Guide to Herbal Supplements
Learn the Truth About these Top Sellers
-- By Becky Hand, Licensed & Registered Dietitian
An estimated 18 million adults use herbs in some form, and the sale of these products continues to increase.
Herbal supplements, which come from plants that have medicinal properties, claim to cure, treat, or prevent disease. But when an herbal supplement is billed as “natural” on the label, that doesn’t ensure its efficacy, purity, or safety. Although there are proven health benefits for some herbal products, potentially harmful effects exist for others.
Claims about herbal products are often based on folklore or testimonial instead of scientific studies. It is important to read reliable information and search out unbiased sources of research, when available. Because herbal supplements are not standardized, the same herb can be found in different products in varying amounts. This can lead to toxic levels that may cause harmful reactions in the body. Do not assume that "natural" means safe.
To reduce health risks when choosing and using herbal supplements:
- Always tell your doctor if you are taking herbs. Herbs can interact with other medications causing serious side effects.
- Do not self-treat serious medical conditions with medicinal herbs.
- Do not take herbal supplements if you are pregnant or breastfeeding. There is no way to determine what level of herbs may harm a fetus or nursing infant.
- Do not give herbal products to children under 3 years of age. Always check with your child’s pediatrician first.
- Only purchase herbal supplements that display an expiration (or use-by) date, as well as a lot or batch number.
- The herbal supplement should state which part of the plant was used to make the product, such as root, leaf, or blossom.
- If a blend of ingredients is used in the herbal supplement, the label should list the individual ingredients as well as the amount of each.
- Although not required, the supplement should indicate the type of solvent used when processing the herb.
Check for certification symbols, such as:
- A United States Pharmacopeia (USP) symbol verifies that the product contains the stated ingredients in amounts and strength, is pure, meets limits for contaminants, and disintegrates quickly.
- NSF International verifies products for content and label accuracy, purity, contaminants, and manufacturing processes.
- ConsumerLab.com independently tests supplements for purity and active ingredients. A supplement company can pay to have its product evaluated, use the seal of approval, and be listed on the website.
Be a smart shopper! Use the following resources to research beyond the product information provided in stores:
- National Library of Medicine
- National Center for Complementary and Alternative Medicine
- The Health Professional’s Guide to Popular Dietary Supplements, Allison Sarubin Fragakis, MS, RD, American Dietetic Association, 2003
- The ABC Clinical Guide to Herbs, Blumenthal M, Brinckmann J, Wollschlaegar B, American Botanical Council, 2002
Commonly Used Herbal Supplements
Black Cohosh is a member of the buttercup family. Some evidence indicates that as an alternative to hormone replacement therapy, it may help manage menopausal symptoms like hot flashes, irritability, and anxiety. It is also used to relieve premenstrual cramping and pain, but more research is needed. However, no drug interactions have been reported. Women who are pregnant (it can stimulate uterine contractions), lactating, or at high risk for breast cancer (it may make breast cancer more likely to spread) should not use Black Cohosh.
Research on chamomile tea supports claims that it reduces muscle spasms in the gastro-intestinal tract, indigestion, and menstrual cramps. Individuals who are allergic to ragweed or pollen may have an allergic reaction to chamomile.
Drinking cranberry juice (about 10 ounces daily) may reduce the incidence of urinary tract infections. However, more research is needed to determine the efficacy of cranberry extract supplements. There is no evidence that cranberry juice or pills can treat an existing urinary tract infection, so consult your health care provider for treatment.
Echinacea is also known as the purple coneflower. Studies suggest Echinacea enhances the immune system and may reduce upper respiratory infections, but it should be taken intermittently (not permanently) and only when ill. Individuals with autoimmune disorders should avoid Echinacea (it may offset the effects of drugs that suppress the immune system), and those with asthma or sensitivity to grass or pollen may experience allergic reaction.
Feverfew is effective in treating migraine headaches, possibly by inhibiting inflammatory mediators. It is most effective when taken daily as a preventive measure. Choose tablets, which only contain a small amount of the active ingredients. Chewing the leaves can cause mouth sores as well as allergic reactions. Feverfew reacts adversely with anticoagulant and anti-platelet medications.
Garlic supplements (2-5 grams daily) have been shown to reduce cholesterol and blood pressure, as well as fight infection and reduce platelet aggregation. Garlic may cause gastrointestinal discomfort in some and increased bleeding. Therefore, avoid garlic seven days prior to surgery; if you take blood-thinning drugs, talk to your physician first.
Studies support the use of ginger (250 mg, 2-4 times per day) to alleviate motion sickness. No toxic effects have been reported, but ginger may interact with anticoagulant drugs. Pregnant and nursing women should consult their physicians.
Ginkgo Biloba improves blood flow in areas of decreased circulation and may help with memory loss that is due to decreased blood flow. Several studies suggest that ginkgo may slow the progression of dementia, particularly in Alzheimer’s disease. However, not all studies report improvement—it does not improve memory and concentration in healthy individuals. It may also be used for diabetic neuropathy and peripheral vascular diseases. Since ginkgo acts as a blood thinner, taking it with other blood-thinning agents could increase one’s risk for excessive bleeding and even stroke.
Ginseng is the most frequently purchased herb in the United States. There are three different species of ginseng: American, Asian, and Siberian. Each has 20 or more active compounds in varying amounts. Marketing claims boast improved exercise performance, energy, and cognitive function, mood elevation, diabetes control, increased immunity, heart health, and cancer prevention. However, there is not much reliable research or evidence to support any of these claims. Ginseng may also decrease the efficacy of warfarin (coumadin) medication by reversing the drug’s effects.
Kava Kava lacks controlled studies to back claims of inducing a deep, restful sleep and relieving insomnia and nervousness. More data is needed about safe usage (since it may cause liver toxicity) but it shouldn’t be used for more than three months. Kava Kava may affect motor reflexes (so use caution when driving or operating machinery), compound the effects of substances that depress the central nervous system, and bring on tremors, muscle spasm, and decrease the effectiveness of Parkinson’s medication.
St John’s Wart (SJW) may improve symptoms of mild to moderate depression, according to clinical trials conducted in Europe. But its effects on patients with major depression are contradictory and much more research is needed. There is no evidence that SJW elevates mood or improves emotional well-being in individuals without clinical depression. Combining herbal and prescription antidepressants could lead to adverse side effects. Consult your physician for usage.
Valerian may improve sleep quality without morning drowsiness, but more studies are needed to see if it reduces anxiety and stress. Valerian is not for extended use. It may add to the effects of sedatives, alcohol, and sleeping pills and cause dangerous interactions.