Natural health products include vitamins and minerals, herbal products, homeopathic remedies, traditional medicines (like Chinese medicine), probiotics, and other products like amino acids and essential fatty acids. Many of us already know problems can come from combining different medications. While the terms natural, alternative and complementary may make these products seem harmless, natural does not always mean safe.
Like conventional medication, natural health products have side effects and interact with other substances. During the Middle Ages, herbal plant goat’s rue (also known as French lilac or Galega officinalis) was used to lower blood glucose. It is not safe to use, as it has very toxic side effects like liver and kidney damage, and a high risk of lactic acidosis. Instead, this plant remedy led to the development of a much safer drug called metformin – the most commonly prescribed oral medication for diabetes.
Many other medications have been developed from plant material. Digitalis is extracted from foxglove to treat the heart. Quinine for malaria comes from cinchona tree bark. Taxol, an anti-tumour drug, comes from the bark of the western yew tree. All have potential side effects.
Keep in mind that illegal drugs can also be harvested from plants. Opium comes from poppies, and cocaine from the leaves of the cocoa plant. Certainly these natural substances are capable of doing harm. Calling a product ‘natural’ does not mean it will not react with other medications, or that it is free of harmful side effects.
Assessing the full effect of a natural medication made from a plant is challenging. The strength varies depending on growing conditions. The final product is affected by the amount of rain and sun, where a plant is grown, when it is harvested, the part of the plant used, the length of storage, and the type of processing. The term standardized on the label refers to the strength of a specific ingredient. However, that ingredient may not be the one which provides a benefit. The benefit may come from multiple ingredients.
In Canada, natural health products are governed by the Natural Health Products Regulations, under the Natural and Non-prescription Health Products Directorate. These regulations ensure that proper manufacturing processes are used to make all licensed products, so quality material reaches the shelves. A licensed product will have either a NPN (natural product number) or a DIN-HM (drug identification number for homeopathic medicine) number on the label. Labels of licensed products provide information on dosage, length of use, ingredients, the part of the plant used, risks, and cautions. Previously regulations allowed health claims on labels. Even when no scientific evidence was available, the health claim could be based on traditional references (folklore). In December 2012, a New Approach to Natural Health Products application review was published. It includes standards for health claims.
These catch phrases are a hint that you shouldn’t believe the product claims:
Before trying any natural product, research it thoroughly. Consider the evidence you find. Did just one or two studies show an effect? What influences on blood glucose were not controlled in the study? How many people participated in the study, for how long, and at what dose? What were the side effects? Studies on natural medicines are often poorly designed and based on only a few patients. They are often done for too little time to offer clear evidence of long-term effectiveness. Think about where the information comes from. Is it a reputable source or is it only from the provider of the product?
Be critical of headlines. Sound health advice is generally based on research over time, not a single study promoted in the media. Question quick fix results that are not based on scientific research and established dietary guidelines. Learn to spot unlikely claims. Remember, if something sounds too good to be true, it probably is. Finally, consider that natural products are often expensive.
If you want to try a natural medicine, talk to your diabetes health care team. Be sure that the product will not interfere with your prescription diabetes medication before you start taking it. Use it along with, not instead of, prescription medication.
When you begin using it, check your blood glucose frequently to see how the product affects you. Look for single-ingredient products, rather than combinations. With a combination product, you cannot know which ingredient is helping or harming you.
You can find a chapter on natural health products in the Diabetes Canada 2013 guidelines. It includes a review of randomized controlled trials that lasted at least 12 weeks and reported changes in glycated hemoglobin (A1C). Eleven natural health products were reported to lower A1C by 0.5 per cent or more. These included: Coccinia cordifolia, Ganoderma lucidum, Salacia reticulata, soybean-derived pinitol extract, touchi soybean extract, Pterocarpus marsupium, Gynostemma pentaphyllum, marine collagen peptides, silymarin, Citrullus colocynthis, and Trigonella foenum-graecum (fenugreek). These were mostly single, small trials. There is not yet enough evidence to recommend regular use of these products. Other products that met the requirements for review failed to lower A1C by 0.5 per cent or more, or had conflicting effects on A1C.
Certain products are rumoured to make a difference in diabetes care. They include berberine, bilberry, bitter melon, chromium, cinnamon, Coccinia indica, fenugreek, glucomannan, Gymnema sylvestre, nopal, and vanadium. Reviewing the existing research can help in deciding whether or not to try one of these products.
Berberine (Coptis chinensis) – In a systemic review and meta-analysis, this product was found to lower A1C by 0.5 per cent or more. It was also effective when combined with glucose-lowering agents. Study participants took 500 milligrams of this product, two or three times daily. Side effects included abdominal upset and constipation. Use of this product comes with some warnings. Women who are pregnant or breast-feeding should not use berberine, nor should it be given to babies. Do not take it with cyclosporines, statins or calcium channel blockers.
Bilberry (Vaccinium myrtillus) – This dried fruit extract has been used to treat diabetes and diarrhea, and to aid vision and night vision. However, only one study in diabetic rats actually showed reduced blood glucose. Any effect that it might have in humans would probably be due to the high chromium content in the leaf (see Chromium). Side effects of taking bilberry include mild digestive distress, skin rashes and drowsiness. Bilberry may increase the blood-thinning effects of medications and natural health products. In theory, bilberry could add to the hypoglycemic effect of some diabetes medications.
Bitter melon (Momordica charantia, bitter gourd, bitter cucumber, karela, balsam pear) – In studies, bitter melon failed to show any substantial effect on blood glucose. One side effect of ingesting bitter melon is gastrointestinal discomfort. Pregnant or breast-feeding women, children, or anyone with allergies to the melon family should not use it. Those of Mediterranean or Middle Eastern descent who have a known glucose-6-phosphate dehydrogenase deficiency should also avoid it. In theory, bitter melon could cause low blood glucose when combined with certain diabetes medications.
Chromium – This essential mineral plays a role in glucose metabolism. For insulin to be effective, chromium is also needed. In some severe cases of chromium deficiency, the associated diabetes was reversed once the person received an adequate amount of chromium. These case studies led to the marketing of chromium for diabetes, but most people have adequate chromium levels. Whole grains, egg yolks, broccoli and brewer’s yeast are natural sources with high quantities of chromium.
Cinnamon – This spice was reviewed in a small study of 60 patients for 60 days. Although the study made national headlines, further studies failed to show any effect on A1C. Side effects include allergic skin reactions, and possible bleeding and liver toxicity due to the coumarin in the cinnamon. Do not combine cinnamon with any natural health products or medications with anticoagulant properties. In theory, it could cause hypoglycemia if combined with certain diabetes medications.
Coccinia indica (Coccinia cordifolia, ivy gourd) – This herb is listed in the Diabetes Canada guidelines as a product that can potentially lower A1C by 0.5 per cent or more. No significant side effects or drug interactions have been noted.
Fenugreek (Trigonella foenum-graecum) – This is also listed in the Diabetes Canada guidelines as a product with the potential to lower A1C by 0.5 per cent or more. Side effects are mostly uncomfortable gastrointestinal effects that may resolve in a few days. Fenugreek can cause contractions of the uterus, so pregnant women should not take it. It may appear in breast milk, causing infants to have side effects. People with allergies to peanuts, chickpeas, soybeans or green peas should avoid fenugreek. Drug interactions can occur with antiplatelet and anti-inflammatory medications, or herbs that have blood-thinning effects.
Glucomannan (konjac) and nopal (Opuntia streptacantha, prickly pear cactus) – These products are promoted for diabetes due to their high fibre content, which slows digestion and improves the body’s sensitivity to insulin. They often have a laxative effect. If that goes on too long, the body’s electrolyte balance can be disturbed.
Gymnema sylvestre – GS4, a proprietary extract from the leaf, has been studied in just two non-randomized trials in both type 1 and type 2 diabetes patients. The two studies, which reported improvements in fasting blood glucose and A1C, were poorly designed. The results cannot be used as evidence for the treatment of diabetes. No adverse effects have been reported. In theory, this extract could cause hypoglycemia if combined with certain diabetes medications.
Vanadium – This trace mineral is not recommended, as it accumulates in bones, kidneys, lungs, and the liver. As well, the doses sometimes suggested are well above the 1.8 mg/day recommended as a maximum intake. Vanadium causes abdominal discomfort, gas, nausea, diarrhea, and greenish discoloration of the tongue. Prolonged high doses may damage the kidneys.
After careful research and consultation with your diabetes team, you may decide to try a natural medicine. If so, use your blood glucose monitor as a tool to evaluate the effectiveness of the product. Monitor more frequently, write down your results, and note any side effects. Discuss the results with your diabetes health care team. Together, you can decide whether a natural health product will help you to stay in the best possible health.