Health Studies 301 Complementary and Alternative Therapies

Study Guide: Unit 10

Herbalism

A herbal infusion being made of crushed buds from the flower St. John’s wort (Hypericum Perforatum) by soaking it in spirits. Ingwik, 2009, Public Domain.

Herbalism is the use of plant products to cure and prevent disease. Herbal remedies have been used for centuries for this purpose. Many of the pharmaceutical products we use today are of plant origin. Although some herbs have been scientifically proven to have medicinal properties, others show little or no therapeutic benefits, and some herbs are toxic.

Learning Objectives

Upon completion of Unit 10, you should be able to

• define herbalism, and discuss the nature of herbalism.
• identify commonly used herbs, describe the therapeutic benefits attributed to them, and state whether research evidence supports the claimed benefits.
• determine the effectiveness of treatment with herbal products and potential hazards.
• identify trends and issues related to herbal therapy.

Learning Activities

Study Questions

As you complete the activities for Unit 10, keep the following questions in mind. You may want to use the Personal Learning Space wiki on the course home page, and answer these questions as a way of keeping notes to focus your learning.

1. What are some potential benefits that herbalism offers in the treatment of disease?
2. What are some of the potential dangers posed by the use of medicinal herbs?
3. What steps are the herbal industry and Canada’s government taking to make sure herbals are safe, pure, and of high quality?

Unit 10 Discussion Forum

When you have completed the other activities for this unit, answer at least one of the questions in the Unit 10 Discussion Forum and respond to at least one post by a fellow learner.

The more questions you answer, the better prepared you will be for the final exam!

Read

In addition to the notes provided here, read in the textbook:

Micozzi, M. (2019). Fundamentals of Complementary, Alternative, and Integrative Medicine. Page 374 to page 380 (to heading “Inflammation”) and page 394 (from heading “General Considerations”) to page 397.

Herbal Medicine

The opinions expressed by the authors of this chapter are very positive towards herbalism.

Throughout history, cultures have used plants and herbs for medicinal purposes, both for treatment and for prevention. With the advent of modern medicine, the North American medical community has moved away from the use of plants for medicine. However, practitioners in Europe and Asia have continued to use and study herbs, and practitioners in many nations where modern medicine is not readily available still rely on plants as their main source of medicine.

Many people in North America have become disillusioned with the limited ability of modern medicine to cure everything, and this had led many to turn to CAM, including herbal remedies, hoping to solve health problems and improve well-being. Recent years have seen a dramatic growth in the range of herbal products sold in drugstores.

Some people consider plant remedies better than synthetic drugs because they are “natural.” But because something is natural does not mean it is harmless. After all, many highly toxic substances are found in plants, for example tobacco, cocaine, and heroin. Likewise, many of the naturally occurring common metal salts are highly toxic (lead, cadmium, mercury, arsenic).

Plants are a complex mixture of thousands of substances. While some of these can be toxic, many of the substances in plants are vital for nutrition: vitamins, minerals, starch, and so forth. And some substances have medical value. Indeed, many of today’s common drugs were originally discovered because of the use of particular plants in herbal medicine. Subsequent research identified the active chemical, which was then reborn as a drug. Examples include aspirin, curare, digitalis, ephedrine, morphine, and quinine. This story is far from over. Scientists are searching the world for plants that can serve as sources of new drugs.

It is important to bear in mind that if a substance has medicinal value, then it makes no difference whether it is delivered to the body packaged up as a herb or purified and given as a drug. The body cannot distinguish between a pure compound of natural or synthetic origin. The authors of the textbook chapter do not hold this view, as clearly shown by comments on page 378 (see third paragraph of left-hand column; and the fifth point in Box 26-3).

Much of the controversy over the medicinal use of herbs arises from the weak regulation of herbal remedies in North America as well as the lack of scientifically credible research carried out on the many plants believed to have medicinal properties. In addition, herbal preparations have a wide variation in the concentration of active ingredients.

Practice of Herbal Medicine

Herbalism is practised by every human society. Traditionally, healers in a community have prescribed herbal treatments. Knowledge of plant remedies is passed from generation to generation through an apprentice system.

Herbal medicine has been integrated into other forms of medicine. In the previous unit, we saw that naturopaths often use herbal treatments. This is also the case with other systems, including traditional Chinese medicine, medicine used by North American Indigenous peoples (Unit 15), and Ayurveda (traditional medicine practised in India). We shall see in the next unit that health food stores sell many herbal products as part of their broad promotion of dietary supplements. But at the same time, herbal medicine has survived as a distinct form of CAM. Its philosophy has much in common with naturopathy. This is shown by the first, second, and fifth points of Box 26.1 on page 375 of the textbook.

For many years, there was no unifying body in Canada representing practitioners of herbal medicine. However, the Canadian Council of Herbalist Associations was formed in 2005. Herbalists carry out their own training program, but herbalism still lacks formal recognition by any licensing body. We see, therefore, that herbal medicine has a much weaker organizational structure than some other forms of CAM.

Herbal medicine comes in two major forms. Traditionally, herbal treatments were prepared on an individual basis, often from several different herbs. In contrast, the modern trend is that herbal products have been transformed into a large commercial enterprise where standardized products are sold directly to the public. These herbal products are sold in health food stores and the pharmacy section of most supermarkets. They are found alongside dietary supplements. Millions of people are, in effect, acting as their own herbalist and self-medicating.

The following reading shows the very weak state of the supporting evidence regarding the value of individualized herbal medicine. The paper is also very informative for two other reasons: it shows how a systematic review is carried out, and it shows how experts critically evaluate the known facts in a particular area.

Learning Activity

Read

Guo, R., Canter, P.H., & Ernst, E. (2007). A systematic review of randomised clinical trials of individualized herbal medicine in any indication. Postgraduate Medical Journal, 83, 633–637.

Herbal Products

There are a great number of herbal products. This section takes a close look at 15 herbs that are commonly used in North America. One reason for the selection is that a survey on the use of supplements in the United States indicated that they are the ones most often used (Timbo, Ross, McCarthy, & Lin, 2006). In addition, some herbs were chosen because ads have appeared for them in Canadian newspapers.

It is important to appreciate that a number of different products may share the same name, yet have altogether different chemical composition. There are several reasons for this:

• There may be two or more species of plants that have the same name. Typically, they are closely related; nevertheless, there may be major differences in their content of substances with health-related effects.
• Different parts of the plant may be used for preparation of the herbal products (e.g., the flower or the root).
• Processing methods can differ widely. The plant (or a part of it) may be simply crushed, or substances may be extracted using alcohol or water. Herbal products may then be sold as bulk herbs, teas, fluid extracts, and tablets or capsules.
• Manufacturers of herbal products may simply substitute cheaper products for more costly ones.

What this means in practice is as follows: Suppose the results of a study are published reporting that herb X is effective for a particular condition. A person who buys a herbal product with a label indicating that it contains herb X may well receive little or none of the active ingredient that generated the positive results in the research study. This problem is far less likely to occur with nutritional products (such as vitamins or minerals) or with drugs.

The information stated in this section is based mainly on summaries from two websites: Mayo Clinic and NIH–[U.S.] National Center for Complementary and Integrative Health (NCCIH).

• Aloe vera is the source of two products that are completely different in their chemical composition and their therapeutic properties. Aloe vera gel is a jelly-like substance obtained from the inner portion of aloe leaves. It has been used topically for thousands of years to treat wounds, skin infections, burns, and numerous other dermatologic conditions. There is promising evidence that it may improve wound healing and skin inflammation.

  Aloe juice (or latex), on the other hand, is used as a laxative. It is certainly effective. However it cannot be recommended as it has various side effects. It has been reported to induce tumours of the large intestine in rats.

• Black cohosh has been used to treat symptoms associated with menopause, including hot flashes, night sweats, and vaginal dryness. Study results are mixed as to its effectiveness.

  Some people taking black cohosh have experienced mild side effects, including stomach discomfort, headache, or rash. There has been some alarm that the herb may be a cause of liver disease, but this is far from clear.

• Chamomile is often used for sleeplessness, anxiety, and gastrointestinal conditions, such as upset stomach, gas, and diarrhea. However, there is little evidence to support its use for any condition. The herb is generally believed to be safe, but there are some reports of serious allergic reactions.

• Cranberry juice is often recommended in the prevention of urinary tract infections. The juice appears to inhibit the ability of the microorganisms to adhere to the epithelial cells that line the urinary tract, thus rendering the environment less suitable for the growth of the bacteria. Some clinical studies have yielded supporting evidence, but, overall, the evidence is not strong (Jepson, Williams, & Craig, 2012). Excessive amounts may cause gastrointestinal upset or diarrhea.

  Cranberry juice has also gained popularity as a treatment for urinary tract infections. Here again, the supporting evidence for the value of this treatment is weak.

• Echinacea (coneflower) has become popular for treating or preventing colds, flu, and other infections. There have been several randomized trials, but results have not been consistent: some studies have found echinacea to be helpful, while other studies have not seen any benefit. An overview of the evidence was carried out in 2014, with a focus on the common cold (Karsch-Völk, Barrett, & Linde, 2015). Echinacea may lead to a small reduction in the incidence of the common cold but with no reduction in symptoms when used as a treatment.

  A likely factor that helps explain these inconsistencies is that echinacea products can contain different concentrations of the herb, and the extracts used can come from the flowers, stems, or roots of three different echinacea plant species. On current evidence, some echinacea supplements may shorten the duration of a cold by about half a day and may slightly reduce symptom severity. Based on this rather weak evidence, echinacea cannot be recommended for the treatment or prevention of either colds or flu. More research is needed before firm conclusions can be made.

  Echinacea apparently contains substances that stimulate the immune system non-specifically rather than against particular organisms. This is the explanation for any benefit seen against infections.

  Echinacea generally doesn’t cause problems for most people, but some people taking the herb have reported side effects such as headache and nausea. Echinacea also has the potential to interact with other medications.

• Evening primrose oil is used for eczema (a skin condition) and for other conditions involving inflammation, such as rheumatoid arthritis. It is also used for conditions affecting women’s health, such as breast pain associated with the menstrual cycle, menopausal symptoms, and premenstrual syndrome (PMS).

  The herb appears to have modest benefits for eczema, and it may be useful for rheumatoid arthritis and breast pain. However, study results are mixed, and most studies have been small and not well designed. Evening primrose oil does not appear to affect menopausal symptoms. The herb contains gamma-linolenic acid (GLA), an omega-6 essential fatty acid. This appears to be the active ingredient.

  These findings from clinical studies are typical of what is seen with many herbs: strong claims being made that the herb has important benefits, some supporting evidence from some studies (usually small ones that were poorly designed), but a failure to confirm the results in other studies (usually larger ones that were well designed).

  This herbal product is well tolerated by most people. Mild side effects include gastrointestinal upset and headache.

• Garlic: some studies have suggested that garlic can reduce high blood pressure, lower blood cholesterol, and possibly slow the development of atherosclerosis. However, these effects, while useful, appear to be quite weak. Some evidence suggests that garlic may lower the risk of certain types of cancer.

  Garlic poses very little risk of harm for most adults. Side effects include breath and body odour, heartburn, upset stomach, and allergic reactions. These problems are more common with raw garlic. Garlic can impede blood clotting in a manner similar to aspirin.

• Ginger: The rhizomes (underground stems) of the ginger plant are used as a spice and also as a medicine. Ginger can be used fresh, dried and powdered, or as a juice or oil. It is an ingredient in many digestive, anti-nausea, and cold and flu supplements. It is also used for nausea associated with pregnancy, motion, chemotherapy, or following surgery.

  Studies suggest that the short-term use of ginger can safely relieve pregnancy-related nausea and vomiting. However, the evidence is much less clear for nausea caused by motion, chemotherapy, or surgery. Ginger has also been used for rheumatoid arthritis, osteoarthritis, and joint and muscle pain. Again, there is little hard evidence that ginger is effective for these conditions.

  Ginger taken in small doses is quite safe. However, it may lead to gas, bloating, heartburn, and nausea, especially in the powdered form.

• Ginkgo biloba is another herb with a history of medicinal use dating back thousands of years. It has gained much popularity based on claims that it improves the memory and may be helpful in the treatment or prevention of Alzheimer’s disease and other types of dementia. This was tested in a randomized trial on more than 3000 older adults in the United States (age 72 and older). After six years of follow-up, there was no evidence that subjects given ginkgo biloba gained any benefit with regard to the rate of cognitive decline or preventing the onset of dementia (Snitz, O’Meara, & Carlson, 2009).

  These results stand in contrast to some earlier trials, which did generate positive findings. However, those trials were much smaller and had much shorter periods of follow-up. Taken as a whole, these findings provide little solid evidence that ginkgo biloba is of any real value for either improving the memory in older adults or for helping to prevent dementia.

  Some evidence suggests that the herb may improve memory and speed of mental processing in healthy young to middle-aged people. Could it be that ginkgo is effective for brain function in young and middle-aged people but not in the elderly? Clearly, we will not have the answer to this question until the results emerge from large, well-conducted randomized trials.

  Ginkgo biloba is also used to treat a variety of conditions, including asthma, bronchitis, fatigue, and tinnitus (ringing in the ears). However, there is little supporting evidence from well-conducted trials.

  Like the large majority of herbs, use of ginkgo has been linked to side effects although these seem quite mild. They may include headache, nausea, gastrointestinal upset, diarrhea, dizziness, and allergic skin reactions. Some reports suggest that the herb can increase bleeding risk.

• Ginseng is another herb whose popularity dates back more than 2000 years. It is among the most popular of herbs and is used for a variety of reasons. Purported benefits include delaying the aging process, anti-stress capabilities, enhanced sexual performance (in men), improved cardiovascular function, improved immune function, improved glycemic control in type 2 diabetes, and protection against some cancers. The most popular use is for increasing a sense of well-being and stamina, and improving mental and physical performance.

  Several different plants are called ginseng. Most research has been on ginseng from Asia, also known Asian ginseng, Chinese ginseng, and Korean ginseng. American ginseng is also a true ginseng (Panax). However, Siberian ginseng (Eleutherococcus) is not a true ginseng.

  There are many conflicting studies regarding the medicinal benefits of ginseng. One problem is that much of the supporting evidence rests on its use in traditional Asian medicine over many centuries combined with much anecdotal evidence. But as has been stressed several times in this course, such evidence is notoriously unreliable. Another major problem is the species of ginseng studied. It seems likely that many products called “ginseng” are made from cheap substitutes. Processing methods may also be an important source of variation between products.

  These problems explain why an analysis of 25 ginseng products purchased from health food stores in Los Angeles revealed an enormous range in concentration of active ingredients (Harkey, Henderson, Gershwin, Stern, & Hackman, 2001). Some products had a concentration of standardized preparations with ingredients that was dozens of times higher than with other products. Research using standardized known content of the active ingredient (ginsenoside) needs to be carried out in placebo-controlled, double-blind controlled studies.

  Some research evidence indicates that Asian ginseng may lower blood glucose in people with type 2 diabetes and that it has beneficial effects on immune function. Other evidence suggests that it may improve memory, attention, and mood. Some beneficial effects have been reported when ginseng was used in combination with ginkgo. Beyond that, there is very little solid evidence that ginseng lives up to the many lofty claims made for it.

  Short-term use of ginseng (less than three months) appears to be safe for most people, but some side effects have been reported with long-term use. The most common side effect is trouble sleeping (insomnia). Other problems may include headaches and diarrhea. Asian ginseng can cause allergic reactions.

• Goldenseal is used for several disorders, particularly infections such as colds and other respiratory tract infections. However, there is little solid supporting evidence for its use with any health problem. It is considered safe for short-term use in adults, but there is little available information regarding long-term use or the safety of high dosages. Some evidence suggests that the herb may cause changes in the way the body metabolizes drugs, and it could possibly alter the effects of many drugs.
• Kava is used for anxiety, insomnia, and menopausal symptoms. Some studies suggest that kava may be beneficial for the management of anxiety. However, there is evidence that it causes liver damage, including hepatitis and liver failure (which can cause death). In addition, it may interact with several drugs.
• Milk thistle is claimed to have protective effects on the liver and improve its function. It is given as a treatment for liver cirrhosis, chronic hepatitis (liver inflammation), and gallbladder disorders. There is some supporting evidence of efficacy, but this is far from conclusive. Few adverse effects have been seen in patients other than minor gastrointestinal disturbances and mild allergic reactions.
• Saw palmetto is recommended mainly for treating an enlarged prostate gland (benign prostatic hypertrophy [BPH]). This herb provides yet another example in which earlier, smaller studies gave positive results while later, larger studies were negative. Taking an overall average, the fairest statement is that the herb may provide, at most, some modest benefit. It has a good safety record.
• Sea buckthorn is being promoted as a source of omega-7 fatty acids that, supposedly, have a wonderful effect on the skin. However, there is extremely little information on this herbal product.
• Soy can be eaten in the form of soybeans and as part of the diet. Extracts are available that contain isoflavones or soy protein or both. Soy is commonly used for lowering cholesterol, and for this purpose it has a modest but beneficial effect. It is also used for the treatment of menopausal symptoms (primarily hot flashes). The value of these products has been investigated in several dozen randomized studies. A detailed review of this evidence concluded that supplements “were associated with modest reductions in the frequency of hot flashes and vaginal dryness but no significant reduction in night sweats. However, because of general suboptimal quality and the heterogeneous nature of the current evidence, further rigorous studies are needed to determine the association of plant-based and natural therapies with menopausal health” (Franco et al., 2016). Soy is safe as part of the diet, but the safety of long-term use of soy isoflavones taken as a supplement is not known.

• St. John’s wort has been used for centuries to treat mental disorders and nerve pain. In recent years there has been a huge interest in this herb as a treatment for mild to moderate depression. The evidence for effectiveness is mixed: several trials reported that it is as effective as some antidepressant drugs, while other studies have given negative results. No definite conclusion is therefore possible.

  The major side effect from use of St. John’s wort is that it interferes with a variety of medications.

An Overview of Herbal Medicine

It should be clear by now that many herbal products fail to live up to the claims made for them. This is a recurring story throughout this course. The reasons are the same as for other forms of CAM.

Many of the claims in support of herbal products are based on their use by healers as a part of traditional medicine, often with a history going back to ancient times. At the same time, many people have faith in herbal medicine because it is in sync with their philosophical viewpoint of the relationship between humans and nature. In support of the efficacy of herbal products are testimonials in which users state with complete confidence that the herb really does work.

However, folklore and testimonials leave open the possibility that many of the supposed cures are, in reality, observations that reveal nothing of any medical importance. There are often more plausible explanations for the claimed benefit from a herbal treatment, including 1) the practitioner of herbalism may be cherry-picking his/her success stories; 2) the illness was following its natural course (for example, with many infections, the body naturally recovers even in the absence of treatment); 3) spontaneous remission (conditions such as migraine and arthritis often go through periods where symptoms become very mild); 4) misdiagnosis; or 5) the placebo effect. Unit 2 presents a more detailed overview of the challenges in evaluating therapies.

Even where a carefully conducted clinical trial demonstrates that a herb does achieve the claimed benefit, we must still be very cautious before we assume that every bottle claiming to contain that herb will duplicate the benefit. That is because of the wide variation in the content of active ingredients from one product to the next. There are multiple reasons for this, as discussed earlier. A survey of 81 randomized controlled trials reported that the investigators determined the actual contents of the herbal preparation in only 15% of the trials (Wolsko, Solondz, Phillips, Schachter, & Eisenberg, 2005). This means that, in most cases, we really do not know what was actually being tested.

But it would be a serious mistake to paint all herbal products with the same brush. As mentioned earlier, numerous drugs used by conventional medicine have their origins in herbal medicine. No doubt there are many more waiting to be discovered. Indeed, a major research effort is under way to discover potential new drugs by studying chemicals isolated from plants, often from rainforests.

Several of the herbs discussed above have harmful side effects. Quite a number of herbs may interact with drugs. This can create real potential for harm, especially as many users do not inform their physician. In one survey in the United States, more than half of subjects who used herbs did not disclose this information to a conventional medical professional (Gardiner et al., 2007).

A notorious example of the potential dangers of herbal products is the case of ephedra (ma huang) (Bent, Tiedt, Odden, & Shlipak, 2003; Woolf, Watson, Smolinske, & Litovitz, 2005). This ancient Chinese herb contains ephedrine and pseudo-ephedrine, which are also found in asthma drugs and decongestants. Ephedra became popular during the 1990s to bring about weight loss. However, it was discovered that it can cause stroke, cardiac arrhythmia, and death. It almost certainly caused dozens of deaths and hundreds of cases of adverse reactions. As a result it was banned in the United States, Canada, and other countries.

Quite apart from the herb itself there are other potential hazards with herbal products. There have been many cases reported of herbal products that contain toxic heavy metals or added pharmacologic drugs. These extra substances are not identified on the label. This problem is examined further in the next unit, when we look at dietary supplements in general.

In the United States, about 2000 cases are reported each year where a herb has caused significant harm (Woolf et al., 2005). However, this figure includes only cases that are reported and where a herbal product is the only substance involved. There is little doubt that the true figure is many times higher. In many instances, the adverse effect may be due to the herb itself, but often there are extra substances present in the herbal product.

The people who are especially vulnerable to harm from herbal products are pregnant and nursing women. There is also an increased potential toxicity for infants, elderly, and those who are sick or malnourished.

It must be stressed that it can be very difficult to identify whether a particular herb is causing health problems. This is best demonstrated by the history of tobacco. Millions of men took up smoking starting around 1920. The habit causes a huge increase in the risk of lung cancer, as well as of several other major diseases. Yet it was not until around 1950 that medical scientists first noticed the problem and another 10 years after that before this was confirmed. It is likely to be far more difficult to detect an adverse side effect associated with using a herb, especially if the person’s physician is unaware that the herb is being used.

Canadian regulations that cover herbal products are discussed in the following unit.

Conclusion

A great many people use herbal products based on claims that they have the ability to improve health and help cure a variety of diseases. Much of the supporting evidence is based on traditional use of the herb dating back centuries, anecdotal evidence, and small clinical trials. Quite often, the herbal product fails to generate the desired results when tested in a large, carefully designed, randomized study. In addition, many herbal products are linked to adverse side effects.

But on the positive side, some herbs do indeed have value for improving health. Also, many plant products contain bioactive substances that have great potential to serve as sources of new drugs. However, much research needs to be conducted to understand the potential benefit of herbs and plants in improving human health.

Learning Activity

Self-test Quiz

Do the self-test quiz for Unit 10 as many times as you wish to check your recall of the unit’s main points. You will get a slightly different version of the quiz each time you try it. (This quiz does not count toward your final grade).

If you have trouble understanding the material, please contact your Academic Expert.

References