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Dietary Supplements – Caveat Emptor (Buyer Beware)

By Morwenna Given

Dietary supplements are hugely popular, with billions of dollars spent in the hope of staving off or treating chronic diseases, including cancer. University of Guelph researchers recently published a study, finding that herbal supplement labels might not match the contents of the bottles. The researchers looked for the DNA of 100 plant species amongst their DNA library, in 44 products from 12 manufacturers, reporting, “Product substitution occurred in 30/44 of the products tested and only 2/12 companies had products without any substitution, contamination or fillers. Some of the contaminants we found pose serious health risks to consumers.”

Such checks are not routine for Health Canada. Indeed, until recently in Europe and Canada, the industry was largely unregulated. The EU initially brought in tighter controls, and Canada followed with its system of Natural Product Numbers or NPNs. In brief, manufacturers have to show that the contents are not harmful, and broadly will do what the manufacturer says they will do.

Even if supplements are accurately labelled, how much are you getting for your money? No products were publicly identified by either Guelph or Health Canada, but I decided to review the first product that came up on a web search. This was Resveratrol by Jamieson, with “Red Wine Extract with Grape Seed“ in finer print.

Resveratrol is a much touted compound found in the natural state in plants such as Pueria lobata (Kudzu) and fruits, and is widely available as a supplement. Resveratrol is a phytoalexin, a compound that plants produce to defend themselves against injury or infection. First identified in 1940, in the last 20 years the compound has been revisited and shown to be cardioprotective and to have anti-cancer properties, based on extensive laboratory research and more limited research in humans..

A pharmacy chain priced the 30 capsule “Resveratrol” container at $24.99. Content is broken down by weight/component. Along with phosphatidylcholine from soy and various non-medicinal ingredients, Vitis vinifera is listed as 50 mg per capsule, of which 10% (5 mg) is t-resveratrol. In nature, compounds can have two isomeric forms, cis and trans, but humans can only utilise trans, hence t-resveratrol. For an average female of approximately 60 kg, to achieve the generally accepted dosage of 5-10 mg per kg per person you need 60 capsules per day to achieve a physiological response. This would be is a monthly cost of about $1500 plus tax.

If you are interested in cancer prevention with compounds such as Resveratrol then you might consult a professional specialising in this area such as a Medical Herbalist. Any compound with medicinal effects may interact with other supplements and medications. Metabolic pathways are central to development of cancer, and no one chemical compound has been shown in isolation to achieve an inhibition of this disease. For example, Turmeric (Curcuma longa) has been shown to affect more of these pathways, in more cancer types than any other substance. Unfortunately there is no “silver bullet.”

Morwenna Given BA MA (Oxon) BSc OHA BHG AHG RH is a British University trained Medical Herbalist practising in Toronto specialising in endocrine issues including cancer and pre- cancerous conditions. She undertook further specialist training in the USA and UK with oncologists, haematologists and Herbal Medicine specialists in cancer. She can be reached via her website


Also in the WINTER 2014 Issue of An Ounce

Published: February 4th, 2014


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