Читать книгу American Diabetes Association Guide to Herbs and Nutritional Supplements - Laura Shane-McWhorter - Страница 6
ОглавлениеI would like to thank my family, friends, and administrative personnel, who have provided much encouragement, support, and counsel during my work on this book. Specifically, I would like to thank my husband, Jerry, as well as my children, Chris, Sandy, Randy, and David, and my grandson, Cody. I would like to give a special thank-you to my friend Dick for his invaluable technical support.
This book would not be possible without the vision that Victor Van Beuren had about writing a consumer guide. I would also like to acknowledge Kate Ruder for her sage advice and expertise in writing consumer guides in the area of diabetes.
You want to live healthy and well with your diabetes. You try to visit your health care provider regularly, take your prescribed medications, eat a balanced diet, and exercise regularly. Yet, there is one aspect of your health that may not be addressed in your regular medical visits, but you may still have questions about—taking dietary supplements.
Today, more and more people use dietary supplements. It’s a multibillion-dollar-a-year industry. And studies show that people with diabetes are more likely to use supplements than people without diabetes. The National Health Interview Survey found that 22 percent of people with diabetes used some type of herbal therapy, while another study found that 31 percent used dietary supplements. Certain ethnic groups, such as Hispanics, Native Americans, Asians, and African Americans are also more likely to use dietary supplements.
If you’re one of the many people taking dietary supplements, you’re probably concerned about doing the right thing for your body. People with diabetes who use complementary and alternative medicines, such as supplements, tend to have healthy habits. One study found that they’re more likely to visit their primary care providers and get their flu shots. However, finding reliable information about the benefits and safety of these products is difficult. There are hundreds of dietary supplements—each purporting their own health benefits. You’ve probably browsed the vitamin aisle at the pharmacy or a health food store. Maybe you felt overwhelmed so you didn’t purchase anything, or you just grabbed a supplement marketed for people with diabetes. In either case, you probably had unanswered questions about the safety and efficacy of these products.
HOW TO USE THIS BOOK
So, what’s a discerning consumer to do? First, read this book. It’s intended to give you enough information about dietary supplements to have an educated discussion with your health care provider. You should always consult your health care provider when making any change to your medication regimen, and taking a dietary supplement is no exception.
This section, Part I, discusses what dietary supplements are, why you should exercise caution when taking supplements, and how to talk to your health care provider. It also describes how dietary supplements are regulated and how to shop wisely for these products.
Part II summarizes 40 dietary supplements commonly used to treat diabetes and its complications. This is not a comprehensive directory of all the dietary supplements used to treat diabetes—just a snapshot of the most well-known products. The supplements are listed in alphabetical order so that you can easily look up a product in which you’re interested or considering taking. Each summary includes details on the supplement’s origin, general information about how the product is thought to work, potential side effects and drug interactions, and relevant scientific studies.
Part III summarizes the information from Part II into a quick-reference table, making it easier to locate and read a brief summary of a particular supplement. While this table makes it convenient to identify a supplement quickly, it is recommended that you also read the full entry for any supplement in which you are interested.
TYPES OF DIETARY SUPPLEMENTS
Dietary supplements include everything from vitamins and minerals to herbs such as cinnamon and St. John’s wort. Hundreds of plant species have been used to treat diabetes throughout the ages. Indeed, the widely prescribed drug metformin belongs to a class of drugs that is related to the plant French lilac, or goat’s rue. Dietary supplements also come in a number of forms including tablets, capsules, powders, softgels, gelcaps, and liquids. And they are sold from a number of retailers including pharmacies, grocery stores, vitamin and health food stores, websites, and mail-order catalogs.
The main types of dietary supplements this book will cover include:
• Botanicals (derived from plants and possibly including herbs)
• Vitamins
• Minerals
• Fatty Acids
• Other Dietary Supplements
REASONS FOR CAUTION: SIDE EFFECTS AND DRUG INTERACTIONS
Dietary supplements may seem safe or mild because they’re natural. Many think that something natural couldn’t hurt them. Yet, serious side effects and drug interactions can occur when taking dietary supplements. For example, supplements such as aloe vera, fenugreek, and vanadium may cause excessive bleeding during surgery or interact with anesthetics. Other supplements may interfere with prescription medications. For instance, ginseng may be used to treat diabetes, but may interfere with the drug warfarin’s ability to prevent blood clotting. St. John’s wort, which people often take for depression, can interact with antidepressants, as well as many other prescription medications. In Part II, you’ll find more examples of side effects and drug interactions for individual supplements.
Your health care provider is the best resource for assessing the risks and benefits of taking a dietary supplement. He or she should know the potential side effects of supplements—and the risk for interactions with your other medications.
TALKING TO YOUR HEALTH CARE PROVIDER
Despite the risks, people generally don’t tell their health care providers that they take dietary supplements. A recent analysis found that 69% of patients who use prescription medications and dietary supplements do not talk about supplements with their health care providers. Certain ethnic groups, such as Hispanics, are less likely than others to tell their health care providers that they take supplements.
Patients may not consider these products “drugs,” or they may just forget to mention them during their doctor’s visits. Patients may also think their health care providers will disapprove of their choices. Not disclosing supplement use can present dangerous circumstances. For example, a patient may experience a side effect of a dietary supplement that the provider may then attribute to another medication.
Your pharmacist, doctor, or diabetes educator is the most reliable source for information about the safety and efficacy of dietary supplements. Pharmacists are the most accessible of all health care providers. While retailers in health food stores may seem knowledgeable, they probably don’t have the medical background or familiarity with your personal health to recommend products. The same is true for retailers on the Internet.
Following are some tips for talking with your doctor, pharmacist or diabetes educator:·
• Always tell your doctor about any supplements you’re taking, including multivitamins. List them as medications in your written records.
• Tell your doctor why you are taking that supplement.
• Don’t wait for your doctor to ask you about your supplement use. Many health care providers forget to ask about these products.
• Conversely, tell your doctor if you intend to stop or have already stopped taking a supplement.
• If you’re planning to take a new supplement, ask whether it has any side effects or interactions with other medications or supplements, or whether it may interact with another one of your medical conditions.
• Ask how the supplement might affect your health—including your blood glucose, blood pressure, cholesterol, or other medical conditions.
• Your doctor might recommend that you take one product at a time to evaluate how your body reacts. He or she may recommend that you monitor your blood glucose more closely when you start taking a new supplement.
• Make a list of the supplements you take before your appointment, or put the bottles in a bag and bring them with you. Also list in what dose, how often, and for how long you’ve been taking the supplement.
• Never stop taking your traditional diabetes medications without telling your health care provider.
• Continue to be forthright about the supplements you’re taking, even if your doctor has discouraged their use.
WHERE TO RESEARCH YOUR DIETARY SUPPLEMENTS ONLINE
If your doctor is unsure about possible side effects or drug interactions, you may want to research information to share with your doctor. The following websites are good places to start:
http://www.nlm.nih.gov/medlineplus/dietarysupplements.html#cat42
U.S. National Library of Medicine and National Institutes of Health, “Medline Plus: Dietary Supplements”
http://ods.od.nih.gov/factsheets/DietarySupplements.asp
National Institutes of Health Office of Dietary Supplements, “Dietary Supplements: Background Information”
http://nccam. nih. gov/ health/bottle
National Institutes of Health National Center for Complementary and Alternative Medicine, “Get the Facts: What’s in the Bottle? An Introduction to Dietary Supplements”
http://dietarysupplements.nlm.nih.gov/dietary
National Institutes of Health and U.S. National Library of Medicine Dietary Supplements Labels Database
REGULATION OF DIETARY SUPPLEMENTS
If you believe the U.S. Food and Drug Administration (FDA) approves dietary supplements, you are not alone. A 2002 poll showed that 58 percent of Americans believe that government agencies, such as the FDA, must approve herbal products before they can be sold to the public.
However, dietary supplements do not need FDA approval. Under legislation passed in 1994, called the Dietary Supplement Health and Education Act, supplements are considered foods, not drugs. Therefore, supplements do not have to undergo the same stringent approval process as drugs. Supplement manufacturers do not have to prove the safety, quality, or efficacy of their products before they arrive on shelves.
This reclassification has resulted in serious consequences. Sometimes contaminants or substitutes have been found in products. For instance, some diabetes products have been contaminated with lead, and other products touted as being “herbal” have contained prescription drugs.
How do these dangerous lapses occur? Because of the Dietary Supplement Health and Education Act, the FDA does not routinely analyze the contents of dietary supplements for their safety or efficacy. The manufacturer—not the government—is responsible for ensuring that the label is accurate and the ingredients are safe. Indeed, the FDA would have to prove that a supplement were unsafe in order to be allowed to remove it from the market.
LABELS AND CONTENTS
Although limited in its oversight, the FDA requires manufacturers of dietary supplements to follow certain guidelines when describing their products. For example, manufacturers of dietary supplements can make claims regarding the ability to maintain “structure and function” of the body, but cannot make claims regarding diagnosis, treatment, cure, or prevention of disease. The label must include the following statement: “This statement has not been evaluated by the Food and Drug Administration (FDA). This product is not intended to diagnose, treat, cure, or prevent any disease.” The manufacturer must notify the FDA within 30 days after a product is on the market if it bears such a label.
The FDA also bans implied, as well as expressed, disease treatment claims. In other words, claims made by a manufacturer that a buyer could misconstrue as indicating treatment or prevention of a disease are no longer allowed. In new regulations, a product may make health maintenance claims but not disease treatment claims (i.e., “maintains a healthy prostate” is allowed, but “treats benign prostatic hyperplasia” is not).
The FDA requires that supplement labels (see Figure 1) contain certain information, so look for these details when you shop for products.
• Name of the product
• Name and address of the manufacturer
• Complete list of ingredients, including a “Supplement Facts” panel, which identifies each ingredient in the product. If an ingredient is not listed on the “Supplement Facts” panel, it must be listed in the “other ingredients” statement below the panel.
• Directions for use
• Net quantity of the contents
FIGURE 1.
Sample Supplement Label
Despite these requirements, the labels of dietary supplements can be confusing and misleading. A study of more than 800 bottles of popular herbs sold in retail stores found that over half the products were inconsistent in reporting benchmark ingredients and recommended daily doses.
In addition, the actual contents of products may not be reflected in the packaging. A study of the popular botanical Echinacea, which is taken to relieve cold symptoms, found numerous discrepancies in the ingredients listed on products. Ten percent of “Echinacea” products contained no measurable Echinacea.
INDEPENDENT TESTING
ORGANIZATIONS
Luckily, a handful of independent organizations accuracy Luckily, a handful of independent organizations test the accuracy of the labels and contents of dietary supplements. They offer “seals of approval” that you may want to look for when shopping for supplements. However, keep in mind that these organizations do not test the efficacy of products.
U.S. Pharmacopeia (USP) Dietary Supplement Verification Program
The “USP-verified mark” on the label indicates the label product ingredients are accurate and that the product is pure, will dissolve properly, and has been manufactured using good manufacturing practices. The USP website also lists manufacturers that have undergone the evaluation process (www.usp.org).
NSF International
Formerly known as National Sanitation Foundation, NSF International verifies the accuracy of supplement labels and contents, checks for purity and contaminants, and audits the manufacturing process for good manufacturing practice compliance (www.nsf.org).
Consumer Lab
Consumer Lab tests supplements for the accuracy and purity of their ingredients (www.consumerlab.com).
The Consumers Union
The Consumers Union also tests certain reports findings in its publication, Consumer Reports www.consumerreports.com ; subscription required for some content).
The Natural Products Association
The Natural Products Association has launched a good manufacturing practice program (www.naturalproductsassoc.org).
SIZING UP THE PRODUCT AND MANUFACTURER
It’s best to use a dietary supplement that comes in a pure, standardized form. You can check the purity of a product by consulting the United States Pharmacopoeia (www.usp.org). You’ll also want to purchase products from large, nationally known companies. These companies are more likely to incorporate good manufacturing practices and stringent quality assurance.
If you have questions about a product, you may want to contact the manufacturer directly. The manufacturer should be able to answer the following questions:
• Has your product been evaluated in scientific studies that have been published in reputable medical journals? If so, are you willing to share these studies? Or, is most of the product information the result of testimonials by people with diabetes who have used the product?
• Can you explain how the product works? Do you have scientific studies that verify the mechanism of action?
• Does your company conduct a chemical analysis of the active and inactive ingredients to verify that the product contains what it says on the label?
• Does the product break down and dissolve appropriately in the stomach?
• Does your company specify specific storage or stability instructions, such as what temperature to store the product, whether light may affect the product, or whether it should be stored in a dark place? Do you list an expiration date for the shelf life of the product?
• Do you specify any side effects or possible interactions with other supplements or prescription drugs or disease states? Do you specify which patients should not use the product?
Even when armed with these questions and the best intentions, consumers may find it difficult to evaluate the safety and efficacy of products. Unfortunately, many of the scientific studies done on dietary supplements are unreliable. For example, studies may include only small numbers of patients. Some scientists never examine the actual contents of the studied products, so their results could be unintentionally skewed. For these reasons and others, the Natural Standard, an independent group of scientists who evaluate complementary and alternative medicines, has given most dietary supplements for diabetes a grade “B” or lower in terms of efficacy.
In Part II, you’ll find summaries of the best studies done on each individual supplement, as well as tips for evaluating the results. Keep in mind that some supplements have been more rigorously studied than others. It’s always best to talk with you health care provider about questions regarding the efficacy and safety of product, rather than trying to troubleshoot on your own.
HOW MUCH SHOULD YOU TAKE?
The National Academy of Sciences provides information reference daily intake (RDI) for many—but not all—vitamins and minerals. Most other dietary supplements, such as herbs, do not have recommended daily allowances. In fact, the appropriate doses of many dietary supplements are unknown. In Part II, you’ll find the available information on recommended doses for individual supplements.
Some dietary supplements are sold in “packs” to people with diabetes. These packs may contain a handful of supplements marketed for improving diabetes. These products can make it difficult for patients to evaluate their responses to individual supplements. Instead of taking supplements together as they are packaged, take only one supplement at a time to determine your body’s response when beginning new products. However, if you wish to take a “pack,” then make sure you obtain it from a reputable manufacturer and discuss this with your doctor. Then the doctor may assess the impact on the control of your diabetes or other medical conditions.
TIPS FROM THE FDA
Because manufacturers may use deceptive marketing tactics to promote their products, the FDA has put together a number of helpful resources for evaluating products.
“How to Spot Health Fraud”
Web article available at www.fda.gov
This website warns against a single product that the manufacturers claim benefits a variety of unrelated diseases (i.e., difficulties ranging from menstrual problems to asthma to rheumatic complaints). It also suggests buyers be wary of evidence of benefit based on personal testimonials, claims of unusually rapid benefit, or use of meaningless phrases that may sound scientifically impressive to lay consumers but do not actually describe a beneficial medicinal effect.
“Tips for the Savvy Supplement User”
Web article available at www.cfsan.fda.gov
Includes basic points to consider, such as talking with a health care provider before using a supplement and broaching the issue that some supplements may interact with prescription or over-the-counter medicines or have untoward effects during surgery. It also provides information on how to report adverse effects of dietary supplements. Furthermore, it provides tips on searching the Internet for information on supplements, including pointers on how to find out who operates a product website, the purpose of the site, the information sources and references, and whether the information is current.
“Tips for Older Dietary Supplement Users”
Web article available at www.cfsan.fda.gov
Discusses potential risks, such as the danger of substitution of dietary supplements for conventional medications or consuming more than recommended amounts. It also advocates discussion of dietary supplement use with a health care provider. It provides a checklist of important considerations such as issues with side effects, drug interactions, and possible discontinuation before scheduled surgery.
Contacting the FDA to report an issue
The FDA encourages patients and their health care providers to report any adverse effects related to dietary supplements through the FDA’s MedWatch online at www.fda.gov/safety/medwatch/default.htm or by calling 1-800-FDA-1088.
A NOTE ON CLINICAL STUDIES
There is a lot of perplexing information regarding products. When deciding whether or not to use a particular supplement, it is important for you as a consumer to understand information about different clinical studies, especially since the media may not always accurately represent the information from studies. Many times, the reporting on clinical studies leaves out important details or fails to mention how the study was conducted. This means that results from poorly designed studies are sometimes given more credence than they deserve, and results from well-run trials may be cherry-picked for the most sensational tidbits.
In this book, each supplement or herb has information about different studies regarding the type of scientific evaluations that have been published. Thus, to better understand the significance of these studies, knowing some important definitions and terms is essential.
What are the characteristics of a good clinical study?
A clinical study is simply an experiment where a researcher tests whether a specific product (such as a medication, herb, or supplement) or a type of intervention (such as a special diet or a certain type of exercise) will work to achieve a certain endpoint. An “endpoint” is simply an event or outcome that has been defined and that a clinical study will evaluate. For instance, an endpoint may be losing a certain amount of weight, or improving a certain disease, symptom, or a laboratory value such as blood glucose or cholesterol.
Not all studies are equal, however, and it is important to understand the characteristics of a good clinical study. The most important aspect of a clinical study is how it is set up—this is called the “study design.” The study design is critical in determining whether the published results are reliable enough to help you decide whether a product is worth taking. Some of the characteristics of a good study include the following:
• It is “randomized, double-blind, and placebo-controlled”
• It includes a large number of patients
• It has well-defined events or endpoints
• It has been evaluated mathematically by appropriate statistical analysis
What do all of these terms mean? The following is an explanation of important terms related to clinical studies.
Randomization : This method assigns an individual or patient to a particular study group or intervention based on chance. This decreases the possibility of some sort of “bias” or result that favors a particular treatment.
Double blind : This means that the medication, supplement, or intervention being used in the study is hidden from both the patient and the researcher. In other words, neither the patient nor the researcher knows what the patient is taking no one knows whether the patient is taking the medication, or supplement, or a “dummy pill”) and both the researcher and the patient are “blind” to what is being used. The purpose of double-blind” design is to decrease the possibility of “bias,” since knowing what treatment is being used may influence either party.
Placebo : This is an inactive or “dummy pill” or treatment that looks and tastes and smells like the real product. The purpose of a placebo group is to compare the effectiveness of the active treatment or real medication, supplement, or herb against something that has no treatment value (the placebo).
Endpoint: An endpoint is an event that has been pre-defined and is being measured in the clinical study. For instance, examples of an “endpoint” would be a change in A1C (to see whether or not there is diabetes improvement), a change in pain scores (to determine improvement in pain due to neuropathy), or a change in laboratory values such as LDL cholesterol the “bad” type of cholesterol).
An excellent “endpoint” is one that measures an effect on mortality (death) or on morbidity (a disease outcome such as heart attack or stroke; or on adverse occurrence such as blindness, nerve damage or amputations, or kidney failure). A good study that shows decreases in mortality and morbidity has usually been conducted for a long period of time (for years) and has sufficiently large number of patients to demonstrate a benefit.
Open-label: In an open-label study, both the researcher and the patient know what is being taken. This type of study design introduces “bias,” possibly because of the power of suggestion. Hence, an “open-label” study is not optimal.
Run-in: A run-in is a phase or period where no treatment is being given, often at the beginning of a study. This is sometimes done to provide some sort of baseline observation or to try to eliminate persons who may not cooperate. For instance, a participant does not show up for important pre-study meetings or treatments, they probably will not comply with the treatments being studied (such as sticking to a diet).
Washout: This is the period of time needed for a drug or herb or other treatment to be eliminated from the body. Some times a “run-in” may be called a “washout” to allow enough time for the drug or herb to be cleared out from the body. An adequate “washout” becomes important when a participant is being changed to a different treatment during the study.
Cross-over: In a cross-over study, patients are given a certain medication, supplement, or herb for a period of time, and then the researchers might change them (“cross-over”) to a different medication or supplement. A well-run cross-over study will also include a washout, since this allows time for the first treatment to be cleared from the body. If patients are “crossed- over” directly (without a “washout”), then the first medication or supplement may still be in the body, and the results may be falsely influenced by the treatment that is still in the body.
“Statistically significant” or “significant results”: These are mathematically analyzed results that are meaningful. For instance, a supplement may decrease blood glucose, but the results may not be statistically significant. Thus, even though the product has shown some benefit, the results are not strong enough or “significant” enough to justify taking the product. The opposite is also true—although sometimes the results are statistically significant, they are not enough to get a patient to his or her desired goals. For instance, a product may decrease fasting glucose “significantly” from 250 to 200 mg/dl, but the results are not at the desired goal of 70–130 mg/dl.
Participants: When determining the merit of a study or trial, it is also important to consider the participants. This information is almost never reported in major media coverage of trials, but can usually be found in the original published reports or with a little digging on the Internet. Factors to consider include:
• Who were the patients that participated? Were they healthy or did they actually have the disease that was being studied? A study focused on a blood glucose treatment but filled with non-diabetes participants would be less useful than the same study using people with diabetes.
• What were the characteristics of the patients at the start of the clinical trial? The patients in each group should have similar characteristics (for instance, age, health status, gender, or ethnicity) at the beginning of a well-run clinical trial. Differences in characteristics at the start could potentially affect the results, making the findings potentially less trustworthy.
• How many patients dropped out? If there is a difference between the study groups due to dropouts, then perhaps there could be a problem. For instance, if many people dropped out of the treatment group but the results are very favorable in that group, then the results may be suspicious because the sample size is smaller and people who responded negatively may not be represented in the final findings.
While there are many more terms, methods, and definitions associated with clinical studies, this list should cover most of what is discussed in the following text. Most important is that you remain vigilant as a consumer of medications and supplements. When you learn the results of a study, you should also learn how the study was conducted before making a decision. Search out literature on clinical trials and studies, and discuss studies with your doctor or pharmacist.
