The dose is the poison

Why is it that when we hear about how beneficial a particular nutrient or compound is in keeping us healthy or fighting off disease that we think that if a little is helpful, that more is better? Or that we think that if it’s for sale as a supplement, particularly a vitamin and mineral preparation, it must be safe.

Well you might want to think again.

Paracelsus, a 16th century physician who is frequently referred to as the father of toxicology, summed it all up pretty well. He stated, “What is there that is not poison? All things are poison and nothing is without poison. Solely the dose determines that a thing is not a poison,”

Yes, the dose is the poison.

When it comes to vitamins and minerals in food, while moderation is the key, if you’re healthy, you usually don’t really need to worry about the amounts naturally present in food. But there are the exceptions- for example, those people who suffer from carotenemia – orange skin that can result from excessive carrot consumption.

Supplements, though, are another matter. Recent reports about the potential for harm are certainly food for thought.

Here are just a few examples of the possible effects of too much of a good thing. But keep in mind that there are individual variations. While one person may suffer adverse effects of overdoing a nutrient, others may be fine.

Vitamin D and kidney function

A 54-year-old Canadian man, after returning from a sunbathing vacation in Southeast Asia, showed increased levels of creatinine, which can go hand in hand with abnormal kidney functioning. After seeing a kidney specialist and undergoing testing, the culprit was thought to be the high doses of vitamin D he had been taking at the advice of a naturopath. The daily dose of 8000 to 12, 000 IU was thought to lead to very high levels of calcium in the blood, resulting in significant kidney damage.

The recommended tolerable upper intake level (UL) for vitamin D is set at 4,000 IU per day. The UL of nutrients is set by the government at a level that poses no adverse health effects for the average person.

Here’s something else to consider, though. High doses of vitamin D are being researched as part of a treatment regimen for those with colon cancer. But make no mistake about this: when it’s being used in this way, it’s key to consider it as a medication, not a nutritional supplement.

Biotin and thyroid testing

Biotin, one of the family of B vitamins, is marketed by supplement companies as an elixir for healthy hair and nails. While the research on the effects is pretty thin, the potential impact of these high dose supplements is now emerging. As it’s a water-soluble vitamin, many often mistakenly think the excess is simply excreted in your urine. While the daily recommendation of 30 mcg per day can be achieved through diet alone, multivitamin preparations do contain the nutrient in amounts ranging from 30-300 mcg biotin. Hair and nail supplements can range as high as 5,000 to 10,000 mcgs.

But here’s the problem. High doses of biotin can lead to false results in a number of different medical tests including thyroid functioning. In a recent study of more than 1900 subjects, 149 patients (7.7%) reported taking biotin supplements. Of these, 29.5% did not know what dose they were taking, 8.1% reported taking 10,000 mcgs, 14.8% reported 5,000mcgs, 18.1% reported 1,000 mcg and 47% reported taking less than 1000 mcgs.

Besides these biotin supplements being linked to falsely elevated thyroid tests, they may also lead to inaccurate results such as in tests used to see if a person has had a heart attack.




Coming up next: other examples of excess and the unacceptable lack of information on Canadian supplement labels

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Categories: Nutrition News, Research Roundup

Author:Rosie Schwartz

Rosie Schwartz is a Toronto-based consulting dietitian and writer.

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2 Comments on “The dose is the poison”

  1. Susanne
    April 11, 2019 at 10:54 am #

    Hi Rosie,
    Always enjoy your blog. To be fair to the naturopath, my understanding from other reports was that the man had taken more than what the naturopath had recommended. But it is vital that the public get the message that too much of a good thing is often problematic!

    • April 11, 2019 at 12:36 pm #

      Susanne, thanks for the feedback! I have seen other reports which state that he was advised to take 8 drops but that those 8 drops may not have been dosed exactly right. Capsules or tablets offer more exact measurements but in any case, that amount was too high for him!

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