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CAM & Life Style >  Natural Remedies - Caveats of Dietary Supplements

Last update: 03/31/2014

Comment or Question? | In the News

So when we talk about “synthetic” versus “natural” substances,
we’re referring the difference between how they are made—
not any difference between their molecules. The molecules are identical.

chemheritage.org

Natural Supplements as treatments for cancer?

Formula for inappropriate commercial success:
 
1) Put forth an untested theory about how your product will "cure you without any side effect." 
2) Provide testimonials to "prove" it works. 
3) Make up a conspiracy theory to explain why doctors don't endorse it.

Confusion about Prevention versus Treatment

That certain life style practice can reduce the risk of getting a disease does not mean it will also be effective as a treatment for that disease.  For example, we can effectively reduce the risk of lung cancer if we quit smoking, but cessation of smoking is unlikely to reverse an existing lung cancer. 

When it comes to the potential of lifestyle changes to influence a disease, the type of disease matters. 

... Improving ones diet and exercising can help to manage heart disease and reduce the risk of stroke - because these diseases are mediated by dietary factors - such as the type of fats we eat.   

But cancer is another matter. 

... We wish it was otherwise, but food-level doses* of herbs, or changes to diet are not likely to change the mutations that drive the behavior of cancer cells.  It is just not plausible.

What about organic foods - can these help?   Choosing organ foods is a good idea to reduce risk and to maintain the health of our planet.  It will reduce our risk by reducing exposure to pesticides.  But in cell cultures, cancer cells will thrive as well as normal cells in an organic medium. 

Adopting a healthful lifestyle will help indirectly, or might reduce the risk of a second cancer - but it should not be considered an alternative to treatment when treatment is needed - and there is no evidence from a well-controlled clinical trial to support the claim that dietary supplements or changing ones diet can effectively treat cancers.

* Cancer drugs are derived from natural sources - vincristine, etoposide, and Taxol are a few examples.  For natural compounds to influence the behavior of cancer cells requires study to identify the dose that achieves therapeutic levels in the blood.  At such doses there will also be side effects.
 

Consider the dose  

It's common to see reports about the activity for a natural compound in cell culture experiments.  But we should ask: how much of the compound would I need to take to approximate the dose in the cell culture?  Is it safe to take at that dose?  Can the dose (the blood level) be achieved by taking the compound orally?

These experiments are sometimes done on cancer cells that may be similar but are very different than the cancer cells in our body.  Cancer cells can be challenging to keep alive outside the body in cell cultures - so the effects of compound on these cells is only a starting point in research.

Information about the effective doses for specific conditions, and also the bioavailability of natural products is rarely provided by promotions of herbs and vitamins as cancer therapy.

Natural does not mean not toxic

We may associate "natural" with safety. But many plants and animals produce poisons in order to avoid being eaten by animals and insects, or to kill off competing plants. Consider how many common house plants are toxic to our pets.

Example of natural compounds that have been developed to treat cancer: Taxol (Yew tree),  Etoposide (may apple), Vincristine (periwinkle) ...

Supplements that are considered to be safe may be toxic at high doses.

When you give vitamins or herbs at very high doses, the compounds can have drug-like effects, which may have risks that are not known or understood.

Rule of thumb:   When a compound is given at a dose that is sufficient to have treatment effect on cancer it will almost certainly also have side effects.

Supplements may interfere with treatment or with how a drug is metabolized. Therefore, we believe it's prudent to avoid taking any supplements the same day you are receiving treatment medications.

Clinical evidence 

Theories are easy to come by.  But when experiments show that a natural compound can help to treat a disease it would be actively studied in a prospective (pre-specified) clinical trial and the results would be published.  

Efficacy trials require a control group to objectively compare the results with a placebo or another treatment. 

The study of cancer compounds begins with dose-finding studies - to identify the dose that is needed to have a treatment effect - and if that dose is safe.  If there is potential for a natural product as a cancer therapy it will be first studies in this way - monitoring blood levels and patient safety.

Testimonials can be persuasive.  But such accounts should not be confused with clinical evidence.  See for the many limitations of testimonials - the  many reasons they should be regarded with suspicion.

Mixed and unexpected effects

When supplements are taken at doses that achieve high levels in the blood there can be unexpected and adverse effects and interactions - particularly if used during treatment.

Mouse studies (the basis for some herbal promotions)

Unfortunately, mouse studies do not reliably predict effects in the body.

Bill writes: "A mouse is not a man (or woman). The behavior of a drug in a mouse need not be the same as in a human. Meaning, the drug may distribute differently, proportional differences per blood and organs and tumor, in mouse vs. man. Drug exposures (the amount of drug and for how long) in different body parts , including tumor, may be quite different ... " Full text

Petri dish experiments (the basis for some herbal promotions)

(Other terms: in-vitro / cell culture experiments)

Such experiments do not predict effects in the complex environment of the human body.

Often, natural products are promoted based on cell culture activity that fail to take into account how the compound is affected by digestion, and other metabolic processes - its bioavailability.

"To understand the translation of cell culture studies to the whole person, we must first consider all of the systems operating in the human body that are not present when human cells are grown in plastic Petri dishes. .... (DEAM) 

Drug: Distribution | Excretion  | Absorption  | Metabolism

While measuring bioavailability, scientists also do sophisticated calculations to determine the peak blood concentrations, when they occur, and how quickly the body clears the substance.

Source:  Why Petri dish studies don't always translate into benefit for patients
 

In vitro studies (the basis for some herbal promotions)

This refers to experiments on cells that are done outside the body in test tubes or cell cultures.

Cancer cells are changed significantly when removed from the host environment - the cells may die spontaneously when removed from the body. Thus, evidence of activity of a herb or vitamin in a cell culture is only a starting point for additional experiments and studies.

For Open-source background: wikipedia.org

Impurities in supplements

Natural products and supplements are not regulated by an independent agency, and the risk or ingesting inferior or contaminated herbal products is significant and well documented.

Boosting immunity with herbs and diet?

Supplements may only improve our immune system if a deficiency in the vitamin is the underlying cause.

The issue with cancer is not immune strength but a failure to recognize and act on the abnormal cells - in part because cancer cells are considered to be part of oneself - cells that belong.  

Strategies that boost immunity by introducing antigen-like substances (pokeweed, etc.) are more likely to rev up the system, like sirens and whistles without a plan. This course of action is unproductive and perhaps may contribute to immune depletion in the long run.   See for more detail:  PAL

In summary, adopting a healthful life style is recommended to improve one's general health and fitness. However, there is no evidence that taking dietary supplements and herbs will be effective as treatments for cancer. 

 Prepared by PAL

 


In the News

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Curr Drug Metab. 2011 Dec;12(10):989-96.

Toxicities by herbal medicines with emphasis to traditional Chinese medicine. http://www.ncbi.nlm.nih.gov/pubmed/21892916
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Dietary Supplements in Cancer Care http://bit.ly/dqs2oY
Webcam presentation by registered dietician, Susan Dixon, Cancer Nutrition specialist

 


BC Cancer Agency:
Guidance on unconventional therapies

.bccancer.bc.cam

For unconventional therapies that are taken by mouth or put into the body: Do not take any of these during chemotherapy, hormonal therapy or immunotherapy. Do not take any them in conjunction with any other medications without checking with the BCCA Patient Education Pharmacist about possible drug interactions.

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Tell your oncologist about supplements and alternative therapies
you may be using.
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When you use herbs, do so only for short periods, and in moderation.
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Check to see if the therapy has been proven to be harmful.
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Do not use alternative therapies to replace prescribed treatment.
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Purchase from established and reputable suppliers.

Some herbs and supplements have been found to contain toxins, such as heavy metals. Ask about what you are buying: Are the Latin names of herbs, the quantities and uses listed?
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Do not give children under age two herbal teas.
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Be cautious in using very concentrated oils and teas.
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How Quackery Harms Cancer Patients quackwatch.com

There is a saying: "The highwayman demands 'your money OR your life,' but quacks demand 'your money AND your life!'" This statement is particularly true when it comes to dubious cancer treatment. The harm done by quackery may be categorized as economic, direct, indirect, psychological and societal.


Dietary Supplements in Patients With Cancer:
Risks and Key Concepts

Laura Boehnke Michaud; Julie Phillips Karpinski; Kellie L. Jones; Janet Espirito
Am J Health-Syst Pharm. 2007;64(4):369-381. ©2007 American Society of Health-System Pharmacists

Purpose: The risks and key concepts regarding the use of dietary supplements in patients with cancer are described.

Summary: There are six common characteristics of dietary supplements that must be addressed when used by patients with cancer.

Clinicians must establish if the supplement:
is an antioxidant,
is an anticoagulant or procoagulant,
has immunosuppressive or
immunomodulating properties,
has hormonal properties,
has known safety issues,
and has known or theoretical drug interactions.

These six characteristics of the dietary supplements commonly used by patients with cancer are reviewed to aid in the analysis of the scientific data and communication of the results with the patient or family members.

A framework upon which clinicians can adequately help patients make informed decisions regarding the use of complimentary and alternative medicine and dietary supplements is also described.

When evaluating the appropriateness of a supplement for use by a patient with cancer, clinicians must conduct a safety review (evaluate the six characteristics). If the supplement is considered safe, an efficacy review must be conducted, after which the clinicians can recommend the supplement’s use, accept the patient’s decision to use the supplement if no or inconclusive evidence exists, or discourage use if there is conclusive evidence supporting inefficacy.

Available resources for locating information regarding dietary supplements are also discussed.

Conclusion: Counseling patients with cancer about dietary supplements requires a systematic thought process that considers the available theories and data, as well as the patients’ views about the agents.

I: http://www.medscape.com/viewarticle/553692_print
II: http://www.medscape.com/viewarticle/553699_print


Related Resources

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Discussing CAM with your doctor - scienceblogs.com:80/terrasig 

"For many centuries doctors used leeches and lancets to relieve patients of their blood. They KNEW bloodletting worked. Everybody said it did. When you had a fever and the doctor bled you, you got better. Everyone knew of a friend or relative who had been at death’s door until bloodletting cured him. Doctors could recount thousands of successful cases."

Why We Need Science: “I saw it with my own eyes” Is Not Enough 

 

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Final Rule Promotes Safe Use of Dietary Supplements FDA.gov

Under the final rule, manufacturers are required to evaluate the identity, purity, quality, strength, and composition of dietary supplements.

 
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professional medical advice or to replace your relationship with a physician.
For all medical concerns,  you should always consult your doctor. 
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