Dietary supplements such as herbs, amino acids, botanical extracts, vitamins, and minerals are increasingly popular, including among people with diabetes.

A recent Canadian study found that nearly one-third of people with diabetes used alternative remedies. The most popular were garlic, echinacea, glucosamine, chromium, ginkgo biloba, fish oil, cayenne, and St. John's wort--a list that includes two remedies that can be harmful for people with diabetes. Clearly, increased use has not been accompanied by increased knowledge of how to use supplements safely.

Natural Does Not Equal Safe

For some people, remedies derived from naturally growing plants just seem less scary than remedies created in the lab. This presumed safety is an illusion. Your body can't tell the difference between a chemical made by a growing plant and the same chemical synthesized by scientists.

In truth, prescription drugs are often safer than natural products, for several reasons:

• Any product that produces a medicinal effect could have side effects. The difference between drugs and supplements is that drugs have undergone intensive study, and most of their problems have been discovered and described. Supplements have not undergone the same scrutiny. So there's usually no way to know what side effects you might experience or which of your other drugs they might interact with.
• Lab-made drugs are purer. In addition to the active ingredient, herbal preparations contain dozens of other chemicals from the original plant, each of which can have biological effects of its own or cause allergic reactions. In contrast, drugs contain mostly active ingredient, with as few other ingredients as possible.
• Drugs contain a known amount of active ingredient. But the amount of active ingredient can vary greatly from one batch of supplement to another. One reason is that some companies have sloppy manufacturing procedures. Another is that the chemical makeup of a plant, including how much active ingredient it contains, varies depending on growing conditions such as rainfall and soil quality.
• Drugs must go through strict studies to test whether they work and are safe before the Food and Drug Administration considers them for approval. The rules are completely different for supplements. A manufacturer does not need to prove either that they work or are safe. In fact, the manufacturer doesn't even need to prove that the bottle contains what the label says it does (and many supplements don't contain what they claim to).

Interactions With Drugs

Some drags and herbs should not be taken together. The herb may increase the drug's effect or negate it. People with kidney or liver problems or other chronic illness are at extra high risk for problems.

Here are some interactions that can occur with widely used drugs.

• If you take a blood thinner such as aspirin or warfarin (Coumadin), increased bleeding can result if you also take alfalfa, chamomile, evening primrose oil, feverfew, garlic, ginger, ginkgo biloba, ginseng, meadow sweet poplar, or red clover.
• If you take a drug that causes sleepiness, certain herbs can increase the effect. Kava kava and valerian interact with benzodiazepines such as alprazolam (Xanax) and diazepam (Valium). Valerian also interacts with barbiturates such as pentobarbital (Nembutal) and secobarbital (Seconal). St. John's wort interacts with SSRI antidepressants such as fluoxetine (Prozac) and paroxetine (Paxil).
• If you take a diabetes pill, ginseng can further lower your blood sugar levels, possibly causing low blood sugar reactions.
• If you take an MAOI antidepressant such as phenelzine (Nardil) or tranylcypromine (Pamate), ginseng and St. John's wort may increase the action of these drugs.
• If you take a drug that makes you sun-sensitive, St. John's wort can make it worse.
• If you take certain drugs that suppress the immune system such as azathioprine (Imuran), prednisolone (various brands), or prednisone (Deltasone and other brands), echinacea can counteract their effects. St. John's wort can reduce the effectiveness of cyclosporine (Neoral, Sandimmune, SangCya).
• If you take the anti-HIV drug indinavir (Crixivan), St. John's wort may make it (and possibly other anti-HIV drugs) less effective.
• If you take the heart drug digoxin (Lanoxin) or a thiazide diuretic (a large class of drugs often used to treat high blood pressure), dried aloe latex by mouth (not the topical form used for minor burns), cascara sagrada, senna, and large amounts of real licorice can cause too-low potassium levels.

To avoid interactions, people on certain drugs should probably avoid herbs altogether. These include people taking drugs whose levels must be repeatedly measured so that doses can be kept within a narrow safe and effective range and those on warfarin.

Supplements You Should Never Take

With some herbs and supplements, any benefit is far outweighed by the dangers. The box on page 96 lists some supplements you should never take.

In addition, studies suggest that some supplements may present special dangers for people with diabetes:

• Glucosamine may boost blood sugar levels or worsen insulin resistance.
• Echinacea may bolster the immune system. So it's possible echinacea could make autoimmune diseases such as type 1 diabetes worse. (See "Echinacea For Colds?" on page 14 of the October 2000 Diabetes Forecast.)

Safe Supplement Use

There are many steps you can take to protect yourself.

• Always, always tell your doctors what herbs and supplements you use. If you are having surgery, it's vital to tell the surgeon and anesthesiologist what you are taking because some supplements can make you bleed more easily, cause your blood sugar levels to fall too low, or intensify the sedative effect of the anesthesia. Your pharmacist also needs to know so that he or she can catch possible drug interactions when you fill prescriptions.
• Look for herbs and supplements that carry the new United States Pharmacopeial Convention verification mark on their label. This mark means that the supplement contains the ingredients it claims while not containing more than a certain amount of pesticides and other contaminants and that the manufacturer made the supplement using good manufacturing practices.
• Look for other signs that a manufacturer might have some quality control standards, such as lot numbers and expiration dates.
• Buy from a store that turns over products quickly so that you're not getting old, deteriorating products.
• Don't believe everything you hear. Plenty of people would like to sell you useless products. Even friends and relatives may urge you to take something in the false belief that it might be helpful to you. Check out claims with your pharmacist and doctor and at reputable Web sites, such as those of the National Institutes of Health or universities.
• Be wary of products that promise quick cures or claim to treat multiple conditions.
• If you want a medical problem diagnosed, talk to a doctor, not the health-food store sales clerk, who not only has no medical training but also would like to make a sale.
• Before trying any supplement, discuss it with your doctor. Doing so is extra important if you are pregnant or breastfeeding, have a chronic disease, or are taking any drugs, including over-the-counter ones. Your pharmacist and dietitian are also good sources of information.
• Never stop your current drugs or other therapy when you start a supplement.
• Two to three weeks before surgery, stop taking all supplements. If you must have surgery with little warning, take your supplements to the hospital and show the anesthesiologist what you are taking.
• Never give supplements to children.
• Read the supplement label and follow the dosage instructions.
• Take supplements only for the length of time recommended; don't take them indefinitely.
• If a supplement causes side effects, stop taking it.
• Monitor your blood sugar levels often if you take a supplement. Hundreds of plants can lower blood sugar levels in lab animals. Some may do so in people as well, making low blood sugar reactions more likely.

Dangerous herbs and supplements you should never take

• Chaparral
• Coltsfoot
• Comfrey
• Ephedrine (ephedra or ma huang)
• Germander
• Jin bu huan
• Lobelia
• Phenylalanine
• Sassafras
• L-Tryptophan
• Yohimbe

Shauna S. Roberts, PhD, is a science and medical writer in New Orleans, La.

Source:  Diabetes News: Diabetes Forecast.

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