and Minerals Can Be Toxic

First of all, whole herbs are plants and NOT drugs. If you extract one ingredient from any herb and concentrate it and patent it, then yes it becomes a drug. Drug companies are famous for using herbs as a source for new drugs. For example, some companies have extracted THC from marijuana, then concentrated it and patented it as a drug. The fact that this extract doesn’t work as well as the whole plant is of no concern to drug companies. Adverse drug reactions are the fourth leading cause of death in North America. None of these fatal reactions involve commonly used herbs or other supplements.  Conventional medical doctors and their prescription drugs kill more patients in one day than any natural therapy ever did. 

This is not to say that herbs are free of side effects, just that there is no evidence that they come anywhere close to the danger posed by prescription and over-the-counter drugs. Poison control center statistics from the U.S. have shown a total of zero deaths in the past 30 years from any vitamin, mineral, herb, amino acid or nutritional supplement. The myth of nutritional supplement toxicity is therefore unwarranted, yet continues to die hard. Some herbal remedies like St. John’s Wort can interact with numerous drugs but, once again, reports of toxicity are nonexistent and exaggerated by big pharma and medical sources. As many have now stated, “Where are the dead bodies?”

A few years ago, there was much concern about the mildly relaxing herb known as kava kava. In fact, it was taken off the market in Canada due to concerns about liver toxicity. These reports were later shown to be unproven so kava was put back on the market and you can get it now from any health food store.

At one time, beta carotene supplements were accused of causing lung cancer. The study that made this ridiculous argument was later debunked because cigarette smokers were used as study subjects in order to make this erroneous conclusion. There have also been false reports of the absurd belief that folic acid can increase cancer risk. All these myths are completely without evidence.

I frequently recommend 10,000 IU of vitamin D to adults who have low blood levels, fail to get enough sun exposure, use sunscreen on a daily basis due to cancer fears, and who have been advised by doctors to stay out of the sun. Often, these patients will go back to their family doctors who quickly scare them about vitamin D causing liver toxicity, kidney stones, and other horrible side effects at doses over 1,000 IU daily. The patients then return to my office and we re-check the blood levels of vitamin D and, of course, they are still too low, below the acceptable reference range.

There is zero evidence that vitamin D or any fat-soluble vitamin is toxic at the 10,000 IU therapeutic dose. If one is on blood thinning medication and a long list of drugs, there are indeed drug-nutrient interactions, mostly evidenced by a depletion of nutrients by the drugs and not the other way around. For example, statin drugs used to lower cholesterol will deplete vitamin D and coenzyme Q10. For more information on this see my article in the March 2017 issue of Vitality (

Yet another piece of false news is that vitamin E causes high blood pressure. When subjected to scientific scrutiny, this turns out to be completely false. In fact, one study (Archives of Neurology 2000; 57:1503-1509) concluded that the reverse was true: taking vitamin E if you have high blood pressure reduces the risk of stroke. And if your blood pressure is normal, vitamin E has no effect on it or your risk of developing a stroke.

Editor’s note: To see the Reference List for this article, or the complete Top 10 Nutrition Myths article, view the extended version posted online at:



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About the Author

More Articles by Dr. Zoltan P. Rona, MD, M.Sc.

Dr. Zoltan P. Rona, MD, M.Sc.

Dr. Zoltan P. Rona practises Complementary Medicine in Toronto and is the medical editor of The Encyclopedia of Natural Healing. He has also published several Canadian best-selling books including Vitamin D, The Sunshine Vitamin. Visit his website at: For appointments, call (905) 764-8700; Office: 390 Steeles Ave. W. Unit 19, Thornhill, ON.